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

Possible network problem?

Katty Torla Puga — Mon, 12 Dec 2005 07:21:07 GMT

Hello,

I have a Proliant ML370 G4 with RedHat ES 4
The network cards are:
PCI Embedded HP NC7781 Gigabit Server Adapter
PCI Slot 4 HP NC7771 Gigabit Server Adapter

All seems to work ok, but sometimes the two interfaces does'nt respond neither to a ping from a pc. I lost the connection with the server, but normally after few seconds I retrieve the connection.

I've tried to use the new driver bcm5700 from http://h18000.www1.hp.com/support/files/server/us/download/23666.html but the behaviour is the same.

I add the /proc/net/nicinfo/eth*.info

Any idea?

Another question, are normal the values of PCI amb Part_Number for the embedded nic? Is normal that the eth1 corresponds to the pci embedded nic?

Thank you for all,

Re: Possible network problem?

Sivakumar TS — Mon, 12 Dec 2005 09:42:03 GMT

Dear Katty,

Are you sure that the NIC has got the problem ?

Sometimes a faulty network cable /switch also could cause this probelm.

Try some swaping between a know working SET OF CABLE & PORT to this and observe, we will be able to conclude.

With Regards,

Siva.

Re: Possible network problem?

Bill Thorsteinson — Mon, 12 Dec 2005 11:14:23 GMT

Check the output of dmesg to see if the
kernel is noticing the network dropout.

The dropouts should also be logged in
/var/log/syslog or /var/log/messages.

Re: Possible network problem?

Bill Thorsteinson — Mon, 12 Dec 2005 11:16:05 GMT

Also check the output of /sbin/ifconfig
for errors and events for the interfaces.
The number and type of errors and events
may give you a hint as to what is happening.

Re: Possible network problem?

Katty Torla Puga — Tue, 13 Dec 2005 02:31:48 GMT

We have another servers in the same modul Gigabit of the Cisco 4507R. The other servers work ok. If I connect the Proliant in the port of another server or with another cable, the behaviour is the same ... so it seem's that it's not a problem of the network equipment.

I append a file with the outputs ...

Thank you

Re: Possible network problem?

Alan_152 — Tue, 13 Dec 2005 10:38:00 GMT

check the cabling, and make sure that the speed/duplexing is the same on both sides of the connection (sometimes, autonegotiate doesn't work right, so you'll have to set them manually).

Re: Possible network problem?

rick jones — Tue, 13 Dec 2005 12:54:05 GMT

"Never" harcode a gigabit NIC - unless, and _perhaps_ if you are hardcoding it to 100 Megabit operation. Gigabit operation basically requires autonegotiation.

The suggestions to try other cables are good.

Also, you might consider installing and trying linkloop - it is a sourceforge project which is a port of the HP-UX linkloop command. This is a "link-level" "ping" command that you can use. If ping does not work, but linkloop does, it suggests some issues with IP addresses.

Re: Possible network problem?

Katty Torla Puga — Thu, 15 Dec 2005 05:45:49 GMT

I've dowload linkloop from http://freshmeat.net/projects/linkloop/

When I try linkloop against a server RedHat9 in the same subnesk ... the results are:

linkloop -i eth0 -d 00:30:37:00:06:0E
interface=eth0 timeout=2 num=1 size=1500
Link connectivity to LAN station: 00:30:37:00:06:0E (HW addr 00:30:37:00:06:0E)
Getting MAC address of interface 'eth0'
Testing via eth0 (HW addr 00:12:79:D4:20:F8)
sent TEST packet to 00:30:37:00:06:0E
** TIMEOUT (2 seconds)
Retry 0...
-- NO RESPONSE --

A ping to this server works ok.

Another thing:

By default, the system assigns eth0 to the external network card and eth1 to the internal network cars. I've modified
/etc/sysconfig/network-scripts/ifcfg-eth?
to force the HWADDR parameter ... so, now eth0 is the internal ...

Since this change, it seems that the connectivity is ok ... but I would like to be more secure about this event ...

What do you think about it?

Re: Possible network problem?

Ivan Ferreira — Thu, 15 Dec 2005 06:24:47 GMT

Check if you continue to receive packages when the problem occurs, you should always receive packages even when you are not using the network, because of broadcast. Check the RX Packets in the output of ifconfig, should always increment after an interval. That should be a good indicator of link.

Also, do you have any messages in the /var/log/messages file? like NETDEV WATCHDOG, etc.

Check your adapter at the time of the problem with ethtool.

Use tcpdump to monitor the interface to see if you can see any packages going to the interface.

Re: Possible network problem?

Katty Torla Puga — Thu, 15 Dec 2005 07:50:29 GMT

RX ifconfig -> ok
No NETDEV nor WATCHDOG in messages
ethtool -> ok

I append a file with the other information

Thank you,

Re: Possible network problem?

rick jones — Thu, 15 Dec 2005 13:27:12 GMT

Unless the remote system is HP-UX, he "linkloop" daemon needs to be running on it as the default linux NIC drivers do not automagically respond to the XID/TEST message that linkloop uses.

Re: Possible network problem?

Ivan Ferreira — Thu, 15 Dec 2005 13:49:58 GMT

I think that you should run tcpdump in logging mode. And pay atention to the moment where you loss the connectivity. The moment that you ran tcpdump seems that everything was working. I would like to know what is happening when the network does not work.

Re: Possible network problem?

Katty Torla Puga — Fri, 03 Feb 2006 03:11:03 GMT

Hello,

And the problem goes on ...

I append a file with the tcpdump. Near the end of the file you can see the moment where I lost the connectivity.

Thank you

Re: Possible network problem?

Ivan Ferreira — Fri, 03 Feb 2006 08:57:03 GMT

Sorry, there are lots of unusefull packets on your capture, and you did not specify the hosts with problems.

Please run again with a filter, for example:

tcpdump -w tcpdump.out host faraday.upc.es and pc11290.euetib.upc.es

So, there will be less information and will be more usefull.

Also, when you have the problem, get the output from:

netstat -nr
netstat -ni

Ensure that you don't have installed a software like portsentry.

Re: Possible network problem?

Ivan Ferreira — Fri, 03 Feb 2006 09:30:36 GMT

Also, you should run the tcpdump on both hosts, source and destination, to match the output. Also, record the output of netstat -n too see the state of the connections.

Re: Possible network problem?

Jorge Cocomess — Fri, 03 Feb 2006 15:21:34 GMT

I had this same problem serveral months ago. What happened was at the port setting on the switch was set for 100 /aut_neg and I set my NIC to 100 full /NOAUTO_NEG - Older Cisco switches doesn't like auto too much as I learned from this. Pick your settings for both ends and implement.

Try that and let us know the result.

Re: Possible network problem?

paolo barila — Tue, 07 Feb 2006 15:13:02 GMT

Hi,
check and/or post

# ethtool eth0
(or)
# mii-tool -v

Pablo