WO2013053337A1 - Mise en œuvre de commutation de lsp - Google Patents

Mise en œuvre de commutation de lsp Download PDF

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Publication number
WO2013053337A1
WO2013053337A1 PCT/CN2012/082963 CN2012082963W WO2013053337A1 WO 2013053337 A1 WO2013053337 A1 WO 2013053337A1 CN 2012082963 W CN2012082963 W CN 2012082963W WO 2013053337 A1 WO2013053337 A1 WO 2013053337A1
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WIPO (PCT)
Prior art keywords
lsr
label
forwarding
forwarding entry
link
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PCT/CN2012/082963
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English (en)
Inventor
Jinrong YE
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Hangzhou H3C Technologies Co., Ltd.
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Publication of WO2013053337A1 publication Critical patent/WO2013053337A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
    • H04L12/42—Loop networks
    • H04L12/437—Ring fault isolation or reconfiguration
    • 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
    • H04L45/22—Alternate routing
    • 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
    • H04L45/28—Routing or path finding of packets in data switching networks using route fault recovery
    • 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]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
    • H04L41/06—Management of faults, events, alarms or notifications

Definitions

  • MPLS Multi-protocol Label Switching
  • OAM Operation Administration Maintenance
  • a ring network has a network topology structure which can provide high reliability and self-healing ability, and the MPLS TP is widely used in the ring network and packets are forwarded between corresponding Label Switching Routers (LSRs) of a work Label Switched Path (LSP) in the ring network.
  • LSRs Label Switching Routers
  • LSP work Label Switched Path
  • Figure 1 is a schematic diagram illustrating an example of conventional forwarding performed by a work LSP in a ring network.
  • FIGS. 2a and 2b are schematic diagrams respectively illustrating conventional LSP switching forwarding implemented by using a Wrapping mode caused by different reasons.
  • Figure 3 is a schematic diagram illustrating direction definitions in a ring network according to an example of the present disclosure.
  • Figure 4 is a schematic diagram illustrating a work LSP configured in a ring network according to an example of the present disclosure.
  • Figures 5a and 5b are schematic diagrams respectively illustrating two modes of a (FEC to NHLFE map) FTN entry to implement a working forwarding entry of an ingress node according to an example of the present disclosure.
  • Figures 6a and 6b are schematic diagrams respectively illustrating two modes of a (Incoming Label Map) ILM entry to implement a working forwarding entry of a transit node according to an example of the present disclosure.
  • Figures 7a and 7b are schematic diagrams respectively illustrating two modes of an ILM entry to implement a working forwarding entry of an egress node according to an example of the present disclosure.
  • Figure 8 is a schematic diagram illustrating a protection loop configured in a ring network according to an example of the present disclosure.
  • Figures 9a and 9b are schematic diagrams respectively illustrating initial states of two modes of an ILM entry for implementing a protection forwarding entry according to an example of the present disclosure.
  • Figures 10a to 10d are schematic diagrams illustrating LSP switching forwarding implemented by using a protection switching forwarding entry according to an example of the present disclosure.
  • Figures 11 a and 11 b are schematic diagrams respectively illustrating two modes of a FTN entry to implement a protection switching forwarding entry according to an example of the present disclosure.
  • Figures 12a and 12b are schematic diagrams respectively illustrating two modes of an ILM entry to implement a protection switching forwarding entry according to an example of the present disclosure.
  • Figures 13a and 13b are schematic diagrams respectively illustrating changing states of two modes of an ILM entry to implement a protection forwarding entry according to an example of the present disclosure.
  • Figure 14 is a schematic diagram illustrating sending a failure notification by a LSR detecting link failure and using a protection forwarding entry pre-configured according the failure notification according to an example of the present disclosure.
  • Figure 15 is a schematic diagram illustrating forwarding entries configured in different LSRs according to an example of the present disclosure.
  • Figure 16 is a flowchart illustrating a method for implementing LSP switching according to an example of the present disclosure.
  • Figure 17 is a schematic diagram illustrating a hardware structure according to an example of the present disclosure.
  • FIG 1 is a schematic diagram illustrating an example of conventional forwarding performed by a work LSP in a ring network.
  • a ring network including LSR A-LSR H is taken as an example
  • a work LSP in which LSR G is an ingress node and LSR A is an egress node is configured in the ring network (taking a clockwise direction as an example).
  • the work LSP includes LSR F-LSR A, and incoming working labels of LSR F-LSR A on the work LSP are W6-W1 respectively (as shown by the arrowheads on the outside of the ring network and in the clockwise direction ).
  • a normal forwarding process implemented by the work LSP when LSR A-LSR H in the ring network work normally includes the following operations.
  • the ingress node LSR G receives a packet to be transmitted via the work LSP from a location external to the ring network, the packet is represented as a rectangular block, the letter B in the rectangular block indicates a stack bottom label of the packet.
  • LSR G pushes W6 into the packet by using a push operation and sends the packet to LSR F.
  • W6 is the incoming working label of LSR F, which is a downstream neighbor of LSR G.
  • each LSR from LSR F to LSR B is a transit node of the work LSP.
  • each LSR as the transit node determines that the packet needs to be forwarded by the LSR when the packet carries the incoming working label of the LSR on the work LSP, and swaps the incoming working label of the LSR carried by the packet for an incoming working label of a downstream neighbor of the LSR, by using a Swap operation.
  • LSR F identifies W6 carried by the packet and swaps W6 for W5
  • LSR E identifies W5 carried by the packet and swaps W5 for W4
  • LSR D identifies W4 carried by the packet and swaps W4 for W3
  • LSR C identifies W3 carried by the packet and swaps W3 for W2
  • LSR B identifies W2 carried by the packet and swaps W2 for W1 .
  • the packet received by LSR A carries W1 , which is the incoming working label of LSR A on the work LSR And LSR A, as the egress node, pops W1 carried by the packet by using a Pop operation, and sends the packet to a location external to the ring network.
  • the ring network is a network topology structure that may provide high reliability and self-healing ability. Therefore, if the MPLS TP is applied in the ring network, the MPLS TP needs to have LSP switching capability to support the high reliability and self-healing ability of the ring shaped networking.
  • the LSP switching refers to: when the path between the ingress node and the egress node of the work LSP has failed, a new path between the ingress node and the egress node is re-selected to perform forwarding.
  • a failure may occur on a link between arbitrary two LSRs or on a LSR taken as the transit node. It should be noted that, if the failure occurs on the LSR taken as the ingress node and/or occurs on the LSR taken as the egress node, the LSP switching cannot be performed.
