MPLS-TP tunnels are configured using the mpls-tp LSP type at an LER under the LSP configuration, using the following CLI tree:
config
router
mpls
lsp <xyz> [bypass-only | p2mp-lsp | mpls-tp <src-tunnel-num>]
to node-id {<a.b.c.d> | <1.. .4,294,967,295>}
dest-global-id <global-id>
dest-tunnel-number <tunnel-num>
[no] working-tp-path
lsp-num <lsp-num>
in-label <in-label>
out-label <out-label> out-link <if-name>
[next-hop <ipv4-address>]
[no] mep
[no] bfd-enable [cc | cc-cv]
[no] bfd-trap-suppression
[no] oam-template <name>
[no] shutdown
exit
[no] shutdown
exit
[no] protect-tp-path
lsp-num <lsp-num>
in-label <in-label>
out-label <out-label> out-link <if-name>
[next-hop <ipv4-address> ]
[no] mep
[no] bfd-enable [cc | cc-cv]
[no] bfd-trap-suppression
[no] oam-template <name>
[no] protection-template <name>
[no] shutdown
exit
[no] shutdown
exit
<if-name> could be numbered or unnumbered interface using an Ethernet port.
<src-tunnel-num> is a mandatory create time parameter for mpls-tp tunnels, and has to be assigned by the user based on the configured range of tunnel ids. The src-global-id used for the LSP ID is derived from the node-wide global-id value configured under config>router>mpls>mpls-tp. A tunnel cannot be brought up unless the global-id is configured.
The from address of an LSP to be used in the tunnel identifier is taken to be the local node’s node-id/global-id, as configured under config>router>mpls>mpls-tp. If that is not explicitly configured, either, then the default value of the system interface IPv4 address is used.
The to node-id address may be entered in 4-octet IPv4 address format or unsigned 32-bit format. This is the far-end node-id for the LSP, and does do need to be routable IP addresses.
The from and to addresses are used as the from and to node-id in the MPLS-TP Tunnel Identifier used for the MEP ID.
Each LSP consists of a working-tp-path and, optionally, a protect-tp-path. The protect-tp-path provides protection for the working-tp-path is 1:1 linear protection is configured (see below). Proactive OAM, such as BFD, is configured under the MEP context of each path. Protection for the LSP is configured under the protect-tp-path MEP context.
The to global-id is an optional parameter. If it is not entered, then the destination global ID takes the default value of 0. Global ID values of 0 are allowed and indicate that the node’s configured Global ID should be used. If the local global ID value is 0, then the remote to global ID must also be 0. The to global ID value cannot be changed if an LSP is in use by an SDP.
The to tunnel number is an optional parameter. If it is not entered, then it is taken to be the same value as the source tunnel number.
LSPs are assumed to be bidirectional and co-routed. Therefore, the system assumes that the incoming interface is the same as the out-link.
The next-hop ip-address can only be configured if the out-link if-name refers to a numbered IP interface. In this case, the system determines the interface to use to reach the configured next-hop, but checks that the user-entered value for the out-link corresponds to the link returned by the system. If they do not correspond, then the path does not come up. If a user changes the physical port referred to in the interface configuration, BFD, if configured on the LSP, goes down. Users must ensure that an LSP is moved to a different interface with a different port configuration to change the port that it uses. This is enforced by blocking the next-hop configuration for an unnumbered interface.
There is no check made that a valid ARP entry exists before allowing a path to be un shut. Therefore, a path is only held down if BFD is down. If static ARP is not configured for the interface, then it is assumed that dynamic ARP is used. The result is that if BFD is not configured, a path can come up before ARP resolution has completed for an interface. If BFD is not used, then it is recommended that the connectivity of the path is explicitly checked using on-demand CC/CV before sending user traffic on it.
The following is a list of additional considerations for the configuration of MPLS-TP LSPs and paths:
The working-tp-path must be configured before the protect-tp-path.
Likewise, the protect-tp-path must be deleted first before the working-tp-path.
The lsp-num parameter is optional. The default values are 1 for the working-tp-path and 2 for protect-tp-path.
The mep context must be deleted before a path can be deleted.
An MPLS interface needs to be created under config>router>mpls>interface before using/specifying the out-label/out-link in the Forward path for an MPLS-TP LSP. Creation of the LSP fails if the corresponding mpls interface does not exist even though the specified router interface may be valid.
The system programs the MPLS-TP LSP information upon a no shutdown command of the TP-Path only on the very first no shutdown. The working-tp-path is programmed as the primary and the protect-tp-path is programmed as the backup.
The system does not deprogram the IOM on an admin shutdown of the MPLS-TP path. Traffic gracefully moves to the other TP-Path if valid, as determined by the proactive MPLS-TP OAM. This should not result in traffic loss. However, it is recommended that the user does moves traffic to the other TP-Path through a tools command before performing the admin shutdown command of an Active TP-Path.
Deletion of the out-label/out-link sub-command under the MPLS-TP Path is not allowed after it is configured. This can only be modified.
MPLS allows the deletion of an admin shutdown TP-Path. This causes MPLS to deprogram the corresponding TP-Path forwarding information from IOM. This can cause traffic loss for users that are bound to the MPLS-TP LSP.
MPLS does not deprogram the IOM on a specific interface admin shut/clear unless the interface is a System Interface. However, if MPLS informs the TP-OAM module that the MPLS interface has gone down, then it triggers a switch to the standby tp-path if the associated interface went down and if it is valid.
If a MEP is defined and shut down, the corresponding path is also operationally down. The MEP admin state is applicable only when a MEP is created from an MPLS-TP path.
It is not mandatory to configure BFD or protection on an MPLS-TP path to bring the LSP up.
If bfd-enable cc is configured, then CC-only mode using ACh channel 0x07 is used. If bfd-enable cc_v is configured, then BFD CC packets use channel 0x22 and CV packets use channel 0x23.
Under the MEP context, the bfd-trap-suppression command allows the reception of AIS packets on the path to suppress BFD Down traps if a BFD session goes down on that path.
The protection template is associated with an LSP as a part of the MEP on the protect path. If only a working path is configured, then the protection template is not configured.
BFD cannot be enabled under the MEP context unless a named BFD template is configured.