topic Re: Problem with default routing. in Operating System - Linux

Problem with default routing.

skiran — Fri, 11 Nov 2005 09:17:50 GMT

Hello All,
We are facing a problem with one of our Linux box. Some time I cannot connect to other system across router(Traceroute /ping doesnt work).

netstst -rn will display the proper routing setting.

But temporary workaround is , If I remove and add the default router (route delete default ; route add default gw xx.xx.xx.xx ) will solve the problem.

We will face this problem 3-4 times a week.

Is Anyone faced such problem like this ..??

Thanks ,
shashi

Re: Problem with default routing.

Ivan Ferreira — Fri, 11 Nov 2005 09:28:25 GMT

I had a problem once with routes very extrange and was that another device had the same IP of the router.

When the problem occurs, you should verify the MAC associated to the IP of the router by using the arp -a command.

When the problem occurs, can you ping the router? Where the traceroute command stops?

Re: Problem with default routing.

skiran — Fri, 11 Nov 2005 09:37:00 GMT

HI , Thank s for quick respone.I can ping the router but not the host .

Thanks & regards,
shashi

Re: Problem with default routing.

Mark Ellzey — Mon, 14 Nov 2005 11:35:47 GMT

Shashi,

Talk to your network people; they may have closed the port that allows ICMP packets. If so, you will be able to login to the host, but not ping it.

Regards,
Mark

Re: Problem with default routing.

Muthukumar_5 — Tue, 15 Nov 2005 01:21:11 GMT

May be a problem with router configuration. When you are able to ping to router then it is the source to decide to route the packets to hosts.

hth.

Re: Problem with default routing.

HGN — Tue, 15 Nov 2005 12:12:17 GMT

Hi

It does not look like a router issue since you had mentioned that during such condition you are able to remove and add the default router.
- If you have redhat support you can ask them if there are any fixes for this (maybe a patch) or is this happening only on 1 server if yes
- then in that case you can try to move this to a different subnet and see (it maybe not be as easy as I'm telling ,changing subnet)but that is another option to sort the issue permanently, or
- there might be some issue with that network interface, you want to move the cable and ip to another ietrface and make sure the hardware is good.

Hope this helps

Rgds

HGN

Re: Problem with default routing.

Ivan Ferreira — Wed, 16 Nov 2005 06:26:32 GMT

When the problem occurs, I would like to the the ouput of:

service iptables status
netstat -nr
arp -a
traceroute destination_host

Cheers.