2 Network Cards & 2 IP's?

Adam Seniuk adams at techweavers.net
Tue Oct 26 10:14:09 PDT 2004


This is more for redundancy, I have 2 on board nic's so if I can use both of
them to do basic dns round robin load balancing and manual failover its more
useful then one network card doing nothing :D


-----Original Message-----
From: Aaron Nichols [mailto:adnichols at gmail.com] 
Sent: Tuesday, October 26, 2004 11:10 AM
To: Adam Seniuk
Cc: questions at freebsd.org
Subject: Re: 2 Network Cards & 2 IP's?

On Tue, 26 Oct 2004 11:00:45 -0600, Adam Seniuk <adams at techweavers.net>
wrote:
> > xl0
> > arp: 192.168.1.100 is on fxp0 but got reply from 00:02:b3:9f:74:89 on
> > xl0
> > arp: 192.168.1.1 is on fxp0 but got reply from 00:07:e9:10:43:78 on
> 
> I get these messages in my logs (quite a few)
> 
> So I am not sure what is wrong. I noticed in another thread that freebsd
> does not allow ips from the same netmask so how does the blundering
windows
> do it?

Those messages are probably technically correct. Since both NIC's are
on the same wire, they are both going to see the same ARP
request/responses. I assume this error is just indicating that there
is already an ARP entry for 192.168.1.100 which indicates that it can
be found via fxp0 and it just saw an ARP response indicating that it
is also available via xl0 - so which should it use?  It's a bit
confusing to a machine which has to select the correct NIC to send
traffic out.

What is the goal of all this? Typically for multipe IP's on the same
subnet you would just use an alias - I assume that's not suitable in
this case but am not sure why.

Aaron




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