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Jlymn
40 pts.
 Cisco 3750 – EIGRP not on common subnet problen
Cisco, Cisco 3750, EIGRP, Subnets, Subnets problem
I'm getting lots of messages on a router IGRP-IPv4:(50)(Default-IP-Routing-Table:50): Neighbor 10.13.1.251 not on common subnet for Vlan11

i tried to ping but 10.13.1.251 doesnt respond

show ip route shows 10.13.1.251 is directly connected on Vlan1. This must be off one of the trunk ports but how can i find out which port this neighbor connects on so i can fix the problem?

vlan 11 is 10.20.1.0 255.255.255.0.

Vlan 1 is 10.13.1.0 255.255.255.0.

So something is misconfigured with wrong ip address, but i can't see what it is or where it connects to be able to fix. If i could find MAC address of device i could trace to a port and console on - any ideas?

 

 Thanks



Software/Hardware used:
ASKED: May 24, 2011  2:43 PM
UPDATED: June 2, 2011  8:33 PM
RELATED QUESTIONS
Answer Wiki:
have u ever tried show interfaces command? u should try to find ARP table for having MAC Adress , that's what i know.
Last Wiki Answer Submitted:  June 1, 2011  8:32 pm  by  Arash90   60 pts.
All Answer Wiki Contributors:  Arash90   60 pts.
To see all answers submitted to the Answer Wiki: View Answer History.


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It’s almost like the switch is seeing the packet from 10.13.1.251 coming in on vlan 11; so one of your vlan11 ports has that device connected to it. Since it’s expecting to see it on vlan 1 and it’s NOT there, then it reports and error; and further explains why you can’t ping it; as the 3750 is expecting it on a port of vlan1 like you have it configured.

If it’s an unused subnet (?) then delete it from vlan 1, and place it as a secondary interface on vlan 11; OR take a PC with static address within the expected space for your VLAN 1, and connect it to a vlan 11 port. You will then be able to ping that device (and that device only !) and connect to it to change the address or discover what it really is.

PS – does a simple “SH CDP NEIGHbors detail” give you any clue?

Snapper70
 920 pts.