  • the ring network including LSR A-LSR H is taken as an example.
  • a work LSP in which LSR G is an ingress node and LSR A is an egress node, is configured in the ring network (taking a clockwise direction as an example).
  • a close protection loop having an opposite direction is also configured in the ring network (taking a counter-clockwise direction as an example).
  • the work LSP includes LSR F-LSR A
  • incoming working labels of LSR F-LSR A on the work LSP are W6-W1 respectively
  • the protection loop having the opposite direction includes LSR A-LSR H
  • incoming protection labels of LSR A-LSR H on the protection loop are P1 -P8 respectively (as shown by the arrowheads on the inside of the ring network and in the counter-clockwise direction).
  • a procedure of work LSP switching forwarding includes the following operations.
  • the ingress node LSR G receives a packet to be transmitted via the work LSP from a location external to the ring network, the packet is represented as a rectangular block.
  • the letter B in the rectangular block indicates a stack bottom label of the packet.
  • LSR G pushes W6 into the packet by using a push operation and sends the packet to LSR F.
  • W6 is the incoming working label of LSR F which is a downstream neighbor of LSR G.
  • LSR F As the transit node of the work LSP, LSR F identifies W6 carried by the packet and swaps W6 for W5. Because the failure occurs on the link between LSR F and LSR E, LSR F detects the link between LSR F and LSR E, which is the downstream neighbor of LSR F on the direction of the work LSP is failed. Hence, the packet carrying W5 can only be forwarded on the protection loop having the opposite direction.
  • LSR F needs to push P7 into an outer layer of W5 by using a push operation.
  • P7 is the incoming protection label of LSR G which is in the downstream of LSR F on the protection loop, so that the label carried by the packet includes W5 (inner layer) + P7 (outer layer).
  • each LSR from LSR G to LSR E determines that the packet needs to be forwarded by the LSR when the packet carries the incoming protection label of the LSR on the protection loop, and swaps the incoming protection label of the LSR carried by the packet for an incoming protection label of a downstream neighbor of the LSR on the protection loop, by using a Swap operation, and no processing is performed for W5 in the inner layer;
  • LSR G identifies P7 carried by the outer layer in the packet and swaps P7 for P8
  • LSR H identifies P8 carried by the outer layer in the packet and swaps P8 for P1
  • LSR A identifies P1 carried by the outer layer in the packet and swaps P1 for P2
  • LSR B identifies P2 carried by the outer layer in the packet and swaps P2 for P3
  • LSR C identifies P3 carried by the outer layer in the packet and swaps P3 for P4
  • LSR D identifies P4 carried by the outer layer in the packet and swaps P4 for P5.
  • the packet received by LSR E carries P5, which is the incoming protection label of LSR E on the protection loop.
  • LSR E pops P5 carried by the outer layer in the packet by using a Pop operation, and W5 in the inner layer is exposed.
  • LSR E determines that the packet carrying W5 should be forwarded by LSR E, and swaps W5 for W4.
  • W4 is the incoming working label of LSR D, which is the downstream neighbor of LSR E on the work LSP.
  • LSR B determines that the packet needs to be forwarded by the LSR when the packet carries the incoming working label of the LSR on the work LSP, and swaps the incoming working label of the LSR on the work LSP carried by the packet for an incoming working label of a downstream neighbor of the LSR on the work LSP, by using the Swap operation. That is, LSR D identifies W4 carried by the packet and swaps W4 for W3, LSR C identifies W3 carried by the packet and swaps W3 for W2, and LSR B identifies W2 carried by the packet and swaps W2 for W1 .
  • the packet received by LSR A carries W1 , which is the incoming working label of LSR A on the work LSP, and LSR A, as the egress node, pops W1 carried by the packet by using a Pop operation, and sends the packet to a location external to the ring network.
  • a procedure of work LSP switching forwarding includes the following operations.
  • the ingress node LSR G receives a packet to be transmitted via the work LSP from a location external to the ring network, the packet is represented as a rectangular block, in which the letter B in the rectangular block indicates a stack bottom label of the packet.
  • LSR G pushes W6 into the packet by using a push operation and sends the packet to LSR F.
  • W6 is the incoming working label of LSR F which is downstream neighbor of LSR G.
  • LSR F identifies W6 carried by the packet and swaps W6 for W5. Because the failure occurs on LSR E and LSR D, LSR F detects the link between LSR F and LSR E, which is in the downstream neighbor of LSR F on the direction of the work LSP is failed.
  • the packet carrying W5 can only be forwarded on the protection loop with the opposite direction.
  • LSR F needs to push P7 into an outer layer of W5 by using a push operation.
  • P7 is the incoming protection label of the LSR G, which is in the downstream direction of LSR F on the protection loop, so that the label carried by the packet includes W5 (inner layer) + P7 (outer layer).
  • each LSR from LSR G to LSR C determines that the packet needs to be forwarded by the LSR when the packet carries the incoming protection label of the LSR on the protection loop, and swaps the incoming protection label of the LSR carried by the packet for an incoming protection label of a downstream neighbor of LSR on the protection loop, by using a Swap operation; and no processing is performed for W5 in the inner layer; That is, LSR G identifies P7 carried by the outer layer in the packet and swaps P7 for P8, LSR H identifies P8 carried by the outer layer in the packet and swaps P8 for P1 , LSR A identifies P1 carried by the outer layer in the packet and swaps P1 for P2, LSR B identifies P2 carried by the outer layer in the packet and swaps P2 for P3.
  • the packet received by the LSR C carries P3, which is the incoming protection label of LSR C on the protection loop. Because the failure occurs on LSR E and LSR D, and LSR C detects the failure of the link between the LSR C and the LSR D which is in the upstream of LSR C on the work LSP, the forwarding of the packet on the protection loop is terminated, and the packet is forwarded on the work LSP. Accordingly, LSR C pops P3 carried by the outer layer in the packet by using the Pop operation, and W5 in the inner layer is exposed.
  • LSR D cannot continue to forward the packet via the work LSP according to the procedure defined in Wrapping mode because W5 corresponding to LSR E is carried by the inner layer in the packet.
  • the conventional LSP switching solutions of the Wrapping mode are only adapted to the single link failure, and cannot implement the LSP switching for failures caused by multi-link failures and node failures.
  • Figure 3 is a schematic diagram illustrating direction definitions in a ring network according to an example of the present disclosure.
  • a ring network including LSR A-LSR H is taken as an example, and in the example, the clockwise direction is defined as a first direction S1 and the counter-clockwise direction is defined as a second direction S2.
