William "Chops" Westfield wrote:

> On Feb 10, 2008, at 9:51 AM, Harold Hallikainen wrote:
> 
>> this router had two WAN connections and would load share between the two
> 
> How well this work depends rather a lot on how well the WAN behaves when
> routing packets BACK to you, and how well the cooperate on routing to
> you in general.  With typical consumer ISPs, I suspect the amount of
> cooperation is pretty close to zero.  Most ISPs go to great pain to
> PREVENT customer-premises routers from actually participating in
> "routing."  

I think you get the packet back on the same channel where you initiated the
request. That's just a given, I think. But you can (with some protocols,
like http) decide on which WAN channel you send the request. 

> I don't know  that routing has ever been sensitive to QoS variations
> between two networks, so picking an ISP per-service would probably need
> to be done manually.

>From what I understand, the current crop of consumer grade dual WAN routers
have a number of techniques to address this. For one, some protocols need
to stay on one WAN channel for a session (like https). So wherever a system
on the LAN got routed to when first starting an https connection to a
certain server, that's where all subsequent https requests from that system
to that server need to get routed -- at least within a certain session time
window. Other protocols can be set to be given higher priority (like VoIP
protocols); that's something like a poor man's QoS. Others again need to be
routed to a specific WAN port (often ISP provided SMTP access is restricted
to users on its own network, so that needs to go out on a specific WAN
port). 

I don't know what the methods are to determine QoS on a WAN connection.
Some seem to be using pings to a configurable server; that's of course a
very poor measure.

> The more I think about the problem, the more complicated it looks.

<g> That's why I'm a bit shy to bet on the do-it-myself Linux solution.
That probably would take up more of my time than I have to spend on this
for now.

Gerhard

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