topic Re: network routing problem ? in Operating System - Linux

network routing problem ?

Steven Mertens — Mon, 20 Jan 2003 20:17:46 GMT

hi,

see the attachment for my problem.

thnx.

rgds.

Steven

Re: network routing problem ?

Steven E. Protter — Mon, 20 Jan 2003 20:32:49 GMT

can you give me a netstat -r on the Linux box please.

Also run a couple of traceroute commands to the router and to a point beyond the router.

Nice diagram.

P

Re: network routing problem ?

Ron Kinner — Tue, 21 Jan 2003 16:51:08 GMT

There is a security option to ignore pings which come too close together. Would think that would apply to both NICs but who knows. It's to prevent simple DOS attacks. That's why when you ping your Cisco it will only reply to every other ping. In a previous post a user claimed the file:
/proc/sys/net/ipv4/icmp_echoreply_rate
controlled the response. He said putting a 0 in the file would make it respond to all pings. The same thread also suggested that a bad driver could cause this sort of thing. I have also seen certain HP cards which were sensitive to interference which would fail pings randomly.

You could also try swapping the IP addresses and Ethernet cables to see if the problem moved.

netstat -s might tell you something.

Look at your tcpdump file again and verify that working pings and failing pings both have the same source IP.

Wouldn't hurt to do
sh interface
on the router and see if you have any obvious problems. You could also do an extended ping from the router and see if you see the same result.

Ron

Re: network routing problem ?

Sunshine Aguilar — Thu, 23 Jan 2003 00:52:58 GMT

As a last resort, you could replace the nic (eth0) with a known good one. If it is old, then it could be in the process of failing.

Re: network routing problem ?

Chakravarthi — Thu, 23 Jan 2003 06:54:02 GMT

check the mac of both, and verify after ping with arp command, for the other ip from the remote machine which is in the same network, THis is the first step to check, then if the same guy is responding for both the ip's then stop the routed, as both the network cards are in the same network, you dont require it, and try again