rtp in eigrp...

it's the damndest thing... in response to wtf is rtp anyway...


Nov 12, 2012 9:06 AM

Re: Transport of Dynamic Routing protocols

88

TCP

UDP

Kerberos—authentication system

as you can see for tcp/udp this port is taken...perhaps rtp fits into the pgm model:
http://www.faqs.org/rfcs/rfc3208.html

PGM has no notion of group membership.  It simply provides reliable
   multicast data delivery within a transmit window advanced by a source
   according to a purely local strategy.

russ white in his book eigrp for ip, touches on it only briefly:

In order to ensure that routing updates and queries are not lost, we need a way to make certain other routers have received these multicast packets intact and to recover from errors if they haven’t. For these reasons, updates and queries are handled by the reliable multicast transport in EIGRP.

there is also this from: Troubleshooting IP Routing Protocols

All the EIGRP packets are sent through EIGRP multicast address 224.0.0.10. Every EIGRP-enabled device automatically listens to the 224.0.0.10 address. Because this is a multicast address and multiple devices receive the EIGRP packets at once, EIGRP needs its own transport protocol to ensure reliable delivery of EIGRP packets. This protocol is the EIGRP Reliable Transport Protocol (RTP). The router keeps a transmission list for every neighbor. When a reliable EIGRP packet is sent to the neighbor, the sending router expects an acknowledgment to be sent back from the neighbor indicating that the reliable EIGRP packet has been received. EIGRP RTP maintains the transport window size of only one unacknowledged packet. Therefore, every single reliable packet must be acknowledged before the next reliable EIGRP packet can be sent out. The router retransmits the unacknowledged packet until an acknowledgment is received. If no acknowledgment is received, EIGRP RTP retransmits the same packet up to 16 times. If no acknowledgment is received after 16 retransmissions, EIGRP resets the neighbor relationship.