topic Re: network error in Operating System - Linux

network error

Adithyan — Wed, 18 Jul 2007 10:09:41 GMT

Hi Friends,

There is a query.

I have 2 network interface, eth0 and eth1, Supposed if the network connectivity from the switch failed to eth0. In this state if I issue a service network restart command, Will it bring up both the interfaces with out error?

Re: network error

Van den Broeck Tijl — Wed, 18 Jul 2007 10:21:46 GMT

Yes in Static mode.

Regardless of the physical connection the software side will be set up on service restart. You can try that by yanking your network cable, restarting networking & ping yourself (ip, not on localhost).

However, using DHCP will probably cause the service to restart rather slowly (initial waiting on DHCP ACK) on eth0, the dhcpcd process will then be backgrounded and networking will come up further on eth1.
So eth0 will be stuck without IP until connectivity is restored.

Solution for avoiding all this is the use of "bonding".
See more about bonding here http://docs.hp.com/en/B9903-90050/ch05s05.html and here http://www.linuxhorizon.ro/bonding.html

Re: network error

Ivan Ferreira — Wed, 18 Jul 2007 10:35:33 GMT

Why you need to do a network restart if that was a switch problem? You should not need to do that.

You could also do just ifup eth0 to avoid shutting down eth1.

Re: network error

Van den Broeck Tijl — Thu, 19 Jul 2007 03:29:26 GMT

@Ivan: It's a theoretical question: "if I issue a service network restart command, Will it bring up both the interfaces with out error"

In the real world I agree with you, you wouldn't do that at all :-)

Re: network error

Stuart Browne — Thu, 19 Jul 2007 06:00:36 GMT

If you do a 'service network restart', it will drop both eth0 and eth1, break basically all network services that are currently running that's bound to either interface (sshd, httpd, nfs, etc. etc.), and then bring them up again.

Using 'network restart' is the sledge-hammer. It's inadvisable to do it. *EVER*. on a live system.

As for whether it'll bring the interfaces up without error, that depends on the error, the switch fault, and far too many other variables to say conclusivly.

Assuming it's just the switch going wonky and a 'replug' of the cable would fix it (or shutdown of interface and bring back up), then yeah.. Sure..

If it's anything more complicated than that, then.. No, probably not.

Re: network error

Don Vanco - Linux Ninja — Thu, 19 Jul 2007 07:27:48 GMT

man ip

You can enact on a single interface without the shotgun to the face of a "service" command

Re: network error

skt_skt — Sat, 21 Jul 2007 17:22:35 GMT

Post the result when you get a chance to test with ip command