N:1 stateful application gateway redundancy model

A stateful application gateway redundancy system and method. Configuration information defines a service processing unit on a service gateway and associates a first redundancy set and a second redundancy set with the service processing unit, wherein the first and the second redundancy sets include a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set. In response to detecting a critical event for the first redundancy set, the service gateway transitions the first redundancy set from the standby redundancy state to the master redundancy state, adds a first signal-route associated with the first redundancy set to a Routing Information Base (RIB) and advertises the first signal-route to routing protocol peer network devices.

TECHNICAL FIELD

The techniques of this disclosure relate to computer networks and, more specifically, to providing high availability within computer networks.

BACKGROUND

A computer network is a collection of interconnected computing devices that can exchange data and share resources. In a packet-based network, the computing devices communicate data by dividing the data into small blocks called packets, which are individually routed across the network from a source device to a destination device. The destination device extracts the data from the packets and assembles the data into its original form. Dividing the data into packets enables the source device to resend only those individual packets that may be lost during transmission.

Certain devices, referred to as routers, maintain routing information that describes routes through the network. A “route” can generally be defined as a path between two locations on the network. Routers include a control plane, sometimes called a management plane, which maintains the routing information, and a forwarding plane, which forwards received packets according to the routing information.

The goal of high availability computer network environments is to provide users and other entities with “always on” service. That is, high availability computer network environments should provide reliable, continuous operation service. To accomplish this, network devices in a high availability environment perform error detection and implement recoverability for detected errors. Unfortunately, network devices occasionally fail.

When a network device fails, all network traffic flowing through the failed network device may cease. For an enterprise that depends on such network traffic, this may be unacceptable, even if this failure occurs only for a short time. To minimize the possibility of a failure causing all network traffic to cease, redundant hardware such as a standby controller or a separate standby network device may be installed. When the primary controller fails, this primary controller (which may also be referred to as a “master controller”) may switch over (or, in other words, fail-over) to the standby controller. Likewise, when the primary network device fails, this primary network device (which may also be referred to as a “master network device”) may switch over (or, in other words, fail-over) to the standby network device. After failing over or switching over to the standby device, the standby device becomes the master device.

Redundancy in devices or controllers that extends across two or more chassis provides enhanced reliability. Current inter-chassis redundancy solutions, however, are geared toward providing redundancy across two homogeneous chassis within the same network. A typical network, however, is not a collection of homogeneous chassis.

SUMMARY

In general, a framework is described for application aware inter-chassis redundancy with granular control to failover groups of applications between sets of two or more network elements. The framework provided by the techniques may be used to define user interface constructions that leverage routing protocols for facilitating redundancy-related actions, such as redirecting traffic between service gateways. The network elements can be homogeneous or heterogeneous (physical or virtual) and can spread across different networks or across geographies. The redundancy mechanism provides traffic redirection agnostic of underlying network protocols and provides options for triggering, preventing and resuming both manual and automated switchovers of groups of services based on their health status.

For example, a method is described that includes receiving, at a service gateway having a services redundancy manager and a plurality of service processing cores, service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set; establishing the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information; receiving, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set; placing the first and second redundancy sets in the standby redundancy state; defining a first signal-route, the first signal-route used to trigger actions related to the first redundancy set; monitoring for the critical event; and in response to detecting the critical event, transitioning the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, adding the first signal-route to a Routing Information Base (RIB), and advertising the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In another example, a system is described that includes a network, N redundancy sets, wherein N is greater than one, wherein each redundancy set of the N redundancy sets has a master redundancy state, a standby redundancy state and one or more redundancy policies, wherein the one or more redundancy policies include at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set and a plurality of service gateways connected to the network, wherein each service gateway includes a services redundancy manager and a plurality of service processing cores, wherein the services redundancy manager tracks redundancy state for redundancy sets assigned to the service gateway of the services redundancy manager. One of the plurality of service gateways is a standby service gateway, wherein the standby service gateway assigns one or more service processing cores to a first service processing unit and assigns the N redundancy sets to the first service processing unit. One or more of the plurality of service gateways host second service processing units, wherein hosting includes assigning one or more service processing cores to each second service processing unit and assigning one of the N redundancy sets to each second service processing unit, wherein each of the N redundancy sets is assigned to a different second service processing unit. When the services redundancy manager of the standby service gateway detects a redundancy event associated with a particular one of the N redundancy sets, the services redundancy manager of the standby service gateway transitions the particular redundancy set from the standby redundancy state to the master redundancy state on the standby service gateway and, when the services redundancy manager of the service gateway having the second service processing unit that is associated with the particular redundancy set detects the redundancy event, the services redundancy manager transitions the particular redundancy set in the service gateway from the master redundancy state to the standby redundancy state.

In another example, a service gateway includes a network interface, a service plane having a plurality of service processing cores connected to the network interface; and a routing plane connected to the network interface, the routing plane including memory and one or more processors connected to the memory, wherein the memory includes instructions that, when executed by the one or more processors, cause the processors to establish a services redundancy daemon, receive service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set, establish the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information, receive, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set, place the first and second redundancy sets in the standby redundancy state, define a first signal-route, the first signal-route used to trigger actions related to the first redundancy set, monitor for the critical event and, in response to detecting the critical event, transition the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, add the first signal-route to a Routing Information Base (RIB) and advertise the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In yet another example, a computer readable medium is described that includes instructions that, when executed by one or more processors, cause the one or more processors to establish a services redundancy daemon, receive service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set, establish the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information, receive, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set, place the first and second redundancy sets in the standby redundancy state, define a first signal-route, the first signal-route used to trigger actions related to the first redundancy set, monitor for the critical event and, in response to detecting the critical event, transition the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, add the first signal-route to a Routing Information Base (RIB) and advertise the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

The details of one or more embodiments of the techniques are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques will be apparent from the description and drawings, and from the claims.

DETAILED DESCRIPTION

It can be advantageous to extend redundancy in devices or controllers across two or more chassis. Inter-chassis redundancy solutions enhance reliability but are difficult to implement when the chassis, devices or controllers are not homogenous.

Techniques are described for application aware inter-chassis redundancy with granular control to failover groups of applications between sets of two or more network elements. The techniques may be used to define user interface constructions that leverage routing protocols for facilitating redundancy-related actions, such as redirecting traffic between service gateways. The network elements controlled may be homogeneous or heterogeneous (physical or virtual) and can spread across different networks and across geographies. The redundancy mechanism provides traffic redirection agnostic of underlying network protocols and provides options for triggering, preventing and resuming both manual and automated switchovers of groups of services based on their health status.

In one example approach, a protocol and network agnostic mechanism is used to set up N Stateful Application Service Gateways operating in a Master state backed up by a single common Stateful Application Service Gateway operating in a Standby State. The technique provides a flexible and robust mechanism to achieve N:1 Stateful Application Gateway Redundancy. A communication mechanism is termed network or protocol agnostic if the signaling mechanism used by the communicating protocols is independent of the communicating protocols' specifications.

FIG. 1is a block diagram illustrating an example redundant service gateway system4operating in accordance with techniques described herein. In the example approach shown inFIG. 1, redundant service gateway system4includes service gateways (here, gateways8A.1through8A.N and8B, collectively, “gateways8”) distributed across two or more chassis but logically associated as a redundant service delivery system27. In one example approach, redundant service gateway system4ofFIG. 1includes a subscriber access network6connected to a service provider core network7and, through service provider core network7, to public network12. In one example approach, service provider core network7operates as a private network to provide packet-based network services to subscriber devices16A-16N (collectively, “subscriber devices16”) across subscriber access network6. In one such example approach, service provider core network7provides authentication and establishment of network access for subscriber devices16such that the subscriber device may begin exchanging data packets with public network12, which may be an internal or external packet-based network such as the Internet.

In the example ofFIG. 1, subscriber access network6provides connectivity to public network12via service provider core network7and gateways8. In one example approach, service provider core network7and public network12provide packet-based services that are available for request and use by subscriber devices16. As examples, core network7and/or public network12may provide, for example, bulk data delivery, voice over Internet protocol (VoIP), Internet Protocol television (IPTV), Short Messaging Service (SMS), Wireless Application Protocol (WAP) service, or customer-specific application services. Public network12may include, for instance, a local area network (LAN), a wide area network (WAN), the Internet, a virtual LAN (VLAN), an enterprise LAN, a layer 3 virtual private network (VPN), an Internet Protocol (IP) intranet operated by the service provider that operates subscriber access network6, an enterprise IP network, or some combination thereof. In various example approaches, public network12is connected to a public WAN, the Internet, or to other networks. In some such examples, public network12executes one or more packet data protocols (PDPs), such as IP (IPv4 and/or IPv6), X.25 or Point-to-Point Protocol (PPP), to enable packet-based transport of public network12services.

In the example shown inFIG. 1, redundant service delivery system is configured as an N:1 Stateful Application Gateway Redundancy model. In one example approach, each of the service gateways8A include one or more service processing units (SPUs)30and provide a set of services10through their associated SPUs30. In some example approaches, gateways8provide these services10via one or more SPUs30operating in a service plane within each of gateways8. In the example shown inFIG. 1, service gateways8A.1through8A.N are each in a master state providing their respective services10.1-10.N (“services10”) as configured while service gateway8B is in a standby state supporting each of the master service gateways8A.1-8A.N. In one example approach, standby service gateway8B automatically takes over the mastership of one or more of the gateways8A when the gateway8A suffers a critical error, ensuring uninterrupted application service for each of the ailing gateways8A. A potential advantage of such an approach is that it increases the utilization factor (μ) of Standby Service Gateway8B.

In one example approach, each service processing unit30receives network traffic received on an inbiound interface. In one such example approach, each SPU30acts as a standby node for two or more master gateways8A. From a SPU point of view, such a model helps achieve an active:active model. Although described for purposes of example with service gateway8B being a standby, in some examples any of the service gateways8may operate as a master for one or more services and a standby for one or more other services, e.g., with different roles on a per service basis or on a per SPU basis.

Subscriber devices16connect to service processing interfaces of gateways8via subscriber access network6to receive connectivity to subscriber services for applications hosted by subscriber devices16. A subscriber may represent, for instance, an enterprise, a residential subscriber, or a mobile subscriber. Subscriber devices16may include, for example, personal computers, laptop computers or other types of computing device associated with subscribers. In addition, subscriber devices16may include mobile devices that access the data services of redundant service gateway system2via radio access network (RAN)9. Example mobile subscriber devices include mobile telephones, laptop or desktop computers having, e.g., a 3G wireless card, wireless-capable netbooks, video game devices, pagers, smart phones, personal data assistants (PDAs) or the like. Each subscriber device16may run a variety of software applications, such as word processing and other office support software, web browsing software, software to support voice calls, video games, videoconferencing, and email, among others. In some example approaches, subscriber devices16connect to subscriber access network6via access links5that comprise wired and/or wireless communication links. The term “communication link,” as used herein, comprises any form of transport medium, wired or wireless, and can include intermediate nodes such as network devices. Each of access links5may comprise, for instance, aspects of an asymmetric DSL network, WiMAX, a T-1 line, an Integrated Service Digital Network (ISDN), wired Ethernet, or a cellular radio link.

In some example approaches, a network service provider operates, or in some cases leases, elements of subscriber access network6to provide packet transport between subscriber devices16and gateways8. Subscriber access network6represents a network that aggregates data traffic from one or more subscriber devices16for transport to/from service provider core network7of the service provider. In some example approaches, subscriber access network6includes network nodes that execute communication protocols to transport control and user data to facilitate communication between subscriber devices16and gateways8. Subscriber access network6may include a broadband access network, network, a wireless LAN, a public switched telephone network (PSTN), or other type of access network, and may include or otherwise provide connectivity for cellular access networks, such as radio access network (RAN)9ofFIG. 1. Examples of radio access network9include networks conforming to a Universal Mobile Telecommunications System (UMTS) architecture, an evolution of UMTS referred to as Long Term Evolution (LTE), mobile IP standardized by the Internet Engineering Task Force (IETF), as well as other standards proposed by the 3rdGeneration Partnership Project (3GPP), 3rdGeneration Partnership Project 2 (3GGP/2) and the Worldwide Interoperability for Microwave Access (WiMAX) forum.

Service provider core network7(hereinafter, “core network7”) offers packet-based connectivity to subscriber devices16attached to subscriber access network6for accessing public network12. Core network7may represent a public network that is owned and operated by a service provider to interconnect a plurality of networks, which may include subscriber access network6. Core network7may implement Multi-Protocol Label Switching (MPLS) forwarding and in such instances may be referred to as an MPLS network or MPLS backbone. In some instances, core network7represents a plurality of interconnected autonomous systems, such as the Internet, that offers services from one or more service providers. Public network12may represent an edge network coupled to core network7, e.g., by a customer edge device such as customer edge switch or router. Public network12may include a data center.

In examples of service gateway system4that include a wireline/broadband access network such as subscriber access network6, each of gateways8may represent a Broadband Network Gateway (BNG), a Broadband Remote Access Server (BRAS), MPLS Provider Edge (PE) router, core router or gateway, or a Cable Modem Termination System (CMTS), for instance. In examples of service gateway system4that include a cellular access network such as subscriber access network6, each of gateways8may represent a mobile gateway, for example, a Gateway General Packet Radio Service (GPRS) Serving Node (GGSN), an Access Gateway (aGW), or a Packet Data Network (PDN) Gateway (PGW). In other examples, the functionality described with respect to each gateway8may be implemented in a switch, service card or other network element or component.

A network service provider administers at least parts of service gateway system4, typically offering services to subscribers associated with devices, e.g., subscriber devices16, that access service gateway system4. Services offered may include, for example, traditional Internet access, Voice-over-Internet Protocol (VoIP), video and multimedia services, and security services. As described above with respect to subscriber access network6, service provider core network7may support multiple types of subscriber access network6infrastructures that connect to service provider network access gateways to provide access to the offered services. In some instances, a service gateway system4may include subscriber devices16that attach to multiple different access networks6having varying architectures.

