Specifications

mpls ldp path-vector maxlength
MP-259
Cisco IOS Multiprotocol Label Switching Command Reference
January 2010
mpls ldp path-vector maxlength
To set the maximum number of router IDs permitted in a path vector type, length, value (TLV) used to
perform path vector loop detection, use the mpls ldp path-vector maxlength command in global
configuration mode. To return the path vector maximum length to the default behavior, use the no form
of this command.
mpls ldp path-vector maxlength nu
mber
no mpls ldp path-vector maxlength
Syntax Description
Command Default If you do not configure this command, the default path vector maximum length value is whatever value
i
s configured for the mpls ldp maxhops command. If you reconfigure the maximum hops value, the path
vector maximum length value automatically changes to the new maximum hops value. If the mpls ldp
maxhops command is not configured, the default value is 254.
Command Modes Global configuration
Command History
Usage Guidelines When an ATM label switch router (LSR) initiates a request for a label binding, and path vector loop
de
tection is enabled, the request includes a path vector TLV that contains the router ID of the requesting
router. Subsequent ATM LSRs along the path to the edge of the ATM label switching region add their
router IDs to the path vector before forwarding the Label Request message to the next hop.
When an ATM LSR receives a Label Request message, it does not send a Label Mapping message in
re
sponse, nor does it propagate the request to the destination next hop if a loop is detected by the path
vector feature. Instead, the ATM LSR returns an error message that specifies that a loop has been
detected. A loop is detected if either of the following occurs:
• The path vector length in the request equals or exceeds the configured Path Vector Limit value
configured by the mpls ldp path-vector maxlength command.
• The receiving ATM LSR finds its own router ID within the path vector list.
number Number from 0 to 254, inclusive, that defines the maximum number of
4
-octet router IDs permitted in the path vector.
The default behavior configured with the no f
orm of this command is to track
and use the value set by the mpls ldp maxhops command (1 to 255).
A value of 0 disables the path-vector loop detection feature.
Release Modification
12.3(19) This command was introduced.
12.4(8) This command was integrated into Cisco IOS Release 12.4(8).
12.4(9)T This command was integrated into Cisco IOS Release 12.4(9)T.