General user network interface (UNI) multi-homing techniques for shortest path bridging (SPB) networks

A method, apparatus and computer program product for providing multi-homing techniques for SPB networks is presented. A set of UNI nodes that receive multicast packets are determined based on Backbone Media Access Control-Destination Address (BMAC-DA)/I-Tag Service Identifier (I-SID) of received multicast packets for multicast packets within a transport network. A separate Egress Port Mask is determined for each Backbone-Virtual Local Area Network (B-VLAN) of the transport network, wherein the Egress Port Mask is determined such that only one UNI node of the set of UNI nodes forwards said multicast packets. A set of UNI copies of said multicast packets are filtered out by applying the Egress Port Mask, wherein copies that are not in the Egress Port Mask are dropped. Copies of multicast packets that are not dropped are sent out.

BACKGROUND

In a computer network, network switching devices (switches) interconnect to form a path for transmitting information between an originator and a recipient. A routing mechanism, or protocol, defines switching logic that forwards the transmitted information in the form of packets between the switches as a series of “hops” along a path. At each switch, the switching logic identifies the next switch, or hop, in the path using an identifier such as a Media Access Control (MAC) address. Shortest Path Bridging (SPB) is a routing mechanism having switching logic such that each switch advertises the nodes it knows about to all the other switches, and eventually all the switches in the network have the same picture of the network and therefore can forward frames to the next hop along a shortest path.

SPB is defined in IEEE-802.1aq: IEEE standard for Shortest Path Bridging, and operates in conjunction with IEEE-802.1ah: IEEE standard for Provider Backbone Bridging, sometimes referred to as Mac-in-Mac encapsulation. Both SPB and SPBM forward packets on shortest path trees with minimum path cost as a first order tie-breaker, where for any pair of nodes A and B, the unicast path for A to B is the exact reverse of the path from B to A (reverse path congruency), and all multicast traffic between the two nodes follows the unicast path (multicast and unicast congruency). These are extensions to fundamental Ethernet forwarding properties in IEEE bridged networks.

SPB technology allows a network administrator to easily form mesh networks that distribute load more evenly across the network topology since it can mitigate bottlenecks at core links for traffic that only needs to go from one distribution switch to another. SPB technology is being adopted in Ethernet based data networks to enable Layer-2 and Layer-3 network virtualization. These networks are expected to continue to deliver business critical services even when a variety of network faults occur (or when maintenance operations are performed on the network).

Multi-homing is a mechanism by which an access network connects to and uses two or more devices in the transport network as if it were connecting to a single device. The multiple devices (network switches) in the transport network exchange information between them which allow them to present the access network to the rest of the transport network as if the access network was connected to a single device in the transport network. Failure of the connection of one of the transport devices to the access network or even the complete failure of one of the transport devices will not cause loss of connectivity between the access network and the transport network. The access network therefore exhibits multi-homed access, which is an access network that uses multi-homing to connect to multiple transport devices, and the transport devices define a multi-homed edge, or a group of partner devices, in the transport network that provide multi-homing service to an access network.

One conventional model for providing dual homing uses an access Link Aggregation Group (LAG) connecting two SPB Edges Nodes configured as a pair of InterSwitch Trunk (IST) switches. From a SPB Network perspective the pair of IST switches appear as two separate SPB Nodes. But from a forwarding plane perspective they appear as a single switch.

Another conventional model utilizes stacking with SPB. A set of SPB Edge Nodes provide a Distributed MultiLink Trunk (D-MLT) connecting an access device to a SPB Network. There can be more than two nodes in the same stack. From an SPB network perspective the stack appears as a single switch from both a control-plane and forwarding plane perspective.

SUMMARY

Conventional mechanisms such as those explained above suffer from a variety of deficiencies. One such deficiency with SMLT Dual-Homing is that some customers want more than just two switch redundancy. SMLT also requires dedicated intra-cluster links (IST) which it expects to be a highly resilient entity that “never” fails. In the event of an IST failure the fate of SMLT traffic varies between undefined, does not forward, causes loops etc. based on implementation.

