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tmc8080

join:2004-04-24
Brooklyn, NY
Reviews:
·ooma
·Optimum Online
·Verizon FiOS
reply to a333

Re: useless...

said by a333:

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.
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.


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

said by tmc8080:

said by a333:

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.
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.
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.