[Gllug] Bandwidth aggregation techniques

Dave Cridland [Home] dave at cridland.net
Sun Nov 17 22:04:36 UTC 2002


On 14 Nov 2002 00:02:09 +0000
Mike Brodbelt <mike at coruscant.demon.co.uk> wrote:

> On Wed, 2002-11-13 at 08:59, Mark Lowes wrote:
> > If you're after a 'virtual connection' which hides all the half-meg
> > pipes and allows you to burst to a single site at up to 5Mbps then
> > you're out of luck without something at the endpoint.  
> 
> Yes, that was the conclusion I'd come to.

But, oddly, not in reverse.

Let's say you had, from somewhere, a "network" ADSL, and from -
preferably the same ISP, at least - a normal "single user" ADSL. We'll
pretend the ISP has allocated 10.0.0.0/24.

You plug them both into one box, and setup equal cost multipath default
routes outbound through both ADSL lines. Now, in theory, your ISP would
block outgoing packets from your 10/24 addresses through the "single
user" ADSL. Except the chances are, actually, pretty small. I did notice
that Demon don't appear to block 10/8 addresses outbound at all, for
instance. (This may have changed since I last looked.)

Your local network now gets 512k (Well, ish) outbound, but still only
512k inbound, since there's effectively one inbound link running idle.

Now, of course, if you happen to have a machine somewhere on Real
Bandwidth (tm), then you can tunnel to it. Then you equal cost multipath
through the two tunnels to that box instead, each tunnel running through
its own ADSL line. Each ADSL line can then be through different
providers, even.

The "world" would see your network address being routed into your hosted
box. It's a solution I've actually helped put together before, although
I hasten to add it's a severe hack.

But this is essentially stretching into handling your own dynamic
routing, after all.

> > The big problem is that you're dealing with 10 connections with unique
> > IPs, and I doubt any ISP is going to setup dynamic routing for you
> > across ADSL, at least not without charging for the service :)
> 
> The ADSL wasn't really the issue - I just used it to illustrate the
> scenario. This was of purely academic interest at the moment. I do like
> the idea of getting fast data paths via bonding multiple interfaces
> though. Would be a great way of getting gigabit speeds with cheap
> hardware. A couple of quad port NIC's would do wonders :-).

Bonding ethernet is rather boring simple these days, I believe.

Just a matter of incanting "ifenslave" with the right arguments.

Dave.

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