Alcatel-Lucent 7450 - Figure 17: BFD Used for Proactive CC on MPLS-TP LSP

MPLS and RSVP
7450 ESS MPLS Guide Page 71
trace packet therefore contains a DSMAP TLV in addition to the MPLS-TP static LSP TLV in the
target FEC stack.
DSMAP/DDMAP is not supported for pseudo wires.
Proactive CC, CV and RDI
Proactive Continuity Check (CC) is used to detect a loss of continuity defect (LOC) between two
MEPs in a MEG. Proactive Connectivity Verification (CV) is used to detect an unexpected
connectivity defect between two MEPs (e.g. mis-merging or mis-connection), as well as
unexpected connectivity within the MEG with an unexpected MEP. This feature implements both
functions using proactive generation of OAM packets by the source MEP that are processed by the
peer sink MEP. CC and CV packets are always sent in-band such that they fate share with user
traffic, either on an LSP, PW or section and are used to trigger protection switching mechanisms.
Proactive CC/CV based on bidirectional forwarding detection (BFD) for MPLS-TP is described in
RFC6428. BFD packets are sent using operator configurable timers and encapsulated without
UDP/IP headers on a standardized G-ACh channel on an LSP or PW. CC packets simply consist of
a BFD control packet, while CV packets also include an identifier for the source MEP in order that
the sink MEP can detect if it is receiving packets from an incorrect peer MEP, thus indicating a
mis-connectivity defect. Other defect types (including period mis-configuration defect) should be
supported. When a supported defect is detected, an appropriate alarm is generated (e.g. log, SNMP
trap) at the receiving MEP and all traffic on the associated transport path (LSP or PW) is blocked.
This is achieved using linear protection for CC defects, and by blocking the ingress data path for
CV defects. The system supports both a CC-only mode and a combine CC / CV mode, as defined
in RFC6428.
Note that when an LSP with CV is first configured, the LSP will be held in the CV defect state for
3.5 seconds after the first valid CV packet is received.
Figure 17: BFD used for proactive CC on MPLS-TP LSP
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