show ip eigrp neighbor output, eigrp map to which osi layer

[sarahr202]

Hi every body

1 ) Ip header use protocol type field to indicate the pay lad. For example  value 6 shows  tcp segment in payload,  value 17 shows udp segment in  the payload field.     Value  88 indicates eigrp packets in the data field of ip header.   The question is at which osi layer eigrp functions ?

2) Show ip eigrp neighbor  output shows  " seq"   which indicates the sequence number of the packet received from a corresponding neighbor.

Hello  is also an eigrp packet,  I noticed  " seq"   does not increment   when a router receives a hello from its neighbor.  Is  it  normal?

i also noticed  updates are unicast, i thouht  eirgrp sends update at multicast address.  

one of the link,  i happened upon while researching says  when two routers become neighbor they initially send the whole routing table in updates  which are unicast.After that, if there is any change in routing table, they send  update at multicast.

Thanks and have a great weekend.

[Richard Burts · Accepted solution]

I do not believe that there is a simple, direct answer about how EIGRP maps to OSI layers. One way to look at it would be to say that since it runs over IP and has its own unique IP protocol number that it maps to the transport layer. Another way to look at it would be to say that since EIGRP learns data, exchanges data with other participants, maintains data tables, and is making logical evaluations of the data that it is running as an application.

HTH

Rick