In general, applications executing on one or more of subscriber devices16may request authorization and data services by sending a session request to one or more of service gateways8. In turn, service gateways8typically access an Authentication, Authorization and Accounting (AAA) server11to authenticate the subscriber device requesting network access. In some examples, service gateways8query policy control server14and/or AAA server11to determine subscriber-specific service requirements for packet flows from subscriber devices16.

Once authenticated, any of subscriber devices16may send subscriber data traffic toward service provider core network7in order to access and receive services provided by public network12. Such packets traverse service gateways8as part of at least one packet flow. The term “packet flow,” “traffic flow,” or simply “flow” refers to a set of packets originating from a particular source device and sent to a particular destination device. A single flow of packets, in either the upstream (sourced by one of subscriber devices16) or downstream (destined for one of subscriber devices16) direction, may be identified by, for example, the 5-tuple: <source network address, destination network address, source port, destination port, protocol>. This 5-tuple generally identifies a packet flow to which a received packet corresponds. An n-tuple refers to any n items drawn from the 5-tuple. For example, a 2-tuple for a packet may refer to the combination of <source network address, destination network address> or <source network address, source port> for the packet. Moreover, a subscriber device may originate multiple packet flows upon authenticating to service provider core network7and establishing a communication session for receiving data services. Path26illustrates routing of data from subscriber devices to public network12and back as defined by one or more gateways8.

As described herein, service processing units30operating within service gateways8provide services10to some or all of the network traffic. As examples, services10in one or more SPUs30may apply firewall and security services, network address translation (NAT) or carrier grade network address translation (CG-NAT), media optimization (voice/video), IPSec/VPN services, deep packet inspection (DPI), session border controller (SBC), virtual appliance, virtual cache, network traffic acceleration, Quality of Service (QoS), access control, hyper-text transfer protocol (HTTP) filtering, counting, accounting, charging, and load balancing of packet flows or other types of services applied to network traffic. In some examples, services provided by SPUs30may be composite services composed of two or more services and may form a single externally visible service to subscribers16. As one example, services10may be a composite service consisting of NAT services and firewall services.

In some examples, SPUs30may run as virtual machines in a virtual compute environment provided by service gateways8or within other execution environments. For example, although described herein as provided by compute blades within service gateways8, the compute environment for SPUs30may instead, or in addition, be provided by a scalable cluster of general computing devices, such as x86 processor-based servers. As another example, SPUs30may reside on a combination of general purpose computing devices and special purpose appliances. SPUs30may also host virtualized, individual network services that scale as in a modern data center, through the allocation of virtualized memory, processor utilization, storage and network policies, as well as by adding additional load-balanced virtual machines.

In one example approach, SPUs30steer individual subscriber packet flows through defined sets of services provided by services10. That is, each subscriber packet flow may be forwarded through a particular ordered combination of services provided by services10within particular SPUs30, each ordered set being referred to herein as a “service chain.” Moreover, a given service chain may include network services provided “on box” within service deliver gateways8or “off box” by a separate computing environment accessed by the gateways8, or by combinations thereof. In this way, subscriber flows may be processed by SPUs30as the packets flow between subscriber access network6and public network12according to service chains configured by the service provider. Some techniques for accomplishing this are described in U.S. patent application Ser. No. 14/042,685, entitled “Session-Aware Service Chaining Within Computer Networks,” filed Sep. 30, 2013, the descriptions of which are incorporated herein by reference.

Once processed at a terminal node of the service chain, i.e., the last service applied to packets flowing along a particular service path, SPU30may direct the traffic back to the forwarding plane of gateway8for further processing and/or for forwarding to public network12.

Whereas a “service chain” defines one or more services to be applied in a particular order to provide a composite service for application to packet flows bound to the service chain, a “service tunnel” or “service path” refers to a logical and/or physical path taken by packet flows processed by a service chain along with the forwarding state for forwarding packet flows according to the service chain ordering. Each service chain may be associated with a respective service tunnel, and packet flows associated with each subscriber device16flow along service tunnels in accordance with a service profile associated with the respective subscriber. Gateways8, after authenticating and establishing access sessions for the subscribers, may determine that a profile of each subscriber device16requires the traffic to be sent on a service tunnel to one or more service nodes13for application of services, and directs packet flows for the subscribers along the appropriate service tunnels within each gateway8, thereby causing services10(e.g., service nodes13that provide the services) to apply the requisite ordered services for the given subscriber.

Services10may, for instance, represent one or more service nodes that implement service chains using internally configured forwarding state that directs packets of the packet flow along the service chains for processing according to the identified set of services10. Such forwarding state may specify tunnel interfaces for tunneling between services10using network tunnels such as Internet Protocol (IP) or Generic Route Encapsulation (GRE) tunnels, or by using Virtual Local Area Networks (VLANs), Multiprotocol Label Switching (MPLS) techniques, and so forth. In some instances, real or virtual switches, routers or other network elements that interconnect services10may be configured to direct packet flow to services10according to the service chains.

As noted above, redundancy in devices or controllers that extend across two or more chassis provides enhanced reliability. Current inter-chassis redundancy solutions, however, are geared toward providing redundancy across two homogeneous chassis within the same network. A typical network, however, is not a collection of homogeneous chassis. To compensate, as described herein, service gateways8may provide user interfaces programmed to support semantics and commands that allow a user to more efficiently define and administer active-active or active-standby redundancy with respect to services10applied to packet flows within service gateway system4. In one example approach, the user interface allows an administrator or network management system to easily specify configuration data defining redundancy mechanisms for administering a cluster of redundant service gateways. The techniques described herein decouple application-layer redundancy mechanisms from underlying communication mechanisms between the devices, thereby allowing protocols, such as routing protocols and inter-chassis communication protocols, to easily be leveraged by the abstracted redundancy mechanisms. The techniques of this disclosure can also allow an administrator to easily configure redundancy arrangements on gateways8on a per-service and/or per composite service level of granularity.

Moreover, the techniques of this disclosure provide a management interface expressivity, i.e., a syntax, that leverages an abstraction that can be used across different types of gateways to hide the underlying hardware. This management interface expressivity may be more useful for system administrators and may also drive the behavior of service provider core network7and service gateways8more efficiently.

In this way, in one example, the framework provided by the techniques may easily be used to define user interface constructions that leverage routing protocols for facilitating redundancy-related actions, such as causing network devices of service provider core network7to redirect traffic from one or more of the service gateways8operating as an application service Masters to the single Service Gateway8operating as the common Standby to the Masters.

In one example approach, application layer services are configured by adding or removing “signal-routes” used to trigger actions related to the redundancy mechanisms, such transitioning a gateway Master to Standby. In one example approach, a signal-route is a route used by applications using the services redundancy process described below to signal changes in application mastership state and to drive routing-policy changes at the same time. In one such example approach, “signal-routes” are static routes manipulated by the service gateway to affect the routing-policies in order to switch mastership between redundant service gateways and to redirect traffic to the new master service gateway.

In one example, the techniques described herein provide user interface (UI) building blocks that allow the user to define and specify logical constructs for a redundant service delivery system, such as redundant service delivery system27ofFIG. 1. The UI building blocks include a support for a syntax allowing a user to define critical events that trigger a switch from gateway mastership for a service to a standby state for that service (“Redundancy Events”). In one example approach, a Redundancy Event (RE) is an event that triggers a services redundancy (SR) daemon operating in one of the service gateways8to switch gateway mastership from one of the service gateways8configured as Master to the service gateway8configured as the Standby service gateway. For example, the user may define a redundancy event in terms of a degradation of performance of the service10such that a service node can no longer provide the services paid for by a service level agreement (SLA) associated with one of subscriber devices16.

In one example approach, the UI building blocks include support for a syntax allowing a user to define a policy (“Redundancy Policy (RP)”) that defines how redundancy events are tied to actions to be taken on the occurrence of the events defined by the redundancy events. In some such approaches, a redundancy policy is a policy that details the actions to be taken on the occurrence of one or more of the underlying critical events. In some examples, the actions may specify that a service redundancy process of service gateway8A updates routing information maintained by the service gateway8A, prompting a routing protocol executing on service gateway8A to issue a routing protocol update to routing peers (not shown) within service provider core network7.

In one example approach, the UI building blocks include support for a syntax allowing a user to group one or more redundancy policies into a set, termed a “Redundancy Set (RS),” and a syntax allowing a user to group one or more redundancy sets into a group of sets, termed a “Redundancy Group (RG).” In this manner, service gateways8include respective user interfaces that support a syntax that allows a user to define one or more redundancy events, redundancy policies, redundancy sets, and redundancy groups, as explained in further detail below. The ability to create redundancy sets and redundancy groups can allow for defining multiple redundancy groups across the same set of service gateway chassis, for example.

In accordance with the techniques of this disclosure, a services redundancy process of each of service gateways8monitors performance levels of services10. In the event that the monitor component detects a failure or degeneration of pre-set service levels for any of services10that meets the definition of a redundancy event, the services redundancy process triggers application of a pre-defined redundancy policy. In some aspects, for example, the services redundancy process may interact with services10to collect statistics, perform handshaking, or carry out other checks to the functionality of services10.

The performance level of the services10are independent of an overall operational state of the service gateway network devices8. In other words, upon detecting a configured redundancy event, in some example approaches, the service gateway8may trigger redundancy-related actions for the service10. This may include, for example, changing primary/standby roles associated with a redundancy set or redundancy group from service gateway8A to service gateway8B, for example, even though service gateway8A and/or the existing service node used for application of the affected service10remains operable. The switchover of network traffic requiring the specific services10occurs without disruption to a subscriber16receiving the services10. Stateful application gateway redundancy mechanisms are described in U.S. Pat. No. 9,985,875, issued May 29, 2018 and entitled “ROUTE SIGNALLING BASED RESILLIENT APPLICATION OVERLY NETWORK,” in U.S. patent application Ser. No. 14/871,492, filed Sep. 30, 2015, and entitled “ROUTE SIGNALLING BASED RESILLIENT APPLICATION OVERLY NETWORK,” and in U.S. patent application Ser. No. 15/377,777, filed Dec. 13, 2016, and entitled “APPLICATION AWARE INTER-CHASSIS REDUNDANCY,” the descriptions of which are incorporated herein by reference.

FIGS. 2A and 2Bare block diagrams illustrating an application overlay network28having three service gateways8.1-8.3hosted on three separate chassis3(shown as chassis3.1-3.3), in accordance with techniques described herein. Each service gateway8includes one or more service processing units (SPUs)30(shown as SPUs30.1-30.3) and a routing engine (RE)34(shown as REs34.1-34.3). Each routing engine34may advertise changes to the signal routes associated with its service gateway8. In some cases, this is done when becoming a Master Service Gateway for a redundancy set. In other cases, this is done when becoming a Standby Service Gateway for a redundancy set. An application overlay network28is said to be resilient when, on the occurrence of a critical fault on any of the Master Service Gateways, the Standby Service Gateway automatically takes over the mastership, ensuring uninterrupted application services.

In the example shown inFIGS. 2aand2B, each service processing unit30receives packets from an ingress forwarding component of service gateway8and transmits the packets using a packet forwarding engine (PFE) of the ingress forwarding component to one or more service processing units30. In the example approach ofFIGS. 2A and 2B, service processing unit30.1and service processing unit30.3are part of redundancy set (RS)1while service processing unit30.2and service processing unit30.3are part of RS2. In the example shown, inFIG. 2A, SPUs30.1and30.2are the master SPUs of RS1and RS2, respectively, while SPU30.3serves as the standby SPU for both RS1and RS2. In some example approaches, service processing units30bundle one or more service processing interfaces to include one or more services (e.g., network address translation (NAT)).

As noted above, in the example approach ofFIGS. 2A and 2B, for a given service, service gateways8.1and8.2are Master Service Gateways while service gateway8.3is a common Standby Service Gateway. In one example approach, the Master/Standby state is stored in the SPU30associated with the service. That is, each SPU30tracks the current Master/Standby state of the redundancy sets to which it is assigned, In an N:1 Stateful Application Gateway Redundancy approach, the SPU30serving as standby for the N masters may need to keep track of up to N different redundancy states.

In another example approach, a services redundancy manager operating separate of SPUs30tracks the Master/Standby state for each RS to which an SPU under its control is assigned. In a gateway8that includes one SPU30acting as standby in an N:1 Stateful Application Gateway Redundancy application and one SPU30acting as standby in an M:1 Stateful Inter-Application Service Gateway Redundancy application, the services redundancy manager of gateway8may have to track up to N+M different redundancy states. In one example approach, the services redundancy manager stores state as a vector having a bit for tracking each of the N+M different states. In one example approach, services redundancy manager tracks redundancy state of a redundancy set assigned to the gateway at the gateway level. That means that a relationship set can only exist in one state on each gateway8. In another example approach, services redundancy manager tracks state at the SPU level. That means that a relationship set can be executing as both a master and a standby on each gateway8.

Service processing units30may include one or more service processing cores. In some example approaches, the service processing cores include one or more central processing units (CPUs). In some example approaches, the service processing cores include one or more virtual central processing units (vCPUs). In yet other example approaches, the service processing cores include one or more network processing units (NPUs). In yet other example approaches, the service processing cores include one or more virtual NPUs (vNPUs). In yet other example approaches, the service processing cores include two or more cores from a selection of service processing cores including cores, CPUs, vCPUs, NPUs and vNPUs. In one example approach, each service processing unit30may include service processing cores selected from, for example, CPUs, vCPUs, NPUs and vNPUs.

