MPLS Basic MPLS Configuration Guide - MPLS Transport Profile [Cisco ASR 1000 Series Aggregation Services Routers] (2024)

Multiprotocol Label Switching Transport Profile (MPLS-TP) tunnels provide the transport network service layer over which IP and MPLS traffic traverses. MPLS-TP tunnels help transition from Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Time Division Multiplexing (TDM) technologies to packet switching to support services with high bandwidth utilization and lower cost. Transport networks are connection-oriented, statically provisioned, and have long-lived connections. Transport networks usually avoid control protocols that change identifiers (like labels). MPLS-TP tunnels provide this functionality through statically provisioned bidirectional label switched paths (LSPs), as shown in the figure below.

MPLS-TP label switched paths (LSPs) support 1-to-1 path protection. There are two types of LSPs: protect LSPs and working LSPs. You can configure the both types of LSPs when configuring the MPLS-TP tunnel. The working LSP is the primary LSP used to route traffic. The protect LSP acts as a backup for a working LSP. If the working LSP fails, traffic is switched to the protect LSP until the working LSP is restored, at which time forwarding reverts back to the working LSP.

Multiprotocol Label Switching Transport Profile (MPLS-TP) label switched paths (LSPs) are bidirectional and co-routed. They comprise of two unidirectional LSPs that are supported by the MPLS forwarding infrastructure. A TP tunnel consists of a pair of unidirectional tunnels that provide a bidirectional LSP. Each unidirectional tunnel can be optionally protected with a protect LSP that activates automatically upon failure conditions.

Several Operations, Administration, and Maintenance (OAM) protocols and messages support the provisioning and maintenance of Multiprotocol Label Switching Transport Profile (MPLS-TP) tunnels and bidirectional label switched paths (LSPs).

The following OAM messages are forwarded along the specified MPLS LSP:

• OAM Fault Management—Alarm Indication Signal (AIS), Link Down Indication (LDI), and Lock Report (LKR) messages (GAL with BFD messages).
• OAM Connection Verification—Ping and traceroute messages (GAL with IP channel by default).
• OAM Continuity Check—Bidirectional Forwarding Detection (BFD) messages—non-IP BFD and IP BFD (GAL with non-IP BFD channel or IP BFD channel depending on message format).

• The following messages are forwarded along the specified pseudowire:

  • Static pseudowire OAM messages
  • Pseudowire ping and traceroute messages
  • BFD messages

• MPLS-TP OAM Fault Management (LDI, AIS, and LKR messages)—LDI messages are AIS messages whose L-flags are set. The LDI messages are generated at midpoint nodes when a failure is detected. From the midpoint, an LDI message is sent to the endpoint that is reachable with the existing failure. Similarly, LKR messages are sent from a midpoint node to the reachable endpoint when an interface is administratively shut down. By default, the reception of LDI and LKR messages on the active LSP at an endpoint will cause a path protection switchover, whereas the reception of an AIS message will not.

• MPLS-TP OAM Fault Management with Emulated Protection Switching for LSP Lockout—Cisco implements a form of Emulated Protection Switching to support LSP Lockout using customized Fault messages. When a Lockout message is sent, it does not cause the LSP to be administratively down. The Cisco Lockout message causes a path protection switchover and prevents data traffic from using the LSP. The LSP remains administratively up so that BFD and other OAM messages can continue to traverse it and so that maintenance of the LSP can take place (such as reconfiguring or replacing a midpoint LSR). After OAM verifies the LSP connectivity, the Lockout is removed and the LSP is brought back to service. Lockout of the working LSP is not allowed if a protect LSP is not configured. Conversely, the Lockout of a protect LSP is allowed if a working LSP is not configured.

• LSP ping and trace—To verify MPLS-TP connectivity, use the ping mpls tp and trace mpls tp commands. You can specify that echo requests be sent along the working LSP, the protect LSP, or the active LSP. You can also specify that echo requests be sent on a locked-out MPLS-TP tunnel LSP (either working or protected) if the working or protected LSP is explicitly specified. You can also specify ping/trace messages with or without IP.

• MPLS-TP OAM Continuity Check (CC) via BFD and Remote Defect Indication (RDI)—RDI is communicated via the BFD diagnostic field in BFD CC messages. BFD sessions run on both the working LSP and the protect LSP. To perform a path protection switchover within 60 milliseconds on an MPLS-TP endpoint, use the BFD Hardware Offload feature, which enables the router hardware to construct and send BFD messages, removing the task from the software path. The BFD Hardware Offload feature is enabled automatically on supported platforms.

