[linux-help] Re: network unreachable

[Tom Hull <thull2@xxxxxxx>]

Jeff Vian wrote:
> On Tue, 2006-05-02 at 01:41 -0500, Tom Hull wrote:
> 
> 
> Just on the off chance, and to rule out one other problem.
> Have you tried a different network cable?
> Have you tried a different port on the switch?

yes. yes.

tried booting ubuntu live disc. network still unreachable.

iptables -L -n shows all rule sets as ACCEPT, which I take to mean no
firewalling.

dmesg shows entries like:

   NETDEV WATCHDOG: eth0: transmit timed out

   eth0: no IPv6 routers present

kernel 2.6.12; driver for eth0 is forcedeth.c 0.41

> You can (at least in Fedora) use ethtool to look at and change settings
> on an adapter.  Pre-FC5 I think it was miitool that did similar things.

not easy to copy the output, but ethtool's basic output looks not
unreasonable (omitting a couple of lines):

   Supported ports: [ MII ]
   Supports auto-negotiation: yes
   Advertised auto-negotiation: yes
   Speed: 100Mb/s
   Duplex: half
   Port: MII
   PHYAD: 1
   Transceiver: externel
   Auto-negotiation: on
   Supports Wake-on: g
   Wake-on: d
   Link detected: yes

netstat -r reports MSS = 0; don't know whether that means no maximum
segment size or 0, which could choke it; my Red Hat machines use 40.

got a chassis intrusion message first time I rebooted after problem;
reset and message went away; would be weird if BIOS disabled ethernet
because of the chassis instrusion detect.

>>>>I have a problem on a recently built Ubuntu Linux system. Sometime in
>>>>the last day or two the machine lost its network connection. Ethernet
>>>>controller is on the motherboard. It is configured with a static
>>>>address, and can ping that address but nothing else on the local
>>>>network. Changing cable and/or port on the otherwise working switch
>>>>has no effect. We had some trouble yesterday when my gateway machine
>>>>couldn't get a DHCP address from Cox for a period of several hours.
>>>>Not sure whether the Ubuntu machine problem occurred at that time,
>>>>since I didn't notice it until much later. I've rebooted since then.
>>>>Don't see anything obviously wrong, e.g. in netstat -r or iptables -L.
>>>>
>>>>Aside from hardware, is there anything you can think of that might
>>>>cause a Linux machine to effectively disconnect itself from a local
>>>>network?
>>>>
>>>>Thanks.

-- 
/*
  *  Tom Hull * http://tomhull.com/ * http://notesoneverydaylife.com/
  */


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