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redhat linux 7.3 server : LAN connection

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MY linux server (redhat 7.3) is loosing lan connection every few minutes. when users try to connect from outlook express to collect mail they cannot because the server keeps loosing the connection on and off what causes this.

9 replies

by cpfeiffe

1) faulty hardware - lan cable, network card, switch/hub port. I'll assume you've checked this, but if not I'd start here. It can give intermittent results.

2) mis-negotiated speed/mode - by default auto negotiate is used. If you also use auto-negotiate on the switch/hub this is OK in most cases, but sometimes the devices don't negotiate properly. This causes a delay in traffic. Some apps (ftp) just run really slow and others may timeout and drop the connection. The easiest way to test this is to FTP a large file (about 32 MB or more) and see if you get the speed you should. On a 100 Mbps network you should be able to move 32 MB in 2.5 seconds. You don't need to get optimal so I would be satisfied with 10 seconds. If you are getting results around the minute and more time range it is likely a negotiation issue. If thats the case email my alias and I'll help you force your linux machine to the right speed.

3) flaky firewall - it seems that this should either allow you to pass or not but I've been in some flaky configs where it was not consistent. Are you using ipchains? If so can you turn it off temporarily? If you suspect it could be ipchains email my alias and I'll send you a couple of entries that should be there.

Other than the negotiation, I wouldn't worry too much about the linux configs. Either it is on the network or it isn't from a config standpoint, unless your kernel is doing something crazy.

by briantruitt

Have you checked your log files? They might point you in the right direction. I'm thinking it's probably your network card.

by peeyush_maurya

hey meeva,

seems like network card/configuration issue
- dmesg | egrep eth0
- Check /etc/sysconfig/hwconf which will tell u what hardware has been detected buy Linux.
- r u using surecom NIC by any chance?
- check /etc/modules.conf :: see if u have any other setting like this :: options eth0 line_speed=100 full_duplex=1

waiting for ur reply

by peeyush_maurya

- i think ur NIC is not breaking connection over 5mb load...try
ping -s 2048 192.168.2.8
and keep incerasing -size and see at what size it start bearkign connection

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