MPLS-TP OAM GACH—Generic Associated Channel (G-ACh) is the control channel mechanism associated with Multiprotocol Label Switching (MPLS) LSPs in addition to MPLS pseudowire. The G-ACh Label (GAL) (Label 13) is a generic alert label to identify the presence of the G-ACh in the label packet. It is taken from the reserved MPLS label space. G-ACh/GAL supports OAMs of LSPs and in-band OAMs of pseudowires (PWs). OAM messages are used for fault management, connection verification, continuity check, and so on.

Multiprotocol Label Switching Transport Profile (MPLS-TP) supports the following combinations of static and dynamic multisegment pseudowires:

• Dynamic-static

• Static-dynamic

• Static-static

With static pseudowires, status notifications can be provided by BFD over VCCV or by the static pseudowire OAM protocol. However, BFD over VCCV sends only attachment circuit status code notifications. Hop-by-hop notifications of other pseudowire status codes are not supported. Therefore, the static pseudowire OAM protocol is preferred. You can acquire per pseudowire OAM for attachment circuit/pseudowire notification over the VCCV channel with or without the control word.

Multiprotocol Label Switching Transport Profile (MPLS-TP) link numbers may be assigned to physical interfaces only. Bundled interfaces and virtual interfaces are not supported for MPLS-TP link numbers.

The MPLS-TP link creates a layer of indirection between the MPLS-TP tunnel and midpoint LSP configuration and the physical interface. The mpls tp link command is used to associate an MPLS-TP link number with a physical interface and next-hop node. On point-to-point interfaces or Ethernet interfaces designated as point-to-point using the medium p2p command, the next-hop can be implicit, so the mpls tp link command just associates a link number to the interface.

Multiple tunnels and LSPs may then refer to the MPLS-TP link to indicate that they are traversing that interface. You can move the MPLS-TP link from one interface to another without reconfiguring all the MPLS-TP tunnels and LSPs that refer to the link.

Link numbers must be unique on the router or node.

See the section Configuring MPLS-TP Links and Physical Interfaces, for more information.

Tunnel LSPs, whether endpoint or midpoint, use the same identifying information. However, it is entered differently.

• At the midpoint, all information for the LSP is specified with the mpls tp lsp command for configuring forward and reverse information for forwarding.

• At the midpoint, determining which end is source and which is destination is arbitrary. That is, if you are configuring a tunnel between your device and a coworker’s device, then your device is the source. However, your coworker considers his or her device to be the source. At the midpoint, either device could be considered the source. At the midpoint, the forward direction is from source to destination, and the reverse direction is from destination to source.

• At the endpoint, the local information (source) either comes from the global device ID and global ID, or from the locally configured information using the tp source command.

• At the endpoint, the remote information (destination) is configured using the tp destination command after you enter the interface tunnel-tp number command. The tp destination command includes the destination node ID, and optionally the global ID and the destination tunnel number. If you do not specify the destination tunnel number, the source tunnel number is used.

• At the endpoint, the LSP number is configured in working-lsp or protect-lsp submode. The default is 0 for the working LSP and 1 for the protect LSP.

• When configuring LSPs at midpoint devices, ensure that the configuration does not deflect traffic back to the originating node.

SUMMARY STEPS

1. enable
2. configure terminal
3. mpls label range minimum-value maximum-value static minimum-static-value maximum-static-value
4. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# mpls label range 1001 1003 static 10000 25000

Device(config)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. mpls tp
4. router-id node-id
5. global-id num
6. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# mpls tp

Device(config-mpls-tp)# router-id 10.10.10.10

Device(config-mpls-tp)# global-id 1

Device(config-mpls-tp)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. bfd-template single-hop template-name
4. interval [microseconds ] {both time | min-tx time min-rx time } [multiplier multiplier-value ]
5. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# bfd-template single-hop mpls-bfd-1

Device(config-bfd)# interval min-tx 99 min-rx 99 multiplier 3

Device(config-bfd)# exit

SUMMARY STEPS

1. enable
2. configure terminal
3. pseudowire-static-oam class class-name
4. timeout refresh send seconds
5. exit

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# pseudowire-static-oam class oam-class1

