Source and destination addresses of targeted Hello packet are the LDP LSR-IDs of systems A and B. The user can configure the local-lsr-id option on the targeted session and change the value of the LSR-ID to either the local interface or to some other interface name, loopback or not, numbered or not. If the local interface is selected or the provided interface name corresponds to an unnumbered IP interface, the unnumbered interface borrowed IP address is used as the LSR-ID. In all cases, the transport address for the LDP session and the source IP address of targeted Hello message is updated to the new LSR-ID value.
The LSR with the highest transport address, that is, LSR-ID in this case, bootstraps the TCP connection and LDP session. Source and destination IP addresses of LDP messages are the transport addresses, that is, LDP LSR-IDs of systems A and B in this case.