Patent Publication Number: US-8996722-B2

Title: Softrouter feature server

Description:
CROSS-REFERENCES 
     The present application claims the benefit of provisional application No. 60/623,885, entitled “SoftRouter: Router Disaggregation,” filed Nov. 1, 2004. In addition, the present application is related to copending application Ser. No. 11/147,642, entitled “SoftRouter,” Ser. No. 11/147,472, entitled “SoftRouter Protocol Disaggregation,” Ser. No. 11/147,665, entitled “SoftRouter Protocol Failovers,” Ser. No. 11/147,937, entitled “SoftRouter Separate Control Network,” Ser. No. 11/147,491, entitled “SoftRouter Dynamic Binding Protocol,” which were filed on the same date as the present application, Jun. 8, 2005. The provisional and related applications are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of networking and, in particular, relates to feature servers and networking applications. 
     BACKGROUND OF THE INVENTION 
     Internet protocol (IP) provides end-to-end datagram delivery service to protocols and applications and can use any link-layer technology that delivers packets.  FIG. 1  illustrates the problem of emerging applications driving more functions to IP, expanding the “waist” of the hour glass. These emerging applications include email, www phone, simple mail transfer protocol (SMTP), hypertext transfer protocol (HTTP), real time protocol (RTP), transmission control protocol (TCP), user datagram protocol (UDP), and other protocols, which involve quality of service (QoS), multicast, mobility, security, virtual private network (VPN), and other features and are transported using Ethernet, point-to-point protocol (PPP), carrier sense multiple access (CSMA) asynchronous transfer mode (ATM), synchronous optical network (SONET), and other protocols over copper, fiber, radio, and other physical transport means. Conventional routers try to incorporate all of the new IP functions into routers, resulting in duplication of complex functions in multiple routers of a network. This also increases capital and operational expenses. 
     The demand for new features, such as VPN exceeds or will soon exceed the scalability allowed in conventional networks. Emerging applications, such as voice over IP (VOIP) and IP video are putting more stringent requirements (e.g., reliability) on conventional networks. There is a need for disaggregation of router hardware from router software using open, standards-based protocols for internetworking. 
     SUMMARY 
     Various deficiencies of the prior art are addressed by the present invention of feature servers in an exemplary SoftRouter architecture, which has many embodiments. 
     One embodiment is a network architecture including a plurality of forwarding elements (FEs) at least one control element (CE), and at least one feature server (FS). The FEs forward packets. The CE is in communication with at least a portion of the FEs for controlling and providing routing information to the FEs. The FS implements at least one application and is in communication with the FEs and CE. The CE and FS are logically separate from the FEs. 
     Another embodiment is a network architecture including a data plane and a control plane. The data plane includes a plurality of forwarding elements (FEs) for packet forwarding. There is at least one control element (CE) for configuring, controlling, and providing routing information to the FEs via a standard protocol. The CE is dynamically bound to the FEs. There is at least one feature server (FS) for adding network-based functionality. The control plane is logically separate from the data plane. The control plane includes the CE and FS. 
     Yet another embodiment is a network architecture including at least one control element (CE) and at least one feature server (FS). The CE controls and provides routing information to a plurality of forwarding elements (FEs). The FEs forward packets. The FS implements at least one application and is in communication with the FEs and CE. The CE and FS are logically separate from the FEs. 