  • the first direction S1 there may be multiple work LSPs, all of or part of the LSRs included in the work LSPs are located in the ring network, Accordingly, on the second direction S2, there may be a close protection loop, and all of the working LSPs use the protection loop having the opposite direction together.
  • the LSRs included in the work LSPs are located in the ring network. If part of the LSRs included in the work LSPs are located in the ring network, the LSRs located in the ring network perform the switching according to the same principle.
  • the terms “downstream” and “upstream” refer to the first direction S1 of the work LSP.
  • FIG 4 is a schematic diagram illustrating a work LSP configured in a ring network according to an example of the present disclosure.
  • a work LSP1 and a work LSP2 in the first direction S1 of the ring network, there are a work LSP1 and a work LSP2, an ingress node and an egress node of the work LSP1 are LSR G and LSR A respectively, and an ingress node and an egress node of the work LSP2 are LSR F and LSR B respectively.
  • a working forwarding entry is preset in each LSR to forward packets on the work LSP1 ; the packet forwarded by each LSR via the work LSP1 by using the working forwarding entry carries an incoming working label on the work LSP1 of a downstream neighbor of the LSR; and on the work LSP1 , except the ingress node LSR G, the incoming working labels of LSR F to LSR A are W6-W1 respectively.
  • a working forwarding entry is preset in each LSR to forward packets on the work LSP2; the packet forwarded by each LSR via the work LSP2 by using the working forwarding entry carries an incoming working label of a downstream neighbor of the LSR on the work LSP2; on the work LSP2, except the ingress node LSR F, the incoming working labels of LSR E to LSR B are X4-X1 respectively.
  • Figures 5a and 5b are schematic diagrams respectively illustrating two modes of a (FEC to NHLFE map) FTN entry to implement a working forwarding entry of an ingress node.
  • the mode shown in Figure 5a is a one-level table, in which a Forwarding Equivalence Class (FEC) and contents of Nexthop Label Forwarding Entry (NHLFE) are all included in the table of the same level.
  • FEC Forwarding Equivalence Class
  • NHSFE Nexthop Label Forwarding Entry
  • the mode shown in Figure 5b is a two-level table, in which the first level table only includes the FEC and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the first level table only includes the FEC and an ID of the NHLFE
  • the contents of the NHLFE are included in the second level table.
  • the FEC of the work LSP is taken as the identifier index of the working forwarding entry implemented by using the FTN entry
  • an included out port is an OutPort-S1 on the first direction S1 of the LSR
  • an included operation type is Push-once
  • an outgoing working label oL of the Push operation is an incoming working label on the work LSP of a downstream neighbor of the LSR on the first direction S1
  • -LSR indicates the work label in Figures 5a and 5b.
  • Figures 6a and 6b are schematic diagrams respectively illustrating two modes of a (Incoming Label Map) ILM entry to implement a working forwarding entry of a transit node.
  • the mode shown in Figure 6a is a one-level table, in which an incoming working label iL and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 6b is a two-level table, in which the first level table only includes the incoming working label iL and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the incoming working label iL of LSR on the work LSP (“-LSR" indicates the work label in Figures 6a and 6b) is taken as the identifier index of the working forwarding entry implemented by using the ILM entry
  • an included out port is an OutPort-S1 of the LSR on the first direction S1
  • an included operation type is Swap
  • an outgoing working label oL of the Swap operation is an incoming working label on the work LSP of a downstream neighbor of the LSR on the first direction S1 .
  • Figures 7a and 7b are schematic diagrams respectively illustrating two modes of an ILM entry to implement a working forwarding entry of an egress node.
  • the mode shown in Figure 7a is a one-level table, in which an incoming working label iL and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 7b is a two-level table, in which the first level table includes only the incoming working label il_ and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the incoming working label il_ of the LSR on the work LSP (“-LSR" indicates the work label in Figures 7a and 7b) is taken as the identifier index of the working forwarding entry implemented by using the ILM entry, an included out port is an non-ring-network-port of the LSR, an included operation type is Pop, and an outgoing working label oL of the Pop operation is null.
  • LSR G implements the working forwarding entry by using the FTN entry as shown in Figures 5a and 5b, takes the FECI of the work LSP1 as identifier index, an included out port is an OutPort-S1 of LSR G on the first direction S1 , an included operation type is Push-once, an outgoing working label oL of the Push operation is W6 which is the incoming working label of LSR F on the work LSP1 , and LSR F is a downstream neighbor of LSR G.
  • LSR F implements the working forwarding entry by using the ILM entry as shown in Figures 6a and 6b, takes W6, which is the incoming working label of LSR F on the work LSP1 as the identifier index, an included out port is an OutPort-S1 of LSR F on the first direction S1 , an included operation type is Swap, an outgoing working label oL of the Swap operation is W5, which is the incoming working label of LSR E on the work LSP1 , and LSR E is a downstream neighbor of the LSR F.
  • LSR E-LSR B are also the transit nodes of the work LSP1 , and implementation of the working forwarding entry by using the ILM entry as shown in Figures 6a and 6b may be deduced by analogy.
  • LSR A implements the working forwarding entry by using the ILM entry as shown in Figures 7a and 7b, takes the incoming working label W1 on the work LSP1 of LSR A as the identifier index, an included out port is a non-ring-network-port of LSR A, an included operation type is Pop, an outgoing working label oL of the Pop operation is null, and thus the packet is forwarded.
  • the implementation of the working forwarding entry on the work LSP2 is similar with that on the work LSP1 , and the work LSP2 corresponds to the FEC2.
  • a protection loop is configured firstly in the examples of the present disclosure.
  • FIG 8 is a schematic diagram illustrating a protection loop configured in a ring network according to an example of the present disclosure. Based on the ring network shown in Figure 3 and as shown in Figure 8, a protection loop is configured on the second direction S2 opposite to the first direction S1 , and the protection loop is close and is on the opposite direction of the work LSP1 and LSP2.
  • a protection forwarding entry is preset in each LSR to forward packets on the protection loop; the packet forwarded by each LSR via the protection loop by using the protection forwarding entry carries an incoming protection label on the protection loop of an upstream LSR (the incoming direction on the protection loop is opposite to the incoming direction on the work LSP); and on the protection loop, the incoming protection labels of LSR A-LSR H on the second direction S2 are P1 ⁇ P8 respectively.
  • FIGS. 9a and 9b are schematic diagrams respectively illustrating initial states of two modes of ILM entry for implementing a protection forwarding entry according to an example of the present disclosure.
