Re: Ethernet driver link state propagation to ip stack

[Ben Greear <greearb@candelatech.com>]

Jüri Põldre wrote:
> All,
> 
> I am experiencing issues with connecting two network adapters to the same
> subnet, eg.
> 
> eth0 192.168.100.200
> eth1 192.168.100.201
> 
> The task is to have redundant connections to two different hubs. In case one
> link goes down the connection should go through the other. The driver
> handles link events with netif_carrier_ok and netif_carrier_on from
> linux/netdevice.h. These eventually send messages to networking stack with
> netdev_change_state from net/core/dev.c
> 
> My question is:  Does the kernel handle  the interface state/routing tables
> modifications due to link changing automatically or is there some external
> daemon required to do that. Any links are greatly appreciated.

As far as I know, you have to handle this sort of thing in user-space.  You may
also have ARP issues with having two interfaces on the same subnet.  Often people
will use two private, non-related IP addresses and then migrate a virtual IP back
and forth, placing it on the preferred (ie, link-ok) interface.

Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com