Bit-indexed explicit replication fast re-route

Abstract

A method implemented by a network node in a bit index explicit replication (BIER) domain for providing fast re-routing protection. The method comprises: copying a bit index routing table (BIRT) of the network node; changing a neighbor node in the copied BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT; deriving a backup bit index forwarding table (BIFT) from the backup BIRT; and forwarding a data packet according to the backup BIFT when the neighbor node fails.

Description

[0001] Cross Reference to Related Applications

[0002] This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 104,985, filed October 23, 2020, and titled “Bit Index Explicit Replication Fast Reroute,” by Chen Huaimou, which is incorporated by reference herein. TECHNICAL FIELD

[0003] The present disclosure relates generally to the field of fast re-route (FRR) protection, and in particular to FRR protection for node failures in a bit index explicit replication (BIER) domain. BACKGROUND

[0004] The BIER mechanism provides optimized multicast packet forwarding through a BIER domain. A BIER domain can not need to use a protocol to explicitly build a multicast distribution tree. Further, a BIER domain can not need intermediate nodes to maintain any per-flow state. BIER is described in further detail in the Internet Engineering Task Force (IETF) Request for Comment (RFC) 8279, entitled “Multicast Using Bit Index Explicit Replication (BIER),” by IJ. Wijnands et al., published November 2017. SUMMARY

[0005] The disclosed aspects / embodiments provide a fast reroute procedure for a BIER domain. To facilitate the fast reroute procedure, a bit index routing table (BIRT) of a network node is replicated to generate a backup BIRT for neighbor nodes. When a neighbor node is a next hop for a destination network node in the backup BIRT, the neighbor node in the backup is replaced with one of a plurality of backup neighbor nodes. A backup bit index forwarding table (BIFT) is derived from the backup BIRT. Then, when the neighbor node fails, data packets are forwarded according to the backup BIFT. The fast reroute procedure can also utilize loop-free alternate (LFA) to reduce redundant data packets. Thus, data packet routing within a BIER domain is improved.

[0006] A first aspect relates to a method implemented by a network node in a bit index explicit replication (BIER) domain, comprising: replicating a bit index routing table (BIRT) of the network node; changing a neighbor node in the replicated BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT; deriving a backup bit index forwarding table (BIFT) from the backup BIRT; and forwarding data packets according to the backup BIFT when the neighbor node fails.

[0007] Optionally, in any of the foregoing aspects, another implementation of the aspect provides that the one of the plurality of backup neighbor nodes for a destination network node is a basic loop-free alternate (LFA) bit forwarding router (BFR) for the destination network node.

[0008] Optionally, in any of the foregoing aspects, another implementation of the aspect provides that the one of the plurality of backup neighbor nodes for the destination network node is a remote loop-free alternate (LFA) bit forwarding router (BFR) for the destination network node.

[0009] Optionally, in any of the preceding aspects, another implementation of such aspects provides that the one of the plurality of backup neighbor nodes of the destination network node is a topology independent loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

[0010] Optionally, in any of the preceding aspects, another implementation of such aspects provides that deriving the backup BIFT includes generating a forwarding bit mask (F-BM) for each destination network node in the backup BIFT using the bit string from each destination BFR of the backup BIRT.

[0011] Optionally, in any of the preceding aspects, another implementation of such aspects provides that deriving the backup BIFT includes generating a forwarding bit mask (F-BM) for two or more of the destination network nodes in the backup BIRT that share a same next hop by applying a logical OR operation to the bit strings of the two or more of the destination network nodes.

[0012] Optionally, in any of the preceding aspects, another implementation of such aspects provides that a forwarding bit mask (F-BM) in the backup BIFT is used when forwarding the data packet according to the backup BIFT.

[0013] Optionally, in any of the preceding aspects, another implementation of such aspects provides that the neighbor node is detected to have failed after the backup BIFT is derived.

[0014] Optionally, in any of the preceding aspects, another implementation of such aspects provides that the destination network nodes in the backup BIRT are represented by a bit forwarding router identifier (BFR-id), a set index, and a bit string.

