Subject: Re: IP distribution across multiple NICs
To: Steven M. Bellovin <>
From: Claude Marinier <>
List: netbsd-users
Date: 01/10/2001 09:44:27
On Wed, 10 Jan 2001, Steven M. Bellovin wrote:
> 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 
> >anyway).
> 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.

Check out SRV resource records (RRs) in RFC 2052. They can do load
balancing. This is in bind 8.2.2 pl 5.

Claude Marinier, Information Technology Group 
Defence Research Establishment Ottawa (DREO)    (613) 998-4901  FAX 998-2675
3701 Carling Avenue, Ottawa, Ontario  K1A 0Z4