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WO2017144943A1 - Procédé et appareil pour une unidiffusion et une multidffusion conformes pour des services ethernet dans un réseau spring - Google Patents

Procédé et appareil pour une unidiffusion et une multidffusion conformes pour des services ethernet dans un réseau spring Download PDF

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Publication number
WO2017144943A1
WO2017144943A1 PCT/IB2016/050981 IB2016050981W WO2017144943A1 WO 2017144943 A1 WO2017144943 A1 WO 2017144943A1 IB 2016050981 W IB2016050981 W IB 2016050981W WO 2017144943 A1 WO2017144943 A1 WO 2017144943A1
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WO
WIPO (PCT)
Prior art keywords
network
mdt
unicast
unicast frame
ethernet
Prior art date
Application number
PCT/IB2016/050981
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English (en)
Inventor
David Ian Allan
Original Assignee
Telefonaktiebolaget Lm Ericsson (Publ)
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telefonaktiebolaget Lm Ericsson (Publ) filed Critical Telefonaktiebolaget Lm Ericsson (Publ)
Priority to PCT/IB2016/050981 priority Critical patent/WO2017144943A1/fr
Publication of WO2017144943A1 publication Critical patent/WO2017144943A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/16—Multipoint routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/16—Arrangements for providing special services to substations
    • H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/32—Flooding
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/48—Routing tree calculation
    • H04L45/484—Routing tree calculation using multiple routing trees
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]

Definitions

  • Embodiments of the invention relate to the field of supporting Ethernet service in communication networks; and more specifically, to maintaining in-order delivery of Ethernet frames in source packet in routing (SPRING) networks.
  • SPRING source packet in routing
  • IP Internet Protocol
  • MPLS multiprotocol label switching
  • mLDP multicast label distribution protocol
  • PIM protocol independent multicast
  • SPF unicast shortest path first
  • MDT loop free multicast distribution tree
  • Shortest path bridging is a protocol related to computer networking for the configuration of computer networks that enables multipath routing.
  • the protocol is specified by the Institute of Electrical and Electronics Engineers (IEEE) 802. laq standard. This protocol replaces prior standards such as spanning tree protocols.
  • IEEE Institute of Electrical and Electronics Engineers 802. laq standard.
  • This protocol replaces prior standards such as spanning tree protocols.
  • SPB enables all paths in the computing network to be active with multiple equal costs paths being utilized through load sharing and similar technologies.
  • the standard enables the implementation of logical Ethernet networks in Ethernet infrastructures using a link state protocol to advertise the topology and logical network memberships of the nodes in the network.
  • SPB implements large scale multicast as part of implementing virtualized broadcast domains.
  • a key distinguishing feature of the SPB standard is that the MDTs are computed from the information in the routing system's link state database via an all-pairs- shortest-path algorithm, which minimizes the amount of control messaging to converge multicast.
  • SPRING is an exemplary profile of the use of MPLS technology whereby global identifiers are used in the form of a global label assigned per label switched route (LSR) used for forwarding to that LSR.
  • LSR label switched route
  • a full mesh of unicast tunnels is constructed via every node in the network computing the shortest path to every other node and installing the associated global labels accordingly.
  • this also allows explicit paths to be set up via the application of label stacks at the network ingress. Encompassed with this approach is the concept of a strict (every hop specified) or loose (some waypoints specified) route dependent on how exhaustively the ingress applied label stack specifies the path.
  • a node in the SPRING network could compute its role in implementing any given multicast (S, G) tree.
  • An algorithm that starts with all pairs shortest path computation augmented with algorithms to identify the nodes with specific roles of root, leave or replication point may be employed by each node.
  • Existing unicast tunnels may be used between sources, replication points and leaves of an MDT such that the overall amount of state in the network is minimized.
  • SPRING networks can be utilized to support other communications technologies such as Ethernet as services over the SPRING network.
  • a SPRING network may utilize both multicast (i.e., MDTs) and unicast for traffic, however there is not guaranteed in-order delivery where unicast traffic is spread across both unicast and multicast as would be the case with bridged Ethernet.
  • Unicast frames are subject to equal cost multipath (ECMP), whereas multicast frames are not. Therefore it cannot be guaranteed that the same frame sent via multicast will follow the same path and therefore encounter the same queuing delays as when sent by unicast.
  • ECMP equal cost multipath
  • a method is provided to be implemented by a network device in a source packet in routing (SPRING) network.
  • SPRING source packet in routing
  • the SPRING network supports a plurality of Ethernet services and defines a plurality local multicast distribution trees (MDTs) for respective ones of the plurality Ethernet services, where the MDTs are implemented as hybrid of unicast tunnels and replication points.
  • MDTs are implemented as hybrid of unicast tunnels and replication points.
  • the network device functions as an ingress node for an Ethernet service from the plurality of Ethernet services.
  • the method includes receiving a unicast frame of the Ethernet service, generating an entropy value common to a set of frames that share a common ordering constraint with the unicast frame, and associating the Ethernet service with a local MDT with a root on the ingress node and leaves corresponding to all possible destinations in the Ethernet service instance.
  • the method further includes flooding the unicast frame via the MDT where the unicast frame is unknown in a forwarding information base (FIB) of the network device, identifying a destination of the unicast frame, where the frame is known in the FIB, and generating a label stack to match a path of the MDT to the destination of the unicast frame.
  • the method pushes the label stack onto the unicast frame, and forwards the unicast frame toward a next hop label of the label stack.
  • FIB forwarding information base
  • a network device in a source packet in routing (SPRING) network is provided.
  • the SPRING network supports a plurality of Ethernet services and defines a plurality local multicast distribution trees (MDTs) for respective ones of the plurality Ethernet services, where the MDTs are implemented as hybrid of unicast tunnels and replication points.
  • the network device functions as an ingress node for an Ethernet service from the plurality of Ethernet services.
  • the network device a non-transitory machine-readable storage medium having stored therein a congruent multicast manager, and a processor coupled to the non- transitory machine-readable storage medium.
  • the processor is configured to execute the congruent multicast manager.
  • the congruent multicast manager is configured to receive a unicast frame of the Ethernet service, generate an entropy value common to a set of frames that share a common ordering constraint with the unicast frame, associate the Ethernet service with a local MDT with a root on the ingress node and leaves corresponding to all possible destinations in the Ethernet service instance, to flood the unicast frame via the MDT where the unicast frame is unknown in a forwarding information base (FIB) of the network device; to identify a destination of the unicast frame, where the frame is known in the FIB, to generate a label stack to match a path of the MDT to the destination of the unicast frame, to push the label stack onto the unicast frame, and to forward the unicast frame toward a next hop label of the label stack.
  • FIB forwarding information base
  • a computing device is in communication with a network device in a source packet in routing (SPRING) network.
  • SPRING network supports a plurality of Ethernet services and defines a plurality local multicast distribution trees (MDTs) for respective ones of the plurality Ethernet services, where the MDTs are implemented as hybrid of unicast tunnels and replication points, the network device functioning as an ingress node for an Ethernet service from the plurality of Ethernet services.
  • the computing device executes a plurality of virtual machines for implementing network function virtualization (NFV).
  • the computing device a non-transitory machine-readable storage medium having stored therein a congruent multicast manager, and a processor coupled to the non-transitory machine -readable storage medium.
  • the processor is configured to execute at least one of the plurality of virtual machines.
  • the at least one virtual machine is configured to execute the congruent multicast manager.
  • the congruent multicast manager is configured to receive a unicast frame of the Ethernet service, generate an entropy value common to a set of frames that share a common ordering constraint with the unicast frame, associate the Ethernet service with a local MDT with a root on the ingress node and leaves corresponding to all possible destinations in the Ethernet service instance, to flood the unicast frame via the MDT where the unicast frame is unknown in a forwarding information base (FIB) of the network device; to identify a destination of the unicast frame, where the frame is known in the FIB, to generate a label stack to match a path of the MDT to the destination of the unicast frame, to push the label stack onto the unicast frame, and to forward the unicast frame toward a next hop label of the label stack.
  • FIB forwarding information base
  • a control plane device is configured to implement a control plane of a software defined networking (SDN) network including a network device in a network with a plurality of network devices, wherein the control plane device is configured to configure the network device in a source packet in routing (SPRING) network.
  • SDN software defined networking
  • SPRING source packet in routing
  • the SPRING network supports a plurality of Ethernet services and defines a plurality local multicast distribution trees (MDTs) for respective ones of the plurality Ethernet services, where the MDTs are implemented as hybrid of unicast tunnels and replication points.
  • MDTs local multicast distribution trees
  • the network device functions as an ingress node for an Ethernet service from the plurality of Ethernet services.
  • the control plane device includes a non-transitory machine-readable storage medium having stored therein a congruent multicast manager, and a processor coupled to the non-transitory machine -readable storage medium.
  • the processor is configured to execute the congruent multicast manage.
  • the congruent multicast manager is configured to receive a unicast frame of the Ethernet service, generate an entropy value common to a set of frames that share a common ordering constraint with the unicast frame, associate the Ethernet service with a local MDT with a root on the ingress node and leaves corresponding to all possible destinations in the Ethernet service instance, to flood the unicast frame via the MDT where the unicast frame is unknown in a forwarding information base (FIB) of the network device; to identify a destination of the unicast frame, where the frame is known in the FIB, to generate a label stack to match a path of the MDT to the destination of the unicast frame, to push the label stack onto the unicast frame, and to forward the unicast
  • Figure 1 is a flowchart of one embodiment of process for handling ingress replication for Ethernet services.
  • FIG. 2 is a diagram of one example of a source packet in routing (SPRING) network supporting Ethernet services with an ingress replication point.
  • SPRING source packet in routing
  • Figure 3A illustrates connectivity between network devices (NDs) within an exemplary network, as well as three exemplary implementations of the NDs, according to some
  • Figure 3B illustrates an exemplary way to implement a special-purpose network device according to some embodiments of the invention.
  • FIG. 3C illustrates various exemplary ways in which virtual network elements (VNEs) may be coupled according to some embodiments of the invention.
  • VNEs virtual network elements
  • Figure 3D illustrates a network with a single network element (NE) on each of the NDs, and within this straight forward approach contrasts a traditional distributed approach (commonly used by traditional routers) with a centralized approach for maintaining reachability and forwarding information (also called network control), according to some embodiments of the invention.
  • NE network element
  • Figure 3E illustrates the simple case of where each of the NDs implements a single NE, but a centralized control plane has abstracted multiple of the NEs in different NDs into (to represent) a single NE in one of the virtual network(s), according to some embodiments of the invention.
  • Figure 3F illustrates a case where multiple VNEs are implemented on different NDs and are coupled to each other, and where a centralized control plane has abstracted these multiple VNEs such that they appear as a single VNE within one of the virtual networks, according to some embodiments of the invention.
  • FIG. 4 illustrates a general purpose control plane device with centralized control plane (CCP) software 450), according to some embodiments of the invention. DESCRIPTION OF EMBODIMENTS
  • the following description describes methods and apparatus for providing unicast and multicast congruence in source packet in routing (SPRING) networks.
  • SPRING source packet in routing
  • the embodiments provide a process and apparatus that support Ethernet services over the SPRING networks such that where an ingress node for the Ethernet service functions as a replication point and is handling frames that are received for the Ethernet service such that unicast frames are handled in the same manner as multicast frames by pushing a label stack on unicast traffic that ensures unicast frames follow the same branch of an MDT as flooded (i.e., multicast) frames follow.
  • an ingress node for the Ethernet service functions as a replication point and is handling frames that are received for the Ethernet service such that unicast frames are handled in the same manner as multicast frames by pushing a label stack on unicast traffic that ensures unicast frames follow the same branch of an MDT as flooded (i.e., multicast) frames follow.
  • references in the specification to "one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
  • Bracketed text and blocks with dashed borders may be used herein to illustrate optional operations that add additional features to embodiments of the invention. However, such notation should not be taken to mean that these are the only options or optional operations, and/or that blocks with solid borders are not optional in certain embodiments of the invention.
  • Coupled is used to indicate that two or more elements, which may or may not be in direct physical or electrical contact with each other, co-operate or interact with each other.
  • Connected is used to indicate the establishment of communication between two or more elements that are coupled with each other.
  • An electronic device stores and transmits (internally and/or with other electronic devices over a network) code (which is composed of software instructions and which is sometimes referred to as computer program code or a computer program) and/or data using machine-readable media (also called computer-readable media), such as machine-readable storage media (e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory) and machine-readable transmission media (also called a carrier) (e.g., electrical, optical, radio, acoustical or other form of propagated signals - such as carrier waves, infrared signals).
  • machine-readable media also called computer-readable media
  • machine-readable storage media e.g., magnetic disks, optical disks, read only memory (ROM), flash memory devices, phase change memory
  • machine-readable transmission media also called a carrier
  • carrier e.g., electrical, optical, radio, acoustical or other form of propagated signals - such as carrier waves, infrared signals.
  • an electronic device e.g., a computer
  • includes hardware and software such as a set of one or more processors coupled to one or more machine-readable storage media to store code for execution on the set of processors and/or to store data.
  • an electronic device may include non- volatile memory containing the code since the non-volatile memory can persist code/data even when the electronic device is turned off (when power is removed), and while the electronic device is turned on that part of the code that is to be executed by the processor(s) of that electronic device is typically copied from the slower nonvolatile memory into volatile memory (e.g., dynamic random access memory (DRAM), static random access memory (SRAM)) of that electronic device.
  • volatile memory e.g., dynamic random access memory (DRAM), static random access memory (SRAM)
  • Typical electronic devices also include a set or one or more physical network interface(s) to establish network connections (to transmit and/or receive code and/or data using propagating signals) with other electronic devices.
  • network connections to transmit and/or receive code and/or data using propagating signals.
  • One or more parts of an embodiment of the invention may be implemented using different combinations of software, firmware, and/or hardware.
  • a network device is an electronic device that communicatively interconnects other electronic devices on the network (e.g., other network devices, end-user devices).
