H3C Technologies H3C S12500-X Series Switches - Manual (Page 39)

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Step Command Remarks
2. Enter LDP view or enter
LDP-VPN instance view.
• Enter LDP view:
mpls ldp
• Enter LDP-VPN instance view:
a. mpls ldp
b. vpn-instance vpn-instance-name
N/A
3. Enable loop detection. loop-detect
By default, loop detection is
disabled.
After loop detection is
enabled, the device uses both
the maximum hop count and
the path vector methods to
detect loops.
4. Specify the maximum hop
count.
maxhops hop-number
By default, the maximum hop
count is 32.
5. Specify the path vector limit. pv-limit pv-number
By default, the path vector limit
is 32.
NOTE:
The LDP loop detection feature is applicable only in networks comprised of devices that do not support TTL
mechanism, such as ATM switches. Do not use LDP loop detection on other networks because it only results
in extra LDP overhead.
Configuring LDP session protection
If two LDP peers have both a direct link and an indirect link in between, you can configure this feature
to protect their LDP session when the direct link fails.
LDP establishes both a Link Hello adjacency over the direct link and a Targeted Hello adjacency over the
indirect link with the peer. When the direct link fails, LDP deletes the Link Hello adjacency but still
maintains the Targeted Hello adjacency. In this way, the LDP session between the two peers is kept
available, and the FEC-label mappings based on this session are not deleted. When the direct link
recovers, the LDP peers do not need to re-establish the LDP session or re-learn the FEC-label mappings.
When you enable the session protection function, you can also specify the session protection duration.
If the Link Hello adjacency does not recover within the duration, LDP deletes the Targeted Hello
adjacency and the LDP session. If you do not specify the session protection duration, the two peers will
always maintain the LDP session over the Targeted Hello adjacency.
To configure LDP session protection:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter LDP view. mpls ldp N/A
3. Enable the session protection
function. session protection [ duration time ]
[ peer peer-prefix-list-name ] By default, session protection is
disabled.