20% of Comcast Users To See DOCSIS 3.0 in 2008 → Re: useless...

DOSCIS 2 shares the 50 megs among like 50 users, so comcast cant use it to offer those speeds to each and every sub. Now, hopefully, with channel bonding and the rest of it, DOSCIS 3.0 should be able to make those speeds possible.

They are always behind, trailing behind what someone else is already doing or has already done. Talk now is people dont even care about DOSIS 3.0 They either want fiber to the home or Verizon Fios. All Comcast ever offers is stupid stuff that cost them nothing to put up. All smoke and mirrors. While in the mean time everyone else is gearing up for the already demand like HD, and much faster Internet Download as well as Upload speeds. Comcast is like Washington State Highways
By time they add a new lane we could use 2 lanes. My guess by all the heat about traffic shaping, fear from share holders, and the pounding from the FCC and everyone else and the fact they dont want to put any real money into what they have, they will sell out in time. Never seen them in it for the long haul anyways.

Actually the node shares a few hundred megabits (100-400 depending upon how many subscribers per node (24-50), which could be *split* to accommodate the greater speeds. It's the capability of the modems which can do in 40/30 megabit range:
»en.wikipedia.org/wiki/DOCSIS

1.x 38-42mbit / 9-10mbits
2.X 38-42mbit / 27-31mbits
3.X 152-171mbit / 108-123mbits

Again, this move means it will cost money to make money to earn back that market share lost to FIOS symmetrical, either way. Keep in mind, the most under-served areas of the comcast network have VERY HIGH node ratios (higher than 50 per node) which scale back the bandwidth all the way down to 1.X mbit per subscriber at $30-65 price ranges which is totally unacceptable in today's market. Might be competition to a QWEST region but nowhere else.

I agree with a333, Cable Companies and Telco's are laid out differently. Cable Companies work on a sharing Network, while Telco's Network starts at the Central Office. DOSCIS 3.0 or Fiber through a Cable Company will still have limitations. Like I said Verizon FiOS is the clear winner anyway you look at it.

Actually Comcast themselves say their average node size is over 450 homes passed and they certainly don't have several downstreams. You can have a vague guess by the different downstream frequencies seen on plant of the same origin but it's certainly not going to be the 10 needed to get close to 400Mbit to a single node.

Even then as the downstreams are not bonded on this gear the maximum available to a single modem is 38Mbit. This is not a limitation of the modem alone but also of the CMTS. The downstreams are discrete and modems contend for bandwidth on each channel not on the entire bandwidth. In at least some areas Comcast use the uBR 7246VXR so can't offer more than 2 downstreams to a node anyway.

50 per node is not a very high node ratio at all. There will be virtually no nodes at all which carry under 50 subscribers. Those nodes that do carry 50 subscribers are probably combined with others as there is no need at all to have nodes that small. a 50hp node is not a node it's FTTK.

DOCSIS 2 can't offer 50Mbit, you need to come to Europe with our 8MHz channels to see 50Mbit on EuroDOCSIS 2.

You do realize FiOS' BPON and/or GPON architecture is shared at the neighborhood node right, not at the Central Office.

ODNs are shared -- a BPON distribution hub (in the metal box at the end of your street) splits 622/155 Mbps among 32 users. In other words, if all 32 Fios users on a hub took 20/20 service and maxed out the upstream they would only be able to get 4.84 Mbps each.

Thats incorrect. Fios uses two data lightwaves upstream and downstream and both are up to 622mbps on BPON. Plus its using TDM so its not actually shared like cable.

FiOS uses TDMA on the upstream as well to solve the "multiple speaker" problem in the same way as cable. Based on my understanding of FiOS, each neighborhood distribution would share 1 port on the head-end. The downstream light path is split to 32 homes with the head-end being the only speaker so there's no chance of transmit collision. Each of the 32 homes off the distribution node sees the same downstream data feed just like cable. On the upstream each home is fed into an optical combiner to go back to a common upstream node port. The reason you are limited to 155mbps upstream is because of the TDMA timing overhead to ensure that upstream data transmissions are handled in a controlled fashion and 2 ONTs don't transmit at the same time.

The biggest difference is network scaling; Verizon needs one head-end port per 32 homes, whereas Comcast can go as wide as 1 head-end port per 1000 homes in some cases.

Technicallity , they are shared at the block muxer. Meaning they are shared at the 32 sub block , where its muxed onto the main fiber ring. But in all real world speak they have less people packed on a "node".

But did you know that Verizon can also add amplitude modulation on top of the time division ?just by updating the "headend" what it does is functionally make up to 4 muxes able to send on the same light wave at different timing intervals after a handshake , pretty neat stuff I say.

Then tell me how cablevision is offering 38/5 with docsis 2.

Exactly my assessment of Comcast since I started with them 3½ years ago after previously having Cablevision/Optimum Online/iO. They should be the industry pacesetters and trendsetters with all the money and resources at their disposal. Instead, they're usually a few steps behind the competition. In addition, they tend to be more expensive.