  • Some network devices are "multiple services network devices" that provide support for multiple networking functions (e.g., routing, bridging, switching, Layer 2 aggregation, session border control, Quality of Service, and/or subscriber management), and/or provide support for multiple application services (e.g., data, voice, and video).
  • a network interface may be physical or virtual; and in the context of IP, an interface address is an IP address assigned to a NI, be it a physical NI or virtual NI.
  • a virtual NI may be associated with a physical NI, with another virtual interface, or stand on its own (e.g., a loopback interface, a point-to-point protocol interface).
  • a NI (physical or virtual) may be numbered (a NI with an IP address) or unnumbered (a NI without an IP address).
  • a loopback interface (and its loopback address) is a specific type of virtual NI (and IP address) of a
  • IP addresses of that ND are referred to as IP addresses of that ND; at a more granular level, the IP address(es) assigned to NI(s) assigned to a NE/VNE implemented on a ND can be referred to as IP addresses of that NE/VNE.
  • Next hop selection by the routing system for a given destination may resolve to one path (that is, a routing protocol may generate one next hop on a shortest path); but if the routing system determines there are multiple viable next hops (that is, the routing protocol generated forwarding solution offers more than one next hop on a shortest path - multiple equal cost next hops), some additional criteria is used - for instance, in a connectionless network, Equal Cost Multi Path (ECMP) (also known as Equal Cost Multi Pathing, multipath forwarding and IP multipath) may be used (e.g., typical implementations use as the criteria particular header fields to ensure that the packets of a particular packet flow are always forwarded on the same next hop to preserve packet flow ordering).
  • ECMP Equal Cost Multi Path
  • a packet flow is defined as a set of packets that share an ordering constraint.
  • the set of packets in a particular TCP transfer sequence need to arrive in order, else the TCP logic will interpret the out of order delivery as congestion and slow the TCP transfer rate down.
  • the embodiments provide a method to provide unicast and multicast congruence and enable the support of Ethernet services over SPRING networks. These embodiments work in combination with other methods of utilizing unicast tunnels within a network as part of multicast tree construction in order to minimize multicast related state.
  • the embodiments utilize the computations of multicast distribution trees (MDTs) and the exemplary information available in shortest path bridging (SPB) implementations such as IEEE 802. laq adapted to other technologies.
  • MDTs multicast distribution trees
  • SPB shortest path bridging
  • IGP interior gateway protocol
  • IEEE 802. laq performs an all-pairs shortest path computation that determines a path from all nodes in a network to all other nodes in the network that selects a shortest path to each node from a source node.
  • Multicast distribution trees can also be computed in a similar manner as they can be derived from the shortest path trees using the notion of reverse path forwarding.
  • MPLS multicast protocol label switching
  • the (S, G) notation indicates an S - source and G - multicast group relation where the multicast tree has a single source and a group of listeners in a network.
  • the multicast labels in the network are carried end to end (E2E). This is inherent to the operation of SPRING.
  • a multicast implementation MPLS could also be envisioned that combined IGP registrations and an LDP signaled unicast tunnel mesh could also be adapted to carry the labels E2E.
  • the example embodiments utilize SPRING for unicast tunneling.
  • the local forwarding information base (LFIB) of each network device in the network will have at least one unicast SPRING-label switched route to each other LSR. It is not necessary, but assumed that the network will also utilize penultimate-hop popping (PHP) on SPRING based LSPs where the outermost label is removed before being forwarded to the last hop to a destination.
  • PDP penultimate-hop popping
  • a shortest path first (SPF) tree i.e., an (S, *) tree where S indicates the node is the source and * indicates the tree reaches all nodes
  • SPF shortest path first
  • the installed state where the node is a root or a replicating node utilizes established a priori unicast tunnels to deliver multicast packets to downstream non- adjacent leaves or replicating nodes. Tunnels do not need to be established for downstream immediately adjacent nodes that have a role in the MDT as they will have installed state for the MDT. Knowledge of the role of each node in the network in relation to a given MDT is an artifact of the all-pairs shortest path computation.
  • each node can be referred to as a label switch router (LSR) and the paths across the SPRING network as label switched paths (LSPs).
  • LSR label switch router
  • LSPs label switched paths
  • a global label exists associated with each LSR and all LSRs include a full unicast forwarding table exists with entries for reaching every LSR in the SPRING network.
  • Any degree of path specificity can be defined via the use of label stacking (i.e., adding a set of ordered labels to data traffic).
  • a 'set,' as used herein refers to any positive whole number of items including one item.
  • a completely loose source route or LSP for a packet can be defined where the final destination label is the only label in the label stack applied at the ingress to the network (i.e., where the packet is received from outside of the network).
  • a completely strict source route or LSP for a packet can be defined where the label for each hop has been pushed in reverse order onto a packet to create a label stack at the ingress node. Any degree of specificity from completely loose to completely strict can be defined by identifying waypoint LSRs in a path and pushing the labels of those LSRs along with the final destination label onto the data packet in reverse order to form the label stack.
  • Ethernet bridging is a mechanism for populating Ethernet forwarding tables based upon reverse path learning.
  • unicast frames for which the destination address is not in the forwarding database are flooded to all receivers in a local area network (LAN). These are referred to as "unknown" frames.
  • Intermediate nodes note the interface of arrival for these frames and associate it with the source media access control (MAC) address in the frame such that the forwarding information base (FIB) of that node is populated.
  • MAC media access control
  • FIB forwarding information base
  • ECMP is a technique for the distribution of traffic over a set of equal cost paths.
  • the embodiments may be statistical in that a hash of flow information is used as the source of entropy modulo the number of interfaces.
  • the technique for providing entropy in the selection of a path for sending traffic over ECMP is the use of an entropy label in the label stack.
  • the source of information to populate an entropy label is a hash of frame data that is common to the frames in a given flow such that all of the frames in the flow will generate the same hash and thus have the same entropy value.
  • the frame data utilized is header information such as the source and destination media access control (MAC) addresses in the frame. Therefore, the entropy value used would be the same for unicast and "unknown" frames flooded via multicast since they have the same source and destination MAC addresses. This ensures a common forwarding and queueing discipline when
  • entropy values may be derived from virtual LAN as well as source and destination MAC addresses.
  • source and destination MAC addresses In the context of use with SPRING and MPLS networks, reliance is likely to be on source and destination MAC addresses.
  • the labels stack governs the routing of the packets.
  • the readable depth of reading the stack for an entropy label is not limited for unicast or multicast.
  • the embodiments overcome the limitations of the prior art, it is possible to take advantage of every node or LSR in the MPLS or SPRING network having knowledge of the complete MDT for a given multicast group (S, G) including all of the replication points in the MDT.
  • S, G multicast group
  • ECMP processing may be encountered between the replication points in the MDT, but the replication points themselves can be handled as pinned waypoints.
