H3C Technologies H3C S10500 Series Switches - Manual (Page 73)

62
To do… Use the command… Remarks
Enter system view system-view —
Enter MPLS LDP view mpls ldp —
Specify the label distribution
control mode label-distribution { independent |
ordered }
Optional
Ordered by default
For LDP sessions existing before the
command is configured, you must
reset the LDP sessions for the
specified label distribution control
mode to take effect.
Enable label re-advertisement for
DU mode
du-readvertise
Optional
Enabled by default
Set the interval for label
re-advertisement in DU mode
du-readvertise timer value
Optional
30 seconds by default
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:
1. 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.
2. 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 checks the path vector list of the message for its MPLS
LSR ID. If its MPLS LSR ID is not in the list, the LSR will add its LSR ID to the path vector list; if in the list, the
LSR considers that a loop appears and terminates the establishment of the LSP.
In the path vector mode, you must also specify the maximum number of hops of an LSP. An LSR will also
terminate the establishment of an LSP when the hop count of the path, or the length of the path vector,
reaches the specified limit.
Follow these steps to configure LDP loop detection:
To do… Use the command… Remarks
Enter system view system-view —
Enter MPLS LDP view mpls ldp —
Enable loop detection loop-detect
Required
Disabled by default
Set the maximum hop count hops-count hop-number
Optional
32 by default
Set the maximum path vector
length
path-vectors pv-number
Optional
32 by default