Hi all.
Problem is that occasionally I lose all networking to my box; can't reach any IP on any port. ifconfig shows correct networking config, and a 'service network restart' returns normal operation immediately.
So what is going on here, what is restarting the service doing exactly? I though it was just a way of applying the config, but this remains unchanged so it must be doing something else. Arping maybe? Is something else stealing my IP(s)?
Cheers
Network dropout -- service restart fixes
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Super Jamie
- Posts: 310
- Joined: 2014/01/10 23:44:51
Re: Network dropout -- service restart fixes
You're on the right track.
It's likely you have a duplicate IP elsewhere on the network. That other system will have responded to an ARP request with your IP but its MAC address, so all remote systems and the switch think your IP is on the other system (because it is).
Running service network restart causes an arping to be sent as the interface comes up, which puts the correct entry into remote MAC tables, and traffic works to your system again.
A common way to troubleshoot this is to pick a third, always-working, system on the same LAN. Wait till your system drops off the network, shut its network down, then from the third system try to reach your IP. The other system should respond. You might try to ping, just to get a MAC address which you can then use on the switch to get which switchport the offending system is plugged into, or if you're the administrator, you could try SSH/RDP into the system and see which one it is.
It's likely you have a duplicate IP elsewhere on the network. That other system will have responded to an ARP request with your IP but its MAC address, so all remote systems and the switch think your IP is on the other system (because it is).
Running service network restart causes an arping to be sent as the interface comes up, which puts the correct entry into remote MAC tables, and traffic works to your system again.
A common way to troubleshoot this is to pick a third, always-working, system on the same LAN. Wait till your system drops off the network, shut its network down, then from the third system try to reach your IP. The other system should respond. You might try to ping, just to get a MAC address which you can then use on the switch to get which switchport the offending system is plugged into, or if you're the administrator, you could try SSH/RDP into the system and see which one it is.
Re: Network dropout -- service restart fixes
Cheers, it did turn out to be an IP clash in the end. IP had been bound to the router as well as the server somehow. 