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Date:      Fri, 27 Aug 2004 13:18:31 -0400
From:      Charles Swiger <cswiger@mac.com>
To:        Bob Ababurko <ababurko@adelphia.net>
Cc:        FreeBSD Questions Mail List <questions@freebsd.org>
Subject:   Re: cannot get rc.conf to configure an second interface
Message-ID:  <1E9D1A2F-F84D-11D8-896C-003065ABFD92@mac.com>
In-Reply-To: <5.2.1.1.0.20040827091804.01c8af40@mail.dc2.adelphia.net>
References:  <5.2.1.1.0.20040824183938.01a70a08@mail.dc2.adelphia.net> <5.2.1.1.0.20040824183938.01a70a08@mail.dc2.adelphia.net> <5.2.1.1.0.20040827091804.01c8af40@mail.dc2.adelphia.net>

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On Aug 27, 2004, at 9:30 AM, Bob Ababurko wrote:
>   I am curious as to how these netmask settings will effect the way my 
> routes will be handled.   If I use a /32, what does that mean....or 
> more specifically, what is going on here?

FreeBSD does not let you configure two network interfaces on the same 
network, because routing table entries need to be unique.  Giving the 
second NIC a different subnet (the /32) associates it with a different 
entry in the routing table.

>   Also.....what I want to do here, or at least, think that I want to 
> do, is have traffic come and go out of each NIC, respectively.  I 
> don't want traffic to come in fxp1 and go out of fxp0.  I want this to 
> occur because I am going to use dummynet to handle some bandwidth 
> issues.

A single NIC runs as fast as the network connection will go.  Having 
two NICs on the same network doesn't usually make things go faster [1], 
although it might be useful for redundancy in case one NIC fails (see 
netgraph).

>   What is the default behavior in this respect in FreeBSD when just 
> adding another NIC to a system and not making any other changes?

If the kernel or a module contains a driver for the NIC, the system 
will bind to the device but leave the interface down.  The interface 
will be a candidate for things like dhclient, or if can be configured 
by ifconfig as normal.

-- 
-Chuck

[1]: For normal network topologies involving hubs, anyway.  If you've 
got a switch, the question becomes more complex, but you would be 
better off configuring a seperate VLAN and using different subnets if 
you've got redundant NICs.



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