Stacking does not suffer from being limited to two switches, but stacking still requires dedicated intra-cluster links and fixed intra-cluster topologies. If the intra-cluster links break in a fashion that results in separate islands of stack units each of which is still connected to the core network as well as access networks a whole slew of problems arise. These are undefined forwarding behaviors, possible network loops, duplication. Also since the stack was originally intended to be operated as a single control plane entity—a segmentation of the intra-cluster links causes the possibility that the each of the islands of the stack could claim to be the control plane for the stack (IP addresses, router-id values, system-id value) and cause general instability to routing protocols.

Embodiments of the invention significantly overcome such deficiencies and provide mechanisms and techniques that provide multi-homing techniques for SPB networks.

In a particular embodiment of a method for providing multi-homing techniques for SPB networks a set of UNI nodes that receive multicast packets are determined based on Backbone Media Access Control-Destination Address (BMAC-DA)/I-Tag Service Identifier (I-SID) of received multicast packets for multicast packets within a transport network. A separate Egress Port Mask is determined for each Backbone-Virtual Local Area Network (B-VLAN) of the transport network, wherein the Egress Port Mask is determined such that only one UNI node of the set of UNI nodes forwards said multicast packets. A set of UNI copies of said multicast packets are filtered out by applying the Egress Port Mask, wherein copies that are not in the Egress Port Mask are dropped. Copies of multicast packets that are not dropped are sent out.

Other embodiments include a computer readable medium having computer readable code thereon for providing multi-homing techniques for SPB networks. A set of UNI nodes that receive multicast packets are determined based on Backbone Media Access Control-Destination Address (BMAC-DA)/I-Tag Service Identifier (I-SID) of received multicast packets for multicast packets within a transport network. A separate Egress Port Mask is determined for each Backbone-Virtual Local Area Network (B-VLAN) of the transport network, wherein the Egress Port Mask is determined such that only one UNI node of the set of UNI nodes forwards said multicast packets. A set of UNI copies of said multicast packets are filtered out by applying the Egress Port Mask, wherein copies that are not in the Egress Port Mask are dropped. Copies of multicast packets that are not dropped are sent out.

Still other embodiments include a computerized device, configured to process all the method operations disclosed herein as embodiments of the invention. In such embodiments, the computerized device includes a memory system, a processor, communications interface in an interconnection mechanism connecting these components. The memory system is encoded with a process that provides multi-homing techniques for SPB networks as explained herein that when performed (e.g. when executing) on the processor, operates as explained herein within the computerized device to perform all of the method embodiments and operations explained herein as embodiments of the invention. Thus any computerized device that performs or is programmed to perform up processing explained herein is an embodiment of the invention.

Other arrangements of embodiments of the invention that are disclosed herein include software programs to perform the method embodiment steps and operations summarized above and disclosed in detail below. More particularly, a computer program product is one embodiment that has a computer-readable medium including computer program logic encoded thereon that when performed in a computerized device provides associated operations providing multi-homing techniques for SPB networks as explained herein. The computer program logic, when executed on at least one processor with a computing system, causes the processor to perform the operations (e.g., the methods) indicated herein as embodiments of the invention. Such arrangements of the invention are typically provided as software, code and/or other data structures arranged or encoded on a computer readable medium such as an optical medium (e.g., CD-ROM), floppy or hard disk or other a medium such as firmware or microcode in one or more ROM or RAM or PROM chips or as an Application Specific Integrated Circuit (ASIC) or as downloadable software images in one or more modules, shared libraries, etc. The software or firmware or other such configurations can be installed onto a computerized device to cause one or more processors in the computerized device to perform the techniques explained herein as embodiments of the invention. Software processes that operate in a collection of computerized devices, such as in a group of data communications devices or other entities can also provide the system of the invention. The system of the invention can be distributed between many software processes on several data communications devices, or all processes could run on a small set of dedicated computers, or on one computer alone.

