[afnog] Cisco 1841 ISR problem

Tue Oct 11 08:56:50 UTC 2011

To be honest I got this solution from a configuration file of my Service provider whom we almost ate each other arguing as to why it was not possible to get layer 3 connection on his layer 2 link that he provided although he was able to see both my MAC addresses of my routers on either ends.

He demanded to get my configuration file I gave him he was not able to see any problem in my configuration and he only suspected that my router was not O.K, I told him that my router was fine since it was doing fine on other links. Then he brought his router and everything was fine.

I was very surprised to see this and I wanted to see the configuration file. Actually the difference in my file and his was only this keyword. I removed his router and edited my route by adding this keyword and surprisingly my router worked and it is still working up to now.

One day I tried to remove that keyword same problem repeated and I returned it.

I googled this and got the same things you have said here of FIB/RIB and I assumed perhaps that the link was fluctuating up and down perhaps so fast that the router can sense while the packet loss cannot be felt significantly.

That is why I have said let the fellow try and see if it works.
People say 'IF there is no workable solution to a problem then try any option you hear provided it won't compromise your aim".

Truly my case was not related to NAT issues but it smells pretty similar (Routing).

Yasini.

-----Original Message-----
From: Mark Tinka [mailto:mtinka at globaltransit.net]
Sent: Tuesday, October 11, 2011 11:26 AM
To: Yasini Kilima
Cc: david aliata; afnog at afnog.org
Subject: Re: [afnog] Cisco 1841 ISR problem

On Tuesday, October 11, 2011 04:21:25 PM Yasini Kilima
wrote:

> Let me give my contribution
>
> Try adding a keyword (permanent) at your default route
> like: I believe your Cisco IOS will support adding this keyword at
> your route.
>
> ip route 0.0.0.0 0.0.0.0 FastEthernet0/0 permanent
>
> If it works I will tell you what it does and why it is needed and the
> situation you may be facing.
>
> I had a similar problem but to me it was not towards the Internet and
> I solved by just adding this small keyword.

Yasini, I'm curious why you think this keyword will help.
For all intents and purposes, the 'permanent' keyword ensures the router doesn't delete the route from the RIB/FIB in case the exit interface were to go down.

Interesting how it solves the NAT issue for the OP. I'd be keen to hear your experiences.

Cheers,

Mark.
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