[0015] Optionally, in any of the preceding aspects, another implementation of such aspects provides that the network node is a bit forwarding router (BFR) and the neighbor node is a bit forwarding router neighbor (BFR-NBR).

[0016] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the destination network node is a bit forwarding egress router (BFER).

[0017] A second aspect relates to a network node in a bit index explicit replication (BIER) domain, comprising: a memory storing instructions; one or more processors coupled to the memory, wherein the one or more processors are configured to execute the instructions to cause the network node to: replicate a bit index routing table (BIRT) of the network node; change a neighbor node in the replicated BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT; derive a backup bit index forwarding table (BIFT) from the backup BIRT; and forward a data packet according to the backup BIFT when the neighbor node fails.

[0018] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one of the plurality of backup neighbor nodes of the destination network node is a bit forwarding router (BFR) of a loop-free alternate (LFA) of the destination network node.

[0019] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one of the plurality of backup neighbor nodes of the destination network node is a bit forwarding router (BFR) of a remote loop-free alternate (LFA) of the destination network node.

[0020] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one of the plurality of backup neighbor nodes of the destination network node is a bit forwarding router (BFR) of a topology-independent loop-free alternate (LFA) of the destination network node.

[0021] Optionally, in any of the preceding aspects, another implementation of the aspect provides that to derive the backup BIFT, the one or more processors are configured to execute the instructions to cause the network node to generate a forwarding bit mask (F-BM) for each destination network node in the backup BIFT using a bit string from each destination BFR in the backup BIRT.

[0022] Optionally, in any of the preceding aspects, another implementation of the aspect provides that to derive the backup BIFT, the one or more processors are configured to execute the instructions to cause the network node to generate a forwarding bit mask (F-BM) for two or more of the destination network nodes in the backup BIRT that share a same next hop by applying a logical OR operation to the bit strings of the two or more of the destination network nodes.

[0023] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the network node is a bit forwarding router (BFR) and the neighbor node is a bit forwarding router neighbor (BFR-NBR).

[0024] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the destination network node is a bit forwarding egress router (BFER).

[0025] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the one or more processors are configured to execute the instructions to cause the network node to detect that the neighbor node fails after deriving the backup BIFT.

[0026] Optionally, in any of the preceding aspects, another implementation of the aspect provides that the destination network nodes in the backup BIRT are represented by a bit forwarding router identifier (BFR-id), a set index, and a bit string.

[0027] A third aspect relates to a network node in a bit index explicit replication (BIER) domain, comprising: a replicating device configured to replicate a bit index routing table (BIRT) of the network node; a modifying device configured to modify a neighbor node in the replicated BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT; a deriving device configured to derive a backup bit index forwarding table (BIFT) from the backup BIRT; and a forwarding device configured to forward a data packet according to the backup BIFT when the neighbor node fails.

[0028] For the sake of clarity, any of the above embodiments can be combined with any one or more of the other embodiments described above to create new embodiments within the scope of the present application.

[0029] These and other features will become more apparent from the following detailed description, taken in conjunction with the accompanying drawings, and the claims. BRIEF DESCRIPTION OF DRAWINGS

[0030] For a more complete understanding of the present application, reference is now made to the following brief description of the drawings taken in conjunction with the detailed description below, in which like reference numerals represent like parts.

[0031] Figure 1 A schematic diagram of a BIER topology including a BIER domain.

[0032] Figure 2 A schematic diagram of a bit index routing table (BIRT) of a network node.

[0033] Figure 3 A schematic diagram of a bit index forwarding table (BIFT) of a network node.

[0034] Figure 4 A schematic diagram of a fast reroute (FRR) BIRT of a network node according to an embodiment of the application.

[0035] Figure 5 A schematic diagram of a FRR BIFT of a network node according to an embodiment of the application.

[0036] Figure 6 A method implemented by a network node in a BIER domain according to an embodiment of the application.