     A further embodiment is a network architecture, including a plurality of forwarding elements (FEs) and at least one feature server (FS). The FEs forward packets. Each FE is controlled by and receives routing information from at least one control element (CE). The FS implements at least one application and is in communication with the FEs and CE. The CE and FS are logically separate from the FEs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates that problem of emerging applications driving more functions to Internet protocol (IP); 
         FIG. 2  is a block diagram showing a traditional router; 
         FIG. 3  is a block diagram showing a high level abstraction of an exemplary SoftRouter architecture; 
         FIG. 4  is a block diagram showing a traditional router-based network; 
         FIG. 5  is a block diagram showing one embodiment of a network based on the exemplary SoftRouter architecture; 
         FIG. 6  is a block diagram showing an exemplary network having a feature server; 
         FIG. 7  is a block diagram showing an IP routing application of an embodiment of the exemplary SoftRouter architecture; 
         FIG. 8  is a block diagram showing a data over optical application of an embodiment of this exemplary SoftRouter architecture; 
         FIG. 9  is a block diagram showing quality of service (QoS) support by an embodiment of the exemplary SoftRouter architecture; 
         FIG. 10A  is a block diagram showing a network with route reflectors  900  in the prior art; 
         FIG. 10B  is a block diagram showing scaling border gateway protocol (BGP) route reflectors for an embodiment of the exemplary SoftRouter architecture; 
         FIG. 11  is a block diagram showing network-based virtual private network (VPN) support and server-based BGP/multiprotocol label switching (MPLS) VPNs, according to an embodiment of the exemplary SoftRouter architecture; 
         FIG. 12  is a block diagram showing scaling mobile IP, according to an embodiment of the exemplary SoftRouter architecture; 
         FIG. 13  is a block diagram showing IPv6, according to an embodiment of the exemplary SoftRouter architecture; and 
         FIG. 14  is a high level block diagram showing a computer. To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention will be primarily described within the general context of an embodiment of an exemplary SoftRouter architecture, however, those skilled in the art and informed by the teachings herein will realize that the disaggregation concept may be used to generate various other embodiments of network architectures and that the invention is applicable to local area networks (LANs), metropolitan area networks (MANs), wide area networks (WANs), and other networks, many open systems interconnection (OSI) layers, gateway protocols, serial line protocols, protocol stack routing and bridging protocols, many other protocols, traffic management, optical, edge/core routing, wireless, cable, data centers, fault management, configuration management, accounting management, performance management, security management, other network management, enterprise, government, military applications, and many other different kinds of networking characteristics and applications. 
     IP is becoming the universal protocol for transport datagrams. Most applications ride on top of IP and IP can be implemented over many diverse link layer technologies. 
     Traditionally, the main function of the IP layer is packet forwarding. That is, when a packet is received at a router, the destination address in the IP packet is matched against a local forwarding table, this yields the output port to which the IP packet should be delivered. The entries in this local forwarding table are maintained by running some form of routing protocols. In the exemplary SoftRouter architecture, the routing protocols need not be run locally at the router, rather they can be run remotely on CEs and the changes in the entries can be communicated using some form of standardized protocols. This separation of forwarding and control allows the FEs to stay simple, while most of the intelligence and complexity is moved to the CEs. 
     As IP matures and grows, more and more features are being added to the IP layer. Some examples include: multicast, security (IPSec), monitoring, accounting, mobile IP, and VPN. Each of these feature additions typically requires additions to both the forwarding and control elements. For example, IP multicast requires an additional multicast forwarding table on the forwarding path and the use of new multicast routing protocols such as protocol independent multicast (PIM) for control. 
     In the exemplary SoftRouter architecture, additions to the IP layer mean addition of functions to a router as both forwarding and control are implemented in the same box. The feature server (FS) follows the basic disaggregation idea as discussed with respect to the exemplary SoftRouter architecture with one difference being that instead of disaggregating basic control, the FS is concerned with disaggregating the control as associated with the more advanced value-added features. The separation here is logical. That is, there is a well-defined interface between the different entities: FE, CE, and FS. 
     This interface can be implemented in many ways. For example, if an implementation integrates the FE and FS in the same physical platform, the interface can be implemented via a local inter-process communication or even a function call (if they are physically on the same processor). Or if an implementation physically disaggregates the FS in a remote physical box from the FE, then the interface can be implemented via a communication protocol. 
     In the exemplary SoftRouter architecture, disaggregation of router hardware from router software using open, standards-based protocols for internetworking has many benefits. The disaggregation concept decouples suppliers for each component, which lowers barriers to entry for hardware vendors and encourages independent software vendors (ISVs) to invest in developing carrier-class routing software to supply new hardware market entrants. This disaggregation concept allows each component to focus on its own innovation curve. Hardware manufacturers can focus on the highest speeds per density at the lowest costs, decreasing capital expenditures and software manufacturers can focus on new applications and manageability, increasing revenue while decreasing operating expenses. 
     An exemplary embodiment of an exemplary SoftRouter architecture is an approach to disaggregating the complex IP functions demanded by emerging applications. SoftRouter centralizes and allows sharing of complexity. SoftRouter enables scalable introduction of new functions without unduly encumbering IP forwarding functions. 
