Mpls Bfd; Protocols And Standards; Configuring Mpls Oam For Lsp Tunnels - HP MSR2000 Configuration Manual

MPLS BFD

MPLS BFD uses a BFD session to proactively verify the connectivity of an LSP tunnel, an MPLS TE tunnel,
or a PW tunnel.
MPLS BFD does the following:
1. Establishes a BFD session between the ingress and egress of the tunnel to be inspected.
2. Adds the label associated with the tunnel into a BFD control packet at the ingress.
3. Sends the packet to the egress node over the tunnel.
4. Determines the tunnel status according to the BFD control packet returned by the egress.
When BFD detects a connectivity failure, it triggers the pre-configured action, such as FRR or path
protection switching, to ensure uninterrupted traffic forwarding.
A BFD session for LSP, MPLS TE tunnel, or PW connectivity verification can be established in one of the
following modes:
Static mode—You manually specify the local and remote discriminators through command lines to
•
establish the BFD session.
Dynamic mode—The system automatically runs MPLS ping to negotiate the discriminators to
•
establish the BFD session.
In static mode, the egress node returns a BFD control packet to the ingress node through the reverse
tunnel. If no reverse tunnel exists, the ingress node cannot receive the BFD control packet, resulting in a
verification failure.
In dynamic mode, the egress node returns a BFD control packet to the ingress node through the reverse
tunnel. If no reverse tunnel exists, the egress mode returns a BFD packet through IP routing.
Use the static mode to test the connectivity of a pair of LSPs or MPLS TE tunnels in opposite directions (one
from local to remote, and the other from remote to local) between two devices. Use the dynamic mode to
test the connectivity of one LSP or MPLS TE tunnel from the local device to the remote device.
A PW is bidirectional. You will get the correct result using either the static or dynamic mode.

Protocols and standards

RFC 4379, Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures
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RFC 5085, Pseudowire Virtual Circuit Connectivity Verification (VCCV): A Control Channel for
•
Pseudowires
• RFC 5885, Bidirectional Forwarding Detection (BFD) for the Pseudowire Virtual Circuit Connectivity
Verification (VCCV)

Configuring MPLS OAM for LSP tunnels

To verify LSP connectivity, you can use one of the following methods:
• Use the ping mpls ipv4 command or the tracert mpls ipv4 command to trigger LSP connectivity
verification as needed.
Configure periodic MPLS traceroute or MPLS BFD for the system to automatically verify LSP
•
connectivity.
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