This is the World Wide Name of the specific remote FC fabric entity this link is configured to accept connections from, where a zero-length value means the link will accept a connection from any remote entity regardless of WWN. Leaving this at zero-length is more permissive and easier to set up but means the link provides no authentication of the remote peer's identity, which matters for security-conscious SAN extension deployments spanning untrusted or third-party IP transport. A storage team extending a SAN across a leased WAN circuit to a disaster-recovery site would typically configure this field with the DR site's specific WWN rather than leaving it zero-length, ensuring the link only accepts connections from that known, authorized fabric.