[c-nsp] cable/dsl/ftth policing, traffic shaping or something else??

[Jared Mauch]

On Tue, Jun 19, 2012 at 04:31:30PM -0500, Doug McIntyre wrote:
> On Tue, Jun 19, 2012 at 01:19:29PM -0400, Chris Evans wrote:
> > Question for you service provider folks.  How do cable modems, dsl, ftth,
> > etc limit bandwidth? I believe that everything is limited at the customer
> > edge demarq device, performing bandwidth limits on a central network device
> > would be too costly to do.
> > 
> > Do the CE devices use a form of traffic shaping, policing or some other
> > algorithm?? I believe it's just traffic shaping as I've looked at packet
> > captures and never see too many retrans taking place.
> 
> 
> First off, DOCIS (ie. Cable Modem) and all the others are totally
> different for the answer. 
> 
> DOCIS devices do mostly get the number of channels and speeds they can
> use from the profile they download from the CMTS. 
> 
> OOTH, DSL, and ethernet type solutions are bandwidth limited at the
> termination device in the field. It is NOT too costly to do it there,
> and is done all the time. DSL routers have zero control over what they
> get for bandwidth setups.

	Some CPE devices can do the rate-limit on the device.  I've
seen this in the Zhone active ethernet CPE hardware.

eg: http://www.zhone.com/products/znid/ae-indoor/

	- Jared

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Jared Mauch  | pgp key available via finger from jared at puck.nether.net
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