[*] RE: Shaw QOS

[Sean Walberg]

On 9/23/07, Paul <root at nizon.ca> wrote:
>
> The surfboard 51xx series modems support QoS, so I believe it's simply
> enabled on the modem (you'll notice the modem reset when it's added) and
> does the same thing your $60 router would do if you enabled it's QoS
> features.
>

Is this a fact or a guess?  DOCSIS does have QoS capabilities.

QoS on the customer router only has the ability to prioritize outbound
packets.  The cable modem itself is still at the mercy of the other traffic
on the cable, that is, can it get a timeslice to send the frame to the head
end fast enough?  Similarily, return traffic has the same problem. Because
upstream traffic is also shared the CMTS has to schedule the delivery of the
prioritized packet before it normally might.  Upstream has also got a
different problem in that the traffic has to be classified in the carrier
network, without the benefit of the user tagging (assuming it was trusted in
the first place)

If, as you said, the cable modem is simply prioritizing traffic (presumably
marked with Diffserv EF for voice) then it's only doing it on the outbound,
and won't make a lick of difference on the inbound (people might hear you
ok, but the person calling you might sound choppy).  If it's actually using
the DOCSIS QoS features, then this is far more than what the router can do.

There are really two questions to ask the carrier:

1. When you say QoS, what treatment are you giving the packet, both on the
cable side and the carrier network, and in both directions?
2. How and where is traffic being classified?

Sean

-- 
Sean Walberg <sean at ertw.com>    http://ertw.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.muug.mb.ca/pipermail/asterisk/attachments/20070923/e2c00fe6/attachment.html