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New Member

show ip eigrp neighbor command

When I view the output of this command, what is the RTO column? I have looked all over CCO and can't seem to find it. Thanks!

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Re: show ip eigrp neighbor command

RTO - Retransmission Time out.

The IOS waits for the RTO time period, before which it retransmits a packet from the retransmission queue for the neighbor.

EIGRP sends hellos as multicast packets to neighbors, on 224.0.0.10.

When reply to the multicast fails, from the neighbor (say neighbor is dead), it starts unicasting the hello packet that particular neighbor. RTO is the time that the software waits for receipt of the acknowledgement for the Unicast hello sent. That means RTO is the time interval between each unicast hello message sent. I think EIGRP software tries this for 10 successive times.

I think the default value of RTO is 200 ms...... and it is increased by the EIGRP software, each time it sends a unicast (and neighbor fails to respond each time). If you wanna test this, first create neighbor relationship between 2 routers using EIGRp, clear the neihbor using clear ip eigrp nei command, and check on the other router, the increase in RTO.

New Member

Re: show ip eigrp neighbor command

Thanks for the reply, that information helps. Do you know where I could go to find out what all the output to the command means? The reason I am pushing the issue is: we have hundreds of VPN tunnels using EIGRP, and when I do the show ip eigrp neighbors, it shows that many of them have very low uptimes. I know the vpn tunnel is up but for some reason the eigrp neighbor association is being re-established quite often.

Re: show ip eigrp neighbor command

I recall, reading what each entry means, one of the CCIE prof. series, from Cisco Press, Routing & Switching book by Jeff Doyle.......

Check this link for ex....

http://www.rhyshaden.com/eigrp.htm

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