H3C Technologies H3C SR8800 - Manual (Page 92)

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Configuring the FRR polling timer
The protection provided by FRR is temporary. Once a protected LSP becomes available again or a new
LSP is established, traffic will be switched to the protected or new LSP. After this switchover, the PLR polls
available bypass tunnels for the best one at the regular interval specified by the FRR polling timer:
To configure the FRR polling timer:
Step Command Remarks
1. Enter system view of the PLR
node.
system-view N/A
2. Enter MPLS view. mpls N/A
3. Configure the FRR polling
timer. mpls te timer fast-reroute
[ second ]
Optional.
The FRR polling timer is 300
seconds by default.
Inspecting an MPLS TE tunnel
On an MPLS TE network, when an MPLS TE tunnel fails, the control plane cannot detect the failure or
cannot do so in time. This brings difficulty to network maintenance. To detect MPLS TE tunnel failures in
time and locate the failed node, the router provides the following mechanisms:
• MPLS LSP ping
• MPLS LSP tracert
• BFD for an MPLS TE tunnel
• Periodic tracert of an MPLS TE tunnel
Configuring MPLS LSP ping
MPLS LSP ping can be used to check the connectivity of an MPLS TE tunnel. At the ingress, it adds the
label for the MPLS TE tunnel to be inspected into an MPLS echo request, which then is forwarded along
the MPLS TE tunnel to the egress. The ingress determines whether the MPLS TE tunnel is normal according
to whether it can receive a reply from the egress.
To check the connectivity of an MPLS TE tunnel:
Task Command
Use MPLS LSP ping to check the
connectivity of an MPLS TE tunnel.
ping lsp [ -a source-ip | -c count | -exp exp-value | -h ttl-value | -m
wait-time | -r reply-mode | -s packet-size | -t time-out | -v ] * te
interface-type interface-number
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 will return an MPLS echo reply to the ingress due to TTL timeout. Thus, the
ingress can collect the information of each hop along the MPLS TE tunnel, so as to locate the failed node.
You can also use MPLS LSP tracert to collect important information of each hop along the MPLS TE tunnel,
such as the label allocated.