MPLS Transport Profile (MPLS-TP)
Page 42 7210 SAS M, T, X, R6, Mxp MPLS Configura-
tion Guide
Linear protection switching of LSPs (see below) is triggered based on a CC or CV defect detected
by BFD CC/CV.
Note that RFC6428 defines two BFD session modes: Coordinated mode, in which the session state
on both directions of the LSP is coordinated and constructed from a single, bidirectional BFD
session, and independent mode, in which two independent sessions are bound together at a MEP.
Coordinated mode is supported.
BFD is supported on MPLS-TP LSPs. When BFD_CV detects a mis-connectivity on an LSP, the
system will drop all incoming non-OAM traffic with the LSP label (at the LSP termination point)
instead of forwarding it to the associated SAP or PW segment.
The following G-ACh channel types are supported for the combined CC/CV mode:
• 0x22 for BFD CC with no IP encapsulation
• 0x23 for BFD CV
The following G-ACh channel types are used for the CC-only mode:
• 0x07
BFD-based RDI
RDI provides a mechanism whereby the source MEP can be informed of a downstream failure on
an LSP, and can thus either raise an alarm, or initiate a protection switching operation. In the case
of BFD based CC/CV, RDI is communicated using the BFD diagnostic field in BFC CC/CV
messages. The following diagnostic codes are supported:
"1 - Control Detection Time Expired”
"9 - mis-connectivity defect”
PW Control Channel Status Notifications (Static Pseudowire Status Signal-
ing)
MPLS-TP introduces the ability to support a full range of OAM and protection / redundancy on
PWs for which no dynamic T-LDP control plane exists. Static PW status signaling is used to
advertise the status of a PW with statically configured labels by encapsulating the PW status TLV
in a G-ACh on the PW. This mechanism enables OAM message mapping and PW redundancy for
such PWs, as defined in RFC6478. This mechanism is known as control channel status signaling
in SR OS.
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