Re: [LARTC] Spill over

From: Taylor Grant <gtaylor@riverviewtech.net>
To: lartc@vger.kernel.org
Subject: Re: [LARTC] Spill over
Date: Sat, 23 Apr 2005 22:11:23 +0000	[thread overview]
Message-ID: <426AC80B.6000009@riverviewtech.net> (raw)
In-Reply-To: <fad9d484050423143460593cb9@mail.gmail.com>

> List
> 
> I need some help, advice or just a starting point on the following 
> situation:
> 
> Link A - 64kbps leased line
> Link B - 512kbps ADSL line
> 
> Is it possible to have Link A saturated constantly and have the excess 
> traffic "spill over" onto Link B? I know it's possible to have packets 
> sent down links in a round-robin fashion and I've read in the howto on 
> load sharing over multiple interfaces 
> (http://lartc.org/howto/lartc.loadshare.html), but I do not have control 
> over the termination of the link at the ISP's (two different one as 
> well). Also note that splitting different protocols over each of these 
> links are not possible in our case.
> 
> Reason being, Link A is a more reliable and more expensive link, so I 
> need to over-use it's capacity if it we're, and use the cheaper ADSL 
> (link B) offering to keep al services running when the leased line (A) 
> is saturated.
> 
> Any tips, suggestions and comments would be welcomed.
> 
> Regards

Off hand the thing that comes to mind would be to use an IPTables rule to estimate the rate of flow (I'm not sure what match this is (limit?) but I do think there is one.) and reset the route or mark traffic and have the routing table reroute traffic that is marked.  Keep in mind that this will only roughly saturate your 64 kbps link on your outbound traffic.  It will do nothing to control the % utilization on the traffic that comes back in to you.

Can I ask why you are wanting to saturate tech 64 kbps leased line?  Are you trying to encourage management that you need a faster leased line by going to them with graphs stating that the ADSL they purchased did not really solve the problem like they were wanting it to?  ;)

Another not so nice trick that you could do is just send bogus traffic, via packet gen, out the 64k at a lower priority than the rest of your legitimate traffic thus insurring that the 64 kbps line is full all the time even if you don't have that much legitimate traffic on it.  Yes I should probably be thumped or at least pelted with Nerf Darts for this idea, but it is an answer if you are just trying to saturate the 64 kbps line.  (Time to run and hide as I hear the Nerf guns being pumped up!)

Grant. . . .
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