Bidirectional Lsps - Cisco ASR 9000 Series Configuration Manual

Implementing MPLS Transport Profile
• Use of Generic Alert Label (GAL) and Generic Associated Channel Header (G-ACH) to transport control
• BFD is used as a continuity check (CC) mechanism over MPLS-TP LSP
• Remote Defect Indication (RDI) based on BFD
• Fault OAM functions
These services are supported over MPLS-TP tunnels:
• Dynamic spoke pseudowire (for H-VPLS) over static MPLS-TP tunnels.
• Static spoke pseudowire (for H-VPLS) over static MPLS-TP tunnels.
• MS-PW services where static and dynamic pseudowire segments can be concatenated.
• MPLS ping and traceroute over MPLS TP LSP and PW.
• Static routes over MPLS-TP tunnels.
• Pseudowire redundancy for static pseudowire.
• VPWS using static or dynamic pseudowire pinned down to MPLS-TP tunnels.
• VPLS and H-VPLS using static or dynamic pseudowire pinned down to MPLS-TP tunnels.

Bidirectional LSPs

MPLS transport profile (MPLS-TP) LSPs are bidirectional and congruent where LSPs traverse the same path
in both directions. An MPLS-TP tunnel can be associated with either working MPLS-TP LSP, protect MPLS-TP
LSP, or both. The working LSP is the primary LSP backed up by the protect LSP. When a working LSP goes
down, protect LSP is automatically activated. In order for an MPLS-TP tunnel to be operationally up, it must
be configured with at least one LSP.
MPLS-TP Path Protection
Path protection provides an end-to-end failure recovery mechanism (that is, full path protection) for MPLS-TP
tunnels. MPLS-TP LSPs support 1:1 path protection. You can configure the working and protect LSPs as part
of configuring the MPLS-TP tunnel. The working LSP is the primary LSP used to route traffic, while the
protect LSP is 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 traffic forwarding reverts back to the working LSP (revertive
mode).
Fault OAM Support
The fault OAM protocols and messages support the provisioning and maintenance of MPLS-TP tunnels and
bidirectional LSPs:
OL-28381-02
packets; for example, BFD packets and pseudowire OAM packets
Cisco ASR 9000 Series Aggregation Services Router MPLS Configuration Guide, Release 4.3.x
Bidirectional LSPs
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