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Date: Sat, 10 Sep 2005 11:37:40 -0400
From: Chuck Swiger <cswiger@mac.com>
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To: Blake Covarrubias <blake@yfug.yumaed.org>
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Cc: freebsd-isp@freebsd.org
Subject: Re: VLAN interfaces on FreeBSD; performance issues
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Blake Covarrubias wrote:
> I have a question about VLAN interfaces on FreeBSD. I've read the  
> documentation and have set them up on a machine. After doing so  though 
> the machine seems less network responsive. Does implementing  VLAN 
> interfaces / tagging slow down network performance?

Some, yes, although not by much and that depends to some extent on whether your 
NIC has VLAN_MTU hardware support.

> The reason for wanting VLAN tagging is the machine has once NIC and I wanted
> to multi-home it without having to install another NIC. The network card is
> using the 'fxp' driver.

fxp is a good NIC hardware.  However, if you are trying to connect two distinct 
subnets, playing ISO layer-2 games with VLANs is not going to result in a good 
substitute for layer-3 IP routing.

You cannot truthfully multihome a machine with a single NIC.

-- 
-Chuck