[0037] Figure 7 A schematic diagram of a network device according to an embodiment of the application. Detailed Implementation

[0038] First, it should be understood that although illustrative implementations of one or more embodiments are provided below, the disclosed systems and / or methods can be implemented using any number of techniques, whether currently known or existing. The invention is by no means limited to the illustrative implementations, drawings, and techniques described below, including the exemplary designs and implementations illustrated and described herein, but can be modified within the full scope of the appended claims and their equivalents.

[0039] One proposed technique for providing FRR in a BIER domain requires a bit forwarding router (BFR-NBR) to route packets to a backup BFR using a routing layer tunnel when the neighbor bit forwarding router (BFR-NBR) fails. However, this technique has drawbacks. First, it will not work unless a routing layer tunnel is established. Furthermore, it cannot prevent redundant packets from being transmitted within the BIER domain.

[0040] This paper discloses a fast re-routing procedure for BIER domains that overcomes one or more of the problems mentioned above. To facilitate the fast re-routing procedure, the bit index routing table (BIRT) of network nodes is copied, and a fast re-reroute (FRR)-BIRT (also known as a backup BIRT) is generated for neighboring nodes. When a neighboring node is the next hop to the destination network node in the FRR-BIRT, the neighboring node in the FRR-BIRT is replaced with one of the backup neighboring nodes. An FRR bit index forwarding table (FRR-BIFT) (also known as a backup BIFT) is derived from the FRR-BIRT. Then, when a neighboring node fails, packets are forwarded according to the FRR-BIFT. The fast re-routing procedure also utilizes loop-free alternate (LFA) to reduce redundant packets. Therefore, packet routing within the BIER domain is improved.

[0041] Figure 1A diagram of a BIER topology 100 including a BIER domain 102. The BIER domain 102 can be part of a larger BIER domain (not shown). Thus, the BIER domain 102 can be referred to herein as a BIER subdomain. The BIER domain 102 includes a plurality of network nodes 104, 106, 108, 110, 112, 114, 116, and 118. While eight network nodes 104-118 are shown in the BIER domain 102, more or fewer nodes can be included in actual applications.

[0042] For ease of discussion, all of the network nodes 104-118 are assigned alphabetical names. For example, network node 104 has the name A, network node 106 has the name B, network node 108 has the name C, network node 110 has the name D, network node 112 has the name E, network node 114 has the name F, network node 116 has the name G, and network node 118 has the name H.

[0043] Each of the network nodes 104-118 is a bit forwarding router (BFR). Some of the network nodes, namely network nodes 104, 110, 112, 114, and 118, are disposed at the edge of the BIER domain 102. Network nodes 104, 110, 112, 114, and 118 that receive multicast packets from outside the BIER domain 102 can be referred to as ingress BFRs (BFIRs). Network nodes 104, 110, 112, 114, and 118 that transmit multicast packets from within the BIER domain 102 can be referred to as egress BFRs (BFERs). Depending on the direction of multicast packet traffic, each of the network nodes 104-118 can act as either a BFIR or a BFER.

[0044] Each of the network nodes 104, 110, 112, 114, and 118 can be referred to herein as a destination network node. The network nodes 104, 110, 112, 114, and 118 are each assigned a BFR identifier (BFR-id), a set index (SI), and a bitstring. For example, network node 110 has a BFR-id of 1, a SI of 0, and a bitstring of 00001 (in binary), network node 112 has a BFR-id of 2, a SI of 0, and a bitstring of 00010 (in binary), and network node 114 has a BFR-id of 3, a SI of 0, and a bitstring of 00011 (in binary). Figure 1The following are collectively referred to as 1 (0:00001): Network node 114 has a BFR-id of 2, an SI of 0, and a bit string of 00010 (collectively referred to as 2 (0:00010)). Network node 112 has a BFR-id of 3, an SI of 0, and a bit string of 00100 (collectively referred to as 3 (0:00100)). Network node 118 has a BFR-id of 4, an SI of 0, and a bit string of 01000 (collectively referred to as 4 (0:01000)). Network node 104 has a BFR-id of 5, an SI of 0, and a bit string of 10000 (collectively referred to as 5 (0:100000)).

