Mpls-Tp Ip-Less Support - Cisco ASR 9000 Series Configuration Manual

MPLS-TP IP-less support

MPLS-TP IP-less support
Generally, MPLS-TP functionality can be deployed with or without an IP address. However, the main motivation
for the IP-less model is this: an LSR can be inserted into an MPLS-TP network without changing the
configurations on adjacent LSRs. In the past Cisco IOS-XR MPLS-TP release, if an interface does not have
a valid IP address, BFD packets cannot be transmitted over that link, and hence MPLS-TP LSP cannot be
brought up on that link. In this release, the IP-less TP link operates only in a point-to-point mode.
This feature, therefore, makes the need for an IP address on a TP link optional. You may deploy LSRs running
Cisco IOS-XR in MPLS-TP networks with or without an IP address. With such extra flexibility, LSRs running
Cisco IOS-XR can be easily deployed not only with LSRs running IOS, but with LSRs from other vendors
too.
MPLS-TP LSP Wrapping
In the MPLS-TP LSP Wrapping protection scheme, a protected MPLS-TP tunnel is associated with a working
LSP and protect LSP. This helps to prevent traffic loss as soon as a mid-point LSR detects a failure at physical
layer rather than waiting for BFD to time-out. Also, a delay in activating protection switch due to mid-point
failure does not further increase the traffic loss.
MPLS-TP LSP wrapping has to enabled only on the MID node. MPLS-TP LSP wrapping helps in detecting
mid-link failure scenarios; other failures and failures on end node is detected by BFD timeout and TP-OAM
message.
As shown in the figure below, when an LSR (e.g., Router B) detects a failure, it forwards the incoming traffic
over an impacted LSP onto the reverse LSP, if it exists. The traffic re-directed into the reverse LSP is loopback
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
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node ID, optionally the global ID, and optionally the destination tunnel number. If you do not specify
the destination tunnel number, the source tunnel number is used.
Implementing MPLS Transport Profile
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