  • the mode shown in Figure 9a is a one-level table, in which an incoming working label il_ and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 9b is a two-level table, in which the first level table only includes the incoming working label il_ and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the incoming protection label iL of the LSR on the protection loop ("-Protect" indicates the protection label in Figures 9a and 9b) is taken as the identifier index of the protection forwarding entry implemented by using the ILM entry
  • an included out port is an OutPort-S1 on the second direction S2 of the LSR
  • an included operation type is Swap
  • an outgoing protection label oL of the Swap operation is an incoming protection label on the protection loop of a downstream neighbor LSR on the second direction S2.
  • FIGS 10a to 10d are respective schematic diagrams illustrating LSP switching forwarding implemented by using a protection switching forwarding entry according to an example of the present disclosure.
  • the switching forwarding modes shown in Figures 10a to 10d belong to the Wrapping mode.
  • packets are represented as rectangular blocks, in which the letter B in the rectangular block indicates a stack bottom label of the packet.
  • a protection switching forwarding entry is preset in each LSR to forward packets via the protection loop; each LSR forwards packets via the protection loop by using the protection switching forwarding entry of the LSR (the LSR is a upstream LSR of a failed link) only when the LSR detects the link between the LSR and a downstream neighbor LSR is failed; when the packet is forwarded by using the protection switching forwarding entry, an inner layer of the packet carries an incoming working label on the work LSP1 of a downstream LSR of the failed link, and an outer layer of the packet carries an incoming protection label on the protection loop of an upstream neighbor of the LSR.
  • the upstream LSR of the failed link forwards the packet by using the protection switching forwarding entry
  • the downstream LSR of the failed link needs to be able to pop the incoming protection label from the outer layer of the received packet, rather than keeping to perform the switching, so that the upstream LSR of the failed link can swap the incoming working label in the inner layer after popping the incoming protection label in the outer layer, and thus the packet is continually forwarded via the work LSP1 .
  • the LSR not detecting the link failure forwards the packet by using the working forwarding entry or protection forwarding entry based on the above described modes.
  • a failure occurs on a link between LSR F and LSR E, LSR F detects the link between the LSR F and the downstream neighbor LSR E is failed, and starts to use the protection switching forwarding entry.
  • the inner layer In the packet forwarded by the LSR F by using the protection switching forwarding entry, the inner layer carries W5, i.e., the incoming working label on the work LSP1 of LSR E, which is the downstream LSR of the failed link.
  • the outer layer carries P7, i.e., the incoming protection label on the protection loop of LSR G, which is the upstream neighbor of LSR F, and thus the label carried by the packet includes W5 (inner layer) +P7 (out layer).
  • LSR G, LSR H, LSR A-LSR D passed by the protection loop swap the incoming protection label in the out layer by using the protection forwarding entry, and the packet arrives at LSR E which is the downstream LSR of the failed link.
  • LSR E pops the incoming protection label P5 carried in the outer layer, swaps the incoming working label W5 carried in the inner layer for W4 which is the incoming working label on the work LSP1 of the downstream neighbor LSR D, so that the packet is forwarded continually via the work LSP1 .
  • the label carried by the packet forwarded by LSR F by using the protection switching forwarding entry includes W3 (inner layer) + P7 (out layer).
  • LSR C which is the downstream LSR of the failed link via the protection loop.
  • LSR C pops the incoming protection label P3 carried in the outer layer, swaps the incoming working label W3 carried in the inner layer for W2, which is the incoming working label on the work LSP1 of the downstream neighbor LSR B, so that the packet is forwarded continually via the work LSP1 .
  • a protection switching forwarding entry is preset in each LSR to forward packets via the protection loop; each LSR forwards packets via the protection loop by using the protection switching forwarding entry of the LSR only when the LSR detects the link between the LSR and a downstream neighbor LSR is failed.
  • the inner layer of the packet carries an incoming working label on the work LSP2 of a downstream LSR of the failed link
  • an outer layer of the packet carries an incoming protection label on the protection loop of an upstream neighbor of the LSR.
  • the downstream LSR of the failed link needs to be able to pop the incoming protection label from the outer layer of the received packet.
  • the LSR not detecting the link failure forwards the packet by using the working forwarding entry or protection forwarding entry based on the above described modes.
  • failures occur on a link between LSR F and LSR E and a link between LSR E and LSR D, LSR F detects the link between LSR F and the downstream neighbor LSR E is failed, and starts to use the protection switching forwarding entry.
  • the label carried in the packet forwarded by LSR F by using the protection switching forwarding entry includes X3 (inner layer) +P7 (out layer).
  • the packet arrives at LSR D which is the downstream LSR of the failed link.
  • the LSR D pops the incoming protection label P4 carried in the outer layer, swaps the incoming working label X3 carried in the inner layer for X2, which is the incoming working label on the work LSP2 of the downstream neighbor LSR C by using the working forwarding entry, so that the packet is forwarded via the work LSP2 continually.
  • a single-node failure occurs on LSR E, LSR F detects the link between LSR F and the downstream neighbor LSR E is failed, and starts to use the protection switching forwarding entry.
  • the label carried in the packet forwarded by LSR F by using the protection switching forwarding entry includes X3 (inner layer)+P7 (out layer).
  • LSR D which is the downstream LSR of the failed link via the protection loop.
  • LSR D pops the incoming protection label P4 carried in the outer layer, swaps, by using the working forwarding entry, the incoming working label X3 carried in the inner layer for X2, which is the incoming working label on the work LSP2 of the downstream neighbor LSR C, so that the packet is forwarded continually via the work LSP2.
  • the inner layer of the packet carries the incoming working label of the LSR in the downstream direction of the failed link, rather than the incoming working label of the LSR at which the packet cannot arrive. Therefore, when the failure occurs on the link between two nodes, occurs on one node, and/or occurs on more than one link or occurs on more than one node, the switching forwarding of the work LSP1 and LSP2 is implemented by using the protection switching forwarding entry implemented by the ILM entry.
  • Figures 11 a and 11 b are schematic diagrams respectively illustrating two modes of a FTN entry to implement a protection switching forwarding entry according to an example of the present disclosure.
  • the mode shown in Figure 11 a is a one-level table, in which an FEC and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 11 b is a two-level table, in which the first level table only includes the FEC and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the FEC of the work LSP is taken as the identifier index
  • an included out port is an OutPort-S2 of the LSR on the second direction S2
  • an included operation type is Push-twice
  • an inner layer label oL of the first Push is an incoming working label on the work LSP of a downstream LSR of the failed link
  • -LSP indicates the work label in Figures 11 a and 11 b
  • an outer layer label of the second Push is an incoming protection label on the protection loop of an upstream neighbor of the LSR
  • -Protect indicates the protection label in Figures 11 a and 11 b).