  • an ingress LSR handling any Ethernet service can associate an Ethernet local area network (LAN) service instance with a multicast group (*, G) and thus when computing the MDT for that multicast group and the local (S, G) tree (where the ingress LSR is the source or root) the LSR will have knowledge of all replication points between itself and the set of destinations in the LAN service. Therefore, the LSR can push a label stack onto unicast traffic that ensures the unicast frames will follow the same branches of the MDT that a flooded multicast frame would follow in reaching the same destination node for that Ethernet service and thus will only encounter ECMP path selection at the same points in the network. This requires the ingress LSR generate entropy label values that are common for known and unknown frames that share an ordering constraint such that any ECMP processing encountered will result in identical forwarding decisions for both "known" and "unknown” frames.
  • FIG 1 is a flowchart of one embodiment of process for handling ingress LSR operation for supporting Ethernet services over a MPLS or SPRING network.
  • this process is initiated in response to receiving a unicast frame of an Ethernet service at an ingress replication point of a SPRING or MPLS network (Block 101).
  • An entropy value may be generated for the received unicast frame using data from the frame that is common to a flow or set of frames that share a common ordering constraint with the particular unicast frame (Block 102).
  • the replication point has already associated the Ethernet service with an MDT for forwarding data traffic related to the Ethernet service within the network.
  • the unicast frames for the Ethernet service are associated with the MDT of the Ethernet service (Block 103).
  • the ingress LSR may maintain a mapping of the local MDTs and Ethernet services.
  • the MDTs can be constructed for each Ethernet service in the manner of Ethernet endpoints being treated as multicast group subscribers.
  • FIG. 2 is a diagram of one example of a source packet in routing (SPRING) network supporting Ethernet services with an ingress LSR replication point.
  • the MDT for a given multicast group (S, G) is rooted at the ingress replication node (i.e., node 9 in this example). If the ingress replication point were to only push the global label for the destination node 16 onto received unicast frames with this destination, then path would not necessarily be congruent with the MDT paths to node 16.
  • a frame flooded (i.e., multicast) on the MDT rooted on the ingress replication node 9 may get to node 16 via either path 9-12-3-4-16 or 9-12-8-4-16.
  • a unicast frame directed only to node 16 may take any of the equal cost paths to reach node 16. These equal cost paths may not be a possible path within the MDT. For example, the path 9-12-8-2-16 would be an equal cost path that is not consistent with the MDT. If a unicast frame were sent over this path, then it may arrive out of order relative to flooded multicast frames that follow the MDT.
  • the embodiments provide a label information base (LIB) that is maintained by the LSR that services as the replication node 9.
  • This LIB provides the label information for reaching each destination in the MDT.
  • the LIB can be utilized to determine a label stack to reach node 16 that is congruent with the MDT. Specifically, in the illustrated case, the path would need to include at least a label for the pinned waypoint to node 4 in addition to the label for node 16.
  • replication node 9 can push a label stack onto the unicast frames destined for node 16 that pins congruence with the MDT while still permitting the benefits of ECMP where there are multiple equal cost paths between the replicating waypoints.
  • node 4 is a replicating point and is pinned as a waypoint.
  • ECMP is possible between it and node 12 that is also a replicating point to reach node 16 while maintaining congruency with the MDT.
  • an ingress replication point can identify Ethernet services associated with received unicast frames and correlate them with an MDT for that Ethernet service.
  • the path to a destination of the unicast frames that is congruent with the MDT can be determined to ensure in-order delivery.
  • the bandwidth efficiency of combining multicast with unicast is achieved without introducing congruency issues and while supporting ECMP thereby enabling services such as Ethernet over MPLS and SPRING networks.
  • Figure 3A illustrates connectivity between network devices (NDs) within an exemplary network, as well as three exemplary implementations of the NDs, according to some
  • Figure 3A shows NDs 300A-H, and their connectivity by way of lines between 300A-300B, 300B-300C, 300C-300D, 300D-300E, 300E-300F, 300F-300G, and 300A-300G, as well as between 300H and each of 300A, 300C, 300D, and 300G.
  • These NDs are physical devices, and the connectivity between these NDs can be wireless or wired (often referred to as a link).
  • NDs 300A, 300E, and 300F An additional line extending from NDs 300A, 300E, and 300F illustrates that these NDs act as ingress and egress points for the network (and thus, these NDs are sometimes referred to as edge NDs; while the other NDs may be called core NDs).
  • Two of the exemplary ND implementations in Figure 3 A are: 1) a special-purpose network device 302 that uses custom application-specific integrated-circuits (ASICs) and a special-purpose operating system (OS); and 2) a general purpose network device 304 that uses common off-the-shelf (COTS) processors and a standard OS.
  • ASICs application-specific integrated-circuits
  • OS special-purpose operating system
  • COTS common off-the-shelf
  • the special-purpose network device 302 includes networking hardware 310 comprising compute resource(s) 312 (which typically include a set of one or more processors), forwarding resource(s) 314 (which typically include one or more ASICs and/or network processors), and physical network interfaces (NIs) 316 (sometimes called physical ports), as well as non- transitory machine readable storage media 318 having stored therein networking software 320.
  • a physical NI is hardware in a ND through which a network connection (e.g., wirelessly through a wireless network interface controller (WNIC) or through plugging in a cable to a physical port connected to a network interface controller (NIC)) is made, such as those shown by the connectivity between NDs 300A-H.
  • WNIC wireless network interface controller
  • NIC network interface controller
  • the networking software 320 may be executed by the networking hardware 310 to instantiate a set of one or more networking software instance(s) 322.
  • Each of the networking software instance(s) 322, and that part of the networking hardware 310 that executes that network software instance (be it hardware dedicated to that networking software instance and/or time slices of hardware temporally shared by that networking software instance with others of the networking software instance(s) 322), form a separate virtual network element 330A-R.
  • VNEs 330A-R includes a control communication and configuration module 332A-R
  • a given virtual network element (e.g., 330A) includes the control communication and configuration module (e.g., 332A), a set of one or more forwarding table(s) (e.g., 334A), and that portion of the networking hardware 310 that executes the virtual network element (e.g., 33 OA).
  • the special-purpose network device 301 can implement a congruent multicast manager 364.
  • the congruent multicast manager 364 can be a program or similar set of instructions that implement the methods described herein above in reference to Figures 1 and 2 that provide congruent forwarding of unicast frames and multicast frames in a SPRING network.
  • the congruent multicast manager 364 can be stored by the non-transitory machine readable storage media 318 and executed by the compute resources 312.
  • the special-purpose network device 302 is often physically and/or logically considered to include: 1) a ND control plane 324 (sometimes referred to as a control plane) comprising the compute resource(s) 312 that execute the control communication and configuration
  • ND forwarding plane 326 (sometimes referred to as a forwarding plane, a data plane, or a media plane) comprising the forwarding resource(s) 314 that utilize the forwarding table(s) 334A-R and the physical NIs 316.
  • the ND control plane 324 (the compute resource(s) 312 executing the control communication and configuration module(s) 332A-R) is typically responsible for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) and storing that routing information in the forwarding table(s) 334A-R, and the ND forwarding plane 326 is responsible for receiving that data on the physical NIs 316 and forwarding that data out the appropriate ones of the physical NIs 316 based on the forwarding table(s) 334A-R.