       FIG. 2  shows a traditional router  200  having integrated control and transport planes. The traditional router  200  has software  202  and hardware  204  communicating through a proprietary interface  206 . 
     By contrast,  FIG. 3  shows a high level abstraction of this exemplary SoftRouter architecture  300  that disaggregates the control and transport planes in separate hardware that communicate using standard protocols. The SoftRouter architecture  300  has a control element and features server component  302  and a packet forwarding element component  304  that communicate using a standards-based protocol  306 . 
       FIG. 4  shows the traditional router architecture, which has a number of interconnected routers  400 . 
       FIG. 5  shows one embodiment of the exemplary SoftRouter architecture  500 . In this exemplary SoftRouter architecture  500 , the software servers include control elements (CEs)  502  and feature servers (FSs)  504 . CEs  502  are responsible for traditional routing, e.g., for both interior gateway protocol (IGP) (e.g., open shortest path first (OSPF)) and exterior gateway protocol (EGP) (e.g., border gateway protocol (BGP)). FSs  504  are responsible for value-added functions and network-based applications, e.g., QoS, security, VPN, and mobile IP. Both CEs  502  and FSs  504  interface to forwarding elements (FEs)  506 . CEs  502  and FSs  504  may have additional interfaces to each other. This exemplary SoftRouter architecture separates and centralizes the software-based route controller (as implemented in a CE and value-added functions as implemented in a FE) from the predominantly hardware-based transport and packet forwarding. 
     A FS  504  facilitates adding optional network-based functionality to an embodiment of the SoftRouter architecture in ways that scale better than the traditional router architectures. A FS  504  may have an application programming interface (API) allowing network-based functionality to be created by others. Some examples of network-based functionality include QoS support, scaling BGP route reflectors, network-based VPN support, scaling mobile IP support, introducing IPv6 into existing and future networks, end-to-end network security, and network monitoring (metering). Network-based functionality adds value to embodiments. Some allow service providers to charge fees for providing an optional service, such as QoS and security. The FS  504  hosts one or more applications of network-based functionality and the applications may be activated at a particular time. Because the FS  504  is centralized in the exemplary SoftRouter architecture, the FS  504  is able to provide an application for a number of users, clients, enterprises, and the like. For example, a FS  504  may host a particular service that enterprise A uses, but enterprise B does not use. A FS  504  may host a particular service that many enterprises use, but it only needs to be installed once at the FS  504  and not for each enterprise. Unlike the traditional router architecture, the FS  504  is not in each of the forwarding elements, but is in a control plane in the exemplary SoftRouter architecture. 
     There are many benefits to customers, including lower costs, new revenue opportunities, better scalability, added reliability, and increased security. Lower costs come from commoditized, standards-based hardware with a lower capital expense and dedicated control plane servers, implying fewer management points and a lower operational expense. There are new revenue opportunities, because network-based applications to support new services that are more easily added using open application programming interfaces (APIs) and incremental deployment is made simpler through centralized management. There is better scalability, because centralized control plane servers are easier to scale using well-established server scaling techniques. There is added reliability, because forwarding elements are more robust due to reduced software and other reliability enhancing mechanisms, (e.g., failover and overload control) that are easier to implement in the server-based control plane. There is increased security, because the centralized control plane servers are easier to secure using perimeter defense systems, e.g., firewalls. 
       FIG. 6  shows an exemplary network having a feature server. This exemplary network is divided into three domains: domain 1  600 , domain 2  602 , and domain 3  604 . In domain 1  600 , there four FEs  506  connected to two FSs  504  and one CE  502 . In domain 2  602 , there are two FEs  506  connected to two of the FEs  506  in domain 1 and connected to a CE  502  and a FS  504 . In domain 3  604 , there are two FEs  506 , one FE  506  connected to an FE  506  in domain 1  600  and another FE  506  connected to an FE  506  in domain 2  602 . The two FEs  506  in domain 3  604  are also connected to an FS  504  and a CE  502 . 
     The FSs  504  are not necessarily the same. Each FS  504  may be implementing different applications. The operation of a FS  504  may include interaction with one or more of FEs  506 , CEs  502 , and other FSs  504 . 