It is to be understood that the embodiments of the invention can be embodied strictly as a software program, as software and hardware, or as hardware and/or circuitry alone, such as within a data communications device. The features of the invention, as explained herein, may be employed in data communications devices and/or software systems for such devices such as those manufactured by Avaya, Inc. of Basking Ridge, N.J.

Note that each of the different features, techniques, configurations, etc. discussed in this disclosure can be executed independently or in combination. Accordingly, the present invention can be embodied and viewed in many different ways. Also, note that this summary section herein does not specify every embodiment and/or incrementally novel aspect of the present disclosure or claimed invention. Instead, this summary only provides a preliminary discussion of different embodiments and corresponding points of novelty over conventional techniques. For additional details, elements, and/or possible perspectives (permutations) of the invention, the reader is directed to the Detailed Description section and corresponding figures of the present disclosure as further discussed below.

DETAILED DESCRIPTION

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing embodiments of the invention. Upon reading the following description in light of the accompanying figures, those skilled in the art will understand the concepts of the invention and recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

The preferred embodiment of the invention will now be described with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein; rather, this embodiment is provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The terminology used in the detailed description of the particular embodiment illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, like numbers refer to like elements.

The presently described method and apparatus relating to General User Network Interface (UNI) Multi-homing Techniques for Shortest Path Bridging (SPB) Networks provides the next stage of evolution of the SMLT and Stacking solutions. The present invention provides redundancy of more than two nodes and does not require special intra-cluster links. Further, the present invention provides defined behaviors and traffic protection in the event of any combination of failures of cluster nodes, access links, network links and core nodes, and does not destabilize the routing protocol with any combination of failures (however unlikely). Further still, the present invention is fully active/active traffic forwarding and provides continuous and pre-defined management access to all active members of a multi-homed LAG solution.

Referring now toFIG. 1, an environment10including a transport network (SPB) and associated edge devices are shown. BEB-A and BEB-B are arranged in a conventional SMLT arrangement wherein an IST is used to send messages between the two devices. BEB-C is a stand-alone device and operates in conventional ways.

Devices labeled Cluster1-1through cluster1-16are multi-homed to form a UNI LAG in accordance with the present invention. Devices labeled Cluster2-1through cluster2-16are also multi-homed to form a UNI LAG in accordance with the present invention.

Normally when multicast traffic is received at an edge device it is sent to all the UNI access points on the service. This would happen for multicast traffic received by BEB-A, BEB-B and also BEB-C.

For cluster devices1-1through1-16and also cluster devices2-1through2-16, the following rules are executed. First, for multicast traffic decide the set of UNI access-points that will receive the traffic based on the BMAC_DA/I-SID. Second, filter out the set of UNI copies by applying an Egress Port Mask (for each B-VLAN is there is a separate Egress Port Mask). A separate Egress Port Mask is determined for each B-VLAN such that only one UNI node forwards the multicast traffic. Next, copies that are not in the port mask are dropped, while the other copies are sent out.

The Egress Port Mask is manipulated to achieve the following goals. Each SPB Node is responsible for forwarding multicast traffic received on at least one of the B-VLANs to the Multi-homed LAGs. For example, cluster devices2-1through2-16each are responsible for one of 16 BVLANs (e.g., cluster device2-1is responsible for BVLAN1; cluster device2-2is responsible for BVLAN2, etc.)

If there are more B-VLANs than nodes in a cluster, then some of the nodes are responsible for multicast traffic on more than one B-VLAN. For example if there are 17 BVLANs, then cluster device2-1is responsible for BVLAN1and BVLAN17, cluster device2-2is responsible for BVLAN2, etc.

If there is an access network fault on a UNI LAG at one of the nodes in the cluster then the Egress Mask(s) of the BVLAN(s) assigned to that node are modified in such a way that one of the other nodes in the cluster that still has a connection to the UNI LAG is now responsible for making the copies for each of these B-VLANs. For example if there are 16 BVLANs, and cluster device2-2failed, then cluster device2-1is responsible for BVLAN1and BVLAN2, cluster device2-3is responsible for BVLAN3, etc. while cluster device2-2is down.