In the example approach ofFIGS. 2A and 2B, application overlay network28is configured as an N:1 Stateful Inter-Application Service Gateway, where N=2. That is, the two master nodes (service gateways8.1and8.2) are supported by a single backup node (service gateway8.3). Each Master Service Gateway8is associated with a Redundancy Set. Each Redundancy Set (RS) includes a service gateway designated as master and a service gateway designated as standby. In the example shown inFIGS. 2A and 2B, Redundancy Set1(RS1) includes service gateway8.1as Master and service gateway8.3as Standby while Redundancy Set2(RS2) includes service gateway8.2as Master and service gateway8.3as Standby.

In this example, RS1and RS2each maintain their own Master-Standby state. Service Gateway1hosts RS1and Service Gateway2hosts RS2, but Service Gateway3hosts both RS1and RS2. By containing the state in each Redundancy Set and hosting both Redundancy Sets on single SPU(0), Service Gateway3is able to act as the Standby Service Gateway for both Service Gateway1and Service Gateway2.

In the example shown inFIG. 2B, SPU30.2on service gateway8.2suffers a failure and switches RS2mastership to the standby SPU for that Redundancy Set, SPU30.3of service gateway8.3. As can be seen inFIG. 2B, SPU30.3of service gateway8.3becomes the master service gateway for RS2but remains the standby service gateway for RS1.

In one example approach, each SPU30is configured to support two or more Redundancy Sets, each of which may be in a different state. Finally, each Routing Engine (RE)34is configured to support multiple Redundancy Sets, each of which may be in a different state. One potential advantage of such a system is to increase the utilization factor (μ) of the Standby Service Gateway. From a SPU point view, this model helps achieve an active:active model. Application Overlay Network28demonstrates, therefore, a protocol and network agnostic mechanism used to set up N Stateful Application Service Gateways operating in a Master state backed up by a single Stateful Application Service Gateway operating in a Standby State. The technique provides a flexible and robust mechanism to achieve N:1 Stateful Application Gateway Redundancy.

In one example approach, service gateways8.1,8.2and8.3form a redundant service delivery system27controlled by one or more service redundancy (SR) daemons24. In one such approach, user interface (UI) building blocks are used to define events (Redundancy Events), to define a redundancy policy for reacting to such events (Redundancy Policies), and to group the redundancy policies into sets (Redundancy Sets). The redundancy policies detail the action to take on the occurrence of the defined redundancy event.

In one example approach, a redundancy set not only groups one or more redundancy policies into a set, but also assigns states to that set. In one such approach, each redundancy set includes a master state and at least one standby state; the UI building blocks include a technique for defining the critical events that lead to a change in state. In one example approach, each redundancy set therefore establishes the granularity of conditions that drive changes in master/standby states as a function of redundancy policies and their underlying redundancy events. In one example approach, a redundancy set also binds one or more service-sets to drive the Stateful Synchronization state related to these service sets, in which state is synchronized across service gateways based on the redundancy sets for potential failover of redundancy sets.

In one example approach, the UI building blocks described herein include a technique for grouping two or more redundancy sets into a “Redundancy Group (RG).” In one such example approach, a redundancy group is a collection of one or more redundancy sets; redundancy groups may be defined for each service gateway8.

The UI framework defined herein provides the ability to extend service redundancy across chassis for different groups, events and actions. The framework allows administrators to define custom events that can be used as triggers for switchovers and custom redundancy polices that include actions to be taken for the switchovers. The chassis that make up the redundancy groups can be homogeneous or heterogeneous chassis, can be connected over L2 or L3 networks, and can be geographically separated.

FIG. 3Ais a block diagram illustrating an example service gateway in accordance with the techniques described in this disclosure. In the example ofFIG. 3A, the service gateway network device (service gateway8) includes a forwarding plane130, a routing plane132and a service plane134. Forwarding plane130may be provided by dedicated forwarding integrated circuits normally associated with high-end routing and forwarding components of a network router. U.S. Pat. No. 8,050,559, issued Nov. 1, 2011 and entitled MULTI-CHASSIS ROUTER WITH MULTIPLEXED OPTICAL INTERCONNECTS, describes a multi-chassis router in which a multi-stage switch fabric, such as a 3-stage Clos switch fabric, is used as a high-end forwarding plane to relay packets between multiple routing nodes of the multi-chassis router, the descriptions of which are incorporated herein by reference.

Service gateway8may integrate a routing plane132and a service plane134in a manner that utilizes shared forwarding plane130. Forwarding plane130may represent a rich and dynamic shared forwarding plane, in some cases distributed over a multi-chassis router. Moreover, forwarding plane130may be, as noted above, provided by dedicated forwarding integrated circuits normally associated with high-end routing components of a network router such that routing plane132and forwarding plane130operate as a high-end router. In one example approach, service plane134may be tightly integrated within service gateway8(e.g., by way of service cards136) so as to use forwarding plane130of the routing components in a shared, cooperative manner. Details of such routing can be found in U.S. Pat. No. 8,339,959, issued Dec. 25, 2012 and entitled “STREAMLINED PACKET FORWARDING USING DYNAMIC FILTERS FOR ROUTING AND SECURITY IN A SHARED FORWARDING PLANE,” the descriptions of which are incorporated herein by reference.

As seen inFIG. 3A, routing plane132provides a routing component138that is primarily responsible for maintaining a routing information base (RIB)140to reflect the current topology of a network and other network entities to which service gateway8is connected. For example, routing component138provides an operating environment for execution of routing protocols by a routing protocol process such as routing protocol daemon142(RPd). Example protocols include routing and label switching protocols, such as a border gateway protocol (BGP), Open Shortest Path First (OSPF), intermediate-systems to intermediate-system (ISIS) routing protocol, a resource reservation protocol (RSVP), RSVP with traffic engineering extensions (RSVP-TE), an interior gateway protocol (IGP), link state protocols, and a label distribution protocol (LDP). Routing protocol daemon142may represent a software component or module that communicates with peer routers and periodically updates RIB140to accurately reflect the topology of the network and the other network entities. While described as a daemon or software module executed by routing component138, routing protocol daemon142may be implemented as a hardware module or as a combination of both hardware and software.

Routing component138may receive this routing information via routing protocol daemon142and update or otherwise maintain RIB140to reflect a current topology of core network7. This topology may provide for multiple different paths through core network7to reach any given subscriber device16. In the example ofFIG. 1, a path exists from public network12through each of service gateways8to subscriber devices16. Routing component138in one of the gateways8may, in some instances, select the path to use to connect a subscriber device16to public network12.

In the example shown inFIG. 3A, an admin145may interface with routing component138via a user interface (UI) module146, which may represent a module by which a user or provisioning system may interface with routing component138. UI module146may, for example, include a command line interface (CLI), which may accept inputs in the form of commands and/or scripts, or may include a graphical user interface (GUI). Admin145may interface with UI module146to configure various components service gateway8, including routing component138. Once configured, routing component138may then resolve RIB140to generate forwarding information. Routing component138may then interface with forwarding plane130to install this forwarding information into a forwarding information base (FIB)148.

Ingress forwarding component150A and egress forwarding component150B (“forwarding components150”) may represent software and/or hardware components, such as one or more interface cards (not shown), that forward network traffic. In one example approach, forwarding component150A maintains FIB148that associates network destinations with specific next hops and corresponding interface ports of output interface cards of service gateway8. In some such example approaches, routing component138generates FIB148in the form of a radix tree having leaf nodes that represent destinations within network7. U.S. Pat. No. 7,184,437, issued Feb. 27, 2007, provides details on exemplary example approaches of a router that utilizes a radix tree for route resolution, the descriptions of which are incorporated herein by reference.

In one such example approach, when forwarding a packet, forwarding component150A traverses the radix tree to a leaf node based on information within a header of the packet to ultimately select a next hop and output interface to which to forward the packet. Based on the selection, forwarding component may output the packet directly to the output interface or, in the case of a multi-stage switch fabric of a high-end router, may forward the packet to subsequent stages for switching to the proper output interface.

As seen inFIG. 3A, service plane134represents a logical or physical plane that provides one or more services using service cards136. Service cards136A and136B (collectively “service cards136”) may represent physical cards that are configured to be inserted into service gateway8and coupled to forwarding plane130and routing plane132via a backplane, switch fabric or other communication medium. Typically, service cards136may comprise cards that couple directly to the switch fabric. Service cards136may be removable from service gateway8. Admin145may interface with UI module146to interface with routing component138to specify which packet flows are to undergo service processing by one or more of service cards136.

In one example approach, each service card136includes two or more service processing cores31. In one such example approach, service processing cores are assigned to service processing units30, allowing more than one SPU30per service card136. Splitting each service card136into two or more SPUs30may increase the number of redundancy sets supported by each service card136and does provide finer granularity in the assignment of resources.

After specifying the flows, routing component138may update RIB140to reflect that these flows are to undergo service processing, such that when resolving FIB148, the forwarding information may indicate that various flows are to undergo service processing. Often, this forwarding information may specify that these flows require service processing by specifying a next hop for these flows that directs packets of these flows to one of service cards136(where this next hop may be referred to as an “internal next hop”), as described in further detail below. Additional next hops may be specified that are external to service gateway8, where the external next hop may specify, in this example, on which path the packet is to be forwarded. The internal next hop may be linked to the external next hop, where in this example, service gateway8may maintain two next hops (and possibly more) for any given flow.

Service cards136may each represent a card capable of applying one or more services. Although described for purposes of example with respect to service cards, in some examples service cards136may be any of the examples described with respect to service processing units30ofFIGS. 2A-2B. Service card136may include a control unit151, which may represent one or more general processors that execute software instructions, such as those used to define a software or computer program, stored to a non-transitory computer-readable medium such as a storage device (e.g., a disk drive, or an optical drive), or memory (such as Flash memory, random access memory or RAM) or any other type of volatile or non-volatile memory, that stores instructions to cause the one or more processors to perform the techniques described herein. Alternatively, control unit151may represent dedicated hardware, such as one or more integrated circuits, one or more Application Specific Integrated Circuits (ASICs), one or more Application Specific Special Processors (ASSPs), one or more Field Programmable Gate Arrays (FPGAs), or any combination of one or more of the foregoing examples of dedicated hardware, for performing the techniques described herein. In some instances, control unit151may be referred to as a processor.

Control unit151may implement an SPU30from one or more of the service processing cores31. Each SPU30may represent a module or unit that applies one or more services to packets, flows of packets and/or sessions of packets (where a session refers to the combination of a flow to a destination from a source and a flow from the same destination to the same source). SPUs30may include software and/or hardware components that apply services in accordance with service policy rules defined by policy configuration data stored by service policies (not shown). The service policies may be configured by administrator145via UI module146, and programmed by management daemon160, for example. Each SPU30may perform any type of service, including those listed above and below. For purposes of illustration, SPU30may implement a service that modifies, edits or updates information in packets that is generally used in performing path selection or otherwise making forwarding decisions. Example services that modify, edit or updates this information may comprise a NAT service and a tunneling service.

In the example ofFIG. 3A, forwarding component150A receives a packet149and, acting as an ingress forwarding component, invokes a flow control unit154. Flow control unit154represents a module that selectively directs packets to service plane134for processing. In some example approaches, service plane134is a virtual machine. Flow control unit154may access FIB148to determine whether packet149is to be sent to an internal next hop, e.g., one of the SPUs30associated with service cards136of service plane134, or to an external next hop via another one of the forwarding components that acts as an egress forwarding component for the flow to which packet149corresponds (such as, e.g., egress forwarding component150B). While referred to as ingress forwarding component150A and egress forwarding component150B, each of forwarding components150A,150B may be the same or similar to one another in terms of underlying hardware and/or logic. That is, the ingress and egress designation of forwarding components150A,150B is merely to denote that forwarding component150A acts as the ingress forwarding component for the packet flow to which packet149corresponds and forwarding component150B acts as the egress forwarding component for the packet flow to which packet149corresponds. Moreover, forwarding plane130may include more than two forwarding components, where these additional forwarding components are not shown in the example ofFIG. 3Afor ease of illustration purposes.

In the example shown inFIG. 3A, control unit151assigns three cores31(31.1-31.3) to an SPU30. In one example approach, SPU30receives traffic from ingress forwarding component150A, applies the required services via cores31.1-31.3, and returns result to ingress forwarding component150A. In one example approach, control unit151load balances the traffic distributed across cores31.1-31.3of SPU30.

In one example approach, flow control unit154may determine that packet149is to be transmitted to service card136. In response to determining that packet149is to be transmitted to service card136so that an SPU30on service card136can apply a service to packet149, in some examples flow control unit154of ingress forwarding component150A may append an internal service packet header (which may also be referred to as a “service cookie”). Flow control unit154may specify this internal service packet header to include a field that stores an ingress identifier that identifies forwarding component150A. Flow control unit154may append this internal service packet header to packet149to generate an updated packet156. Flow control unit154may then direct packet156to service card136of service plane134. In one example approach, service card136may receive this packet and remove the internal service packet header, parsing the ingress identifier from the internal service packet header. Control unit151of service card136may then invoke one or more SPUs30, which apply the service(s) of each SPU30to updated packet156, generating a serviced packet158. Serviced packet158is assumed to differ from packet149and156in that at least one aspect of serviced packet158used when making forwarding decisions or performing path selection differs from that of packets149and156(such as at least one aspect of the five-tuple of serviced packet158differs from the five-tuple of packet149and packet156). In this respect, service card136applies, via SPUs30, the service to updated packet156to generate serviced packet158such that the five-tuple of serviced packet158is different from the five-tuple of updated packet156.

Service card136, or an SPU30executing on service card136, may then transmit serviced packet158back to flow control unit154using the ingress identifier previously parsed from the internal service packet header so as to maintain load balancing of packet flows across forwarding components of service gateway8. That is, service card136may actively identify the one of forwarding components150A,150B (and any other forwarding components not shown in the example ofFIG. 3Afor ease of illustration purposes) that originally received packet149, that acts as the so-called ingress forwarding component, and/or that maintains the single point of contact for the flow to which packet149corresponds. As a result, service card136transmits serviced packet158to ingress forwarding component150A identified by the ingress identifier without applying a hash function to at least a portion of serviced packet158to identify ingress forwarding component150A and/or without determining a next hop of the to which to forward serviced packet158. Moreover, service card136transmits serviced packet158to ingress forwarding component150A such that ingress forwarding component150A receives the packet as if the packet had been received by ingress forwarding component150A via an interface (not shown in the example ofFIG. 3A) associated with ingress forwarding component150A that couples to another network device rather than via a switch fabric coupling service card136to ingress forwarding component150A. By selecting ingress forwarding component150A, service card136maintains the load balancing of packet flows across the links/forwarding components (of the receiving router) decided by the upstream router in accordance with weighted equal cost multi-path (WECMP).

Flow control unit154receives this serviced packet158and accesses FIB148using the five-tuple of serviced packet158in order to retrieve an entry specifying a next hop for the flow to which serviced packet158corresponds. In other words, flow control unit154determines the next hop to which to forward serviced packet158based on the five-tuple of serviced packet158. Assuming flow control unit154identifies a next hop that involves forwarding serviced packet158via an interface associated with egress forwarding component150B, flow control unit154forwards this packet158to egress forwarding component150B, which in turn forwards packet158to the next hop.

As can be seen inFIG. 3A, routing plane132includes a management daemon160coupled to user interface module146and to a configuration database162. Management daemon160receives configuration information from user interface module146and stores the configuration information in configuration database162. In some examples, routing plane132also includes a services redundancy daemon (SRd)164(also referred to herein as a services redundancy process), which operates as a services redundancy manager in conjunction with route policies database166to configure and control redundant services delivery system27. SRd164also interfaces with service plane134, such as to permit configuration of SPUs30within service cards136A,136B by management daemon160. SRd164may represent a software module that updates RIB140based on configuration database162and route policies database166. While described as a daemon, software process, or software module executed by routing component138, SRd164may be implemented as a hardware module or a combination of both hardware and software.

As noted above, in one example approach, Master/Standby state is maintained in each service processing unit30. In one such example approach, this state is stored as a signal route vector70, in which each bit of vector70is associated with a Master/Standby pair. In one such example approach, each service processing unit30receives information or commands from SRd164informing the SPU30to keep or change state.

User interface module146may represent a software and/or hardware module that presents an interface with which an administrator or an administrative device, represented by “ADMIN”145, may interact to specify certain operational characteristics of service gateway8. In response to invocation by admin145, user interface module146interacts with other components of service gateway8, such as to retrieve, configure, copy, and/or delete policy configuration data stored in route policies database166, update service data of services plane143via SRd164, and to perform other management-related functions. In one example approach, admin145may interact with user interface module146to enter configuration information for SRd164, such as configuration information defining redundancy events, redundancy policies, redundancy sets and redundancy groups, and this configuration information is also stored in configuration database162.

FIG. 3Bis a block diagram illustrating a service processing unit having service processing cores assigned from various service cards, in accordance with the techniques described in this disclosure. In the example ofFIG. 3B, the service processing cores31from four different service processing nodes are assigned to an SPU30. The cores assigned to SPU30are shaded inFIG. 3B. In one example approach, service processing cores31are assigned to SPU30via the following syntax:

In the above example, “mams” represents a service processing core31, with mams9, mams10, mams11and mams12representing service cards136A-136D, respectively. The second digit indicates the number of the service processing core31on service card136. For instance, Mams10/4/0represents core31.4on service card136B. AMS10is the name assigned to SPU30.

In the example syntax shown above, SPU30applies load balancing across each of the cores31. In addition, in the example shown, traffic into SPU30is received via interface799, distributed to the cores31assigned to AMS10and returned via interface800.

Redundancy sets will be discussed next. In one example approach, each redundancy set30includes a node in a master state and one or more nodes in standby states. As noted above, nodes in master states can share nodes that are in standby states. Master service gateways that share a single, common standby service gateway are in the N:1 Stateful Application Gateway Redundancy configuration discussed above. Likewise, Master service gateways that share two standby common service gateways are in a N:2 Stateful Inter-Application Service Gateway Redundancy configuration.

In one example approach, service gateways get elected as Master based, e.g., on the health of applications. During operation of service deliver gateway8, one or more services redundancy processes (such as services redundancy daemons164) in each service gateway8may continuously monitor the health-status of the groups of applications and exchange this information across all the related chassis. For example, SRd164inFIG. 3Amay detect a failure or degradation in an application (e.g., a service provided by SPU30of service card136A, such as a firewall service), and may notify Inter-Chassis Control Protocol (ICCP) module155, which sends information about the affected application to a respective counterpart ICCP module executing on one or more other chassis.

SRd164may monitor performance of one or more of the SPUs30that make up the standby SPUs. In addition, as noted above, service plane134may provide an operating environment for running one or more applications across one or more SPUs30. In some aspects, SPUs30running in parallel may each expose an application programming interface (API) by which SRd164inspects performance data (e.g., loading levels) for the respective service. Alternatively, SRd164may expose a universal interface, which each of the SPUs30may invoke to communicate current performance data. As another example, an SRd164in a service gateway8may periodically ping each SPU30in service gateway8or may monitor output communications from each of the services provided by the SPUs30of service gateway8or the operating-system level resources consumed by each of the services of the SPUs30assigned to service gateway8. In some examples, SRd164can monitor any of a variety of parameters associated with SPUs30, which may be defined via a management plane of services delivery gateway network device8, e.g., via user interface module146and management daemon160.

In one example approach, SRd164monitors parameters associated with SPUs30, such as per-process central processing unit (CPU) usage, memory usage, rate of output, number of available connections, or other such parameters for detecting whether an SPU30is performing according to expected levels. For example, if an SPU30is expected to provide an output at a threshold rate, SRd164may be used to detect when the actual rate of output falls below the threshold rate. An administrator145may configure the performance level thresholds via user interface module146, such as when an application or other service is initially deployed on an SPU30of service gateway8. The performance level thresholds may be stored in configuration database162. The performance level thresholds may be selected relative to SLA requirements, to trigger action when performance levels fall below what is required by subscribers16, for example.

In some example approaches, SRd164continuously monitors for system events of gateway8, such as interface down events, physical interface card (PIC) reboots, flexible PIC concentrator (FPC) reboots, RPD aborts/restarts, and peer gateway events. For example, SRd164may communicate with Bidirectional Forwarding Detection (BFD) module157and/or ICCP module155in forwarding plane130to obtain information by which to detect occurrence of system events. In one example approach, user interface module146also supports a syntax that provides the user the ability to define custom “dummy” redundancy events that can be used to manually pause switchovers or force switchovers, irrespective of the health status of applications.

On detecting the occurrence of redundancy events including application-related events or critical system events, depending on its mastership state, in some example approaches, SRd164communicates with the network layer in a protocol agnostic manner to redirect traffic to the next standby node that gets elected as the master. For example, in response to SRd164detecting a redundancy event and in accordance with route policies database166previously defined by administrator145, SRd164may update signal-routes in RIB140, which in turn triggers one or more routing protocols executed by routing protocol daemon142to advertise the updated signal-routes to routing protocol peer network devices, thereby causing network devices to route traffic differently and send network traffic requiring the affected services to a different service gateway8. Also, in response to SRd164detecting the redundancy event, SRd164may update data specifying Stateful Sync roles, which may be stored, for example, in service plane134. Stateful sync refers to session-level redundancy state maintained by SPUs30executing on one or more of the service cards136A,136B of gateway8according to the stateful sync roles, which allows for synchronization of the necessary session-level state across master and standby service cards for a seamless transition from master to standby. This process is termed a switchover and ensures uninterrupted application services for the end user. By virtue of the message exchanges across all the members of a group, the techniques of this disclosure allow for continuous, fully-automated application switchovers across the chassis.

As one example, a network address translation (NAT) function provided by one of SPUs30may support a number of connections. Admin145may configure a threshold number of connections below which the NAT service should not fall for an expected performance level and may use the syntax described herein to define a redundancy event (via UI module146) that expresses the threshold number of connections. Admin145may also use the syntax described herein to define a redundancy policy (via UI module146) that specifies an action to occur upon detection of the defined redundancy event, such as modifying a signal-route stored in RIB140to cause routing protocol daemon142to advertise an updated signal-route. Admin145can use the syntax described herein to further define one or more redundancy sets and redundancy groups. Management daemon160configures configuration database162to store the redundancy event, redundancy policy, redundancy sets, and redundancy groups. SRd164may continuously or periodically monitor the number of connections being supported by the NAT service and if SRd164detects that the number of connections available by the NAT service falls below the threshold number of connections, SRd164detects occurrence of the redundancy event and applies the redundancy policy to trigger the designation of a new master for providing the NAT service, as described herein.

The techniques described herein decouple the application redundancy decision from the underlying network communication mechanism, using a protocol independent mechanism to communicate with the network layer. It allows for custom events to be triggered to simulate failure events to induce switchovers or switchbacks manually.

Further, as described herein, the techniques provide mechanisms by which applications are able to signal network protocols in a protocol agnostic manner using predesignated routes. The applications may use, for example, a signal-route vector, which is a predesignated set of routes called signal-routes each of which map to mastership and standby states which get updated by the application layer on the occurrence of predefined events such as critical faults and user-initiated transitions.

FIG. 4is a block diagram illustrating an example set of service chains of services according to the techniques described herein. In one example approach,FIG. 4illustrates a set of service chains34A-34E supported by a service gateway8. Service chains34represent an example set of service chains provided by services10within, or external to, one or more service gateways8.

In this example, one or more subscriber packet flows36A are directed along a first service chain34A to receive network address translation (NAT) service38. Similarly, one or more subscriber packet flows36B are directed along a second service chain34B for application of an HTTP filter service40, NAT service42and session border controller (SBC) services43for voice over IP (VoIP) processing and control. In service chain34C, packet flows36C are directed only to firewall service48. In service chain34D, packet flows36D are directed to HTTP filter46and subsequently to firewall service48. As another example, packet flows36E are directed along service chain34E for application of HTTP filter50, NAT52and intrusion detection and prevention (IDP) (e.g., deep packet inspection) service54.

As noted above, current inter-chassis redundancy solutions are geared toward providing redundancy across two or more homogeneous chassis within the same network. The techniques disclosed herein provide a framework for application-aware inter-chassis redundancy with granular control to fail over groups of applications between sets of two or more network elements. The network elements can be homogeneous or heterogeneous (physical or virtual) and can spread across different networks or across geographies. The redundancy mechanism provides traffic redirection to the new master agnostic of underlying network protocols and provides options for triggering, preventing and resuming both manual and automated switchovers of groups of services based on their health status; the redundancy mechanism will be discussed further in the context of the discussion ofFIG. 5below.

FIG. 5is a block diagram illustrating master and standby redundancy states in redundancy sets20across service gateways8in a redundant service delivery system27. In the example approach shown inFIG. 5, system27includes service gateways8.1-8.3. Gateways8.1-8.3are located in separate chassis as labeled and are connected via communications channel22. Each service gateway8includes one or more SPUs30. Each SPU30is assigned to one or more redundancy sets20.

Each redundancy set20inFIG. 5is shown in either a Master state or a Standby state. For instance, RS2in gateway8.2is in a master redundancy state while RS2in gateway8.3is in a standby redundancy state. At the same time, RS3in gateway8.1is in a master redundancy state while RS3in gateway8.3is in a standby redundancy state. A single SPU30in service gateway8.3is assigned to redundancy sets RS2and RS3. As such, RS2and RS3are set up in a 2:1 N:1 Stateful Application Gateway Redundancy relationship, sharing SPU30in gateway8.3as a standby node.

The framework described above establishes a set of building blocks that provides the ability to extend service redundancy across multiple chassis for different groups, events and actions. The framework allows the user to define for each application the custom events that can be used as triggers for switchovers to other chassis and custom redundancy polices that include actions to be taken for the switchovers. The chassis that make up sets of SPUs30may be homogeneous or heterogeneous chassis, they may be connected over either a L2 or a L3 network and they may be geographically separated. In some examples, every redundancy set has a master and one or more standbys that get elected based on the health of the application associated with that redundancy set20.

FIG. 5illustrates how two or more service gateways8operate in an “Active-Active” mode by assigning Mastership to redundancy set20on one service gateway8and assigning Standby Redundancy State to the same redundancy set20on a different service gateway8. For instance, referring toFIG. 4, health monitoring for network address translation (NAT) service38, for intrusion detection and prevention (e.g., deep packet inspection) service54and for session border controller (SBC) services43may be performed by SPUs30assigned to redundancy set3, while health monitoring for HTTP filter service40may be performed by SPUs30assigned to redundancy set2. Since the mastership for redundancy set2is shown to reside in the chassis for gateway8.2, all the above services for RS2are performed by an SPU30on gateway8.2. Likewise, since the mastership for redundancy set3is shown to reside in the chassis for gateway8.1, all the above services for RS3are performed by an SPU30on gateway8.1. For this example, NAT service38executes on an SPU30of gateway8.1.

If NAT service38in gateway8.1were to experience a critical event (such as, e.g., failure of a service card136B of service gateway8.1that supplies service processing cores to the SPU30assigned to RS3), a redundancy event occurs for redundancy set3, and RS3on gateway8.1transitions to a standby redundancy state while RS3on gateway8.3transitions to a master redundancy state. The SPU30assigned to redundancy sets2and3on gateway8.3as shown inFIG. 5then takes over execution of all the services of redundancy set3on gateway8.3. This results in an “Active-Active” subdivision of services between gateways8.1,8.2and8.3. In this example, flows such as flows36B,36D and36E will now be routed through both gateways8.2and8.3, while flow36A may be routed only through gateway8.3and flow36C remains within gateway8.2.

During operation, a services redundancy daemon164executing within each gateway8continuously monitors the health-status of groups of applications and exchanges this information across communications channel22to all chassis in the redundancy group. Each services redundancy daemon164also continuously monitors redundancy events such as critical system and application faults. On the occurrence of such faults, depending on its mastership state, services redundancy daemon164communicates with the network layer in a protocol agnostic manner to redirect traffic to the next standby node slated to be elected as the master. This process is termed a switchover and it ensures uninterrupted application services for the end user. As detailed above, in one example approach, ICCP provides connectivity between peer redundancy groups. Such an approach is shown in more detail inFIG. 6.

FIG. 6is a block diagram illustrating communication between gateways in the network system ofFIG. 1. In the example shown inFIG. 6, redundancy groups communicate via an Inter-Chassis Control Process (such as an Inter-Chassis Control Protocol daemon (ICCPd)31). In one such example approach, services redundancy daemon164establishes Unix (Interprocess Communication (IPC) with ICCP for transport and notification service across communications channel22.FIG. 6also illustrates configuration information32used to configure ICCP.

In the example shown inFIG. 6, communications channels22between the gateways8that make up redundant service delivery system27exchange information between the gateways. In some such examples, Inter-Chassis Control Protocol (ICCP) provides connectivity to peer gateways8. In one approach, ICCP is established as follows:

In some example approaches, Bidirectional Forwarding Detection (BFD) is used in addition to ICCP to detect failures. BFD157provides very fast failure detection in the forwarding plane130of gateway device8. BFD157also provides a single mechanism for such detection independent of media, routing protocol and data protocol. In one example approach, BFD157executes in the packet forwarding engine (PFE) of ingress forwarding component150A. Such an approach ensures that the remote peer is transparent to control plane switchover if, for instance, non-stop forwarding is configured.

By virtue of the message exchanges across all the members of a group, the techniques described herein allow for continuous, fully-automated application switchovers across the chassis. They even provide the user the ability to pause switchovers or force switchovers, overriding the health status of applications. The techniques decouple the application redundancy decision from the underlying network communication mechanism, using a protocol independent mechanism to communicate with the network layer. It allows for custom events to be triggered to simulate failure events to induce switchovers or switchbacks manually.

In one example approach, management daemon160presents user interface module146by which an administrator145(“ADMIN”) can enter commands to configure gateway8and service processing unit30. In some examples, user interface module146may be configured to receive text-based commands. According to the techniques of the invention, management daemon160supports a command syntax that allows administrator145to define redundancy events and routing policies that specify how gateway8is to respond to redundancy events. Management daemon160may store the configuration input received from administrator145as configuration data in configuration database162, which may take the form of a text file, such as an ASCII file. Alternatively, management daemon160may process the configuration input and generate configuration data in any one of a number of forms, such as one or more databases, tables, data structures, or the like. Configuration data may take the form of one or more commands for adding new settings to the current configuration of gateway8, commands for deleting or modifying existing settings of the current configuration, or combinations thereof. Gateway8may further parse configuration data and input from administrator145and resolve the references to appropriately configure gateway8.

Specifically, administrator145inputs commands to user interface module146to configure routing policies for services redundancy daemon164, as described in further detail below. Management daemon160then stores the routing policies in route policies database166.

In one example approach, administrator145may also input commands to user interface module146to configure other aspects of gateway8. A services redundancy daemon164in control unit151may, for instance, program SPUs30associated with service cards136with configuration data received from the administrator defining firewall zones and policies with respect to physical interfaces, causing the SPUs30of services engines152to recognize the defined zones and applying the security policies when processing packets from data plane flow control unit154.

As noted above, Redundancy Event (RE) is a critical event that triggers the SR daemon164to switch gateway8mastership to standby gateway8. In one example approach, critical events include interface down events, FPC/PIC reboots, Routing Protocol daemon (RPd) aborts or restarts and Peer gateway events. In one example, each gateway8is configured via UI module146to monitor critical events selected by administrator145that cause a service delivery daemon164in one gateway8to release mastership and that lead a service delivery daemon164in another gateway8to take up mastership of the redundancy group.

In one example approach, administrator145defines a redundancy event RELS_MSHIP_CRIT_EV and lists the critical events that are members of that redundancy event. In one such example, the current configuration of redundancy event RELS_MSHIP_CRIT_EV may be displayed through a show command:root@SG1# show event-options redundancy-event RELS_MSHIP_CRIT_EVand, in one example approach, the results displayed for redundancy-event RELS_MSHIP_CRIT_EV of gateway8are:

monitor {link-down {ae62.3203;ams10.100;ms-1/0/0;}process {routing {restart;abort;}}}
where ams10is a specific service processing unit30and ams10.100is an input for ams10.

In the above example, a link-down event is triggered when, for instance, an interface down event occurs. A process event occurs when there is a Routing Protocol daemon164(RPd) restart. In this example, either the link-down event or the RPd restart event is sufficient to trigger a transfer of gateway mastership away from that gateway8.

The above are simply examples of critical events. Other critical events may be defined as tied to specific services, or to service chains. For instance, a failure or degradation in a service provided by one or more SPUs30on service cards136could serve as a critical event, as could failure or degradation in one of the communication mechanisms available for communicating between gateways8, or between a gateway8and another network device.

As noted above, a Redundancy Policy is a policy that ties a Redundancy Event to one or more actions to be taken on the occurrence of those critical events. In one example, an administrator can request the contents of redundancy policy REL_MSHIP_POL to be displayed through a show command as follows:

and the results are displayed for redundancy-policy RELS_MSHIP_POL of gateway8in one example as:

That is, if RELS_MSHIP_CRIT_EV is triggered by specified critical events, or administrator145triggers a mastership switch manually using redundant event RELS_MSHIP_MANUAL_EV, mastership is transferred to the highest rated standby gateway8.

In another example, an administrator can request the contents of redundancy policy ACQU_MSHIP_POL to be displayed through a show command as follows:root@SG1# show policy-options redundancy-policy ACQU_MSHIP_POL
and the results are displayed for redundancy-policy ACQU_MSHIP_POL of gateway8in one example as:

In one example approach, an administrator can request the contents of redundancy policy WARN POL to be displayed through a show command as follows:

and the results are displayed for redundancy-policy ACQU_MSHIP_POL of gateway8in one example as:

One approach for setting up gateway8to trigger a mastership change is as follows:

As noted above, a redundancy set establishes the granularity of the master/standby states driven by redundancy policies. In one example approach, a redundancy set may also bind one or more service-sets to drive the Stateful Sync state related to the service-sets. In one example, a first redundancy set (redundancy-set) is defined for a gateway8and can be displayed through a show command as follows:root@SG1# show services redundancy-set
and the results are displayed for one example redundancy set as:

A Redundancy Group (RG) is a collection of Redundancy Sets and defines common peering properties across a set of gateways8. RGs allow for different peering settings across same peers. In one example, a first redundancy group (redundancy-group1) is defined for a gateway8and can be displayed through the same show command as used for the redundancy set, and achieves the same result:root@SG1# show services redundancy-group
and the results are displayed for one example redundancy group1as:

FIG. 7is a block diagram illustrating a mastership transition to a peer in accordance with techniques described herein. In some examples, Peer Events are defined as a type of Redundancy Events that are exchanged between SRd peers. Redundancy Policies tied to Peer Events allow a local SRd peer to act based on Peer Events reported by remote SRd peers as shown inFIG. 7. In the example ofFIG. 7, a redundancy event occurs on a service gateway8A, and SG1releases mastership to SG2executing on service gateway8B. In one example approach, a message is sent to SG2from SG1via ICCP telling SG2to take over as master. In one such example, a group of peer events are defined for a gateway8. In some such examples, the members of the group of critical peer events can be displayed through a show command as follows:root@SG2# show event-options redundancy-events PEER_MSHIP_RELS_EV
and the results are displayed as:

One potential advantage of the user interface and redundancy framework discussed above may be the ability to provide redundancy for one or more groups of applications across two or more chassis, independent of the underlying network protocols. The framework is highly extensible by the use of the system of redundancy events, redundancy policies, and redundancy groups, making is easy to incorporate new events and actions for supporting network function virtualization (NFV) based use-cases. The redundancy framework may provide for uninterrupted availability of services (termed Non-Stop Services for applications). The redundancy framework also allows a set of two or more chassis function in an ‘Active-Active’ mode by virtue of sub dividing the services mastership in to multiple redundancy-groups across the same set of chassis. The approach described herein is also routing protocol agnostic, in that the syntax allows the administrator to express the redundancy events and redundancy policies in a way that is independent of the underlying routing protocol that is ultimately used by the router for communicating a change in mastership.

In one example approach, SRd164may also be used to synchronize the configuration across all the peers in a redundancy set. Consider the firewall configurations tied to service processing interfaces ams10.799and ams10.800via redundancy sets RS1and RS2. In the example shown, redundancy set1(RS1) is defined as:

service-set MX2_SFW4_AMS10 {syslog {source-address 1.2.1.3;}host local {class {ids-logs;}}}stateful-firewall-rules SFW4_15G-r2;next-hop-service {inside-service-interface ams10.799;outside-service-interface ams10.800;}redundancy-set-id 2;}
through which SRd164can ensure that the contents of service-set MX1_SFW4_AMS10, which are tied to RS1, are synchronized all the nodes that are a part of RS1and that the contents of service-set MX2_SFW4_AMS10, which are tied to RS2, are synchronized all the nodes that are a part of RS2. Since both RS1and RS2are tied to the same service processing interface (ams10.799and ams10.800), the underlying service processing unit30is now shared by two redundant sets or two service sets. In one example approach, each SPU30maintains the state of the redundancy sets to which it is assigned. For instance, in one N:1 Stateful Application Gateway Redundancy model, the SPU30assigned as the standby node must maintain the state of all N redundancy sets to which it is assigned. In another example approach, SRd164maintains states for each of the SPUs30in its gateway8. For instance, in one N:1 Stateful Application Gateway Redundancy model, SRD164of the service gateway8hosting the standby node must maintain the state of all N redundancy sets to which the SPU30assigned as the standby node is assigned.

In one example approach, resources are assigned to an SPU30using the syntax introduced above. For instance, ams10in this example is assigned resources as follows:

In this example, ams10is a service processing unit that is made up of three service processing cores31from a single service card136. Traffic into ams10is via unit799(ams10.799) while traffic out of ams10is via unit800(ams10.800). In one example approach, ams10.799and ams10.800make up a service next hop pair that can be used to string together SPUs30as a chain of next hops.

In one example approach, service next hops may be used to connect SPUs30in series or in parallel. For instance, in one example approach, a second SPU may be configured using the definition of ams10, but with a different service next hop pair:

next-hop-service {inside-service-interface ams10.699;outside-service-interface ams10.700;}
Network traffic directed to ams10.799would be sent to the first SPU while network traffic directed to the ams10.699would be sent to the first SPU.

At the same time, one may configure the second SPU using the definition of ams10, but with a different input interface and the same output interface as follows:

next-hop-service {inside-service-interface ams10.699;outside-service-interface ams10.800;}
Network traffic directed to ams10.799would be sent to the first SPU while network traffic directed to the ams10.699would be sent to the first SPU. The results from both would, however, be sent to the SPU connected to ams10.800.

Any event in a router or gateway can be mapped into a redundancy event and used to trigger a transition in the state of a redundancy set. In one example approach, a generic operating system event (e.g., a generic system JUNOS event) is configured as a redundancy event (RE) as follows:

FIG. 8Ais a block diagram illustrating communication between application nodes in the redundant service gateway system ofFIG. 1. In the example ofFIG. 8A, three network elements (network nodes60A-60C) communicate through communications channel22. Application services nodes62A through62C are associated with network elements60A through60C, respectively, and are arranged in an N:1master/standby relationship, with application services Masters62A and62B sharing a single application service Standby62C. In one example approach, the communication mechanism shown inFIG. 8Aand described herein permits communicating in a protocol and network agnostic manner between application nodes in redundant service delivery system27. In one example methodology, application services nodes62signal network-protocols in a protocol agnostic manner using predesignated routes.

FIG. 8Bis a block diagram illustrating a signal-route vector70used to store state for each redundancy set. As can be seen in the example shown inFIG. 8B, signal-route vector70is a predesignated set of routes called signal-routes, each of which map to mastership and standby states for particular redundancy sets or particular service sets. In the example shown inFIG. 8B, signal-route vector70includes one or more signal-routes72and one or more signal-route states74organized as signal-route/signal-route state pairs. In some example approaches, state74is a zero when the SPU30associated with the signal-route72is to be in a stand-by state and a one when the signal-route72is to be in a master state. In other example approaches, state74is a zero when the SPU30associated with the signal-route72is to be in a master state and a one when the signal-route72is to be in a stand-by state. In one example approach, each SPU30maintains a copy of the signal-route state74for each redundancy set to which it is assigned. In another example approach, each gateway's SRd164maintains a copy of the signal-route state74for each redundancy set to which the gateway's SPUs30are assigned.

In some approaches, an application executing in the application layer updates the signal-routes on the occurrence of redundancy events such as critical faults. It is not a requirement for the destination represented by the routes that make up the signal-route vector70to be reachable since the routes only are used for signaling between the application and the network layers. Routing-policies, which drive routing-protocols, are coupled to the existence or non-existence of these routes. As soon as the application layer (e.g., SRd164) adds or removes these signal-routes from RIB140, the routing policies are implicated, resulting in redirection of traffic to the new master service gateway8. In one example approach, standby nodes synchronize state from the master so that anytime the master fails, the next best standby can take over the mastership. An application services node62taking over application mastership begins to perform one or more application services such as Mobility services, Stateful firewall, CGNAT, NAT, IDP, proxy services, application acceleration, etc., on the network traffic.