     A FS  504  may interact with a FE  506 . In one scenario, the FE  506  collects information from the forwarding path and sends the information to the FS  504  for processing. Examples of such information include protocol packets that are received the FE  506  or local information (e.g., packet count) gathered by the FE  506 . Based on the result of its processing, a FS  504  can also send a command to a FE  506  to affect its action. For example, in a security application, the FS  504  installs a packet filter on the FE  506  so that packets matching the packet filer criteria are dropped. 
     A FS  504  may interact with a CE  502 . For example, a FS  504  that is performing traffic engineering for a domain needs to have information about the routing topology of the network. In the exemplary SoftRouter architecture, the routing topology is maintained by CEs  502 . In the reverse direction, if a FS  504  decides to change certain routes based on traffic engineering considerations, the FS  504  notifies a CE  502  of the route changes, which, in turn, propagates the route changes down to the FEs  504 . 
     A FS  504  may interact with another FS  504  in the same domain or in a different domain. Depending on the applications, multiple FSs  504  in the same domain may need to work together. The relationship between the FSs  504  varies depending on the application. For some applications, the FSs  504  may work as peers in a completely distributed fashion and, for some other applications, the FSs  504  may work in a master-slave relationship, where a particular FS  504  acts as the master for the whole group. An application where a peer relationship exists between FSs  504  is a security monitoring. Each FS  504  controls a number of FEs  506  that have firewall capability and all FSs  504  cooperate to implement the control for the aggregate distributed firewall. Specifically, any traffic deemed undesirable is blocked in firewalls and the control is propagated through the distributed set of FSs  504 . An application where a master-slave relationship exists between FSs  504  is traffic engineering. A number of FSs  504  serve to collect the current traffic usage information, but there is only a single path computation element (the master FS  504 ) that decides which changes to make. 
     Inter-domain FSs  504  interactions also vary depending on the application, but, typically, the FS  504  interaction is more of the peer-to-peer nature. One use of inter-domain FS interaction is to implement a value-added protocol that has been agreed on by a confederation of service providers (domains). In this way, a new feature is deployed incrementally first among only a small set of providers. New providers join in by simply deploying the needed feature on its FS  504 . An example of this is specialized routing for selected applications. For example, if a confederation of service providers agrees to specialized routing performed for VOIP traffic for voice quality reasons, then the service providers deploy the new VOIP traffic routing protocol on their respective FSs  504 . The FSs  504  then cooperate among themselves to compute the best route for VOIP traffic. 
     Another exemplary embodiment of the SoftRouter architecture includes FEs  506  for switching, a SoftRouter having CEs  502  for layer  3  control and FSs  504  and applications for VPN and other application support. This exemplary SoftRouter architecture has many applications, including IP routing and data over optical, such as voice over IP (VOIP) and IP video. 
       FIG. 7  shows an IP routing application of an embodiment of this exemplary SoftRouter architecture. This exemplary SoftRouter architecture can be applied to enterprise  700 , access  702 , and core  704  networks. 
       FIG. 8  shows a data over optical application of an embodiment of this exemplary SoftRouter architecture. In  FIG. 8 , there is an enterprise network  800 , a SONET/synchronous digital hierarchy (SDH) metro network  802  with integrated packet switching, point of presence (POP)/IP services  804 , and a SONET/wavelength division multiplexing (WDM) core network  806 , which are interconnected. 
     In the enterprise network  800 , there is enterprise data access  808  for a number of computers  810  via a router  400  at digital signal, level 1 (DS0)/digital signal, level 1 (DS1)/digital signal, level 3 (DS3). There is enterprise voice  812  for a number of telephones  814  via a private branch exchange (PBX) switchboard at DS0/DS1. The router  400  and PBX switchboard are connected to the SONET/SDH metro network  802 . 
     In the enterprise network  800 , there is another Ethernet switch/route  816  and router  400  connecting more computers  810  and telephones  814  with VOIP device  818 . The router  400  and VOIP device  818  are also connected to the SONET/SDH metro network  802 . 
     In the SONET/SDH metro network  802 , there is time-division multiplexing (TDM) of voice  820  from the enterprise network  800  over a network of FEs  506 , which are connected to a SoftRouter having CEs  502  and/or FSs  504 . The SONET/SDH metro network  802  is connected to POP/IP services  804 . 
     In the POP/IP services  804 , there is a network of core routers  400 . The POP/IP services  804  are connected to the SONET/WDM core network  806 . 