A private protocol is used between nodes in the cluster to exchange port state information for the Multi-homed UNI LAG. The Egress Port Mask is manipulated for each of the B-VLANs based on Multi-Homed UNI port state information received on the clustering protocol. The SPB Network is used to build a multipoint transport channel for the clustering protocol.

The present invention provides several advantages as compared to conventional arrangements. The present invention lifts the limitation of two nodes in a cluster. There are no requirements for dedicated intra-cluster links and so there are no ill effects from severing of intra-cluster links. There is no multiple personality disorder—where isolated islands of the cluster exist in the same network. A multipoint protocol is used for cluster discovery and synchronization. The clustering protocol survives as long as the network routing protocol maintains connectivity between the cluster nodes.

Referring now toFIG. 2, a particular embodiment of a method for providing General User Network Interface (UNI) Multi-homing Techniques for Shortest Path Bridging (SPB) Networks is shown. Method100begins with processing block102which discloses determining, for multicast packets within a transport network, a set of User Network Interface (UNI) nodes that receive the multicast packets based on Backbone Media Access Control-Destination Address (BMAC-DA)/I-Tag Service Identifier (I-SID) of the received multicast packets. Processing block103shows the set of nodes have a multi-homed connection to an access device network using link aggregation. Processing block104states using a private clustering protocol between nodes in a cluster to exchange port state information for a multi-homed UNI Link Aggregation Group (LAG).

Processing block106recites determining a separate Egress Port Mask for each Backbone-Virtual Local Area Network (B-VLAN) of the transport network, wherein the Egress Port Mask is determined such that only one UNI node of the set of UNI nodes forwards the multicast packets to the multi-homed UNI.

Processing block108states manipulating the Egress Port Mask for each of the B-VLANs based on Multi-Homed UNI port state information received on the clustering protocol. As shown in processing block110, when there are more B-VLANs than nodes in a cluster then some of the nodes are responsible for multicast packets on more than one B-VLAN. Processing block112recites wherein when there is an access network fault on a UNI LAG at one of the nodes in the cluster, then any Egress Port Mask of a BVLAN assigned to the node experiencing the fault are modified in such a way that one other node in the cluster that still has a connection to the UNI LAG is now responsible for making the copies for each of the B-VLANs formerly associated with the node experiencing the fault.

Processing continues with processing block114which discloses filtering out a set of UNI copies of the multicast packets by applying the Egress Port Mask wherein copies that are not in the Egress Port Mask are dropped. Processing block116states sending out copies of multicast packets that are not dropped.

As shown in processing block118, the transport network is used to build a multipoint transport channel for the clustering protocol. As further shown in processing block120each node of the transport network is responsible for forwarding multicast packets received on at least one of the B-VLANs to the Multi-homed LAGs.

FIG. 3is a block diagram illustrating an example architecture of a computer system210that executes, runs, interprets, operates or otherwise performs a multi-homing for SPB networks operating application240-1and multi-homing for SPB networks operating process240-2suitable for use in explaining example configurations disclosed herein. As shown in this example, the computer system210includes an interconnection mechanism211such as a data bus or other circuitry that couples a memory system212, a processor213, an input/output interface214, and a communications interface215. The communications interface215enables the computer system210to communicate with other devices (i.e., other computers) on a network (not shown).

The memory system212is any type of computer readable medium, and in this example, is encoded with a multi-homing for SPB networks operating application240-1as explained herein. The multi-homing for SPB networks operating application240-1may be embodied as software code such as data and/or logic instructions (e.g., code stored in the memory or on another computer readable medium such as a removable disk) that supports processing functionality according to different embodiments described herein. During operation of the computer system210, the processor213accesses the memory system212via the interconnect211in order to launch, run, execute, interpret or otherwise perform the logic instructions of a multi-homing for SPB networks operating application240-1. Execution of a multi-homing for SPB networks operating application240-1in this manner produces processing functionality in the multi-homing for SPB networks operating process240-2. In other words, the multi-homing for SPB networks operating process240-2represents one or more portions or runtime instances of a multi-homing for SPB networks operating application240-1(or the entire a multi-homing for SPB networks operating application240-1) performing or executing within or upon the processor213in the computerized device210at runtime.