  • data e.g., packets
  • the ND forwarding plane 326 is responsible for receiving that data on the physical NIs 316 and forwarding that data out the appropriate ones of the physical NIs 316 based on the forwarding table(s) 334A-R.
  • Figure 3B illustrates an exemplary way to implement the special-purpose network device 302 according to some embodiments of the invention.
  • Figure 3B shows a special- purpose network device including cards 338 (typically hot pluggable). While in some embodiments the cards 338 are of two types (one or more that operate as the ND forwarding plane 326 (sometimes called line cards), and one or more that operate to implement the ND control plane 324 (sometimes called control cards)), alternative embodiments may combine functionality onto a single card and/or include additional card types (e.g., one additional type of card is called a service card, resource card, or multi-application card).
  • additional card types e.g., one additional type of card is called a service card, resource card, or multi-application card.
  • a service card can provide specialized processing (e.g., Layer 4 to Layer 7 services (e.g., firewall, Internet Protocol Security (IPsec), Secure Sockets Layer (SSL) / Transport Layer Security (TLS), Intrusion Detection System (IDS), peer-to-peer (P2P), Voice over IP (VoIP) Session Border Controller, Mobile Wireless Gateways (Gateway General Packet Radio Service (GPRS) Support Node (GGSN), Evolved Packet Core (EPC) Gateway)).
  • Layer 4 to Layer 7 services e.g., firewall, Internet Protocol Security (IPsec), Secure Sockets Layer (SSL) / Transport Layer Security (TLS), Intrusion Detection System (IDS), peer-to-peer (P2P), Voice over IP (VoIP) Session Border Controller, Mobile Wireless Gateways (Gateway General Packet Radio Service (GPRS) Support Node (GGSN), Evolved Packet Core (EPC) Gateway)
  • GPRS General Pack
  • the general purpose network device 304 includes hardware 340 comprising a set of one or more processor(s) 342 (which are often COTS processors) and network interface controller(s) 344 (NICs; also known as network interface cards) (which include physical NIs 346), as well as non-transitory machine readable storage media 348 having stored therein software 350.
  • processor(s) 342 execute the software 350 to instantiate one or more sets of one or more applications 364A-R. While one embodiment does not implement virtualization, alternative embodiments may use different forms of virtualization.
  • the virtualization layer 354 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 362A-R called software containers that may each be used to execute one (or more) of the sets of applications 364A-R; where the multiple software containers (also called virtualization engines, virtual private servers, or jails) are user spaces (typically a virtual memory space) that are separate from each other and separate from the kernel space in which the operating system is run; and where the set of applications running in a given user space, unless explicitly allowed, cannot access the memory of the other processes.
  • the multiple software containers also called virtualization engines, virtual private servers, or jails
  • user spaces typically a virtual memory space
  • the virtualization layer 354 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and each of the sets of applications 364A-R is run on top of a guest operating system within an instance 362A-R called a virtual machine (which may in some cases be considered a tightly isolated form of software container) that is run on top of the hypervisor - the guest operating system and application may not know they are running on a virtual machine as opposed to running on a "bare metal" host electronic device, or through para- virtualization the operating system and/or application may be aware of the presence of virtualization for optimization purposes.
  • a hypervisor sometimes referred to as a virtual machine monitor (VMM)
  • VMM virtual machine monitor
  • a hypervisor executing on top of a host operating system
  • each of the sets of applications 364A-R is run on top of a guest operating system within an instance 362A-R called a virtual machine (which may in some cases be considered a tightly
  • unikernel(s) which can be generated by compiling directly with an application only a limited set of libraries (e.g., from a library operating system (LibOS) including drivers/libraries of OS services) that provide the particular OS services needed by the application.
  • libraries e.g., from a library operating system (LibOS) including drivers/libraries of OS services
  • unikernel can be implemented to run directly on hardware 340, directly on a hypervisor (in which case the unikernel is sometimes described as running within a LibOS virtual machine), or in a software container
  • embodiments can be implemented fully with unikernels running directly on a hypervisor represented by virtualization layer 354, unikernels running within software containers represented by instances 362A-R, or as a combination of unikernels and the above-described techniques (e.g., unikernels and virtual machines both run directly on a hypervisor, unikernels and sets of applications that are run in different software containers).
  • the instantiation of the one or more sets of one or more applications 364A-R, as well as virtualization if implemented, are collectively referred to as software instance(s) 352.
  • the virtual network element(s) 360A-R perform similar functionality to the virtual network element(s) 330A-R - e.g., similar to the control communication and configuration module(s) 332A and forwarding table(s) 334A (this virtualization of the hardware 340 is sometimes referred to as network function virtualization (NFV)).
  • NFV network function virtualization
  • CPE customer premise equipment
  • each instance 362A-R corresponding to one VNE 360A-R
  • alternative embodiments may implement this correspondence at a finer level granularity (e.g., line card virtual machines virtualize line cards, control card virtual machine virtualize control cards, etc.); it should be understood that the techniques described herein with reference to a correspondence of instances 362A-R to VNEs also apply to embodiments where such a finer level of granularity and/or unikernels are used.
  • the virtualization layer 354 includes a virtual switch that provides similar forwarding services as a physical Ethernet switch. Specifically, this virtual switch forwards traffic between instances 362A-R and the NIC(s) 344, as well as optionally between the instances 362A-R; in addition, this virtual switch may enforce network isolation between the VNEs 360A-R that by policy are not permitted to communicate with each other (e.g., by honoring virtual local area networks (VLANs)).
  • VLANs virtual local area networks
  • the general purpose network device 304 can implement a congruent multicast manager 364A-R.
  • the congruent multicast manager 364A-R can be a program or similar set of instructions that implement the methods described herein above in reference to Figures 1 and 2 that provide congruent forwarding of unicast frames and multicast frames in a SPRING network.
  • the congruent multicast manager 364A-R can be stored by the non-transitory machine readable storage media 348 and executed by the software instances 352 and processors 342.
  • the third exemplary ND implementation in Figure 3A is a hybrid network device 306, which includes both custom ASICs/special-purpose OS and COTS processors/standard OS in a single ND or a single card within an ND.
  • a platform VM i.e., a VM that that implements the functionality of the special-purpose network device 302 could provide for para-virtualization to the networking hardware present in the hybrid network device 306.
  • each of the VNEs receives data on the physical NIs (e.g., 316, 346) and forwards that data out the appropriate ones of the physical NIs (e.g., 316, 346).
  • a VNE implementing IP router functionality forwards IP packets on the basis of some of the IP header information in the IP packet; where IP header information includes source IP address, destination IP address, source port, destination port (where "source port" and
  • FIG. 3C illustrates various exemplary ways in which VNEs may be coupled according to some embodiments of the invention.
  • Figure 3C shows VNEs 370A.1-370A.P (and optionally VNEs 370A.Q-370A.R) implemented in ND 300A and VNE 370H.1 in ND 300H.