  • Figures 12a and 12b are schematic diagrams respectively illustrating two modes of an ILM entry to implement a protection switching forwarding entry according to an example of the present disclosure.
  • the mode shown in Figure 12a is a one-level table, in which an incoming working label iL and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 12b is a two-level table, in which the first level table only includes the incoming working label iL and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the first level table only includes the incoming working label iL and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the implementation of the protection switching forwarding entry on the work LSP1 is as follows. Taking the case in Figures 10a and 10b as an example, when the protection switching forwarding entry is implemented by using the ILM entry, W6, which is the incoming working label on the work LSP1 of LSR F, is taken as the identifier index iL, an included out port is an OutPort-S2 of the LSR F on the second direction S2, an included operation type is Push-twice, an inner layer label oL i of the first Push is W5 or W3, i.e., the incoming working labels on the work LSP1 of LSR E or LSR C, which is the downstream LSRs of the failed link, and an outer layer label of the second Push oL o is P7, i.e., the incoming protection label on the protection loop of LSR G which is an upstream neighbor of LSR F.
  • FIGS 10c and 10d are schematic diagrams respectively illustrating changing states of two modes of an ILM entry to implement a protection forwarding entry according to an example of the present disclosure.
  • the mode shown in Figure 13a is a one-level table, in which an incoming working label il_ and contents of NHLFE are all included in the table of the same level.
  • the mode shown in Figure 13b is a two-level table, in which the first level table includes only the incoming working label il_ and an ID of the NHLFE, and the contents of the NHLFE are included in the second level table.
  • the LSR E, LSR D, or LSR C in the downstream of the failed link pops the protection label in the outer layer by using the protection forwarding entry the operation type of which is changed to Pop, and W5 or W3, which is the incoming working label on the work LSP1 in the inner layer, or X4 or X3, which is the exposed incoming working label on the work LSP2, is exposed, so that the corresponding working forwarding entry may be identified according to the principle of the Wrapping mode, and the packet is forwarded via the work LSP1 and the work LSP2.
  • the LSR can configure the protection forwarding entry as blocked (V indicates the blocked state in Figures 10a to 10d), so as to indicate that the upstream neighbor LSR on the protection loop cannot forward the packet.
  • V indicates the blocked state in Figures 10a to 10d
  • each LSR may determine the downstream LSR of the failed link among the LSRs in the ring network via various modes after detecting the link between the LSR and the downstream neighbor LSR is failed; and each LSR may pre-configure all possible protection switching forwarding entries for each work LSP in which the LSR is the ingress node or transit node, and start to use the switching forward entry corresponding to the downstream LSR of the failed link after determining the downstream LSR of the failed link; or, each LSR may configure the switching forward entry corresponding to the downstream LSR of the failed link for each work LSP in which the LSR is the ingress node or transit node after determining the downstream LSR of the failed link.
  • Figure 14 is a schematic diagram illustrating the sending of a failure notification by a LSR detecting link failure and using a protection forwarding entry pre-configured according to the failure notification according to an example of the present disclosure.
  • the downstream LSR of the failed link is determined by using a failure notification mechanism, all possible protection switching forwarding entries are pre-configured, and the switching forward entry corresponding to the downstream LSR of the failed link is used after determining the downstream LSR of the failed link.
  • Figure 14 refers to a manner in which the downstream LSR of the failed link is determined by using a failure notification mechanism.
  • LSR D detects a link between LSR C and an upstream neighbor LSR D is failed
  • LSR F detects a link between LSR F and a downstream neighbor LSR E is failed.
  • LSR C is the downstream LSR of the failed link
  • LSR F is the upstream LSR of the failed link.
  • LSR F needs to know which LSR is the downstream LSR of the failed link in the ring network.
  • LSR C further sends a failure notification carrying an ID corresponding to LSR C via the ring network on the first direction S1 of the work LSP, and the failure notification finally arrives at LSR F after being forwarded via the ring network.
  • LSR F After detecting the link failure between LSR F and the downstream neighbor LSR E, LSR F waits for the failure notification. If the failure notification is received, LSR F determines LSR C sending the failure notification as the downstream LSR of the failed link according to the ID in the failure notification.
  • the failure notification may be implemented by a control layer signaling, i.e., signaling of MPLS TP Ring Protection State Coordination (MR-PSC) protocols. And the failure notification may also be sent via any conventional tunnel outside the ring network, which will not be described herein.
  • MR-PSC MPLS TP Ring Protection State Coordination
  • Figure 14 shows how to pre-establish all possible protection switching forwarding entries and how to use the switching forward entry corresponding to the downstream LSR of the failed link after a determination that the downstream LSR of the failed link is made.
  • each LSR pre-configures a work LSP path record, and in the work LSP path record, for each work LSP including the LSR, the incoming working labels on the work LSR of all of the other LSRs that belong to the work LSP and are in the downstream of the LSR.
  • LSR G which is the ingress node of the work LSP1
  • LSR F to LSR A which are in the downstream direction of LSR G on the work LSP1 , correspond to the incoming working labels W6-W1 .
  • LSR F which is the transit node of the work LSP1 and the ingress node of the work LSP2
  • LSR E to LSR A which are in the downstream direction of LSR F on the work LSP1
  • LSR E to LSR B which are in the downstream direction of LSR F on the work LSP2
  • the rest may be deduced by analogy.
  • each LSR can know the incoming working label of each of the downstream LSRs on the work LSP, and thus the LSR can configure, for each work LSP including the LSR, the protection switching forwarding entry corresponding to each of the downstream LSRs on the work LSP in advance.
  • LSR F can pre-configure the protection switching forwarding entries corresponding to LSR E-LSR A respectively for the work LSP1 , and the inner layer labels oL i of the Swap-first operation in the protection switching forwarding entries are W5-W1 respectively, and the outer layer label of the Push-later operation are all P7.
  • the mode of configuring the protection switching forwarding entries for the work LSP2 is similar.
  • the LSR After receiving the failure notification and determining the downstream LSR of the failed link in the ring network, the LSR starts to use the protection switching forwarding entry, which is pre-configured and corresponds to the determined LSR.
  • LSR F starts to use the protection switching forwarding entry corresponding to LSR C for the work LSP1 .
  • the inner layer labels oL i of the Swap-first operation is W3 and the outer layer label of the Push-later operation is P7.
