R3303-HP HSR6800 Routers MPLS Configuration Guide

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Configuring MPLS LSP tracert
MPLS LSP tracert can be used to locate errors of an MPLS TE tunnel. It sends MPLS echo requests to the
nodes along the MPLS TE tunnel to be inspected, with the TTL increasing from 1 to a specific value. Each
node along the MPLS TE tunnel returns an MPLS echo reply to the ingress due to TTL timeout. Thus, the
ingress can collect information about each hop along the MPLS TE tunnel, so as to locate the failed node.
You can also use MPLS LSP tracert to collect information about each hop along the MPLS TE tunnel, such
as the label allocated.
To locate errors of an MPLS TE tunnel:
Task Command Remarks
Use MPLS LSP tracert to locate
errors of an MPLS TE tunnel.
tracert lsp [ -a source-ip | -exp
exp-value | -h ttl-value | -r
reply-mode |-t time-out ] * te
interface-type interface-number
Available in any view.
Configuring BFD for an MPLS TE tunnel
You can configure BFD for an MPLS TE tunnel to implement fast detection of the connectivity of the tunnel.
After you configure BFD for an MPLS TE tunnel, a BFD session is established between the ingress and
egress of the tunnel. The ingress adds the label for the tunnel into a BFD control packet, forward the BFD
control packet along the tunnel, and determine the status of the tunnel according to the BFD control
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 reestablish the
tunnel within a specific period of time, MPLS TE removes the failed RSVP-TE tunnel and then reestablish
it.
Configuration guidelines
• You cannot establish both a static BFD session and a dynamic BFD session for the same MPLS TE
tunnel.
• After establishing a static BFD session for an MPLS TE tunnel, you cannot modify the discriminator
values of the BFD session.