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Re: Connection Link Aggregation

On Tue, 17 Apr 2012 14:34:37 -0400
Al Zick <> wrote:

> Hi,
> We have very poor connectivity in our office. We have a satellite  
> connection, but it is usually either very slow or simply does not
> work at all. DSL, ISDN, T1, and cable are not available and even cell  
> phones don't work very well here. We are willing to invest in more  
> phone lines and modems. I was wondering if the following setup is  
> doable. I want to connect 4 to 8 modems to a machine running NetBSD  
> and then bind them and set the machine as a gateway/router for the  
> rest of our network. Can I bond them in such a way to achieve  
> transfer rates of 224k or higher? Also, will this effect latency? I  
> would really like less latency than what satellite offers.
> Thanks,
> Al

With pf you can do round-robin routing on multiple WAN interfaces. You
won't get transfer rates equalling the aggregate of all your lines but
you will not have one line (FTP download, for example) tying up your
bandwidth. So if you have two 56k lines and round-robin routing sends
your FTP download out over the first channel then you will still have a
56k line free for other work.

I have this working successfully on a firewall running OpenBSD (set up before I 
knew much about NetBSD) - check their address pools and
load-balancing FAQ to get an idea of what's happening. Then come back to
NetBSD and man pf.conf(5).

Note that https connections don't like this so you would need to set up
your PF so that traffic to port 443 is routed to a single WAN gateway.
As far as I remember FTP is another protocol that doesn't play well with 
round-robin routing. Again, just pick your best line and route FTP
client requests out through that line. Once your normal mail and web
traffic sees this first line saturated it will be automatically routed
by PF to the second WAN interface.

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