  • VNEs 370A.1-P are separate from each other in the sense that they can receive packets from outside ND 300A and forward packets outside of ND 300A; VNE 370A.1 is coupled with VNE 370H.1, and thus they communicate packets between their respective NDs; VNE 370A.2-370A.3 may optionally forward packets between themselves without forwarding them outside of the ND 300A; and VNE 370A.P may optionally be the first in a chain of VNEs that includes VNE 370A.Q followed by VNE 370A.R (this is sometimes referred to as dynamic service chaining, where each of the VNEs in the series of VNEs provides a different service - e.g., one or more layer 4-7 network services). While Figure 3C illustrates various exemplary relationships between the VNEs, alternative embodiments may support other relationships (e.g., more/fewer VNEs, more/fewer dynamic service chains, multiple different dynamic service chains with some common VNEs and some different VNE
  • the NDs of Figure 3A may form part of the Internet or a private network; and other electronic devices (not shown; such as end user devices including workstations, laptops, netbooks, tablets, palm tops, mobile phones, smartphones, phablets, multimedia phones, Voice Over Internet Protocol (VOIP) phones, terminals, portable media players, GPS units, wearable devices, gaming systems, set-top boxes, Internet enabled household appliances) may be coupled to the network (directly or through other networks such as access networks) to communicate over the network (e.g., the Internet or virtual private networks (VPNs) overlaid on (e.g., tunneled through) the Internet) with each other (directly or through servers) and/or access content and/or services.
  • VOIP Voice Over Internet Protocol
  • VPNs virtual private networks
  • Such content and/or services are typically provided by one or more servers (not shown) belonging to a service/content provider or one or more end user devices (not shown) participating in a peer-to-peer (P2P) service, and may include, for example, public webpages (e.g., free content, store fronts, search services), private webpages (e.g.,
  • end user devices may be coupled (e.g., through customer premise equipment coupled to an access network (wired or wirelessly)) to edge NDs, which are coupled (e.g., through one or more core NDs) to other edge NDs, which are coupled to electronic devices acting as servers.
  • one or more of the electronic devices operating as the NDs in Figure 3A may also host one or more such servers (e.g., in the case of the general purpose network device 304, one or more of the software instances 362A-R may operate as servers; the same would be true for the hybrid network device 306; in the case of the special-purpose network device 302, one or more such servers could also be run on a virtualization layer executed by the compute resource(s) 312); in which case the servers are said to be co-located with the VNEs of that ND.
  • the servers are said to be co-located with the VNEs of that ND.
  • a virtual network is a logical abstraction of a physical network (such as that in Figure 3A) that provides network services (e.g., L2 and/or L3 services).
  • a virtual network can be implemented as an overlay network (sometimes referred to as a network virtualization overlay) that provides network services (e.g., layer 2 (L2, data link layer) and/or layer 3 (L3, network layer) services) over an underlay network (e.g., an L3 network, such as an Internet Protocol (IP) network that uses tunnels (e.g., generic routing encapsulation (GRE), layer 2 tunneling protocol (L2TP), IPSec) to create the overlay network).
  • IP Internet Protocol
  • a network virtualization edge sits at the edge of the underlay network and participates in implementing the network virtualization; the network-facing side of the NVE uses the underlay network to tunnel frames to and from other NVEs; the outward-facing side of the NVE sends and receives data to and from systems outside the network.
  • a virtual network instance is a specific instance of a virtual network on a NVE (e.g., a NE/VNE on an ND, a part of a NE/VNE on a ND where that NE/VNE is divided into multiple VNEs through emulation); one or more VNIs can be instantiated on an NVE (e.g., as different VNEs on an ND).
  • a virtual access point is a logical connection point on the NVE for connecting external systems to a virtual network; a VAP can be physical or virtual ports identified through logical interface identifiers (e.g., a VLAN ID).
  • Examples of network services include: 1) an Ethernet LAN emulation service (an Ethernet-based multipoint service similar to an Internet Engineering Task Force (IETF) Multiprotocol Label Switching (MPLS) or Ethernet VPN (EVPN) service) in which external systems are interconnected across the network by a LAN environment over the underlay network (e.g., an NVE provides separate L2 VNIs (virtual switching instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network); and 2) a virtualized IP forwarding service (similar to IETF IP VPN (e.g., Border Gateway Protocol (BGP)/MPLS IP VPN) from a service definition perspective) in which external systems are interconnected across the network by an L3 environment over the underlay network (e.g., an NVE provides separate L3 VNIs (forwarding and routing instances) for different such virtual networks, and L3 (e.g., IP/MPLS) tunneling encapsulation across the underlay network)).
  • Network services may also include quality of service capabilities (e.g., traffic classification marking, traffic conditioning and scheduling), security capabilities (e.g., filters to protect customer premises from network - originated attacks, to avoid malformed route announcements), and management capabilities (e.g., full detection and processing).
  • quality of service capabilities e.g., traffic classification marking, traffic conditioning and scheduling
  • security capabilities e.g., filters to protect customer premises from network - originated attacks, to avoid malformed route announcements
  • management capabilities e.g., full detection and processing.
  • Fig. 3D illustrates a network with a single network element on each of the NDs of Figure 3A, and within this straight forward approach contrasts a traditional distributed approach (commonly used by traditional routers) with a centralized approach for maintaining reachability and forwarding information (also called network control), according to some embodiments of the invention.
  • Figure 3D illustrates network elements (NEs) 370A-H with the same connectivity as the NDs 300A-H of Figure 3A.
  • Figure 3D illustrates that the distributed approach 372 distributes responsibility for generating the reachability and forwarding information across the NEs 370A-H; in other words, the process of neighbor discovery and topology discovery is distributed.
  • the control communication and configuration module(s) 332A-R of the ND control plane 324 typically include a reachability and forwarding information module to implement one or more routing protocols (e.g., an exterior gateway protocol such as Border Gateway Protocol (BGP), Interior Gateway Protocol(s) (IGP) (e.g., Open Shortest Path First (OSPF), Intermediate System to Intermediate System (IS-IS), Routing Information Protocol (RIP), Label Distribution Protocol (LDP), Resource Reservation Protocol (RSVP) (including RS VP-Traffic Engineering (TE): Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol Label Switching
  • Border Gateway Protocol BGP
  • IGP Interior Gateway Protocol
  • OSPF Open Shortest Path First
  • IS-IS Intermediate System to Intermediate System
  • RIP Routing Information Protocol
  • LDP Label Distribution Protocol
  • RSVP Resource Reservation Protocol
  • TE Extensions to RSVP for LSP Tunnels and Generalized Multi-Protocol Label Switching
  • GPLS Signaling RSVP-TE
  • the NEs 370A-H e.g., the compute resource(s) 312 executing the control communication and configuration
  • module(s) 332A-R perform their responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by distributively determining the reachability within the network and calculating their respective forwarding information.
  • Routes and adjacencies are stored in one or more routing structures (e.g., Routing Information Base (RIB), Label Information Base (LIB), one or more adjacency structures) on the ND control plane 324.
  • the ND control plane 324 programs the ND forwarding plane 326 with information (e.g., adjacency and route information) based on the routing structure(s).
  • the ND control plane 324 programs the adjacency and route information into one or more forwarding table(s) 334A-R (e.g., Forwarding Information Base (FIB), Label Forwarding Information Base (LFIB), and one or more adjacency structures) on the ND forwarding plane 326.
