topic Re: RHEL 4 problem with networking in Operating System - Linux

RHEL 4 problem with networking

Josef Forman — Fri, 18 Aug 2006 06:19:01 GMT

Hi everybody!
I have problem with RHEL 4 on my HP server. Every second reboot 'shutdown -r now' i have problem with networking - list using 'route' a can't see default gw (so there is no traffic outside the segment), but after every odd reboot everything is OK.

What can be the problem?

JF

Re: RHEL 4 problem with networking

Steven E. Protter — Fri, 18 Aug 2006 06:52:00 GMT

Shalom,

GATEWAY can be set in one of two files:
/etc/sysconfig/network

/etc/sysconfig/network-scripts/ifcfg-eth0

eth0 may be another device.

It should not be set in both.

There is probably an inconsitency either in the networking environment or the network configuration files.

SEP

Re: RHEL 4 problem with networking

Josef Forman — Fri, 18 Aug 2006 07:02:08 GMT

/etc/sysconfig/network...
NETWORKING=yes
HOSTNAME=bla.bla.cz

/etc/sysconfig/network-scripts/ifcfg-eth0...
DEVICE=eth0
BOOTPROTO=none
BROADCAST=10.32.121.255
HWADDR=00:0b:cd:24:1a:02
IPADDR=10.32.121.48
NETMASK=255.255.255.0
NETWORK=10.32.121.0
ONBOOT=yes
TYPE=Ethernet
GATEWAY=10.32.121.1
USERCTL=no
IPV6INIT=no
PEERDNS=yes

I can't see inconsistency.
In the bad situation i even can't see eth0 device using command 'ifconfig -a'.

Re: RHEL 4 problem with networking

Steven E. Protter — Fri, 18 Aug 2006 07:07:17 GMT

You are correct,

Nothing stands out, perhaps someone will spot something.

I would suggest this could be caused by misconfiguration of the switch the network is plugged into or possibly a duplicate IP address on the network, or at least in an arp table somewhere.

Time to consult with your networking department.

SEP

Re: RHEL 4 problem with networking

Al Licause — Fri, 18 Aug 2006 07:29:18 GMT

If you haven't already done so, try removing the default route from ifcfg-eth0 and included it in the network file. It makes much more sense to have it there anyway.

I don't know if this makes sense but when you associate the default route or any route with the specific network interface, in that nic's configuration file, you're assuming the card will be up and talking to the network at that time and the default gateway will be reachable. Not always a good assumption.

If you first bring up the network card, then some time later, perhaps only a few seconds or less, it will give the nic time to settle and allow the default gateway to appear to be reachable. If the default or other gateway is not reachable many operating systems will not allow the route to be installed.

This is more than likely a timing problem which is very difficult to detect.

Re: RHEL 4 problem with networking

Alexander Chuzhoy — Fri, 18 Aug 2006 07:56:44 GMT

Use "netstat -rn" to see default gateway.
It works when "route" doesn't show default gateway.

Re: RHEL 4 problem with networking

Josef Forman — Fri, 18 Aug 2006 08:15:49 GMT

You are right Al Licause, it makes more sence, but it didn't resolve the problem.

Both 'route' and 'netstat -rn' are showing the same...

Kernel IP routing table
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0

Re: RHEL 4 problem with networking

Josef Forman — Thu, 24 Aug 2006 03:05:47 GMT

Hi everybody,
I finally found the solution - updated SW from last support pack from HP and everything works great.

anyway,
really thanks for your help

PS: this is not advertisement for HP support pack :o)