  • the mode of starting the protection switching forwarding entry for the work LSP2 is similar.
  • the working forwarding entry, protection forwarding entry, and protection switching forwarding entry may switch to each other and are managed respectively. Therefore, in the example of the present disclosure, a default forwarding table corresponding to the LSR and a sub-forwarding table corresponding to each of the other LSRs are configured in each LSR.
  • the working forwarding entry and the protection forwarding entry only serve the LSR, and thus the default forwarding table corresponding to the LSR stores only the working forwarding entry and the protection forwarding entry.
  • the protection switching forwarding entry is used by the LSR to forward packets
  • the inner layer work label of the Push operation is mainly used by the downstream LSR of the failed link (i.e., the LSR sending the failure notification), that is, the protection switching forwarding entry serves not only the LSR but also the downstream LSR of the failed link.
  • the sub-forwarding table corresponding to each of other LSRs stores the protection switching forwarding entry corresponding to the LSR, so that the protection switching forwarding entry can be used when the LSR is the downstream LSR of the failed link. It should be noted that, when the protection forwarding entry is set as blocked or the operation type of the protection forwarding entry is changed as Pop operation, that this does not mean that the protection forwarding entry is changed as another forwarding entry.
  • FIG 15 is a schematic diagram illustrating forwarding entries configured inside different LSRs according to an example of the present disclosure.
  • the forwarding entry shown in Figures 4, 8, and 14 are taken as an example, which are configured in LSR F.
  • the default forwarding table of LSR F includes: a ILM working forwarding entry (for the work LSP1 ) in which the incoming working label W6 of LSR F is taken as the label index and the outgoing working label of the Swap operation is W5; a FTN working forwarding entry (for the work LSP2) in which the FEC2 of the work LSP 2 is taken as the identifier index and the outgoing working label of the Push operation is X4; a ILM protection forwarding entry (for the protection loop) in which the incoming protection label P6 is taken as the label index and the outgoing protection label of the Swap operation is P7.
  • the sub-forwarding table corresponding to LSR E includes: a ILM working forwarding entry (for the work LSP1 ), in which the incoming working label W6 of LSR F is taken as the label index, the outgoing working label in the inner layer of the Swap-first operation is W5, and the outgoing protection in the outer layer of the Push-later operation is P7; a FTN working forwarding entry (for the work LSP2), in which the FEC2 of the work LSP 2 is taken as the identifier index, the outgoing working label in the inner layer of the Push- twice operation is X4, and the outgoing protection label in the outer layer is P7.
  • the sub-forwarding table corresponding to LSR D includes: a ILM working forwarding entry (for the work LSP1 ), in which the incoming working label W6 is taken as the label index, the outgoing working label in the inner layer of the Swap-first operation is W4, and the outgoing protection in the outer layer of the Push-later operation is P7; a FTN working forwarding entry (for the work LSP2), in which the FEC2 of the work LSP 2 is taken as the identifier index, the outgoing working label in the inner layer of the Push-twice operation is X3, and the outgoing protection label in the outer layer is P7.
  • the sub-forwarding table corresponding to LSR C includes: a ILM working forwarding entry (for the work LSP1 ), in which the incoming working label W6 is taken as the label index, the outgoing working label in the inner layer of the Swap-first operation is W3, and the outgoing protection in the outer layer of the Push-later operation is P7; a FTN working forwarding entry (for the work LSP2), in which the FEC2 of the work LSP 2 is taken as the identifier index, the outgoing working label in the inner layer of the Push-twice operation is X2, and the outgoing protection label in the outer layer is P7.
  • the sub-forwarding table corresponding to LSR B includes: a ILM working forwarding entry (for the work LSP1 ), in which the incoming working label W6 is taken as the label index, the outgoing working label in the inner layer of the Swap-first operation is W2, and the outgoing protection in the outer layer of the Push-later operation is P7; a FTN working forwarding entry (for the work LSP2), in which the FEC2 of the work LSP 2 is taken as the identifier index, the outgoing working label in the inner layer of the Push-twice operation is X1 , and the outgoing protection label in the outer layer is P7.
  • the sub-forwarding table corresponding to LSR A includes: a ILM working forwarding entry (for the work LSP1 ), in which the incoming working label W6 is taken as the label index, the outgoing working label in the inner layer of the Swap-first operation is W1 , and the outgoing protection in the outer layer of the Push-later operation is P7.
  • LSR G and LSR H are not the downstream LSR of LSR F on the work LSP1 and work LSP2, the sub-forwarding entries respectively corresponding to LSR G and LSR H are both null.
  • the default forwarding table and each of the sub-forwarding tables may be configured as different logic tables in the same physical table or may be configured as different physical tables.
  • an instance mapping table is also configured in each LSR.
  • the instance mapping table records a mapping relation between a trigger condition of the default forwarding table and a global-instance ID, and a mapping relation between a trigger condition of the sub-forwarding table and each sub-instance ID.
  • the sub-instance ID recorded in the instance mapping table corresponds to the downstream LSR of the failed link.
  • instance mapping table By using the instance mapping table, the switching between different instance forwarding tables is flexible.
  • the detail implementation of the instance mapping table is shown in table 1 .
  • the trigger conditions of the default forwarding table includes that: a label carried by a packet received by the LSR is the incoming protection label on the protection loop of the LSR; or, a label carried by a packet received by the LSR indicates that the LSR is the egress node of the work LSP; or, the link between the LSR and a downstream neighbor LSR on the first direction S1 works normally.
  • an end label field may be pre-configured, so that the LSR can determine whether the label carried by the received packet indicates that the LSR is the egress node of the work LSP, according to whether the label carried by the received packet is in the end label field.
  • the trigger condition of the default forwarding table includes that: When the packet received by the LSR does not include the label (the LSR is the ingress node), or the label carried by the packet is the work label but does not indicate that the LSR is the egress node (the LSR is the transit node), the link between the LSR and the downstream neighbor LSR on the first direction S1 is failed (other link may be also failed).
  • the work LSP is on the first direction S1 and the protection loop is on the second direction S2.
  • other work LSPs may be configured on the second direction at the same time, and correspondingly, a protection loop is configured on the first direction S1 for all work LSPs on the second direction S2.
  • Figure 16 is a flowchart illustrating a method for implementing LSP switching according to an example of the present disclosure. The method is applied when part of or all of the LSRs included in several work LSPs are located in a ring network, and the ring network has a protection loop with an opposite direction. The method is applied to a LSR in the ring network and includes the following operations.
