Does EIGRP use AS number/process number as it's PORT NUMBER between routers in the same AS/group?
I know that EIGRP does NOT use TCP/UDP; I know that that EIGRP uses RTP as a mechanism to establish a layer-4-like function to keep EIGRP packets ordered and sequenced. I also know that there is an AS number in the payload. So please don't state the obvious, and just talk straight to the point.
In this post on the Cisco Support Forums there is an answer which seems a little weird. The question is about the EIGRP port number, and someone answers that "The port number is the EIGRP AS."
I Googled all over the internet, but could not find a single clue about that statement! Is that really true, I mean DOES EIGRP USE THE AS NUMBER as it's PORT NUMBER?
(By the way, there's a link under the mentioned post, but it doesn't load.)
How EIGRP neighbors know not to form a neighbor relationship with adjacent routers that aren't in their AS? The routers get the packets, disassemble it and check the payload to see that the AS# is not matched and then drop it? Or something else is going on?
Sorry to ask this kind of question, but the guy’s name, who has posted this stuff is Russ White, CCIE No. 2635. With all due respect to him, I couldn’t find a single clue to back up his theory of EIGRP using AS# number as port number. Or to back up his statement, “That's how EIGRP neighbors know not to form a neighbor relationship with adjacent routers that aren't in their AS--they won't even receive the packets sent by a router in another AS!”