This carries the remote peer IP address of whichever pseudowire is currently active within a protected pair, telling the admin exactly which far-end device is presently terminating the live traffic path. This may differ from the primary PW's peer address if the protection scheme involves geographically or topologically distinct backup paths terminating on a different remote router. Knowing this active peer address lets the admin immediately target the correct remote device for further troubleshooting of the currently-live path, rather than the primary path's peer which may no longer be relevant.