[0045] Each of network nodes 104-118 has one or more neighboring nodes. As used herein, a neighboring node is a network node that is only one hop away from a network node. For example, network node 106 is... Figure 1 The network has four neighboring nodes: network node 104, network node 108, network node 112, and network node 116. In fact, each of network node 104, network node 108, network node 112, and network node 116 is only one hop away from network node 106.

[0046] Figure 1 Network nodes 104-118 are coupled to each other and communicate with each other via link 120. Link 120 can be wired, wireless, or some combination thereof. Each of the links 120 has a cost. For example, the link cost between network node 106 and network node 112 is 2, such as... Figure 1 As shown in the diagram. Similarly, the link cost between network node 106 and network node 116 is 2, and the link cost between network node 116 and network node 110 is also 2. For Figure 1 For any links in the network that do not display a value next to link 120, the default cost is 1. For example, the link cost between network node 106 and network node 104 is 1.

[0047] Figure 2 This is a schematic diagram of a bit index routing table (BIRT) 200 for a network node (e.g., network node 106). Figure 1 Each of the network nodes 104-118 in the BIER topology 100 builds and maintains a BIRT 200. The BIRT 200 can be built and maintained using, for example, a link state database (LSDB) that takes into account the cost of the links 120 between the network nodes.

[0048] Figure 2 The BIRT 200 depicted in the image is built on... Figure 1BIRT 200 on network node 106 in FIG. 1. As shown, BIRT 200 includes three columns of information. The first column 202 includes the BFR-id of each destination network node in BIER topology 100. The second column 204 includes the prefix associated with each destination network node (BFR prefix of the destination BFER). The third column 206 identifies the neighbor node (BFR-NBR) of network node 106 for reaching the destination network node identified in the first column 202, which is why the neighbor node in the third column 206 can also be referred to as the next hop of network node 106.

[0049] The first row 208 in BIRT 200 indicates that the BFR-NBR (or next hop) on the shortest path to destination node D (a.k.a. network node 110 or network node with BFR-id of 1) is network node C (a.k.a. network node 108). The second row 210 in BIRT 200 indicates that the BFR-NBR on the shortest path to destination node F (a.k.a. network node 114 or network node with BFR-id of 2) is network node C. The third row 212 in BIRT 200 indicates that the BFR-NBR on the shortest path to destination node E (a.k.a. network node 112 or network node with BFR-id of 3) is network node E. The fourth row 214 in BIRT 200 indicates that the BFR-NBR on the shortest path to destination node H (a.k.a. network node 118 or network node with BFR-id of 4) is network node C. The fifth row 216 in BIRT 200 indicates that the BFR-NBR on the shortest path to destination node A (a.k.a. network node 104 or network node with BFR-id of 5) is network node A. Notably, the SI of each of the destination network nodes in the first row 208, the second row 210, and the fourth row 214 in BIRT 200 is 0 and has the same BFR-NBR as network node C.

[0050] Figure 3 A diagram of a bit index forwarding table (BIFT) 300 for a network node (e.g., network node 106). Figure 1 Each of network nodes 104-118 in BIER topology 100 in FIG. 1 derives BIFT 300 based on the BIRT (e.g., BIRT 200) built by network nodes 104-118.

[0051] Figure 3 BIFT 300 depicted in FIG. 3 is built on network node 106 in FIG. 1. Figure 1 BIFT 300 on network node 106 in FIG. 1. As shown, BIFT 300 includes three columns of information. The first column 302 and the third column 306 in BIFT 300 are similar to the first column 202 and the third column 206 in BIRT 200, respectively.Figure 2 The first column 202 and the third column 206 in the BIRT 200 of FIG. 2 are the same. However, the second column 304 includes a forwarding bit mask (F-BM).

[0052] Since the SI for the destination network nodes with BFR-ids of 1, 2, and 4 in the first row 308, the second row 310, and the fourth row 314 of the BIFT 300 are 0, and each has the same BFR-NBR as network node C, the F-BM for these rows is the combination of the bit strings for the destination nodes with BFR-ids of 1, 2, and 4. Specifically, a logical OR operation is applied to the bit strings for the destination nodes with BFR-ids of 1, 2, and 4. The logical OR of the bit strings 00001, 00010, and 01000 results in the F-BM in the first row 308, the second row 310, and the fourth row 314 of the BIFT 300 being 01011.

[0053] Since there are no destination network nodes other than the destination network node E (a.k.a. network node 112) that has a BFR-NBR of network node E, the F-BM in the third row 312 of the BIFT 300 is the same as the bit string for the destination network node E, i.e., 00100. Likewise, since there are no destination network nodes other than the destination network node A (a.k.a. network node 104) that has a BFR-NBR of network node A, the F-BM in the fifth row 316 of the BIFT 300 is the same as the bit string for the destination network node A, i.e., 10000.

[0054] Figure 4 A diagram of a fast reroute (FRR) BIRT 400 for a network node (e.g., network node 106) in accordance with an embodiment of the application. The FRR BIRT 400 can be referred to herein as a backup BIRT. Figure 1 Each of the network nodes 104-118 in the BIER topology 100 of FIG. 1 constructs and maintains a FRR BIRT 400 for each BFR-NBR. Like the BIRT 200 of FIG. 2, Figure 2 Unlike the BIRT 200 of FIG. 2, Figure 4 The BIRT 400 of FIG. 4 is constructed in anticipation of a failure of a BFR-NBR. As an example, Figure 4 The BIRT 400 depicted in FIG. 4 is constructed by the network node 106 of FIG. 1 in anticipation of a failure of the neighbor node C (a.k.a. network node 108). The network node 106 will also construct similar FRR BIRTs for the neighbor nodes G, E, and A. Figure 1 The BIRT 400 depicted in FIG. 4 is constructed by the network node 106 of FIG. 1 in anticipation of a failure of the neighbor node C (a.k.a. network node 108). The network node 106 will also construct similar FRR BIRTs for the neighbor nodes G, E, and A.

[0055] In one embodiment, the network node 106 constructs the FRR BIRT 400 by copying the BIRT 200 of FIG. 2. Figure 2BIRT 200 starts building the FRR BIRT 400. Once BIRT 200 is replicated, network node B replaces neighbor node C in the FRR-BIRT 400 with one of the multiple backup BFR-NBRs when neighbor node C is the next hop to the destination network node in the FRR-BIRT 400. That is, the first column 402 and the second column 404 in the FRR-BIRT 400 are the same as the first column 202 and the second column 204 in the BIRT 200. Figure 2 However, the third column 406 of the FRR-BIRT 400 is updated such that neighbor node C is replaced with a different next hop for a particular destination. Specifically, when network node C fails, the data packets transmitted by network node B must use network node G as the next hop to reach destination node D. When network node C fails, the data packets transmitted by network node B must use network node E as the next hop to reach destination node F. Likewise, when network node C fails, the data packets transmitted by network node B must use network node G as the next hop to reach destination node H. The rest of the column 406 remains unchanged.

[0056] According to the update, the first row 408 in the FRR-BIRT 400 indicates that the BFR-NBR (or next hop) on the shortest path to destination node D is now network node G (instead of network node C). The second row 410 in the FRR-BIRT 400 indicates that the BFR-NBR on the shortest path to destination node F is now network node E (instead of network node C). The third row 412 in the FRR-BIRT 400 still indicates that the BFR-NBR on the shortest path to destination node E is network node E. The fourth row 414 in the FRR-BIRT 400 indicates that the BFR-NBR on the shortest path to destination node H is now network node G (instead of network node C). The fifth row 416 in the FRR-BIRT 400 now indicates that the BFR-NBR on the shortest path to destination node A is still network node A. Notably, the destination network nodes in the first row 208, the second row 210, and the fourth row 214 in the BIRT 200 each have a SI of 0 and have the same BFR-NBR as network node C.

