LDP IPv6 uses a 128-bit LSR ID as defined in draft- pdutta-mpls-ldp-v2-00. See LDP Process Overview for more information about interoperability of this implementation with a 32-bit LSR ID, as defined in draft-ietf- mpls-ldp-ipv6-14.
A Hello adjacency is brought up using a link Hello packet with a source IP address set to the interface link local unicast address and a destination IP address set to the link local multicast address FF02:0:0:0:0:0:0:2.
The transport address for the TCP connection, which is encoded in the Hello packet, is set by default to the LSR ID of the LSR. The transport address is instead set to the interface IPv6 address if the user enables the interface option in one of the following contexts:
config>router>ldp>if-params>ipv6>transport-address
config>router>ldp>if-params>if>ipv6>transport-address
The user can configure the local-lsr-id option on the interface and change the value of the LSR ID to either the local interface or to another interface name, including loopback. The global unicast IPv6 address corresponding to the primary IPv6 address of the interface is used as the LSR ID. If the interface 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.
The LSR with the highest transport address bootstraps the IPv6 TCP connection and IPv6 LDP session.
The source and destination addresses of LDP/TCP session packets are the IPv6 transport addresses.