The 7705 SAR extends the LDP control plane and data plane to support LDP IPv6 adjacencies and sessions using 128-bit LSR ID.
The implementation allows for concurrent support of independent LDP IPv4 (which uses a 32-bit LSR ID) and LDP IPv6 adjacencies and sessions between peer LSRs and over the same interfaces or different set of interfaces.
Figure: LDP Adjacency and Session over an IPv6 Interface shows an example of an LDP adjacency and session over an IPv6 interface.
LSR-A and LSR-B have the following IPv6 LDP identifiers respectively:
<LSR Id=A/128> : <label space id=0>
<LSR Id=B/128> : <label space id=0>
By default, LSR-A/128 and LSR-B/128 use the system interface IPv6 address.
Although the LDP control plane can operate using only the IPv6 system address, it is recommended that the user must configure the IPv4-formatted router ID in order for OSPF, IS-IS, and BGP to operate properly.
The following sections describe LDP IPv6 behavior on the 7705 SAR: