From: Hobbs (deadheadblues@gmail.com)
Date: Thu Jan 29 2009 - 16:07:55 ARST
Hello my friends,
In Routing TCP/IP Volume 1, page 265 it says that if an ACK is not
received from any reliable multicast, a router will unicast the packet
up to 16 times, then drop the neighbor. I tested this but I see over
50 retransmits...
Scenario:
R2 and R1 are on a LAN, hello timer 100.
On R1 and put an ACL that denies EIGRP
On R2 I created a new loopback an advertise it.
This update uses reliable multicast.
R2 does not hear an ACK from its neighbor (192.168.1.1) and it sends a
unicast update.
Look at how many retransmits I get, and the peers only go down because
hold timer expires:
*Mar 2 22:40:46.520: EIGRP: Sending UPDATE on FastEthernet0/0 nbr
192.168.1.1, retry 52, RTO 5000
*Mar 2 22:40:46.528: AS 1, Flags 0x0, Seq 22/27 idbQ 0/0 iidbQ
un/rely 0/0 peerQ un/rely 0/1 serno 14-14
*Mar 2 22:40:51.532: EIGRP: Sending UPDATE on FastEthernet0/0 nbr
192.168.1.1, retry 53, RTO 5000
*Mar 2 22:40:51.540: AS 1, Flags 0x0, Seq 22/27 idbQ 0/0 iidbQ
un/rely 0/0 peerQ un/rely 0/1 serno 14-14
*Mar 2 22:40:54.772: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor
192.168.1.1 (FastEthernet0/0) is down: Peer goodbye received
*Mar 2 22:40:54.792: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor
192.168.1.1 (FastEthernet0/0) is down: Interface Goodbye received
53 retransmits! I thought after 16 the neighbor is declared dead...is
this not default behavior anymore? Or this only for certain reliable
multicasts...the text states "if any packet is reliably multicast..."
thanks,
Blogs and organic groups at http://www.ccie.net
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