Specifying the Transport Address Used by LDP
You can control the transport address used by LDP. The transport address is the address used for the TCP session over which LDP is running. To configure transport address control, include the transport-address statement:
For a list of hierarchy levels at which you can include this statement, see the statement summary section for this statement.
If you specify the router-id option, the address of the router or switch identifier is used as the transport address (unless otherwise configured, the router or switch identifier is typically the same as the loopback address). If you specify the interface option, the interface address is used as the transport address for any LDP sessions to neighbors that can be reached over that interface. Note that the identifier is used as the transport address by default.
You cannot specify the interface option when there are multiple parallel links to the same LDP neighbor, because the LDP specification requires that the same transport address be advertised on all interfaces to the same neighbor. If LDP detects multiple parallel links to the same neighbor, it disables interfaces to that neighbor one by one until the condition is cleared, either by disconnecting the neighbor on an interface or by specifying the router-id option.
