No, What I saw was while on Router A if I telnetted to the 172.16.130.5
address it took me to Router B, so I thought that everything IP wise was
fine. On Tom's comment ISIS does require that IP is correct despite it
using CLNS to form adjacencies. Try it and see, when attempting an
adjacency do a debug isis adj and you will see a line saying no usable IP
addresses to from an appropriate adjacency.
However I thought that this scenario above would be protocol independent BUT
Priscilla seems to have a different result with the same scenario.
Cheers
:-o
-----Original Message-----
From: Priscilla Oppenheimer [mailto:[EMAIL PROTECTED]]
Sent: 13 April 2001 02:05
To: [EMAIL PROTECTED]
Subject: Re: Unusual Aspect of a duplicate IP Address [7:353]
At 01:09 PM 4/12/01, McCallum, Robert wrote:
>Here is a scenario which caught me out BIG time in a real life situation
>using ISIS.
>
>To make it easier
>
>Router A has a serial connection to Router B
>
>
>Everything is up layer 1 & 2i.e CDP can indeed see Router B if you are on
>Router A and vice versa. Router B can't see any routes from Router A or
>beyond.
>
>NOW Routers A serial 0's ip address is 172.16.130.5, Routers B serial 0's
>ip address is 172.16.130.5.
>
>Spot the deliberate mistake.
>
>Although you say AHA he has the same ip address on the serial connections.
>SO, quite rightly ISIS says, go away I will never make an adjacency with
>myself !!!! :-(
>
>However, it took me quite a while to discover that these IP addresses were
>indeed duplicated.
>
>REASON or should I make it a question? I think question would be better.
>
>Q: What do you think would happen if I was on Router A and telnetted to
>172.16.130.5, would I telnet to Router A or B. :->
I think I saw something similar today, though not with ISIS. But duplicate
IP addressing caused us to Telnet to ourselves (i.e. Telnet from Router A
to Router A.) Troubleshooting went downhill for a while until we figured
out that was what was happening.
Is that what you saw too?
Thanks for the cool scenario. I hope the customer stopped breathing down
your back finally.
Priscilla
>A: This is why it took me a while to realise this. I started debugging
>adjacencies, blaming a new controller card which was the first time I had
>used this in ISIS, everything bar the easy problem. Mental Note for me
here
>is don't dive in head first, always fault find the layers and remember this
>fault because it is nasty!!!! :-
>What made it worse was the customer sitting over my shoulder saying WHY
>isn't this working, I knew we shouldn't have bought those new fangled
router
>things!!!!!
>
>Oh the joys of life!!!!
>FAQ, list archives, and subscription info:
>http://www.groupstudy.com/list/cisco.html
>Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
________________________
Priscilla Oppenheimer
http://www.priscilla.com
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