It is noted that example configurations disclosed herein include the multi-homing for SPB networks operating application240-1itself (i.e., in the form of un-executed or non-performing logic instructions and/or data). The multi-homing for SPB networks operating application240-1may be stored on a computer readable medium (such as a floppy disk), hard disk, electronic, magnetic, optical, or other computer readable medium. A multi-homing for SPB networks operating application240-1may also be stored in a memory system212such as in firmware, read only memory (ROM), or, as in this example, as executable code in, for example, Random Access Memory (RAM). In addition to these embodiments, it should also be noted that other embodiments herein include the execution of a multi-homing for SPB networks operating application240-1in the processor213as the multi-homing for SPB networks operating process240-2. Those skilled in the art will understand that the computer system210may include other processes and/or software and hardware components, such as an operating system not shown in this example.

During operation, processor213of computer system200accesses memory system212via the interconnect211in order to launch, run, execute, interpret or otherwise perform the logic instructions of the multi-homing for SPB networks application240-1. Execution of multi-homing for SPB networks application240-1produces processing functionality in multi-homing for SPB networks process240-2. In other words, the multi-homing for SPB networks process240-2represents one or more portions of the multi-homing for SPB networks application240-1(or the entire application) performing within or upon the processor213in the computer system200.

It should be noted that, in addition to the multi-homing for SPB networks process240-2, embodiments herein include the multi-homing for SPB networks application240-1itself (i.e., the un-executed or non-performing logic instructions and/or data). The multi-homing for SPB networks application240-1can be stored on a computer readable medium such as a floppy disk, hard disk, or optical medium. The multi-homing for SPB networks application240-1can also be stored in a memory type system such as in firmware, read only memory (ROM), or, as in this example, as executable code within the memory system212(e.g., within Random Access Memory or RAM).

In addition to these embodiments, it should also be noted that other embodiments herein include the execution of multi-homing for SPB networks application240-1in processor213as the multi-homing for SPB networks process240-2. Those skilled in the art will understand that the computer system200can include other processes and/or software and hardware components, such as an operating system that controls allocation and use of hardware resources associated with the computer system200.

The device(s) or computer systems that integrate with the processor(s) may include, for example, a personal computer(s), workstation(s) (e.g., Sun, HP), personal digital assistant(s) (PDA(s)), handheld device(s) such as cellular telephone(s), laptop(s), handheld computer(s), or another device(s) capable of being integrated with a processor(s) that may operate as provided herein. Accordingly, the devices provided herein are not exhaustive and are provided for illustration and not limitation.

References to “a microprocessor” and “a processor”, or “the microprocessor” and “the processor,” may be understood to include one or more microprocessors that may communicate in a stand-alone and/or a distributed environment(s), and may thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor may be configured to operate on one or more processor-controlled devices that may be similar or different devices. Use of such “microprocessor” or “processor” terminology may thus also be understood to include a central processing unit, an arithmetic logic unit, an application-specific integrated circuit (IC), and/or a task engine, with such examples provided for illustration and not limitation.

Furthermore, references to memory, unless otherwise specified, may include one or more processor-readable and accessible memory elements and/or components that may be internal to the processor-controlled device, external to the processor-controlled device, and/or may be accessed via a wired or wireless network using a variety of communications protocols, and unless otherwise specified, may be arranged to include a combination of external and internal memory devices, where such memory may be contiguous and/or partitioned based on the application. Accordingly, references to a database may be understood to include one or more memory associations, where such references may include commercially available database products (e.g., SQL, Informix, Oracle) and also proprietary databases, and may also include other structures for associating memory such as links, queues, graphs, trees, with such structures provided for illustration and not limitation.

References to a network, unless provided otherwise, may include one or more intranets and/or the internet, as well as a virtual network. References herein to microprocessor instructions or microprocessor-executable instructions, in accordance with the above, may be understood to include programmable hardware.