3Com 8807 Configuration Manual page 520

520 C 48: MPLS B
HAPTER
Configuring LDP Loop
Detection Control
C C
ASIC APABILITY ONFIGURATION
Table 509 Configure Hello transport-address
Operation
Return to the default Hello transport-address
Transport-address defaults to the MPLS LSR ID of the current LSR.
If there are multiple links connecting two neighboring LSRs, all the LDP-enabled
interfaces on the links connecting LSR and its neighbor must have the same
transport address. You are recommended to use the same interface address for all
of them, that is, LSR-ID.
Enabling loop detection
You can enable or disable the loop detection function during LDP signaling
process. The loop detection includes maximum hop count mode and path vector
mode.
The maximum hop count method refers to that the hop-count information is
contained in the message bound with the forwarding label, and the value pluses
one for each hop. When the value exceeds the threshold value, it is considered
that a loop presents, and the process for establishing LSP is terminated.
The path vector method refers to that the path information is recorded in the
message bound with the forwarding label, and, for every hop, the corresponding
router checks if its ID is contained in this record. If not, the router adds its ID into
the record; and if yes, it indicates that a loop presents and the process for
establishing LSP is terminated. When this method is used, if the defined maximum
value is exceeded, it is considered that a loop happens and the LSP establishment
fails.
Perform the following configuration in the system view.
Table 510 Enable loop detection
Operation
Enable loop detection
Disable loop detection
By default, the loop detection is disabled.
Setting the maximum hop count for loop detection
When maximum hop count mode is adopted for loop detection, the maximum
hop-count value can be defined. And if the maximum value is exceeded, it is
considered that a loop happens and the LSP establishment fails.
Perform the following configuration in the system view.
Table 511 Set the maximum hop count for loop detection
Operation
Set maximum hop count for loop detection
Return to the default maximum hop count
Command
undo mpls ldp transport-ip
Command
mpls ldp loop-detect
undo mpls ldp loop-detect
Command
mpls ldp hops-count hop-number
undo mpls ldp hops-count