Configuring Ldp Loop Detection - HP 10500 SERIES Configuration Manual

Configuring LDP loop detection

LSPs established in an MPLS domain may be looping. The LDP loop detection mechanism can detect
looping LSPs and prevent LDP messages from looping forever.
LDP loop detection can be in either of the following modes:
Maximum hop count
•
A label request message or label mapping message carries information about its hop count, which
increments by 1 for each hop. When this value reaches the specified limit, LDP considers that a
loop is present and terminates the establishment of the LSP.
Path vector
•
A label request message or label mapping message carries path information in the form of path
vector list. When such a message reaches an LSR, the LSR examines the path vector list of the
message for its MPLS LSR ID. If its MPLS LSR ID is not in the list, the LSR adds its LSR ID to the path
vector list. If it is in the list, the LSR considers that a loop has occurred and terminates the
establishment of the LSP.
The path vector mode also limits the number of hops of an LSP. An LSR also terminates the
establishment of an LSP when the hop count of the path, or the length of the path vector, reaches
the upper limit.
Configuration guidelines
• The loop detection modes configured on two LDP peers must be the same for setting up an LDP
session.
To implement loop detection in an MPLS domain, you must enable loop detection on every LSR in
•
the MPLS domain.
Configure loop detection before enabling LDP capability on any interface.
•
All loop detection configurations take effect for only the LSPs established after the configurations.
•
Changing the loop detection settings does not affect existing LSPs. You can execute the reset mpls
ldp command in user view, so the loop detection settings also take effect for existing LSPs.
LDP loop detection can result in LSP update, which generates redundant information and consume
•
many system resources. HP recommends configuring the routing protocol's loop detection
mechanism.
Configuration procedure
To configure LDP loop detection:
Step
1. Enter system view.
2. Enter MPLS LDP view.
3. Enable loop detection.
4. Set the maximum hop count.
5. Set the maximum path vector
length.
Command
system-view
mpls ldp
loop-detect
hops-count hop-number
path-vectors pv-number
67
Remarks
N/A
N/A
By default, loop detection is
disabled.
Optional.
The default value is 32.
Optional.
The default value is 32.