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Inspecting an MPLS TE tunnel
When an MPLS TE tunnel fails or affects data forwarding due to performance degradation, the
control plane cannot detect the fault 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 device
provides the following mechanisms:
•
MPLS LSP ping
•
MPLS LSP tracert
Configuring MPLS LSP ping
MPLS LSP ping can be used to test the connectivity of an MPLS TE tunnel. At the ingress, it adds the
label of the tunnel into an MPLS echo request, and sends it 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 test the connectivity of an MPLS TE tunnel:
Task Command
Remarks
Use MPLS LSP ping to test the
validity and 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
Available in any view.
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.