[0057] Figure 5 A diagram of a FRR BIFT 500 for a network node according to an embodiment of the application. The FRR BIFT 500 can be referred to herein as a backup BIFT. Figure 1 Each of the network nodes 104-118 in the BIER topology 100 derives the FRR BIFT 500 based on the FRR BIRT (e.g., the FRR BIRT 400) built by the network nodes 104-118.

[0058] Figure 5 The FRR BIFT 500 depicted is the FRR BIFT 500 constructed on network node 106 in Figure 1 As shown, the FRR BIFT 500 includes three columns of information. The first column 502 and the third column 506 in the FRR BIFT 500 are the same as the first column 402 and the third column 406 in the FRR BIFT 400 of Figure 4 However, the second column 504 includes the F-BM that has been updated, as described below.

[0059] Since the destination network nodes with BFR-ids of 1 and 4 in the first row 508 and the fourth row 514 of the FRR BIFT 500 each have an SI of 0 and each have the same BFR-NBR as network node G, the F-BM for these rows is the combination of the bit strings of the destination nodes with BFR-ids of 1 and 4. Specifically, a logical OR operation is applied to the bit strings of the destination nodes with BFR-ids of 1 and 4. The logical OR of the bit strings 00001 and 01000 results in the F-BM in the first row 508 and the fourth row 514 of the FRR BIFT 500 being 01001.

[0060] Since the destination network nodes with BFR-ids of 2 and 3 in the second row 510 and the third row 512 of the FRR BIFT 500 each have an SI of 0 and each have the same BFR-NBR as network node E, the F-BM for these rows is the combination of the bit strings of the destination nodes with BFR-ids of 2 and 3. Specifically, a logical OR operation is applied to the bit strings of the destination nodes with BFR-ids of 2 and 3. The logical OR of the bit strings 00010 and 00100 results in the F-BM in the second row 510 and the third row 512 of the FRR BIFT 500 being 00110.

[0061] Since there are no destination network nodes other than the destination network node A (a.k.a. network node 104) that has the BFR-NBR of network node A, the F-BM in the fifth row 516 of the FRR BIFT 500 is the same as the bit string of the destination network node A, i.e., 10000. Once the FRR BIFT 500 is derived as described above, data packets (e.g., multicast data packets) can be forwarded according to the FRR BIFT 500 when neighbor node C fails.

[0062] Figure 6A method implemented by a network node in a BIER domain in accordance with an embodiment of the application. The network node can be the network node 106, and the BIER domain can be the BIER domain 102. In block 602, the network node 106 replicates a bit index routing table (BIRT) of the network node.

[0063] In block 604, the network node 106 changes a neighbor node in the replicated BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT (aka a FRR-BIRT). In one embodiment, the one of the plurality of backup neighbor nodes of a destination network node is a basic loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node. Basic LFA is described in detail in the Internet Engineering Task Force (IETF) Request for Comment (RFC) 5286, entitled “Basic Specification for IP Fast Reroute: Loop-Free Alternates,” by A. Atlas et al., published in 2008. In one embodiment, the one of the plurality of backup neighbor nodes of a destination network node is a remote LFA BFR of the destination network node. Remote LFA is described in detail in the IETF RFC 7490, entitled “Remote Loop-Free Alternate (LFA) Fast Reroute (FRR),” by S. Bryant et al., published in April 2015. In one embodiment, the one of the plurality of backup neighbor nodes of a destination network node is a topology independent (TI) LFA BFR of the destination network node. TI LFA is described in detail in the IETF document entitled “Topology Independent Fast Reroute using Segment Routing,” by S. Litkowski et al., published in June 2021.

[0064] In block 606, the network node 106 derives a backup bit index forwarding table (BIFT) from the backup BIRT. In one embodiment, deriving the backup BIFT includes generating an F-BM for each destination network node in the backup BIFT using the bit string of each destination BFR from the backup BIRT. In one embodiment, deriving the backup BIFT includes generating an F-BM for two or more destination network nodes that share the same next hop in the backup BIRT by applying a logical OR operation to the bit strings of the two or more destination network nodes.

