HP 10500 SERIES Configuration Manual page 130

packet received from the egress. Upon detecting an MPLS TE tunnel failure, BFD triggers protection
switching to switch traffic to another tunnel.
A BFD session for MPLS TE tunnel detection can be static or dynamic.
Static—If you specify the local and remote discriminator values by using the discriminator keyword
•
when configuring the mpls te bfd enable command, the BFD session is established with the
specified discriminator values. Such a BFD session can detect the connectivity of a pair of MPLS TE
tunnels in opposite directions (one from local to remote, and the other from remote to local) between
two devices.
Dynamic—If you do not specify the local and remote discriminator values when configuring the
•
mpls te bfd enable command, the MPLS LSP ping is run automatically to negotiate the discriminator
values and then the BFD session is established based on the negotiated discriminator values. Such
a BFD session can detect the connectivity of a unidirectional (from the local device to the remote
device) MPLS TE tunnel between two devices.
After you enable BFD and configure the mpls te failure-action teardown command for an MPLS TE tunnel,
once an RSVP-TE tunnel failure occurs, BFD can detect the failure, and if RSVP does not re-establish the
tunnel within a specific period of time, MPLS TE removes the failed RSVP-TE tunnel and then re-establishes
it.
Configuration guidelines
You cannot establish both a static BFD session and a dynamic BFD session for the same MPLS TE
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tunnel.
After establishing a static BFD session for an MPLS TE tunnel, you cannot modify the discriminator
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values of the BFD session.
If you enable both FRR and BFD for an MPLS TE tunnel, to make sure the BFD session is not down
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during an FRR switching, give the BFD detection interval a greater value than the FRR detection
interval.
• In a BFD session for detecting an MPLS TE tunnel's connectivity, the ingress node always operates
in active mode and the egress node always operates in passive mode. The bfd session init-mode
command does not take effect on the ingress and egress nodes of such a BFD session. Even if you
configure the two nodes to both operate in passive mode, the BFD session can still be successfully
established.
Configuration prerequisites
The source address of the BFD session is the MPLS LSR ID. Before configuring BFD to inspect an
•
MPLS TE tunnel, make sure there is a route on the peer device to the MPLS LSR ID. You can also
configure the BFD session parameters on the tunnel interface as needed. For more information
about BFD, see High Availability Configuration Guide.
• To establish a static BFD session to inspect an MPLS TE tunnel, make sure there is already an LSP
from the local device to the remote device and an LSP from the remote device to the local device.
Configuring BFD for an MPLS TE tunnel
Step
1. Enter system view.
Command
system-view
122
Remarks
N/A