     In the SONET/WDM core network  806 , there is high order circuit switching (synchronous transport signal, level 1 (STS-1)) to a core optical network  822 . 
     Some embodiments of this data over optical application include Ethernet interfaces and switching and provisioned multiprotocol label switching (MPLS) for pseudo-wire emulation (PWE). 
     There are many benefits of this data over optical application of the exemplary SoftRouter architecture, including lower management cost, more robust control plane, and higher element reliability. This is because the control plane software is located in POPs, not distributed info individual optical boxes. This application allows incremental deployment of data capability. Control servers can be incrementally deployed as data capability is incrementally added. 
     An embodiment of the exemplary SoftRouter architecture uses SoftRouter protocol and other protocols among the different SoftRouter elements. If the SoftRouter protocol becomes standardized, vendors can produce commoditized FEs  506  or open their existing boxes to support the SoftRouter protocol. ISVs can produce software for incorporation into CEs  502  and FSs  504 . An ecosystem of FEs  506 , CEs  502 , and FSs  504  can be created to allow service providers to mix and match network elements. 
     FSs  504  can provide many different network-based functions and services to next generation networks. For example, enhancing QoS support, scaling BGP route reflectors, network-based VPN support, scaling mobile IP support, introducing IPv6 into existing and future networks, and enhancing end-to-end network security. 
       FIG. 9  shows QoS support by an embodiment of the exemplary SoftRouter architecture. There is a control plane network  900  that is separate from the IP/MPLS forwarding data plane  902 . In the control plane network  900 , a number of routing and TE servers/controllers  904 , which are labeled A′, B′, C′, D′, and E′, form a network. In the IP/MPLS forwarding data plane  902 , data packets are routed based on data plane topology information and traffic engineered paths. The IP/MPLS forwarding data plane  902  includes a number of FEs  506 , labeled A, B, C, D, and E, in a network. Although  FIG. 9  shows the same number of TE servers/controllers  904  (e.g., CEs  502  and FSs  504 ) as FEs  506 , preferably, there are less elements in the control plane network  900  than in the data plane network  902 , such as a 1:10 ratio where 1 CE  502  controls 10 FEs and 1 FS  504  serves applications to the 10 FEs. 
     The exemplary SoftRouter architecture shown in  FIG. 9  has many benefits for QoS and traffic engineering (TE). TE needs accurate link state monitoring. TE and QoS routing computations are more computationally intensive than the shortest path computations of OSPF. The computational needs for QoS and TE are easier to meet with a server-based implementation. The server-based implementation is within the framework of a distributed IP routing model, but more efficient QoS routing is enabled due to scalable processing power. QoS guarantees will be needed for VOIP. Disaggregated architecture within a QoS and TE server is able to meet this need. 
     When TE is being performed, the CE  502  computes basic routes (e.g., shortest path based on hop count) for FEs  506 , the FS  504  gathers information about FEs  506  (e.g., receiving information about the current topology of the network(s) from the CEs  502 ) and determines traffic conditions at each link, and, then, the FS  504  re-computes QoS routes for select traffic based on actual traffic conditions and passes the QoS routing information to the FEs  506 . Typically, not all traffic requires QoS, so the FS  504  usually computes QoS routes only for select traffic (QoS sensitive traffic), such as VOIP calls where voice samples need to be sent within a very short period of time. Given the routing information, each FE  506  determines which traffic needs a QoS route (from the FS  504 ) and which traffic needs a basic route (from the CE  502 ). 
       FIG. 10A  shows a network with route reflectors  1000  in the prior art, where some routers  400  are designated as reflectors  1002 . In the traditional router architecture, BGP route reflection is done within routers  400  that have integrated control and forwarding functions. 
       FIG. 10B  shows scaling BGP route reflectors for an embodiment of the exemplary SoftRouter architecture.  FIG. 10B  shows a server-based implementation of route reflectors, where route reflectors are hosted on the FS  504 . The concept of FSs  504  allows the BGP route reflection function to be hosted on a FS  504  without incurring the total cost of a traditional router  400  that has functionality that is not needed. 
