Tags

Hi, I know RIP is outdated and IETF doesnt support it anymore. Knowing this i couldnt think of a more appropriate place to post this query: I keep seeing RIP packets with a tag field filled with some non zero number. Any clues on why this is happening? I know that the border routers were meant to use this to fill their AS numbers there, but is there any vendor that really uses this. Moreover, does it make any sense now in doing so. Thanks, Tom