One potential advantage of this methodology is its ability to ensure resiliency over L2 networks, apart from L3 networks, by communicating with L2 protocols such as Virtual Router Redundancy Protocol (VRRP) which support route-tracking. In fact, since the SRd interacts with L3, L2 and Stateful Sync components of router operating systems, respective debugging commands can be used to troubleshoot SRd interactions. The SRd on each service gateway8may also generate Simple Network Management Protocol (SNMP) traps for state changes. SNMP traps may be used, for example, to notify another device of a change in state of one of an application executing on one of the redundant service gateways. SNMP traps do this by sending a message known as a trap of the event to the other device.

In one example approach, an if-route-exists condition detects the presence or absence of a signal-route. In one such example approach, a change in the presence or absence of a particular signal-route is advertised using as-path-prepend values. In one such example approach, a change in the presence or absence of a particular signal-route is advertised using different local-preference values.

Another potential advantage of this methodology is the ability for applications to drive resiliency of the application overlay network over both L2 and L3 networks in a protocol-agnostic manner. The techniques described may allow for applications to create an overlay network of peers and allows for applications62to drive and adapt the routing over the underlying network. It also allows for a geo-redundant inter-chassis redundancy solution. In a real-world application, the approach reduced route convergence time by 95% (convergence was in about a second), ensuring uninterrupted failovers for millions of application sessions across the overlay network for a 99.999% High Availability.

In one example, the signal-routes are static routes manipulated by SRds of service gateway8based on the mastership state changes. An example of adding a static route is:root@SG2# show policy-options redundancy-policy ACQU_MSHIP_POL
and the result is:

In some example approaches, routing policies advertise routes based on the existence or non-existence of signal-routes. In one such example approach, routing policies are preconfigured to advertise routes based on the existence or non-existence of signal-routes using the if-route-exists condition.FIG. 9is a diagram illustrating advertising the presence or absence of a signal-route through the use of an as-path-prepend command. In the example ofFIG. 9,

In this example, a check is made in the prefix-list to determine if the route 10.45.45.0/24 exists and, if the route is not present, the SRd increases the cost of the route using the as-path-prepend command. The Autonomous System (AS) path prepend can be used to tell other routing entities in system4to route to a gateway device having a lower routing cost, which also is the gateway device next in line to assume mastership. BGP prefers the shortest AS path to reach a destination. The path that BGP will choose to reach a destination can be manipulated using AS path prepending. AS path prepending allows for artificially lengthening the AS path that BGP advertises to a neighbor.

In another example approach, the presence or absence of the signal-route is advertised through the use of local-preference values.FIG. 10is a diagram illustrating advertising the presence or absence of a signal-route through the use of local-preference values. A local-preference value is a metric used by BGP sessions to indicate the degree of preference for an external route. The route with the highest local preference value is preferred. The local-preference attribute is used in inbound routing policy and is advertised to internal BGP peers and to neighboring confederations. In one such approach, a service gateway master defaults its local-preference value to, for example, 400, while the standby defaults to 350. If mastership transitions to the standby gateway, its local-preference value may be, for example, raised to 450, while the former master retains its local-preference value of 400.

In some examples, the SRd drives L2 connectivity via VRRP route tracking. VRRP is a layer-2 (switching) protocol unlike the routing protocols explained earlier. VRRP route tracking is a VRRP feature which tracks the reachability of signal-routes in order to vary the VRRP priorities dynamically. In one example approach, VRRP route tracking is used to help advertise the route switching signaling the change of mastership. In one such example, VRRP route tracking is configured as follows:

FIG. 11is a flowchart illustrating services switchover to a peer in accordance with techniques described herein. In the example shown inFIG. 11, SRd164assumes mastership (200) of a redundancy set and begins to monitor for critical events as defined by the redundancy events configuration (202). If SRd164detects that a critical event occurs, SRd164adds or removes a route based on a relevant route policy (204). In one example approach (e.g., where SRd164is executing on a gateway that is no longer the master), SRd164also notifies the preferred standby gateway8that it is to take over mastership. In one such example approach, SRd164notifies SRd164of the preferred standby gateway8A using ICCP.

Gateway8then advertises the change in routes, resulting in a change in routing information base140(206). In one example approach, VRRP is used to communicate the advertised priorities for one or more routes. Routers in the network receive the advertisements and, based on the advertised routes, begin forwarding network traffic to the next preferred standby gateway8for application of services (208).

In one example approach, each SR daemon164on the routing engine continuously monitors preconfigured redundancy events. On the occurrence of a redundancy event, SRd164a) adds or removes signal-routes from RIB140as specified in the redundancy policy and b) updates Stateful Sync roles accordingly. Stateful sync refers to session-level redundancy provided on the SPUs30of service cards136A,136B of gateway8. In one such approach, each service10maintains its own application state and shares that application state with its counterparts in standby gateways8. In some examples, SRd164maintains the application state associated with each of the services10and shares the application state.

In one example approach, the addition or removal of signal-routes by SRd164causes routing protocol daemon142to send a routing protocol update message to routing protocol peers to advertise the changes in the routes. In one such example approach, this involves changing the cost of the route via, for example, the as-path-prepend command discussed above.

In some example approaches, the route change also has an effect on the VRRP configuration tracking this route, resulting in different VRRP priority advertisements as noted above. The newly advertised routes and changed VRRP priorities redirect traffic to the next preferred standby gateway8, and SRd164switches over the services mastership to that gateway8. In some such example approaches, VRRP is also used to communicate, to a SRd164in another gateway8, the need for a mastership transition.

In one example approach, SRd164is the services redundancy daemon of an SPU30acting as a Standby node in an N:1 Stateful Application Gateway Redundancy application. SRd164therefore must track state of each of the N Master nodes in the Redundancy application. In one such example approach, when an SPU30associated with a node that previously was a Master node in the N:1 Stateful Application Gateway Redundancy application comes back online, it triggers a critical event in the SRd164associated with the standby node now acting as the Master. The SRd164associated with the Standby node then transitions mastership back to the previous Master as detailed inFIG. 11. In another such example approach, when an SPU30is added to replace a node that previously was a Master node in the N:1 Stateful Application Gateway Redundancy application comes back online, the action triggers a critical event in the SRd164associated with the standby node now acting as the Master. The SRd164associated with the Standby node then transitions mastership over to the new Master node as detailed inFIG. 11.

FIG. 12is a block diagram illustrating a redundancy set state machine for moving between master and standby states in accordance to the techniques described herein. The state machine ofFIG. 12shows the states of an instance of services redundancy daemon164monitoring a service processing unit30of a gateway8in system27. As can be seen inFIG. 12, SRd164boots into an Init state (220) and remains there until SRd164receives a health check success or failure. In one example approach, a service processing unit30of a gateway assigned three redundancy sets maintains three instances of the state machine shown inFIG. 12. In one such example approach, each state machine operates independently of the other.

On a health check success, control moves to a Standby Ready state (222) and remains there until a critical event occurs or a mastership event occurs. On a health check failure, control moves to a Standby Warning state (224) and remains there until a health check success occurs or a forced mastership event occurs.

On a critical event, control moves from state222to a Standby Warned state224. On a mastership event, control moves from state222to a Master state226.

Once in the Master state226, service processing unit30of gateway8remains in the Master state (226) until a critical event occurs. If a critical event occurs, service processing unit30of gateway8moves to a Standby Warned state (224).

Once in the Standby Warned state (224), service processing unit30of gateway8remains in that state until a forced mastership acquires event forces it back to the Master state (226), or a health check success moves it back into the Standby Ready state (222). In some example approaches, SRd164sets a timer on service processing unit30of gateway8entering Standby Warned state (224). When the timer times out, SRd164checks to determine if service processing unit30has recovered from the event. If so, control moves back to Standby Ready state (222). In some such example approaches, control remains in Standby Warned state224until it is initialized or has received a health check success. In some such example approaches, a check is made each time the timer times out to see if the critical event has been resolved. Other standby states may be added to reflect intermediate standby states.

The techniques described above may be extended to the control of other services and devices in the network. Since master and standby state changes drive the addition and deletion of routes, changes in the routes can be used, for example, to change the operation of a firewall to, for instance, the approach desired for a particular master, a particular standby device or a particular combination of standby devices. In one example approach, route changes are used to dynamically change the operation of services such as firewall filters to, for instance, reflect the needs or configuration of the current master. The change may be as simple as disabling a filter, or it may involve the configuration of a number of different devices and a variety of protocols. In one example approach, master and standby state changes drive, for instance, the enabling and disabling of firewall filters, or may redirect traffic to a peer gateway.

FIG. 13is a flowchart illustrating changes in services as a function of the changes in signal-routes during switchover to a peer in accordance with techniques described herein. In the example shown inFIG. 13, SRd164assumes mastership (250) of a redundancy set and begins to monitor for critical events as defined by the redundancy events configuration (252). If SRd164detects that a critical event occurs, SRd164adds or removes a route based on a relevant route policy (254). In one example approach (e.g., where SRd164is executing on a gateway that is no longer the master), SRd164also notifies the preferred standby gateway8that it is to take over mastership. In one such example approach, SRd164notifies SRd164of the preferred standby gateway8A using ICCP.

Gateway8then advertises the change in routes, resulting in a change in routing information base140(256). In one example approach, VRRP is used to communicate the advertised priorities for one or more routes. In one example approach, devices in in service provider core network7receive the advertisements and modify the services they provide to reflect the change in signal-routes (258). Routers in the network receive the advertisements and, based on the advertised routes, begin forwarding network traffic to the next preferred standby gateway8for application of services (260).

In one example approach, each SR daemon164on the routing engine continuously monitors preconfigured redundancy events. On the occurrence of a redundancy event, SRd164a) adds or removes signal-routes from RIB140as specified in the redundancy policy and b) updates Stateful Sync roles accordingly. Stateful sync refers to session-level redundancy provided on SPUs30of one or more of the service cards136A,136B of gateway8. In one such approach, each service10maintains its own application state and shares that application state with its counterparts in standby gateways8. In some examples, SRd164maintains the application state associated with each of the services10and shares the application state.

In one example approach, the addition or removal of signal-routes by SRd164causes routing protocol daemon142to send a routing protocol update message to routing protocol peers to advertise the changes in the routes. In one such example approach, this involves changing the cost of the route via, for example, the as-path-prepend command discussed above.

In some example approaches, the route change also has an effect on the VRRP configuration tracking this route, resulting in different VRRP priority advertisements as noted above. The newly advertised routes and changed VRRP priorities redirect traffic to the next preferred standby gateway8, and SRd164switches over the services mastership to that gateway8. In some such example approaches, VRRP is also used to communicate, to a SRd164in another gateway8, the need for a mastership transition. Finally, these advertisements serve to change the configurations of one or more services, as will be discussed next.

As noted in the discussion ofFIG. 11above, in one example approach, SRd164may be the services redundancy daemon of an SPU30acting as a Standby node in an N:1 Stateful Application Gateway Redundancy application. In that case, SRd164may track state of each of the N Master nodes in the Redundancy application. In one such example approach, when an SPU30associated with a node that previously was a Master node in the N:1 Stateful Application Gateway Redundancy application comes back online, it triggers a critical event in the SRd164associated with the standby node now acting as the Master. The SRd164associated with the Standby node then transitions mastership back to the previous Master as detailed inFIG. 13. In another such example approach, when an SPU30is added to replace a node that previously was a Master node in the N:1 Stateful Application Gateway Redundancy application comes back online, the action triggers a critical event in the SRd164associated with the standby node now acting as the Master. The SRd164associated with the Standby node then transitions mastership over to the new Master node as detailed inFIG. 13.

Examples illustrating use of signal-routes to configure operation of services provided by a network device such as service gateway8are shown inFIGS. 14-18and described next.

FIG. 14is a block diagram illustrating an example set of service chains of services according to one or more aspects of the techniques described herein. In the example of FIG.14, the service gateway network device (service gateway8) includes a forwarding plane130, a routing plane132and a service plane134. Forwarding plane130may be provided by dedicated forwarding integrated circuits normally associated with high-end routing and forwarding components of a network router.

Service gateway8may integrate a routing plane132and a service plane134in a manner that utilizes shared forwarding plane130. As in the service gateway8ofFIG. 3A, forwarding plane130may represent a rich and dynamic shared forwarding plane, in some cases distributed over a multi-chassis router. Moreover, forwarding plane130may be, as noted above, provided by dedicated forwarding integrated circuits normally associated with high-end routing components of a network router such that routing plane132and forwarding plane130operate as a high-end router. In one example approach, service plane134may be tightly integrated within service gateway8(e.g., by way of SPUs30of service cards136) so as to use forwarding plane130of the routing components in a shared, cooperative manner.

As seen inFIG. 14, routing plane132provides a routing component138that is primarily responsible for maintaining a routing information base (RIB)140to reflect the current topology of a network and other network entities to which service gateway8is connected. For example, as noted above, routing component138provides an operating environment for execution of routing protocols by a routing protocol process such as routing protocol daemon142(RPd). Routing protocol daemon142may represent a software component or module that communicates with peer routers and periodically updates RIB140to accurately reflect the topology of the network and the other network entities. While described as a daemon or software module executed by routing engine44, routing daemon61may be implemented as a hardware module or as a combination of both hardware and software.

Routing component138may receive this routing information via routing protocol daemon142and update or otherwise maintain RIB140to reflect a current topology of core network7. This topology may provide for multiple different paths through core network7to reach any given subscriber device16. In the example ofFIG. 1, a path exists from public network12through each of service gateways8to subscriber devices16. Routing component138in one of the gateways8may, in some instances, select the path to use to connect a subscriber device16to public network12.

In the example shown inFIG. 14, admin145may interface with routing component138via a user interface (UI) module146, which may represent a module by which a user or provisioning system may interface with routing component138. UI module146may, for example, include a command line interface (CLI), which may accept inputs in the form of commands and/or scripts, or may include a graphical user interface (GUI). An administrator (“admin145”) may interface with UI module146to configure various components service gateway8, including routing component138. Once configured, routing component138may then resolve RIB140to generate forwarding information. Routing component138may then interface with forwarding plane130to install this forwarding information into a forwarding information base (FIB)148.

Ingress forwarding component150A and egress forwarding component150B (“forwarding components150”) may represent software and/or hardware components, such as one or more interface cards (not shown), that forward network traffic. The terms “ingress” and “egress” are relative terms that refer to the packet flow direction of a packet149entering service gateway8as illustrated inFIG. 14. In one example approach, forwarding component150A maintains FIB148that associates network destinations with specific next hops and corresponding interface ports of output interface cards of service gateway8. In some such example approaches, routing component138generates FIB148in the form of a radix tree having leaf nodes that represent destinations within network7.

As seen inFIGS. 3A, 14 and 15, service plane134may represent a logical or physical plane that provides one or more services using SPUs30defined on service cards136. Service cards136A and136B (collectively “service cards136”) may represent physical cards that are configured to be inserted into service gateway8and coupled to forwarding plane130and routing plane132via a backplane, switch fabric or other communication medium. Service cards136may, for instance, comprise cards that couple directly to the switch fabric. Service cards136may be removable from service gateway8. Service cards136may have one or more service processing cores31. Service processing cores31may be aggregated into service processing units30and each SPU30may be assigned to one or more redundancy sets20as noted above.

Admin145may interface with UI module146to interface with routing component138to specify which packet flows are to undergo service processing by one or more of service cards136. After specifying these flows, routing component138may update RIB140to reflect that these flows are to undergo service processing, such that when resolving FIB148, the forwarding information may indicate that various flows are to undergo service processing. Often, this forwarding information may specify that these flows require service processing by specifying a next hop for these flows that directs packets of these flows to one of the SPUs30of service cards136(where this next hop may be referred to as an “internal next hop”), as described in further detail below. Additional next hops may be specified that are external to service gateway8, where the external next hop may specify, in this example, on which path the packet is to be forwarded. The internal next hop may be linked to the external next hop, where in this example, service gateway8may maintain two next hops (and possibly more) for any given flow. In one example approach, next hops between SPUs30are defined via the service next hop pairs defined for each SPU. The example ofFIGS. 4 and 16illustrate service chains that take advantage of these internal and external hops to apply a series of services to a packet, packet flow or session.

As noted above, service cards136may include one or more SPUs30; each SPU30is capable of applying one or more services. In the example shown inFIG. 14, service card136A supplies a firewall service via an SPU30implementing a firewall engine153and firewall policy storage159. In some examples, firewall engine153receives firewall rules (e.g., via UI module146) and stores the firewall rules at firewall policy storage139to be applied by firewall engine153. In some examples, routing component138stores firewall policies in routing plane132or forwarding plane130.

Service card136may include a control unit151, which may represent one or more general processors that execute software instructions, such as those used to define a software or computer program, stored to a non-transitory computer-readable medium such as a storage device (e.g., a disk drive, or an optical drive), or memory (such as Flash memory, random access memory or RAM) or any other type of volatile or non-volatile memory, that stores instructions to cause the one or more processors to perform the techniques described herein. Alternatively, control unit151may represent dedicated hardware as discussed above. In some instances, control unit151may be referred to as a processor.

In the example ofFIG. 14, forwarding component150A receives a packet249and, acting as an ingress forwarding component, invokes a flow control unit154. Flow control unit154represents a module that selectively directs packets to service plane134for processing. In some example approaches, service plane134is a virtual machine. Flow control unit154may access FIB148to determine whether packet249is to be sent to an internal next hop, e.g., one of the SPUs30of service plane134, or to an external next hop via another one of forwarding components that acts as an egress forwarding component for the flow to which packet249corresponds, such as, e.g., egress forwarding component150B.

In any event, flow control unit154may determine that packet249is to be transmitted to SPU30of service card136A for application by firewall engine153of the firewall rules stored in firewall policy storage139. In response to determining that packet249is to be transmitted to service card136so that the SPU30of the service card136can apply a service to packet249, in some examples, flow control unit154of ingress forwarding component150A may append an internal service packet header (which may also be referred to as a “service cookie”) before directing packet156to SPU30of service card136A of service plane134. Service card136A, or SPU30of service card136A, may receive this packet and remove the internal service packet header, parsing the ingress identifier from the internal service packet header. Control unit151of service card136may then invoke a service engine such as firewall engine153via SPU30, which applies the firewall policy rules to updated packet156, generating a serviced packet158that has had the service applied.

SPU30may then determine an internal next hop to which to forward the serviced packet158along the service chain. In the example ofFIG. 14, SPU30transmits serviced packet158back to flow control unit154, which, in this example, forwards the serviced packet158to egress forwarding component150B. Egress forwarding component150B in turn looks up a next hop to which to forward packet158forwards packet158to the next hop.

In some example approaches, firewall services may alternatively or additionally be implemented in one or more of the ingress forwarding component150A and the egress forwarding component150B. In some example approaches, a firewall network device separate from service gateways8A and8B (such as service node13inFIG. 1) provides firewall services.

In some example approaches, an administrator may configure a firewall filter to 1) restrict traffic destined for the Routing Engine based on its source, protocol, and application, 2) limit the traffic rate of packets destined for the Routing Engine to protect against flood, or denial-of-service (DoS) attacks, and 3) handle fragmented packets destined for the Routing Engine. In some such approaches, an administrator may define stateless firewall filters. In some example approaches, firewall engine153includes a stateless firewall filter used to enhance security through the use of packet filtering. Packet filtering enables firewall engine153to inspect the components of incoming or outgoing packets and then perform the actions specified on packets that match the criteria specified. The typical use of a stateless firewall filter is to protect the Routing Engine processes and resources from malicious or untrusted packets.

In some example firewall engines153, an administrator configures filters on service gateway8to filter packets passing through the gateway8. In one such approach, the administrator configures firewall engine153by grouping source and destination prefixes into disjoint sets defined as source classes and destination classes. In one such approach, source class usage (SCU) filters packets as a function of the Internet Protocol (IP) source address, or the IP source address and the IP destination address. SCU, therefore, makes it possible to track and/or filter packet traffic originating, for instance, from specific prefixes on the service provider core network7to specific prefixes on the customer edge.

Destination class usage (DCU), on the other hand, filters packets from customers by performing lookups of the IP destination address. DCU makes it possible, therefore, to track and/or filter traffic originating from the customer edge and destined for specific prefixes on service provider core router network7.

In one example approach, firewall engines153may be configured to protect service gateway8from excessive traffic transiting the router to a network destination or from traffic destined for the Routing Engine. Firewall filters that control local packets can also protect service gateway8from external incidents such as denial-of-service attacks.

In one example approach, an administrator may configure firewall engine153to control the data packets accepted on and transmitted from the physical interfaces. In one such example approach, the administrator may also control the local packets transmitted from the physical interfaces and to routing component138. In one local packet filtering approach, an administrator applies firewall filters on a loopback interface, which is the interface to the routing component138, to control local packets.

FIG. 15is a block diagram illustrating yet another example service gateway in accordance with the techniques described in this disclosure. In the example shown inFIG. 15, the firewall service is provided by firewall policy storage159A and/or firewall engine153A in ingress forwarding component150A and by firewall policy storage159B and firewall engine153B in egress forwarding component150B. In some example approaches, firewall policy storage159A and firewall engine153A in ingress forwarding component150A provide all firewall services in service gateway8while in other example approaches firewall policy storage159B and firewall engine153B in egress forwarding component150B provide all firewall services in gateway8. In yet other example approaches, service gateway forwards packets to a separate firewall network device (such as service node13inFIG. 1) where the firewall network device applies the desired firewall services before passing the packet back to gateway8.

FIG. 16is a block diagram illustrating an example set of service chains of services according to one or more aspects of the techniques described herein. In one example approach,FIG. 16illustrates a set of service chains302A-302D supported by a service gateway8. Service chains302represent an example set of service chains provided by computer security services300within, or external to, one or more service gateways8.

In this example, a service gateway8directs one or more subscriber packet flows304A along a first service chain302A to receive a firewall service310performed by an SPU30within service gateway8. Similarly, a service gateway8directs one or more subscriber packet flows304B along a second service chain302B for application of firewall service312and intrusion detection and prevention (e.g., deep packet inspection) service314. In one example approach, firewall service312and intrusion detection and prevention service314are performed within a single SPU30of gateway4. In another example approach, firewall service312and intrusion detection and prevention service314are performed by two different SPUs30of gateway4connected as a chain via their service next hop pairs. In yet another example approach, firewall service312and intrusion detection and prevention service314are performed by two different SPUs30located on different chassis, or by a combination of two or more of firewalls153A,153B and SPUs30. In service chain302C, a service gateway8directs packet flows304C to a HTTP filter316and a firewall service318. In service chain302D, a service gateway8directs packet flows304D to HTTP filter320, firewall service322and intrusion detection and prevention (e.g., deep packet inspection) service324. Once again, each chain302may be implemented on a single SPU30, or distributed across two or more SPUs30.

In one example approach, service gateway8receives notice of a signal-route change and uses the change in signal-route to dynamically change the operation of services such as firewall service312and intrusion detection and prevention (e.g., deep packet inspection) service314. The change may be as simple as disabling a filter, or it may involve the configuration of a number of different devices and a variety of protocols. In one example approach, master and standby state changes drive, for instance, the enabling and disabling of firewall filters, or may redirect traffic from a former master to the new master gateway. This ability to change operation of devices such as firewalls and other services will be described in the context of firewall configuration but can be extended to other devices that operate on packets, such as HTTP filter316and intrusion detection and prevention service314.

As can be seen inFIGS. 14 and 15, routing plane132includes a management daemon160coupled to user interface module146and to a configuration database162. Management daemon160receives configuration information from user interface module146and stores the configuration information in configuration database162. Routing plane132also includes a services redundancy daemon (SRd)164(also referred to herein as a services redundancy process), which operates in conjunction with route policies database166and signal-route vector70to configure and control redundant services delivery system27. SRd164also interfaces with service plane134, such as to permit configuration of service cards136A,136B by management daemon160. SRd164may represent a software module that updates RIB140based on configuration database162and route policies database166. While described as a daemon, software process, or software module executed by routing component138, SRd164may be implemented as a hardware module or a combination of both hardware and software.

User interface module146may represent a software and/or hardware module that presents an interface with which an administrator or an administrative device, represented by “ADMIN”145, may interact to specify certain operational characteristics of service gateway8. In response to invocation by admin145, user interface module146interacts with other components of service gateway8, such as to retrieve, configure, copy, and/or delete policy configuration data stored in route policies database166, update service data of services plane143via SRd164, and to perform other management-related functions. In one example approach, admin145may interact with user interface module146to enter configuration information for SRd164, such as configuration information defining redundancy events, redundancy policies, redundancy sets and redundancy groups; this configuration information is also stored in configuration database162.

In one such example approach, on assuming mastership, services redundancy daemon164in services gateway8begins to monitor for critical events as defined by the redundancy events configuration for each of its SPUs30. If SRd164detects that a critical event occurred, SRd164adds or removes a route from the RIB140based on a relevant route policy stored in route policies database166. In some example approaches, SRd164implements a routing policy configured to advertise routes based on the existence or non-existence of signal-routes using the if-route-exists condition as discussed above.

In one example approach (e.g., where SRd164is executing on a gateway that is no longer the master), SRd164also notifies the preferred standby gateway8that it is to take over mastership. In one such example approach, SRd164notifies the services redundancy daemon164of the preferred standby gateway8A of the change using ICCP.

As noted above, a gateway8may use signal-route changes to dynamically change the operation of services such as firewall filters to, for instance, reflect the needs or configuration of the current master service gateway. The change may be as simple as disabling a filter, or it may involve the configuration of a number of different network devices and service cards and a variety of protocols. In one such approach, master and standby state changes drive the addition and deletion of signal-routes and these changes may be used to change the operation of firewall engine153.

In one example approach, SRd164executing on gateway8detects an event and executes a service redundancy policy stored in route policies database166. In one such approach, the service redundancy policy defines changes to services executing on SPUs30on one or more service cards136. For instance, SRd164may change the configuration of firewall engine153by writing firewall configuration bits read from the service redundancy policy to firewall policy storage159or to registers in firewall engine153. The firewall configuration bits, in some instances, may change the data rate of certain packet traffic, may discard certain packet traffic, or may perform other services on such traffic. In some approaches, traffic is grouped as defined in the service redundancy policy and firewall actions (also as defined in the service redundancy policy) are defined by group and applied to particular groups.

In another example approach, the service redundancy policy defines changes to one or more services based on the existence or non-existence of signal-routes using the if-route-exists condition as discussed above. In one such approach, the service redundancy policy defines changes to services executing on SPUs30of one or more service cards136. For instance, SRd164may change the configuration of firewall engine153by writing firewall configuration bits as discussed above. The firewall configuration bits, in some instances, may change the data rate of certain packet traffic, may discard certain packet traffic, or may perform other services on such traffic. In some approaches, traffic is grouped as defined in the service redundancy policy and firewall actions (also as defined in the service redundancy policy) are defined by group and applied to particular groups.

