Re: Two ethernet interfaces puzzle

From: David Haggett (news-spam_at_haggett.demon.co.uk)
Date: 08/08/04 

Date: Sun, 08 Aug 2004 15:29:55 +0100

On Sat, 07 Aug 2004 17:34:25 -0400, Gonzalo wrote:

Actually, the problem is far simpler than Jason suggests (although he is
correct).

The problem is that Linux (in common with other solaris) seperates
the network, data-link and physical layers (OSI network model). The
problem is that the kernel sees both network interfaces as available:

> eth0 Link encap:Ethernet HWaddr irrelevant
> UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
         ^^
 
> wlan0 Link encap:Ethernet HWaddr irrelevant
> UP BROADCAST NOTRAILERS RUNNING MULTICAST MTU:1500 Metric:1
         ^^

It's trying to send packets out of the wired interface, possibly
because 'e' comes before 'w', but there's no physical media to
carry it. By telling the kernel that eth0 is not available you force it
to send packets out of the wireless one.

I read somewhere about a daemon that watches physical interfaces for the
"ethernet link beat" and automatically brings the network up or down.
This would be the best solution for you (same network for both), but
unfortunately I can't remember what it was called.

Sorry - hoping someone else read the same article and can point you in
the right direction. 

-- 
David Haggett
Linux user since 01/01/2003
Email: david<at>haggett<dot>demon<dot>co<dot>uk

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