EIGRP Hello's

Unanswered Question
Sep 25th, 2008

In performing a packet capture to troubleshoot a network issue, I noticed the EIGRP Hello's are spaced roughly 4 to 5 seconds a-part (in wireshark (seconds since previous captured packet)). It seemd a little high too me. See attachment.


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Giuseppe Larosa Thu, 09/25/2008 - 08:57

Hello Brandon,

this is a wanted feature to avoid synchronization effects so hellos are not sent exactly every 5 seconds but a random timer is used.

This is because the DUAL specifications expects to process one packet at a time.

When the EIGRP hello is received the hold timer is resetted.

Hope to help


Richard Burts Thu, 09/25/2008 - 10:14


I am curious why you would think that they were a bit high. For most media the default timer for EIGRP hello messages is 5 seconds. The timers are configurable and can be changed. Is there a reason why you would not want them this frequently?

Guiseppe makes a good point why they are not on precise intervals for transmission.



mbroberson1 Thu, 09/25/2008 - 10:39


I have obviously forgotten the full DUAL process. I was comparing this capture to a "old past capture" and hello's seemed a little different. I think I got confused on the "time since previous packet captured" just seemed a little high. You can really just disregard the post. Sorry for my mess.



Richard Burts Thu, 09/25/2008 - 11:19


No problem. The forum is a good place to explore things like that. Sometimes comparing results of a current capture to results of an old capture can show things that seem different but may not be really significant.

Good luck in getting the issue resolved that caused the current capture.




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