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EIGRP Help

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by sgs_gti_jay 1 view

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If anyone can help me out i would greatly appreciate it. I've been trying to get EIGRP set up across 3 cisco routers. All connections are serial (back to back) connections. Once I add all my ip's etc on interfaces and goto declare Network x.x.x.x with a wildcard I recieve the following across all 3 routers

14:56:01: IP-EIGRP: Neighbor 192.168.145.5 not on common subnet for Serial0 (192.168.145.10 255.255.255.252)

Config:
R1 S0:192.168.145.9/30 to R2-S0:192.168.145.10/30 Network: 192.168.145.8 0.0.0.3

R1-S1:192.168.145.5/30 to R3-S0:192.168.145.6/30 Network: 192.168.145.4 0.0.0.3

R2-S1:192.168.145.13/30 to R3-S1:192.168.145.14/30 Network: 192.168.145.12 0.0.0.3

I do have configs and a topology PDF created if someone want's to really review the set up in depth. Just shoot me a PM with your email and i'll forward the details. I'm also not sure if Split Horizon is causing an issue on R1.

Please help if you can.

Additional Details:
R1 - Cisco 2521 - IOS 12.1
R2 - Cisco 2501 - IOS 12.1
R3 - Cisco 2501 - IOS 12.1

Statments in all configs
------------------------
No auto summary
ip classless
ip subnet-zero
no ip source-route

Jay

8 replies

by sgs_gti_jay

Thanks Nimmo for the links, i've already gone the the cisco docs, the routergeek site shed some light on using the supernet address for the network but i think because i'm using a different scheme or should i say i'm trying to use a different scheme supernets is not what i'm looking to use to declare the network statements in EIGRP.

from what i understand with the way i'm trying to implement things each network declared for a link would be easier to manage as opposed to just declaring a supernet. if i wanted to take 1 link down I have a finer grain of control with the scheme and addressing i'm using .. perhaps i'm wrong, if so please correct me since i'm no subnetting pro.

by nimmo

I may be missing something but I would have thought that you would simply enable eigrp on each router and add the networks to which you want to advertise. Making sure that you have set the clock rate on the DCE routers.

Just a thought are you using the same AS number on each router? Make sure your addressing between each router on the serial interface is in the same subnet.

by sgs_gti_jay

Nimmo

if you look at the original scheme i posted all the addressing is there .. with the DCE and DTE interfaces marked. Instead of using say just

Network 192.168.145.0 (supernet)

I'm using wildcards
Network 192.168.145.8 0.0.0.3 (translates to a /30 subnet or 255.255.255.252

this way i can control each link independantly .. if i want 1 link out of routing it's very easy to take it out so that it's less processing across the whole LAN just simply remove the network. If i understand correctly if i supernet and just declare 192.168.145.0 then i will not be able to do this .. instead i would most likely have to shut the interface but does that also continue to use resources to check for that known route to come back up ?

by sgs_gti_jay

So i think i have found that the problem lies deeper than just with EIGRP configuration. I managed to try changing the Network statements to say just 192.168.145.0 on all routers , still same errors for the not on common subnet issue .. cleared eigrp neighbors and also cleared ip routing tables on all devices ..

Then just to test EIGRP i went to shut down S1 on Router1 and then i saw a msg that S0 changed state to down .. that's def something else happening to do that so i'm going to try fresh tomorrow .. write erase all 3 routers and also might upload a fresh IOS images on all 3 devices to make sure there all clean and running exactly the same versions .. i'll let you know how this goes Nimmo. **Crossing fingers this solves the problem**

by nimmo

I think that removing all the routing (protocols/tables), and starting fresh with a basic config to test and make sure its all working will then narrow down the issue.

by sgs_gti_jay

even though i'm working in a "LAB" environment for my own personal learning this is something to stress for everyone. When in doubt and your running into funny problems "CHECK THE PHYSICAL" side of things. Turns out that all the issues related to my problem was simply a bad serial cable (1 bent pin) - as soon as the cable was changed, routing tables cleared - EIGRP was up and running like a champ with no problems.

Thanks for all the input from everyone :)

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