[0065] In block 608, the network node 106 forwards data packets according to the backup BIFT when a neighbor node fails. In one embodiment, the network node 106 detects that a neighbor node has failed after deriving the backup BIFT. That is, the backup BIFT is built on the network node 106 before any failure is detected.

[0066] Figure 7 A schematic diagram of a network device 700 (e.g., a network node, a destination node, a neighbor node, etc.). The network device 700 is suitable for implementing the disclosed embodiments as described herein. The network device 700 includes ingress ports / ingress devices 710 and receiver units (Rx) / receiving devices 720 for receiving data, a processor, logic unit, or central processing unit (CPU) / processing device 730 for processing data, transmitter units (Tx) / transmitting devices 740 and egress ports / egress devices 750 for transmitting data, and a memory / storage device 760 for storing data. The network device 700 can also include optical-to-electrical (OE) and electrical-to-optical (EO) components coupled to the ingress ports / ingress devices 710, receiver units / receiving devices 720, transmitter units / transmitting devices 740, and egress ports / egress devices 750 for the ingress and egress of optical or electrical signals.

[0067] The processor / processing device 730 is implemented by hardware and software. The processor / processing device 730 can be implemented as one or more CPU chips, cores (e.g., as a multi-core processor), field-programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), and digital signal processors (DSPs). The processor / processing device 730 is in communication with the ingress port / ingress device 710, the receiver unit / receiving device 720, the transmitter unit / transmitting device 740, the egress port / egress device 750, and the memory / memory device 760. The processor / processing device 730 includes a BIER fast reroute module 770. The BIER fast reroute module 770 is capable of implementing the methods disclosed herein. Thus, the inclusion of the BIER fast reroute module 770 provides substantial improvement to the functionality of the network device 700 and effects a transformation of the network device 700 to a different state. Alternatively, the BIER fast reroute module 770 is implemented as instructions stored in the memory / memory device 760 and executed by the processor / processing device 730.

[0068] The network device 700 can also include input and / or output (I / O) or I / O devices 780 for communicating data to and from a user. The I / O devices or I / O device 780 can include output devices, such as a display for displaying video data, speakers for outputting audio data, etc. The I / O devices or I / O device 780 can also include input devices, such as a keyboard, mouse, navigation ball, etc., and / or corresponding interfaces for interacting with such output devices.

[0069] The memory / memory device 760 includes one or more of disk, tape, and solid-state memory devices and can be used as an over-flow data storage device, to store programs when such programs are selected for execution, and to store instructions and data read from a program as such program is executed. The memory / memory device 760 can be volatile and / or non-volatile and can be read-only memory (ROM), random access memory (RAM), ternary content-addressable memory (TCAM), and / or static random-access memory (SRAM).

[0070] While several embodiments have been provided in the present disclosure, it is understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to limit the disclosure to the details given, since the spirit and scope of the present disclosure are capable of many changes and modifications. For example, various elements or components can be combined or integrated within another system, or certain features can be omitted or not implemented.

[0071] Also, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate can be combined or integrated with other systems, components, techniques, or methods without departing from the scope of the present disclosure. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope of the present disclosure.

Claims

1. A method for implementing network nodes in a bit index explicit replication (BIER) domain, characterized in that, include: Copy the bit index routing table (BIRT) of the network node; Change the neighbor node in the replicated BIRT to one of the multiple backup neighbor nodes to generate a backup BIRT; Derive the backup bit index forwarding table (BIFT) from the backup BIRT; When the neighboring node fails, data packets are forwarded according to the backup BIFT.

2. The method according to claim 1, characterized in that, One of the multiple backup neighbor nodes of the destination network node is the basic loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

3. The method according to claim 1, characterized in that, One of the multiple backup neighbor nodes of the destination network node is a remote loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

4. The method according to claim 1, characterized in that, One of the multiple backup neighbor nodes of the destination network node is a topology-independent loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

5. The method according to any one of claims 1-4, characterized in that, Exporting the backup BIFT involves generating a forwarding bit mask (F-BM) for each destination network node in the backup BIFT using the bit string from each destination BFR of the backup BIRT.

6. The method according to any one of claims 1-4, characterized in that, Deriving the backup BIFT involves generating a forwarding bit mask (F-BM) for the two or more destination network nodes that share the same next hop in the backup BIRT by applying a logical OR operation to two or more bit strings in the destination network node.

7. The method according to claim 1, characterized in that, When forwarding the data packet according to the backup BIFT, the forwarding bit mask (F-BM) in the backup BIFT is used.

8. The method according to claim 1, characterized in that, It also includes detecting a failure in the neighboring node after the backup BIFT is exported.

9. The method according to claim 1, characterized in that, The destination network node in the backup BIRT is represented by a bit forwarding router identifier (BFR-id), a set index, and a bit string.

10. The method according to claim 1, characterized in that, The network node is a bit-forwarding router (BFR), and the neighbor node is a bit-forwarding router neighbor (BFR-NBR).

11. The method according to claim 1, characterized in that, It also includes replacing the neighbor node in the backup BIRT with one of the plurality of backup neighbor nodes of the destination network node when the neighbor node is the next hop of the destination network node in the backup BIRT, and the destination network node is a bitforwarding egress router (BFER).

12. A network node in a bit index explicit replication (BIER) domain, characterized in that, include: Memory that stores instructions; One or more processors coupled to the memory, wherein the one or more processors are configured to execute the instructions to cause the network node to: Copy the bit index routing table (BIRT) of the network node; Change the neighbor node in the replicated BIRT to one of the multiple backup neighbor nodes to generate a backup BIRT; Derive the backup bit index forwarding table (BIFT) from the backup BIRT; When the neighboring node fails, data packets are forwarded according to the backup BIFT.

13. The network node according to claim 12, characterized in that, One of the multiple backup neighbor nodes of the destination network node is the basic loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

14. The network node according to claim 12, characterized in that, One of the multiple backup neighbor nodes of the destination network node is a remote loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

15. The network node according to claim 12, characterized in that, One of the multiple backup neighbor nodes of the destination network node is a topology-independent loop-free alternate (LFA) bit forwarding router (BFR) of the destination network node.

16. The network node according to any one of claims 12-15, characterized in that, In order to derive the backup BIFT, the one or more processors execute the instructions to cause the network node to generate a forwarding bit mask (F-BM) for each destination network node in the backup BIFT using the bit string from each destination BFR of the backup BIFT, thereby deriving the backup BIFT.

17. The network node according to any one of claims 12-15, characterized in that, In order to derive the backup BIFT, the one or more processors are configured to execute the instructions to cause the network node to generate a forwarding bit mask (F-BM) for the two or more destination network nodes sharing the same next hop in the backup BIFT by applying a logical OR operation to two or more bit strings in the destination network node.

18. The network node according to claim 12, characterized in that, The network node is a bit-forwarding router (BFR), and the neighbor node is a bit-forwarding router neighbor (BFR-NBR).

19. The network node according to claim 12, characterized in that, The instruction also causes the network node to replace the neighbor node in the backup BIRT with one of the plurality of backup neighbor nodes of the destination network node when the neighbor node is the next hop of the destination network node in the backup BIRT, and the destination network node is a bit forwarding egress router (BFER).

20. The network node according to claim 12, characterized in that, The one or more processors are configured to execute the instructions to cause the network node to detect a failure in the neighboring node after exporting the backup BIFT.

21. The network node according to claim 12, characterized in that, The destination network node in the backup BIRT is represented by a bit forwarding router identifier (BFR-id), a set index, and a bit string.

22. A network node in a bit index explicit replication (BIER) domain, characterized in that, include: A copying device for copying the bit index routing table (BIRT) of the network node; A device for changing a neighbor node in a replicated BIRT to one of a plurality of backup neighbor nodes to generate a backup BIRT; An export device for exporting a backup bit index forwarding table (BIFT) from the backup BIRT; A forwarding device for forwarding data packets according to the backup BIFT when the neighbor node fails.

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