  • the ND can store one or more bridging tables that are used to forward data based on the layer 2 information in that data. While the above example uses the special-purpose network device 302, the same distributed approach 372 can be implemented on the general purpose network device 304 and the hybrid network device 306.
  • FIG. 3D illustrates that a centralized approach 374 (also known as software defined networking (SDN)) that decouples the system that makes decisions about where traffic is sent from the underlying systems that forwards traffic to the selected destination.
  • the illustrated centralized approach 374 has the responsibility for the generation of reachability and forwarding information in a centralized control plane 376 (sometimes referred to as a SDN control module, controller, network controller, OpenFlow controller, SDN controller, control plane node, network virtualization authority, or management control entity), and thus the process of neighbor discovery and topology discovery is centralized.
  • a centralized control plane 376 sometimes referred to as a SDN control module, controller, network controller, OpenFlow controller, SDN controller, control plane node, network virtualization authority, or management control entity
  • the centralized control plane 376 has a south bound interface 382 with a data plane 380 (sometime referred to the infrastructure layer, network forwarding plane, or forwarding plane (which should not be confused with a ND forwarding plane)) that includes the NEs 370A-H (sometimes referred to as switches, forwarding elements, data plane elements, or nodes).
  • the centralized control plane 376 includes a network controller 378, which includes a centralized reachability and forwarding information module 379 that determines the reachability within the network and distributes the forwarding information to the NEs 370A-H of the data plane 380 over the south bound interface 382 (which may use the OpenFlow protocol).
  • the network intelligence is centralized in the centralized control plane 376 executing on electronic devices that are typically separate from the NDs.
  • each of the control communication and configuration module(s) 332A-R of the ND control plane 324 typically include a control agent that provides the VNE side of the south bound interface 382.
  • the ND control plane 324 (the compute resource(s) 312 executing the control communication and configuration module(s) 332A-R) performs its responsibility for participating in controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) through the control agent communicating with the centralized control plane 376 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 379 (it should be understood that in some embodiments of the invention, the control communication and configuration module(s) 332A-R, in addition to communicating with the centralized control plane 376, may also play some role in determining reachability and/or calculating forwarding information - albeit less so than in the case of a distributed approach; such embodiments are generally considered to fall under the centralized approach 374, but may also be considered a hybrid approach).
  • data e.g., packets
  • the control agent communicating with the centralized control plane 376 to receive the forward
  • the same centralized approach 374 can be implemented with the general purpose network device 304 (e.g., each of the VNE 360A-R performs its responsibility for controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and the outgoing physical NI for that data) by communicating with the centralized control plane 376 to receive the forwarding information (and in some cases, the reachability information) from the centralized reachability and forwarding information module 379; it should be understood that in some embodiments of the invention, the VNEs 360A-R, in addition to communicating with the centralized control plane 376, may also play some role in determining reachability and/or calculating forwarding information - albeit less so than in the case of a distributed approach) and the hybrid network device 306.
  • the general purpose network device 304 e.g., each of the VNE 360A-R performs its responsibility for controlling how data (e.g., packets) is to be routed (e.g., the next hop for the data and
  • NFV is able to support SDN by providing an infrastructure upon which the SDN software can be run
  • NFV and SDN both aim to make use of commodity server hardware and physical switches.
  • Figure 3D also shows that the centralized control plane 376 has a north bound interface 384 to an application layer 386, in which resides application(s) 388.
  • the centralized control plane 376 has the ability to form virtual networks 392 (sometimes referred to as a logical forwarding plane, network services, or overlay networks (with the NEs 370A-H of the data plane 380 being the underlay network)) for the application(s) 388.
  • virtual networks 392 sometimes referred to as a logical forwarding plane, network services, or overlay networks (with the NEs 370A-H of the data plane 380 being the underlay network)
  • the centralized control plane 376 maintains a global view of all NDs and configured NEs/VNEs, and it maps the virtual networks to the underlying NDs efficiently (including maintaining these mappings as the physical network changes either through hardware (ND, link, or ND component) failure, addition, or removal).
  • Figure 3D shows the distributed approach 372 separate from the centralized approach 374
  • the effort of network control may be distributed differently or the two combined in certain embodiments of the invention.
  • embodiments may generally use the centralized approach (SDN) 374, but have certain functions delegated to the NEs (e.g., the distributed approach may be used to implement one or more of fault monitoring, performance monitoring, protection switching, and primitives for neighbor and/or topology discovery); or 2) embodiments of the invention may perform neighbor discovery and topology discovery via both the centralized control plane and the distributed protocols, and the results compared to raise exceptions where they do not agree.
  • SDN centralized approach
  • Such embodiments are generally considered to fall under the centralized approach 374, but may also be considered a hybrid approach.
  • Figure 3D illustrates the simple case where each of the NDs 300A-H implements a single NE 370A-H
  • the network control approaches described with reference to Figure 3D also work for networks where one or more of the NDs 300A-H implement multiple VNEs (e.g., VNEs 330A-R, VNEs 360A-R, those in the hybrid network device 306).
  • the network controller 378 may also emulate the implementation of multiple VNEs in a single ND.
  • the network controller 378 may present the implementation of a VNE/NE in a single ND as multiple VNEs in the virtual networks 392 (all in the same one of the virtual network(s) 392, each in different ones of the virtual
  • the network controller 378 may cause an ND to implement a single VNE (a NE) in the underlay network, and then logically divide up the resources of that NE within the centralized control plane 376 to present different VNEs in the virtual network(s) 392 (where these different VNEs in the overlay networks are sharing the resources of the single VNE/NE implementation on the ND in the underlay network).
  • a single VNE a NE
  • the network controller 378 may cause an ND to implement a single VNE (a NE) in the underlay network, and then logically divide up the resources of that NE within the centralized control plane 376 to present different VNEs in the virtual network(s) 392 (where these different VNEs in the overlay networks are sharing the resources of the single VNE/NE implementation on the ND in the underlay network).
  • the centralized control plane 376 can implement a congruent multicast manager 381.
  • the congruent multicast manager 381 can be a program or similar set of instructions that implement the methods described herein above in reference to Figures 1 and 2 that provide congruent forwarding of unicast frames and multicast frames in a SPRING network.
  • Figures 3E and 3F respectively illustrate exemplary abstractions of NEs and VNEs that the network controller 378 may present as part of different ones of the virtual networks 392.
  • Figure 3E illustrates the simple case of where each of the NDs 300A-H implements a single NE 370A-H (see Figure 3D), but the centralized control plane 376 has abstracted multiple of the NEs in different NDs (the NEs 370A-C and G-H) into (to represent) a single NE 3701 in one of the virtual network(s) 392 of Figure 3D, according to some embodiments of the invention.
  • Figure 3E shows that in this virtual network, the NE 3701 is coupled to NE 370D and 370F, which are both still coupled to NE 370E.
  • Figure 3F illustrates a case where multiple VNEs (VNE 370A.1 and VNE 370H.1) are implemented on different NDs (ND 300 A and ND 300H) and are coupled to each other, and where the centralized control plane 376 has abstracted these multiple VNEs such that they appear as a single VNE 370T within one of the virtual networks 392 of Figure 3D, according to some embodiments of the invention.