     Route reflectors are used to handle scalability problems due to a large number of BGP sessions. The server-based implementation shown in  FIG. 10B  has benefits of attack resilience, higher processing capacities; easier handling of higher loads caused by BGP/MPLS VPNs, and is an extension of route reflector architecture. The FS  504  can also be used as a BGP service assurance platform, providing connectivity assurance, privacy assurance, and overload detection and control. 
       FIG. 11  shows network-based VPN support and server-based BGP/MPLS VPNs according to an embodiment of the exemplary SoftRouter architecture. A VPN control server  1100  uses a control session  1101  to create MPLS or IP security (IPSec) tunnels  1102  among provider edge (PE) routers  1104 , which are simple FEs  506 . MPLS tunnels  1102  can be traffic engineered to meet VPN customer requirements. The VPN control server  1100  injects routes in the FEs  506 . Failover sessions  1106  among VPN control servers  1100  make sure that in the event of server failure, the other server takes control over effected FEs  506 . Server upgrades do not impact the network operation, permitting easier upgrades. 
     The concept of FSs  504  allows the VPN support to be hosted on a FS  504 , as opposed to VPN support being in each traditional router  400 . Using FSs  504  in the exemplary SoftRouter architecture scales better, because the FS is centralized allowing it to manage resources better. Centralizing logic, such as VPN support in only a few places also reduces complexity and saves time installing, maintaining, etc. the logic. 
       FIG. 12  shows scaling mobile IP according to an embodiment of the exemplary SoftRouter architecture. Mobile IP home agent  1200  will require increasing scalability as cellular carriers introduce wireless data. The mobile IP home agent  1200  is connected to the Internet  1202 , premise distribution system network (PDSN)/Internet general packet radio service (GPRS) support node (IGSN)  1204 , and a FS  504  that performs mobile IP signaling. The PDSN/IGSN  1204  is connected to a base station controller  1206 . The base station controller  1206  is connected to base stations  1208  that communicate with wireless devices  1210  by code division multiple access (CDMA). The base station is also connected to a mobile switching center  1212 , which is connected to the public switched telephone network (PSTN)  1214 . The PSTN is connected to a home location register (HLR)  1216 . The Internet  1202  is connected to an authentication, authorization, and accounting (AAA) server  1218 . Offloading mobile IP functionality to FSs  504  in the exemplary SoftRouter architecture scales better than the traditional router architecture. 
     There are two approaches to scalability of mobile IP in the prior art, one for routers and another for servers. Routers in the prior art support home agents where signaling it limited to about 100 bindings/second, i.e. supporting less than about 1 updates per hour per user. Servers in the prior art have mobile IP implementation in cluster processors, but scaling the number of home agents is an issue, because IPSec processing is CPU intensive. 
     By contrast, the disaggregated exemplary SoftRouter architecture allows server-based signaling, while retaining hardware-based transport scalability. Transport is handled by FEs  506  with hardware support for IPSec that can support about a million home agents. Signaling capacity can be scaled using multiple blade servers, thus enabling about 60 updates/hour/mobile user or more. 
       FIG. 13  shows IPv6, according to an embodiment of the exemplary SoftRouter architecture. In  FIG. 13 , a network includes an IPv6 control server  1300 , a number of FEs  506 , enterprises  1302 , an IPv6 transition element  1304 , an IPv6 core router  1306 , and a dual IPv6/IPv4 core router. 
     Transport organizations can support Ipv6 in a SoftRouter network by adding the IPv6 control server  1300 . The IPv6 control server  1300  need only be introduced when an organization chooses to move to IPv6. The disaggregation of the exemplary SoftRouter architecture lends itself to incremental transitioning to IPv6. There is a low cost initial outlay for IPv6 future proofing that is required and transitioning resources are added on a pay-as-you-go basis. 
     The exemplary SoftRouter architecture including a FS enables a three-stage deployment for IPv6, in one example. Stage one is future proofing FEs  506 . Basic IPv6 functionality is included in FEs  506 , which is initially disabled. This IPv6 functionality includes standard IPv6 packet routing, IPv6-in-IPv4 or IPv6-in-MPLS tunneling, support to set a default route to the tunneled IPv6 control server  1300  (deployed in a later stage), and IPv6 flow label to MPLS mapping. There is a low cost to implement these functions. 