FIG. 17is a block diagram illustrating the use of signal routes to change a service-related configuration, such as a traffic flow direction, in accordance with one or more aspects of the techniques described in this disclosure. In one example approach, SRd164detects a redundancy event associated with a redundancy set351used by application350and updates the appropriate signal route352in signal-route vector70based on the redundancy event to reflect a change in mastership. In response to the change in the signal route352, RPd142changes the route advertisement, resulting in a change in RIB140. In one example approach, the changes in RIB140invoke policy statements in redundancy policy354to, for instance, direct the flow of network traffic to the new master service gateway. In some example approaches, the redundancy policy may also make changes in parameters of processes applied to network traffic being directed to the new master service gateway.

For example, in one approach, the changes in RIB140invoke policy statements in redundancy policy354to, for instance, change class markings (e.g., SCU or DCU markings) in a firewall policy. In another example approach, the changes in RIB140invoke policy statements in redundancy policy354to, for instance, change markings that are not associated with classes. The firewall policies for one or more of the firewalls153implemented on SPUs30are then changed to reflect the new markings. In yet another example approach, the changes in RIB140invokes policy statements in a service redundancy policy354to modify a service, such as a firewall or other security-related service, on one or more of SPUs30, as detailed inFIG. 13.

FIG. 18is a flowchart illustrating example configuration of services as a function of the changes in signal-routes during switchover to a peer in accordance with techniques described herein.FIG. 18is described for purposes of example in terms of example operation of a service gateway such as service gateway8ofFIG. 15 or 16. In the example shown inFIG. 18, service gateway8receives configuration data defining a redundancy event (400). For example, service gateway8receives configuration data defined by an administrator145. In one such example, administrator145defines a redundancy event ACQU_MSHIP_MANUAL_EV and configures the redundancy event to monitor link down events, such as via the following example input:

Service gateway8receives configuration data defining a redundancy policy at402. The redundancy policy details the actions an application executing in service gateway8should take in the event of any of the link-down conditions monitored by the redundancy event ACQU_MSHIP_MANUAL_EV. An example redundancy policy for redundancy event ACQU_MSHIP_MANUAL_EV follows:

In the example shown inFIG. 18, SRd164of routing component138assumes mastership (404) and begins to monitor for critical events such as events defined by ACQU_MSHIP_MANUAL_EV (406). If SRd164detects that a critical event has occurred, SRd164adds or removes a route based on a relevant route policy stored in route policies database166(408) (such as a route policy defined based on the ACQU_MSHIP_POL presented above. In one example approach (e.g., where SRd164is executing on a gateway that is no longer the master), SRd164also notifies the preferred standby gateway8that it is to take over mastership. In one such example approach, SRd164notifies SRd164of the preferred standby gateway8B using ICCP.

SRD164then advertises the change in routes (410) in the manner defined in the route policy stored, for instance, in route policies database166. In one example approach, SRd164executes a route policy stored in route policies database166to communicate the advertised priorities for one or more routes via VRRP.

In one example approach, the state of each signal-route is shown in signal-route vector70, such as illustrated inFIG. 8B. In the example shown inFIG. 8B, signal-route vector70includes one or more signal-routes72and one or more signal-route states74organized as signal-route/signal-route state pairs. The state of a particular signal-route72may, in some examples, be determined as follows:

SRd164then executes redundancy policies tied to services or devices. In the example approach ofFIG. 18, SRd164configures a firewall based on a service redundancy policy associated with the redundancy event (412). The firewall may be based on a firewall engine153such as is illustrated inFIGS. 14 and 15, or it may be a separate networked firewall device. For instance, in a firewall filter example, SRd164retrieves a service redundancy policy from route policies database166and applies the service redundancy policy to firewall engine153SPU30ofFIG. 14to change the operation of firewall engine153. Routers in the network also receive the advertisements and, based on the advertised routes, begin forwarding network traffic to the next preferred standby gateway8for application of services (412).

In one example approach, each SPU30in a service gateway8may query SRd164to determine if it is the Master node or the Standby node for a particular redundancy set. In an N:1 Stateful Application Gateway Redundancy application, SRd164may need to keep track of up to N different redundancy states for that SPU alone.

A service redundancy policy may define rules to be added, deleted or modified in the rules stored in firewall policy storage159or configuration bits that are written to firewall policy storage159or to a register in firewall engine153to change the operation of firewall engine153. In a similar manner, SRd164retrieves a service redundancy policy from route policies database166and applies the service redundancy policy to change the filter parameters of firewall engine153A and/or firewall engine153B ofFIG. 15or to add, delete or modify rules stored in firewall policy storage159A or159B. In one example approach, class-based filter match conditions are used to filter or to change the data rate of packet traffic based on a source or a destination address or on ranges of source addresses or destination addresses. Class-based filter conditions match packet fields based on source class (via, e.g., SCU) or destination class (via, e.g., DCU). A source class is a set of source prefixes grouped together and given a class name. A destination class is a set of destination prefixes grouped together and given a class name.

In one example approach, SRd164executes a service redundancy policy stored in route policies database166of service gateway8that modifies the firewall filter parameters by marking source class usage (SCU) bits in a register used by firewall engine153. In another example approach, an administrator modifies the firewall filter parameters by marking destination class usage (DCU) bits in a register used by firewall engine153. SRd164may, for instance, configure firewall engine153ofFIG. 14or firewall engine153A ofFIG. 15to change the data rate of packets in a first SCU class or a first DCU class which discarding all traffic in a second SCU or a second DCU class. In one such approach, this configuration may include writing configuration bits to firewall engine153and modified rules to firewall policy database159. In yet another example approach, SRd164retrieves a combination of configuration bits and firewall policy rules from a service redundancy policy stored in route policies database166and configures firewall engine153and firewall policy storage159to, for instance, cause firewall engine153to discard packet fragments when a given signal-route exists or does not exist.

In one example approach, service gateway8applies modifications to a firewall service provided by firewall engine153, firewall engine153A or firewall engine153B based on an if-route-exists condition as follows:

Firewall filters with match conditions based on the selected SCU bits filter the packets that match the conditions. In one example approach, filtered traffic flows to the Standby Service Gateway8B. Network devices such as firewalls and intrusion detection and prevention (IDP) device may be configured in similar ways.

In one example approach class-based filter match conditions may be used to filter based on a source or a destination address. In one such example approach, an administrator may specify the source class in the following way:

Similarly, an administrator may specify a destination class:

In one example approach, firewall actions are performed in a firewall engine153under control of rules stored in firewall policy storage159. For instance, firewall policies may define that firewall engine153may perform a terminating action such as an “accept” or a “discard” to accept a received packet or discard a received packet, respectively, for example. Based on the firewall policies, firewall engine153may alternatively or additionally perform one or more nonterminating actions such as incrementing a counter, a logging information about the packet header, sampling the packet data, sending information to a remote host using system log functionality, forwarding the packet to a next hop, and applying a policer to rate-limit traffic, for example. Firewall engine153may alternatively or additionally perform a flow control action on the packet. Firewall engine153may implement standard firewall actions such as Deep Packet Inspection and actions to detect or mitigate distributed denial-of-service (DDOS) attacks.

In one example approach, as noted above, the firewall is a network device separate from the service gateway. In one such approach, the firewall includes a number of rules that define how the firewall acts on packet traffic. In one such example approach, one or more of the rules include an if-route-exists condition that selectively applies the firewall rules when a route exists. For instance, a firewall may be configured to perform a Deep Packet Inspection of packets when service gateway8A is master but not when service gateways8B or8C are the master. In one such example approach, the firewall reads the contents of route signal vector70to determine if an address exists. In another such example, the SRd164that detected the event uses a service redundancy policy stored in route policies database166that sends new configuration data and/or firewall policy rules to the firewall. Similar route policies may be used to configure other services in service gateway8and services in other networked devices as well.

The techniques described above may offer advantages over previous approaches to redundancy between gateways. SR daemon164on routing component138may continuously monitor preconfigured Redundancy Events. On the occurrence of Redundancy Events, SR daemon164adds or removes signal-routes specified in the Redundancy Policy and updates Stateful Sync roles appropriately. The resulting route change affects the routing policy connected to this route and causes routing protocols executing on the gateways to advertise routes differently. If VRRP is being used, VRRP configuration tracking of this route results in different VRRP priority advertisements. The newly advertised routes and VRRP priorities cause routing peers to redirect traffic to the standby gateway8and SRd164switches over the services mastership to the standby gateway8. In one example approach, as noted above, VRRP may also be used to notify a SRd164on another gateway8that it is to take over mastership of the redundancy set.

In addition, the techniques described above may offer advantages in configuring network devices to reflect a change in mastership. In one such approach, for example, a change in mastership is used to implement changes in in service or changes in a firewall policy.

In one example approach, a method includes receiving, at a service gateway having a services redundancy manager and a plurality of service processing cores, service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set; establishing the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information; receiving, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set; placing the first and second redundancy sets in the standby redundancy state; defining a first signal-route, the first signal-route used to trigger actions related to the first redundancy set; monitoring for the critical event; and in response to detecting the critical event, transitioning the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, adding the first signal-route to a Routing Information Base (RIB), and advertising the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In another example approach, a system includes a network, N redundancy sets, wherein N is greater than one, wherein each redundancy set of the N redundancy sets has a master redundancy state, a standby redundancy state and one or more redundancy policies, wherein the one or more redundancy policies include at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set and a plurality of service gateways connected to the network, wherein each service gateway includes a services redundancy manager and a plurality of service processing cores, wherein the services redundancy manager tracks redundancy state for redundancy sets assigned to the service gateway of the services redundancy manager. One of the plurality of service gateways is a standby service gateway, wherein the standby service gateway assigns one or more service processing cores to a first service processing unit and assigns the N redundancy sets to the first service processing unit. One or more of the plurality of service gateways host second service processing units, wherein hosting includes assigning one or more service processing cores to each second service processing unit and assigning one of the N redundancy sets to each second service processing unit, wherein each of the N redundancy sets is assigned to a different second service processing unit. When the services redundancy manager of the standby service gateway detects a redundancy event associated with a particular one of the N redundancy sets, the services redundancy manager of the standby service gateway transitions the particular redundancy set from the standby redundancy state to the master redundancy state on the standby service gateway and, when the services redundancy manager of the service gateway having the second service processing unit that is associated with the particular redundancy set detects the redundancy event, the services redundancy manager transitions the particular redundancy set in the service gateway from the master redundancy state to the standby redundancy state.

In one such example approach, each services redundancy manager tracks the redundancy states of the redundancy sets to which service gateway service processing units are assigned.

In another such example approach, a first signal-route is used to trigger actions in the system related to the first redundancy set on occurrence of a redundancy event. When the services redundancy manager of the standby service gateway transitions the first redundancy set from the standby redundancy state to the master redundancy state on the standby service gateway, the service gateway adds the first signal-route to a Routing Information Base (RIB) and advertises the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In another example approach, a service gateway includes a network interface, a service plane having a plurality of service processing cores connected to the network interface; and a routing plane connected to the network interface, the routing plane including memory and one or more processors connected to the memory, wherein the memory includes instructions that, when executed by the one or more processors, cause the processors to establish a services redundancy daemon, receive service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set, establish the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information, receive, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set, place the first and second redundancy sets in the standby redundancy state, define a first signal-route, the first signal-route used to trigger actions related to the first redundancy set, monitor for the critical event and, in response to detecting the critical event, transition the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, add the first signal-route to a Routing Information Base (RIB) and advertise the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In one such example approach, the instructions that, when executed by the one or more processors, cause the processors to transition the first redundancy set from the standby redundancy state to the master redundancy state include instructions that, when executed by the one or more processors, cause the processors to implement the actions to be taken on occurrence of a redundancy event associated with the respective redundancy set.

In another such example approach, the instructions that, when executed by the one or more processors, cause the processors to transition the first redundancy set from the standby redundancy state to the master redundancy state include instructions that, when executed by the one or more processors, modify a service associated with the first redundancy set.

In yet another such example approach, the memory further includes instructions that, when executed by the one or more processors, cause the processors to track, within the services redundancy manager, the redundancy state of each redundancy set associated with the service gateway.

In another example approach, a computer readable medium includes instructions that, when executed by one or more processors, cause the one or more processors to establish a services redundancy daemon, receive service processing unit configuration information, the service processing unit configuration information defining a service processing unit, assigning service gateway resources, including one or more of the gateway service processing cores, to the service processing unit, and associating a first redundancy set and a second redundancy set with the service processing unit, each of the first and the second redundancy sets having a master redundancy state, a standby redundancy state and one or more redundancy policies, including at least one redundancy policy defining actions to be taken on occurrence of a redundancy event associated with the respective redundancy set, establish the service processing unit in the service gateway using the service gateway resources assigned in the service processing unit configuration information, receive, at the service gateway, configuration information defining one or more redundancy events for the first redundancy set, wherein the one or more redundancy events include a critical event that, when detected, initiates a transition from master redundancy state to standby redundancy state in the first redundancy set, place the first and second redundancy sets in the standby redundancy state, define a first signal-route, the first signal-route used to trigger actions related to the first redundancy set, monitor for the critical event and, in response to detecting the critical event, transition the first redundancy set, via the services redundancy manager, from the standby redundancy state to the master redundancy state on the service gateway, add the first signal-route to a Routing Information Base (RIB) and advertise the first signal-route to routing protocol peer network devices, wherein the advertised first signal-route causes the routing protocol peer network devices to route traffic associated with the first redundancy set to one or more other service gateways.

In one such example approach, the computer readable medium further includes instructions that, when executed by the one or more processors, cause the processors to track, within the services redundancy manager, the redundancy state of each redundancy set associated with the service gateway.

A computer-readable medium may form part of a computer program product, which may include packaging materials. A computer-readable medium may comprise a computer data storage medium such as random-access memory (RAM), read-only memory (ROM), non-volatile random-access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), Flash memory, magnetic or optical data storage media, and the like. In some examples, an article of manufacture may comprise one or more computer-readable storage media.

Various example approaches have been described. These and other approaches are within the scope of the following claims.