  • the abstraction of a NE or VNE can span multiple NDs.
  • the electronic device(s) running the centralized control plane 376 may be implemented a variety of ways (e.g., a special purpose device, a general-purpose (e.g., COTS) device, or hybrid device). These electronic device(s) would similarly include compute resource(s), a set or one or more physical NICs, and a non-transitory machine-readable storage medium having stored thereon the centralized control plane software.
  • Figure 4 illustrates, a general purpose control plane device 404 including hardware 440 comprising a set of one or more processor(s) 442 (which are often COTS processors) and network interface controller(s) 444 (NICs; also known as network interface cards) (which include physical NIs 446), as well as non-transitory machine readable storage media 448 having stored therein centralized control plane (CCP) software 450.
  • processor(s) 442 which are often COTS processors
  • NICs network interface controller
  • NICs network interface controller
  • non-transitory machine readable storage media 448 having stored therein centralized control plane (CCP) software 450.
  • CCP centralized control plane
  • the processor(s) 442 typically execute software to instantiate a virtualization layer 454 (e.g., in one embodiment the virtualization layer 454 represents the kernel of an operating system (or a shim executing on a base operating system) that allows for the creation of multiple instances 462A-R called software containers (representing separate user spaces and also called virtualization engines, virtual private servers, or jails) that may each be used to execute a set of one or more applications; in another embodiment the virtualization layer 454 represents a hypervisor (sometimes referred to as a virtual machine monitor (VMM)) or a hypervisor executing on top of a host operating system, and an application is run on top of a guest operating system within an instance 462A-R called a virtual machine (which in some cases may be considered a tightly isolated form of software container) that is run by the hypervisor ; in another embodiment, an application is implemented as a unikernel, which can be generated by compiling directly with an application only a
  • VMM virtual machine monitor
  • an instance of the CCP software 450 (illustrated as CCP instance 476A) is executed (e.g., within the instance 462A) on the virtualization layer 454.
  • the CCP instance 476A is executed, as a unikernel or on top of a host operating system, on the "bare metal" general purpose control plane device 404.
  • the instantiation of the CCP instance 476A, as well as the virtualization layer 454 and instances 462A-R if implemented, are collectively referred to as software instance(s) 452.
  • the CCP instance 476A includes a network controller instance 478.
  • the network controller instance 478 includes a centralized reachability and forwarding information module instance 479 (which is a middleware layer providing the context of the network controller 378 to the operating system and communicating with the various NEs), and an CCP application layer 480 (sometimes referred to as an application layer) over the middleware layer (providing the intelligence required for various network operations such as protocols, network situational awareness, and user - interfaces).
  • this CCP application layer 480 within the centralized control plane 376 works with virtual network view(s) (logical view(s) of the network) and the middleware layer provides the conversion from the virtual networks to the physical view.
  • the centralized control plane 376 transmits relevant messages to the data plane 380 based on CCP application layer 480 calculations and middleware layer mapping for each flow.
  • a flow may be defined as a set of packets whose headers match a given pattern of bits; in this sense, traditional IP forwarding is also flow-based forwarding where the flows are defined by the destination IP address for example; however, in other implementations, the given pattern of bits used for a flow definition may include more fields (e.g., 10 or more) in the packet headers.
  • Different NDs/NEs/VNEs of the data plane 380 may receive different messages, and thus different forwarding information.
  • the data plane 380 processes these messages and programs the appropriate flow information and corresponding actions in the forwarding tables (sometime referred to as flow tables) of the appropriate NE/VNEs, and then the NEs/VNEs map incoming packets to flows represented in the forwarding tables and forward packets based on the matches in the forwarding tables.
  • the general purpose control plane device 404 can implement a congruent multicast manager 481.
  • the congruent multicast manager 481 can be a program or similar set of instructions that implement the methods described herein above in reference to Figures 1 and 2 that provide congruent forwarding of unicast frames and multicast frames in a SPRING network.
  • the congruent multicast manager 481 can be stored by the non-transitory machine readable storage media 448 and executed by the software instances 452 and processors 442.
  • Standards such as OpenFlow define the protocols used for the messages, as well as a model for processing the packets.
  • the model for processing packets includes header parsing, packet classification, and making forwarding decisions. Header parsing describes how to interpret a packet based upon a well-known set of protocols. Some protocol fields are used to build a match structure (or key) that will be used in packet classification (e.g., a first key field could be a source media access control (MAC) address, and a second key field could be a destination MAC address).
  • MAC media access control
  • Packet classification involves executing a lookup in memory to classify the packet by determining which entry (also referred to as a forwarding table entry or flow entry) in the forwarding tables best matches the packet based upon the match structure, or key, of the forwarding table entries. It is possible that many flows represented in the forwarding table entries can correspond/match to a packet; in this case the system is typically configured to determine one forwarding table entry from the many according to a defined scheme (e.g., selecting a first forwarding table entry that is matched).
  • Forwarding table entries include both a specific set of match criteria (a set of values or wildcards, or an indication of what portions of a packet should be compared to a particular value/values/wildcards, as defined by the matching capabilities - for specific fields in the packet header, or for some other packet content), and a set of one or more actions for the data plane to take on receiving a matching packet. For example, an action may be to push a header onto the packet, for the packet using a particular port, flood the packet, or simply drop the packet.
  • TCP transmission control protocol
  • an unknown packet for example, a "missed packet” or a "match-miss” as used in OpenFlow parlance
  • the packet (or a subset of the packet header and content) is typically forwarded to the centralized control plane 376.
  • the centralized control plane 376 will then program forwarding table entries into the data plane 380 to accommodate packets belonging to the flow of the unknown packet. Once a specific forwarding table entry has been programmed into the data plane 380 by the centralized control plane 376, the next packet with matching credentials will match that forwarding table entry and take the set of actions associated with that matched entry.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)

Abstract

La présente invention concerne un procédé à mettre en œuvre par un dispositif de réseau dans un paquet source dans un réseau de routage (SPRING). Le réseau SPRING prend en charge une pluralité de services Ethernet et définit une pluralité d'arbres de distribution de multidiffusion (MDT) locaux pour des services respectifs de la pluralité de services Ethernet, les arbres MDT étant mis en œuvre en tant qu'éléments hybrides de tunnels d'unidiffusion et de points de réplication. Le dispositif de réseau fonctionne en tant que nœud d'entrée pour un service Ethernet de la pluralité des services Ethernet. Le procédé consiste à recevoir une trame d'unidiffusion du service Ethernet, à générer une valeur d'entropie commune à un ensemble de trames qui partagent une contrainte d'ordre commune avec la trame d'unidiffusion, et à associer le service Ethernet à un arbre MDT local ayant une racine sur le nœud d'entrée et des feuilles correspondant à toutes les destinations possibles dans l'instance de service Ethernet.
PCT/IB2016/050981 2016-02-23 2016-02-23 Procédé et appareil pour une unidiffusion et une multidffusion conformes pour des services ethernet dans un réseau spring WO2017144943A1 (fr)

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