The source and destination addresses of targeted Hello packets are the LDP IPv6 LSR- IDs of systems A and B in Figure: LDP Adjacency and Session over an IPv6 Interface.
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, including loopback or not. The global unicast IPv6 address corresponding to the primary IPv6 address of the interface is used as the LSR ID. If the user invokes an interface that does not have a global unicast IPv6 address in the configuration of the transport address or the configuration of the local-lsr-id option, the session does not come up and an error message is displayed. In all cases, the transport address for the LDP session and the source IP address of targeted Hello messages are updated with the new LSR ID value.
The LSR with the highest transport address (in this case, the LSR ID) bootstraps the IPv6 TCP connection and IPv6 LDP session.
The source and destination IP addresses of LDP/TCP session packets are the IPv6 transport addresses the LDP LSR IDs of systems A and B in Figure: LDP Adjacency and Session over an IPv6 Interface.