Subject: Re: IP distribution across multiple NICs
To: tester 777 <>
From: Steven M. Bellovin <>
List: netbsd-users
Date: 01/10/2001 07:10:28
In message <>, "tester 777" writes:
>i'm hosting some heavily accessed content over a lan under netbsd1.5 i386.  
>only about 60 megs of data so i've made it all memory resident to up 
>peformance, but my nic is hitting its 11 to 12 megabyte/sec limit though the 
>CPU isn't maxing out.  i've heard of binding an ip to multiple mac addys 
>before (at the OS level) but have no idea if and how this may be 
>accomplished under netbsd.  i don't have the need or net topo or money to 
>dive into gigabit yet so i'm looking for a fast ethernet-based solution.
>ideally, i would hope to be able to distribute the load of a single IP 
>across multiple nics.  (i have 3 intelpro 100b already installed and 
>configured with 3 ips [fxp0, 1, and 2 respectively]).  i'm hoping for a 
>solution that would symmetrically distribute load evenly between all 
>installed nics so i might even maintain nice latency before i hit 300mbit in 
>active load (obviously i would become CPU/bus limited long before this 

If you're getting 12 megabyte/sec on a 100baseT LAN, you're doing very 
well.  What is downstream of that LAN?  A switch?  What is it connected 
to?  What is the output bandwidth there?

A common way to do load-balancing across multiple IP addresses is via 
the DNS.  For the specific solution you're asking for -- I don't know 
how to do that on NetBSD, but that doesn't mean there isn't one.  You 
could probably play games with ARP, if you wished.

		--Steve Bellovin