Fixed or random interface identifier for IPv6 random random Random interface identifier for IPv6 x:x:x:x specify interface identifier for IPv6 Peer interface identifier for IPv6 random calling-sid ipv4 x:x:x:x Interface identifier for IPv6 random Use a random interface identifier for IPv6 ipv4 Calculate interface identifier from IPv4 address, for example 192:168:0:1 calling-sid Calculate interface identifier from calling-station-id Accept peer interface identifier