16
Configuring the label distribution control mode
With the label re-advertisement function enabled, an LSR periodically looks for FECs not assigned with
labels, assigns labels to them if any, and advertises the label-FEC bindings. You can set the label
re-advertisement interval as needed.
To configure the LDP label distribution control mode:
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 two 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 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.
To configure LDP loop detection:
To do…
Use the command…
Remarks
Enter system view
system-view
—
Enter MPLS LDP view
mpls ldp
—
