Daily Archives: April 30, 2013

3.5.a Describe packet types

i didn’t catch this on my last reading… note also that doyle sets hello/ack as distinct packet types whereas cisco pairs them as below…

from doyle:

Requests were a type of packet originally intended for use in route servers. This
application was never implemented, and request packets are noted here only because
they are mentioned in some older EIGRP documentation.

from cisco: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

Packet Formats

EIGRP uses five packet types:

  • Hello/Acks
  • Updates
  • Queries
  • Replies
  • Requests

Request packets are used to get specific information from one or more neighbors. Request packets are used in route server applications. They can be multicast or unicast. Requests are transmitted unreliably.

and wendell below from ccie r&s:

Hello Identifies neighbors, exchanges parameters, and is sent periodically as a
keepalive function
Update Informs neighbors about routing information
Ack Acknowledges Update, Query, and Response packets
Query Asks neighboring routers to verify their route to a particular subnet
Reply Sent by neighbors to reply to a Query
Goodbye Used by a router to notify its neighbors when the router is gracefully shutting down

note: wendell separates hello/ack, doesn’t mention request, sia-query, sia-reply and includes goodbye…

and wireshark chimes in: