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funchords
Hello
Premium,MVM
join:2001-03-11
Yarmouth Port, MA
kudos:6

1 edit

Don't Judge Comcast Too Harshly...

...as its vendor (Cisco, presumably) is not putting out DOCSIS3 equipment qualified at the bonded upload speeds, yet.

said by »www.lightreading.com/document.as···site=cdn :
To help expedite Docsis 3.0 deployments, CableLabs introduced a tiered test program for cable modem termination system (CMTS) equipment. The "Bronze" level introduces downstream channel bonding and IPv6, while "Silver" adds in upstream channel bonding. Modems submitted for Docsis 3.0 testing must support the entire specification.

In the first official Docsis 3.0 test wave at CableLabs, which is presently underway, only one CMTS supplier -- Casa Systems Inc. , a start-up based in Andover, Mass. -- submitted a product for "Full" CMTS testing. Arris Group Inc. and Cisco put their respective CMTS products in for Bronze testing.
It should be noted that the 100 Mbps mentioned is a shared 100 Mbps, similar to the 38 Mbps shared we currently have (or more in Adelphia's old areas). A bump from 6 Mbps to 20 Mbps might happen. One from 6 Mbps to 50 Mbps will not. Again, that's Cablelabs, not Comcast.

The Light Reading article also makes mention of the fact that Comcast intends to make use of the DOCSIS 3 abilities to tie the Internet and Television experiences together at the set-top box.

I am worried that Cablelabs is forgetting that downloading creates an upload path of ACKs/NAKs and etc.. I also don't know how much of CATV's own -- if any -- Video-on-Demand freight will be carried over the IP networks. This could make an upstream pipe full of tiny overhead TCP packets. That could mean trouble for gamers and VoIP.

Comcast has been pretty good about staging roll-outs and testing. The last two upgrades landed here without a problem. But if I were them, I would be careful about announcing anything until they've actually run it in a major market and have seen the results.
--
Robb Topolski -= funchords.com =- Hillsboro, Oregon USA
Are you affected by Comcast's RST forging? How to test it! -or- Read my original report.


Ignite
Premium,VIP
join:2004-03-18
UK
Reviews:
·PlusNet

3 edits
said by funchords:

I also don't know how much of CATV's own -- if any -- Video-on-Demand freight will be carried over the IP networks. This could make an upstream pipe full of tiny overhead TCP packets. That could mean trouble for gamers and VoIP.
No widespread or otherwise implementation of IPTV VoD that I'm aware of uses TCP for its' streams. Some of the setup of the streams such as ordering would be TCP however the stream itself is UDP.

I am interested in where you get that you shared more than 38Mbps in former Adelphia areas though. The vanilla DOCSIS used only supplies a maximum of 38Mbps per channel and while you can send multiple channels down a segment, meaning that each is shared between less people, it's still 38Mbps that they are sharing.

If there was something proprietary going on there or even seeing the light and using EuroDOCSIS then that'd be interesting indeed.


funchords
Hello
Premium,MVM
join:2001-03-11
Yarmouth Port, MA
kudos:6
said by Ignite:

No widespread or otherwise implementation of IPTV VoD that I'm aware of uses TCP for its' streams. Some of the setup of the streams such as ordering would be TCP however the stream itself is UDP.
Good to know. Is there generally an ACK/NAK mechanism that would generate small packets?

I am interested in where you get that you shared more than 38Mbps in former Adelphia areas though. The vanilla DOCSIS used only supplies a maximum of 38Mbps per channel and while you can send multiple channels down a segment, meaning that each is shared between less people, it's still 38Mbps that they are sharing.
Bad assumption on my part. Adelphia was DOCSIS 2 while the rest of Comcast is 1.1. I assumed that DOCSIS 2 would mean more pooled bandwidth, but I guess it just means "more pools."

Thanks for picking that up.
--
Robb Topolski -= funchords.com =- Hillsboro, Oregon USA
Are you affected by Comcast's RST forging? How to test it! -or- Read my original report.


Ignite
Premium,VIP
join:2004-03-18
UK
Reviews:
·PlusNet
said by funchords:

Good to know. Is there generally an ACK/NAK mechanism that would generate small packets?
The major source of small packets is online gaming!

Bad assumption on my part. Adelphia was DOCSIS 2 while the rest of Comcast is 1.1. I assumed that DOCSIS 2 would mean more pooled bandwidth, but I guess it just means "more pools."

Thanks for picking that up.
No worries. DOCSIS 2 doesn't mean anything for downstream bandwidth at all, dual or more downstreams can be done with DOCSIS 1.0 / 1.1 just as well, 2 is purely upstream enhancements.