  • a LSR detects whether a link between the LSR and an upstream neighbor LSR and/or a link between the LSR and a downstream neighbor LSR are failed.
  • the LSR forwards a packet via a work LSP by using a working forwarding entry of the LSR, and/or forwards a packet via a protection loop by using a protection forwarding entry of the LSR.
  • the packet forwarded via the work LSP by using the working forwarding entry carries an incoming working label on the work LSP of the downstream neighbor LSR
  • the packet forwarded via the protection loop by using the protection forwarding entry carries an incoming protection label on the protection loop of the upstream neighbor LSR.
  • the LSR forwards a packet via the protection loop by using a protection switching forwarding entry if the LSP is an ingress node or a transit node of the work LSP.
  • the packet forwarded via the protection loop by using the protection switching forwarding entry carries an inner layer label and an outer layer label.
  • the inner layer label is an incoming working label on the work LSP of a designated LSR
  • the outer layer label is the incoming protection label on the protection loop of the upstream neighbor LSR.
  • the designated LSR is any one of other LSRs in the ring network, and a link between the designated LSR and an upstream neighbor LSR of the designated LSR is failed (that is, the designated LSR is the downstream LSR of the failed link).
  • the LSR pops the outer layer label of the packet received via the protection loop, and forwards the packet via the work LSP by using the working forwarding entry.
  • the outer layer label may be popped by changing the operation type of the protection forwarding entry from Swap to Pop.
  • the LSR may further configure the state of the protection forwarding entry as blocked after detecting that the link between the LSR and the downstream neighbor LSR is failed.
  • the protection switching forwarding entries used in the block 162 may be configured after detecting that the link between the LSR and the downstream neighbor LSR is failed and the protection switching forwarding entry corresponding to the designated LSR is used; or, the protection switching forwarding entry corresponding to each of other LSRs in the ring network may be pre-configured before detecting that the link between the LSR and the downstream neighbor LSR is failed, and the protection switching forwarding entry corresponding to the designated LSR is selected from the pre-configured protection switching forwarding entries and is used after detecting that the link between the LSR and the downstream neighbor LSR is failed.
  • the method further includes: maintaining a default forwarding table corresponding to the LSR and a sub-forwarding table corresponding to each of other LSRs in the ring network; the working forwarding entry and the protecting forwarding entry are both pre-configured in the default forwarding table, each protection switching forwarding entry corresponding to each of other LSRs is pre-configured in the sub-forwarding table corresponding to each of other LSRs; maintaining an instance mapping table; the instance mapping table records a mapping relation between a trigger condition of the default forwarding table and a default-instance ID and a mapping relation between a trigger condition of the sub-forwarding table and any one of sub-instance IDs, the sub-instance ID corresponds to any one of other LSRs determined as the designated LSR.
  • the trigger condition of the default forwarding table includes that: a label carried by a packet received by the LSR is the incoming protection label on the protection loop of the LSR; or, a label carried by a packet received by the LSR indicates that the LSR is the egress node of the work LSP; or, the link between the LSR and the downstream neighbor LSR on the first direction S1 works normally.
  • the trigger condition of the default forwarding table includes that: the link between the LSR and the downstream neighbor LSR is failed.
  • the method may further include pre-configuring an end label field, so that the LSR can determine that the label carried by the received packet indicates that the LSR is the egress node of the work LSP when the label carried by the received packet is in the end label field.
  • the LSR may further send a failure notification to indicate that the LSR is the designated LSR (i.e., the downstream LSR of the failed link).
  • the failure notification is received after detecting the link between the LSR and the downstream neighbor LSR is failed, and the LSR sending the failure notification is determined as the designated LSR (i.e., the downstream LSR of the failed link).
  • the failure notification may also be sent via the ring network by using the work LSP, or via a tunnel outside the ring network.
  • the failure notification may carry an identifier indicating the LSR sending the failure notification (i.e., the designated LSR, the downstream LSR of the failed link).
  • the above method may be implemented by using computer programs, and an apparatus corresponding to the method is provided by the examples of the present disclosure.
  • the examples of the present disclosure provide an apparatus for implementing LSP switching.
  • the apparatus is applied when part of or all of the LSRs included in several work LSPs are located in a ring network, and the ring network has a protection loop with an opposite direction.
  • the apparatus is applied to a LSR in the ring network and includes the following modules.
  • a failure detecting module is to detect whether a link between the LSR and an upstream neighbor LSR and a link between the LSR and a downstream neighbor LSR are failed.
  • a normal forwarding module is to forward a packet via a work LSP by using a working forwarding entry of the LSR
  • a protection forwarding module is to forward a packet via a protection loop by using a protection forwarding entry of the LSR.
  • the packet forwarded via the work LSP by using the working forwarding entry carries an incoming working label on the work LSP of the downstream neighbor LSR
  • the packet forwarded via the protection loop by using the protection forwarding entry carries an incoming protection label on the protection loop of the upstream neighbor LSR.
  • the protection forwarding module is to forward a packet via the protection loop by using a protection switching forwarding entry if the LSP is an ingress node or a transit node of the work LSP.
  • the packet forwarded via the protection loop by using the protection switching forwarding entry carries an inner layer label and an outer layer label.
  • the inner layer label is an incoming working label on the work LSP of a designated LSR
  • the outer layer label is the incoming protection label on the protection loop of the upstream neighbor LSR.
  • the designated LSR is any one of the other LSRs in the ring network, and a link between the designated LSR and an upstream neighbor LSR of the designated LSR is failed.
  • the protection forwarding module When the link between the LSR and the upstream neighbor LSR is failed, the protection forwarding module is to pop the outer layer label of the packet received via the protection loop, and the normal forwarding module is to forward the packet via the work LSP by using the working forwarding entry.
  • the apparatus may further include an entry storing module to store the working forwarding entry, protection forwarding entry, and protection switching forwarding entry. The working forwarding entry, protection forwarding entry, and protection switching forwarding entry described in the above operations are the same as those previously described above.
  • the apparatus may further include an entry maintaining module to change an operation type of the protection forwarding entry from Swap to Pop, so as to pop the outer layer label. According to an example, the maintaining module is further to configure the state of the protection forwarding entry as blocked after detecting that the link between the LSR and the downstream neighbor LSR is failed.
  • the protection switching forwarding entries in the entry storing module may be configured by an entry configuring module further included by the apparatus.
  • the entry configuring module is to configure and use the protection switching forwarding entry corresponding to the designated LSR after the failure detecting module detects that the link between the LSR and the downstream neighbor LSR is failed. Or, the entry configuring module is to pre-configure the protection switching forwarding entry corresponding to each of other LSRs in the ring network before the failure detecting module detects that the link between the LSR and the downstream neighbor LSR is failed, and select the protection switching forwarding entry corresponding to the designated LSR from the pre-configured protection switching forwarding entries and use the protection switching forwarding entry corresponding to the designated LSR after the failure detecting module detects that the link between the LSR and the downstream neighbor LSR is failed.
  • a path recording is to record in advance the incoming working label on the work LSP of each of the other LSRs that belongs to the work LSP and are in the downstream direction of the LSR, so as to conduct to the configuring of the protection switching forwarding entry.
  • the apparatus further includes: an instance maintaining module to maintain a default forwarding table corresponding to the LSR, and a sub-forwarding table corresponding to each of other LSRs in the ring network; the working forwarding entry and the protecting forwarding entry are both pre-configured in the default forwarding table, each protection switching forwarding entry corresponding to each of other LSRs is pre-configured in the sub-forwarding table corresponding to each of other LSRs; an instance mapping module to maintain an instance mapping table; the instance mapping table records a mapping relation between a trigger condition of the default forwarding table and a default-instance ID and a mapping relation between a trigger condition of the sub-forwarding table and any one of sub-instance I Ds, the sub-instance ID corresponds to any one of other LSRs determined as the designated LSR.
  • the trigger condition of the default forwarding table includes that: a label carried by a packet received by the LSR is the incoming protection label on the protection loop of the LSR; or, a label carried by a packet received by the LSR indicates that the LSR is the egress node of the work LSP; or, the link between the LSR and the downstream neighbor LSR on the first direction S1 works normally.
  • the trigger condition of the default forwarding table includes that the link between the LSR and the downstream neighbor LSR is failed.
  • an end label field may be pre-configured in the instance mapping module, so that the LSR can determine that the label carried by the received packet indicates that the LSR is the egress node of the work LSP, when the label carried by the received packet is in the end label field.
  • the apparatus further includes a notification module, which is to send a failure notification after the failure detecting module detects the link between the LSR and the upstream neighbor LSR is failed; and receive the failure notification after the failure detecting module detects the link between the LSR and the downstream neighbor LSR is failed, and determine the LSR sending the failure notification as the designated LSR.
  • a notification module which is to send a failure notification after the failure detecting module detects the link between the LSR and the upstream neighbor LSR is failed; and receive the failure notification after the failure detecting module detects the link between the LSR and the downstream neighbor LSR is failed, and determine the LSR sending the failure notification as the designated LSR.
  • the failure notification may be sent via the ring network by using the work LSP or via a tunnel outside the ring network.
  • the failure notification may carry an identifier indicating the LSR sending the failure notification (i.e., the designated LSR, the downstream LSR of the failed link).
  • the method, apparatus and above mdodules for implementing the LSP switching are implemented based on a hardware structure of the LSR applying the method and apparatus.
  • the modules may be implemented by one or more processors and one or more memories or storage media.
  • Figure 17 is a schematic diagram illustrating a hardware structure according to one possible example of the present disclosure.
  • the example hardware structure of the LSR applying the method and apparatus includes the following chips.
  • a storage media chip to store all working forwarding entries, protection forwarding entries, and protection switching forwarding entries.
  • the storage media chip is further to store the default forwarding table, sub-forwarding tables, and instance mapping tables.
  • a first processing chip may be a CPU, an Application Specific Integrated Circuit (ASIC) or Network Processor (NP), and usually is the CPU.
  • ASIC Application Specific Integrated Circuit
  • NP Network Processor
  • the first processing chip is to generate all of the working forwarding entries, protection forwarding entries, and protection switching forwarding entries of the LSR.
  • the first processing chip is further to configure the work LSP path record and to generate needed work LSP path record, default forwarding table, sub-forwarding tables, and instance mapping tables.
  • a second processing chip which may be a CPU, ASIC or NP, is to detect whether the link between the LSR and the downstream neighbor LSR or the link between the LSR and the upstream neighbor LSR is failed.
  • a third processing chip which may be a CPU, ASIC or NP, is to, when the link between the LSR and the downstream neighbor LSR is failed, determine the downstream LSR of the failed link (i.e., receive and identify the failure notification).
  • the third processing chip is further to change the state of the protection forwarding entry in the storage media chip as blocked, and change the sub-instance ID in the instance mapping table as the sub-instance ID corresponding to the downstream LSR of the failed link.
  • the third processing chip is further to, when the link between the LSR and the upstream neighbor LSR is failed, change the operation type of the protection forwarding entry in the storage media chip from Swap to Pop and send the failure notification.
  • a packet processing chip is to forward the packet by using the working forwarding entry, the protection forwarding entry, and the protection switching forwarding entry when necessary, and is further to forward the protocol packet for detection by the second processing chip, and forward the protocol (e.g., MR-PSC protocol) packet for determining the downstream LSR of the failed link.
  • the storage media chip may be integrated in the packet processing chip or may be independent from the packet processing chip. There is a hardware interface, or a hardware interface and a driver software interface between the third processing chip, the second processing chip, and the storage media chip.
  • the second and third processing chips may be integrated on the same chip. Based on the above division of chips in the hardware structure, the distribution of the steps in the method for implementing the LSP switching and the modules in the apparatus for implementing the LSP switching in the hardware structure is definite. What has been described and illustrated herein are examples of the disclosure along with some variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. Many variations are possible within the scope of the disclosure, which is intended to be defined by the following claims ⁇ and their equivalents ⁇ in which all terms are meant in their broadest reasonable sense unless otherwise indicated.

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Abstract

Selon des exemples de l'invention, un procédé de fonctionnement d'un appareil de mise en œuvre de commutation de LSP comprend le fait que, après qu'une liaison a subi une défaillance, un LSR amont peut inclure une étiquette sur un LSP de travail d'un LSR aval dans une couche interne d'un paquet qui peut être identifié par le LSR aval, et inclut une étiquette sur la boucle de protection dans une couche externe du paquet, ce qui amène le paquet à pouvoir être transmis au LSR aval par la boucle de protection. En conséquence, certaines des liaisons défaillantes du LSP de travail sont commutées vers la boucle de protection, et le paquet peut arriver au LSR aval par la boucle de protection. Enfin, le LSR aval peut acheminer le paquet par le LSP de travail normalement après dépilage de l'étiquette sur la boucle de protection dans la couche externe du paquet.
PCT/CN2012/082963 2011-10-14 2012-10-15 Mise en œuvre de commutation de lsp WO2013053337A1 (fr)

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