     Stage two is providing cut-through IPv6 services only. Global IPv6 services cut through the IPv4 core network. An IPv6 control server  1300  is added to provide: address management (proxy auto-configuration or dynamic host configuration protocol, version six (DHCPv6), tunnel configuration of FEs  506 , MPLS path set-up for end-user QoS-specified connections, and domain naming system (DNS), DHCPv6 forwarding. 
     Stage three is full dual IPv6/IPv4 services. IPv6 transition elements (e.g., network address translation-protocol translation (NAT-PT), 6to4Relay) and required extensions to IPv6 are added. The IPv6 control server  1300  supports all forms of IPv6 and IPv4 inter-working. There is support for IPv6-only to IPv4-only communications and dynamic routing and load balancing to gateway elements, and routing protocol peering (e.g., OSPFv3, BGP4+). 
     Upgrading service is easier to perform using an FS  504  (e.g., IPv6 control server  1300 ) in an embodiment of the exemplary SoftRouter architecture, than in the traditional router architecture. An FE  506  can be upgraded first without implementing the control. This cannot be done as well in the traditional router architecture where everything has to be upgraded at the same time. Later on, the control can be turned on. The control may even be turned on individually for different FEs  506 . 
     Another application facilitated by FSs  504  is network monitoring, e.g., tracing packets and storing filters. Network monitoring is like a metering function where FEs  506  collect and forward information to the FS  504 . 
       FIG. 14  is a high level block diagram showing a computer. The computer  1400  may be employed to implement embodiments of the present invention. The computer  1400  comprises a processor  1430  as well as memory  1440  for storing various programs  1444  and data  1446 . The memory  1440  may also store an operating system  1442  supporting the programs  1444 . 
     The processor  1430  cooperates with conventional support circuitry such as power supplies, clock circuits, cache memory and the like as well as circuits that assist in executing the software routines stored in the memory  1440 . As such, it is contemplated that some of the steps discussed herein as software methods may be implemented within hardware, for example, as circuitry that cooperates with the processor  1430  to perform various method steps. The computer  1400  also contains input/output (I/O) circuitry that forms an interface between the various functional elements communicating with the computer  1400 . 
     Although the computer  1400  is depicted as a general purpose computer that is programmed to perform various functions in accordance with the present invention, the invention can be implemented in hardware as, for example, an application specific integrated circuit (ASIC) or field programmable gate array (FPGA). As such, the process steps described herein are intended to be broadly interpreted as being equivalently performed by software, hardware, or a combination thereof. 
     The present invention may be implemented as a computer program product wherein computer instructions, when processed by a computer, adapt the operation of the computer such that the methods and/or techniques of the present invention are invoked or otherwise provided. Instructions for invoking the inventive methods may be stored in fixed or removable media, transmitted via a data stream in a broadcast media or other signal bearing medium, and/or stored within a working memory within a computing device operating according to the instructions. 
     The present invention has many advantages. SoftRouter FSs  504  remove complexity from routers, allow functions to be implemented on a standard-off-the-shelf server platform, facilitate easy introduction of value-added functions, and scale well. 
     FSs  504  remove complexity from routers by extracting the complex logic for implemented value-added network-based functions from individual routers. As a result, the complexity of each individual router is significantly decreased. This, in turn, improves reliability, manageability, and security of the entire network. 
     FSs  504  allows functions to be implemented on a standard-off-the-shelf server platform. This decreases the capital expenditure (capex) cost for the control plane. With complexity removed from the forwarding plane, capex cost for each forwarding element is substantially lower than that of a traditional router. Disaggregation also opens up the market place for increased competition, new players may provide the different components, and this increased competition will drive down costs. 
     FSs  504  facilitate easy introduction of value-added functions. Deployment and management effort is mostly focused on the FS  504 , and not all the individual FEs  506 . Also, with an open API available on the FS  504 , new independent software vendors may produce a diverse set of new third-party applications for hosting on a FS  504 . This has the potential of significantly accelerating innovations. 
     FSs  504  scale well. FSs scale much easier as needed than a traditional embedded implementation of new network functions in a router. Standard server techniques can be applied. This ease of scaling also allows incremental deployment. As demand for the value-added service increases, more feature server capacity (e.g., adding processing power to an existing FS or adding new FSs) can be added on an as-needed basis. 
     While the foregoing is directed to various embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. As such, the appropriate scope of the invention is to be determined according to the claims, which follow.