[j-nsp] cable modem/dsl/ftth bandwidth limiting

[Chris Kawchuk]

Downstream is Shaped, Definitely. 

The BRAS/CMTS/etc sets up Individual Hardware Queues for each traffic class per subscriber. (Hence why those boxes have 16,000-64,000 HW queues per blade, as each sub may use 2-8 queues depending on what you sell =)..)

Generally 4 prioritized queues (NC, VoIP, Video, Best-Effort), where upper queue can generally starve the lower queue, and Tail-drop the BE queue when the buffer gets full.

>  For upstream the local customer device would limit.

Bingo. Usually limited by the actual physical upstream bandwidth given/negotiated/trained to the CPE device (xDSL upstream link, CMTS-back channel, GPON upstream timeslice/frequency etc.). Again, if multi-service, the CPE needs to be aware of the traffic classes as well. In Germany, the Telco provides the CPE and use different VLAN Tags to prioritize the traffic in each direction (Internet on 100, Voice on 200, Video on 300, etc.). Bit of a pain if you want to supply your own 'home gateway' in that neck of the woods, as their device does it all for you. (incl outbound NAT, etc..)

Hope that all makes sense!

- CK.

On 2012-06-20, at 6:58 AM, Chris Evans wrote:

> Still,  can someone answer if it's shaping or policing?