Device(config-st-pw-oam-class)# timeout refresh send 20

Device(config-st-pw-oam-class)# exit

SUMMARY STEPS

1. enable
2. configure terminal
3. pseudowire-class class-name
4. encapsulation mpls
5. control-word
6. protocol {l2tpv2 | l2tpv3 | none } [l2tp-class-name ]
7. preferred-path {interface tunnel tunnel-number | peer {ip-address | host-name }} [disable-fallback ]
8. status protocol notification static class-name
9. vccv bfd template name [udp | raw-bfd ]
10. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# pseudowire-class mpls-tp-class1

Device(config-pw-class)# encapsulation mpls

Device(config-pw-class)# control-word 

Device(config-pw-class)# protocol none

Device(config-pw-class)# preferred-path interface tunnel-tp2

Device(config-pw-class)# status protocol notification static oam-class1

Device(config-pw-class)# vccv bfd template bfd-temp1 raw-bfd

Device(config-pw-class)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. interface type number
4. xconnect peer-ip-address vc-id {encapsulation {l2tpv3 [manual ] | mpls [manual ]} | pw-class pw-class-name } [pw-class pw-class-name ] [sequencing {transmit | receive | both }]
5. mpls label local-pseudowire-label remote-pseudowire-label
6. mpls control-word
7. backup delay {enable-delay-period | never } {disable-delay-period | never }
8. backup peer peer-router-ip-addr vcid [pw-class pw-class-name ] [priority value ]
9. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# interface Ethernet 1/0

Device(config-if)# xconnect 10.131.191.251 100 encapsulation mpls manual pw-class mpls-tp-class1

Device(config-if-xconn)# mpls label 100 150

Device(config-if-xconn)# no mpls control-word

Device(config-if-xconn)# backup delay 0 never

Device(config-if-xconn)# backup peer 10.0.0.2 50

Device(config)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. interface tunnel-tp number
4. description tunnel-description
5. tp tunnel-name name
6. tp bandwidth num
7. tp source node-id [global-id num ]
8. tp destination node-id [tunnel-tp num [ global-id num ]]
9. bfd bfd-template
10. working-lsp
11. in-label num
12. out-label num out-link num
13. exit
14. protect-lsp
15. in-label num
16. out-label num out-link num
17. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# interface tunnel-tp

Device(config-if)# description headend tunnel

Device(config-if)# tp tunnel-name tunnel 122

Device(config-if)# tp bandwidth 10000 

Device(config-if)# tp source 10.11.11.11 global-id 10

Device(config-if)# tp destination 10.10.10.10

Device(config-if)# bfd mpls-tp-bfd-2

Device(config-if)# working-lsp 

Device(config-if-working)# in-label 111

Device(config-if-working)# out-label 112 out-link

Device(config-if-working)# exit

Device(config-if)# protect-lsp

Device(config-if-protect)# in-label 100

Device(config-if-protect)# out-label 113 out-link

Device(config-if-protect)# end

Note	When configuring LSPs at midpoint devices, ensure that the configuration does not deflect traffic back to the originating node.

SUMMARY STEPS

1. enable
2. configure terminal
3. mpls tp lsp source node-id [global-id num ] tunnel-tp num lsp {lsp-num | protect | working } destination node-id [global-id num ] tunnel-tp num
4. forward-lsp
5. bandwidth num
6. in-label num out-label num out-link num
7. exit
8. reverse-lsp
9. bandwidth num
10. in-label num out-label num out-link num
11. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# mpls tp lsp source 10.10.10.10 global-id 2 tunnel-tp 4 lsp protect destination 10.11.11.11 global-id 11 tunnel-tp 12 

Device(config-mpls-tp-lsp)# forward-lsp

Device(config-mpls-tp-lsp-forw)# bandwidth 100

Device(config-mpls-tp-lsp-forw)# in-label 53 out-label 43 out-link 41

Device(config-mpls-tp-lsp-forw)# exit

Device(config-mpls-tp-lsp)# reverse-lsp

Device(config-mpls-tp-lsp-rev)# bandwidth 100

Device(config-mpls-tp-lsp-rev)# in-label 33 out-label 23 out-link 44

Device(config-mpls-tp-lsp-rev)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. interface type number
4. ip address ip-address mask
5. mpls tp link link-num {ipv4 ip-address | tx-mac mac-address } rx-mac mac-address
6. ip rsvp bandwidth [rdm [bc0 interface-bandwidth ] [[single-flow-bandwidth [bc1 bandwidth | sub-pool bandwidth ]]] [interface-bandwidth [single-flow-bandwidth [bc1 bandwidth | sub-pool bandwidth ]] | mam max-reservable-bw [interface-bandwidth [single-flow-bandwidth ] [bc0 interface-bandwidth [bc1 bandwidth ]]] | percent percent-bandwidth [single-flow-bandwidth ]]
7. end
8. show mpls tp link-numbers

