Controlling IPv6 FEC distribution during an upgrade to 7210 SAS SR OS supporting LDP IPv6

About this task

A FEC for each IPv4 and IPv6 system interface address is advertised and resolved automatically by the LDP peers when the LDP session comes up, regardless of whether the session is IPv4 or IPv6.

To avoid the automatic advertisement and resolution of an IPv6 system FEC when the LDP session is IPv4, perform this procedure before and after the upgrade to the 7210 SAS SR OS version that introduces support of LDP IPv6.

Procedure

Before the upgrade, implement a global prefix policy that rejects prefix [::0/0 longer] to prevent IPv6 FECs from being installed after the upgrade.
In the cold upgrade case:
- If new IPv4 sessions are created on the node, the per-peer FEC capabilities must be configured to filter out IPv6 FECs.
- On older, pre-existing IPv4 sessions, the per-peer FEC-capabilities must be configured to filter out IPv6 FECs.
When all LDP IPv4 sessions have dynamic capabilities enabled, with per-peer FEC-capabilities for IPv6 FECs disabled, the global import policy can be removed.