Inspecting Lsps; Configuring Mpls Lsp Ping; Configuring Mpls Lsp Tracert; Configuring Bfd For Lsps - HP 12500 Series Configuration Manual

Inspecting LSPs

In MPLS, the MPLS control plane is responsible for establishing LSPs. However, when an LSP fails to
forward data, the control plane cannot detect the LSP failure or cannot do so in time. This makes network
maintenance difficult. To find LSP failures in time and locate the failed node, the switch provides the
following mechanisms:
MPLS LSP ping
•
• MPLS LSP tracert
BFD for LSPs
•
Periodic LSP tracert
•

Configuring MPLS LSP ping

MPLS LSP ping is for checking the connectivity of an LSP. At the ingress, it adds the label for the FEC to
be inspected into an MPLS echo request, which then is forwarded along the LSP to the egress. The egress
processes the request packet and returns an MPLS echo reply to the ingress. An MPLS echo reply carrying
a success notification indicates that the lSP is normal, and an MPLS echo reply carrying an error code
indicates that the LSP has failed.
Use the following command to check the connectivity of an LSP:
To do...
Use MPLS LSP ping to check MPLS
LSP connectivity

Configuring MPLS LSP tracert

MPLS LSP tracert is for locating LSP errors. It consecutively sends the MPLS echo requests along the LSP to
be inspected, with the TTL increasing from 1 to a specific value. Then, each hop along the LSP 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 LSP, so as to locate the failed node. You can also use MPLS LSP tracert to collect the
important information of each hop along the LSP, such as the label allocated.
Use the following command to locate errors of an LSP:
To do...
Perform MPLS LSP tracert to locate
an MPLS LSP error

Configuring BFD for LSPs

You can configure BFD to detect the connectivity of an LSP. After the configuration, a BFD session will be
established between the ingress and egress of the LSP, and the ingress will add the label for the FEC into
Use the command...
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 ] *
ipv4 dest-addr mask-length
[ destination-ip-addr-header ]
Use the command...
tracert lsp [ -a source-ip | -exp
exp-value | -h ttl-value | -r
reply-mode |-t time-out ] * ipv4
dest-addr mask-length
[ destination-ip-addr-header ]
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