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# interface ethernet 1/0

Device(config-if)# ip address 10.10.10.10 255.255.255.0

Device(config-if)# mpls tp link 1 ipv4 10.0.0.2

Device(config-if)# ip rsvp bandwidth 1158 100

Device(config-if)# end

Device# show mpls tp link-numbers

SUMMARY STEPS

1. enable
2. configure terminal
3. l2 vfi name point-to-point
4. neighbor ip-address vc-id {encapsulation mpls | pw-class pw-class-name }
5. mpls label local-pseudowire-label remote-pseudowire-label
6. mpls control-word
7. neighbor ip-address vc-id {encapsulation mpls | pw-class pw-class-name }
8. mpls label local-pseudowire-label remote-pseudowire-label
9. mpls control-word
10. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# l2 vfi atom point-to-point

Device(config-vfi)# neighbor 10.111.111.111 123 pw-class atom

Device(config-vfi)# mpls label 101 201

Device(config-vfi)# mpls control-word

Device(config-vfi)# neighbor 10.10.10.11 123 pw-class atom

Device(config-vfi)# mpls label 102 202

Device(config-vfi)# mpls control-word

Device(config)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. pseudowire-tlv template template-name
4. tlv [type-name ] type-value length [dec | hexstr | str ] value
5. end

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# pseudowire-tlv template statictemp

Device(config-pw-tlv-template)# tlv statictemp 2 4 hexstr 1

Device(config-pw-tlv-template)# end

SUMMARY STEPS

1. enable
2. configure terminal
3. pseudowire-class class-name
4. encapsulation mpls
5. control-word
6. protocol {l2tpv2 | l2tpv3 | none } [l2tp-class-name ]
7. exit
8. pseudowire-class class-name
9. encapsulation mpls
10. exit
11. l2 vfi name point-to-point
12. neighbor ip-address vc-id {encapsulation mpls | pw-class pw-class-name }
13. neighbor ip-address vc-id {encapsulation mpls | pw-class pw-class-name }
14. mpls label local-pseudowire-label remote-pseudowire-label
15. mpls control-word
16. local interface pseudowire-type
17. Do one of the following:

• tlv [type-name ] type-value length [dec | hexstr | str ] value
• tlv template template-name

DETAILED STEPS

Device> enable

Device# configure terminal

Device(config)# pseudowire-class mpls-tp-class1

Device(config-pw-class)# encapsulation mpls

Device(config-pw-class)# control-word 

Device(config-pw-class)# protocol none

Device(config-pw-class)# exit

Device(config)# pseudowire-class mpls-tp-class1

Device(config-pw-class)# encapsulation mpls

Device(config-pw-class)# exit

Device(config)# l2 vfi atom point-to-point

Device(config-vfi)# neighbor 10.111.111.111 123 pw-class atom

Device(config-vfi-neighbor)# neighbor 10.111.111.111 123 pw-class atom

Device(config-vfi-neighbor)# mpls label 101 201

Device(config-vfi-neighbor)# mpls control-word

Device(config-vfi-neighbor)# local interface 4

Device(config-vfi-neighbor)# tlv statictemp 2 4 hexstr 1

Device(config-vfi-neighbor)# end

Use the following commands to verify and help troubleshoot your MPLS-TP configuration:

• debug mpls tp —Enables the logging of MPLS-TP error messages.

• logging (MPLS-TP) —Displays configuration or state change logging messages.

• show bfd neighbors mpls-tp —Displays the BFD state, which must be up in order for the endpoint LSPs to be up.

• show mpls l2transport static-oam l2transport static-oam—Displays MPLS-TP messages related to pseudowires.

• show mpls tp tunnel-tp number detail —Displays the number and details of the tunnels that are not functioning.

• show mpls tp tunnel-tp lsps —Displays the status of the LSPs, and helps you ensure that both LSPs are up and working from a tunnel endpoint.

• traceroute mpls tp and ping mpls tp —Helps you identify connectivity issues along the MPLS-TP tunnel path.