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 telcolackeyThe Truth? You can't handle the truth
join:2007-04-06
Death Valley, CA | reply to funchords
Re: Sandvine's MSO Case Study-Reasonable Network Management? said by funchords:The market is demonstrating that the problem has a lot to do with HFC and, in particular, its upload constraint. Cablelabs is behind the competitive ball, and FIOS is taking Cable Internet customers as a result. Cable can't touch a 20/2 tier -- soon to be a 20/20 tier. DOCSIS actually does not have the upstream constraint people think. Most CMTS cards offer equal bandwidth (combined ports) for both upstream and downstream. On the flip side, residential historically is a downstream product and (normally) upsteam users are either running servers / commercial or have rare upstream burst needs (hence powerboost). (please no corner cases)
FIOS 20/20 is as much marketing as technology. It is the same thing cable did to DSL for so many years. FIOS cannot economically support a large number of customers running 20/20 7x24 via their ONT infrastructure.
Technically there are ways to increase capacity for the density of bandwidth requirements, but as you start bringing this level of capacity need upstream the economics start to fall appart.
said by funchords:It's a loss-leader product because they had to lay down new fiber throughout every neighborhood. CableTV companies laid new wire too, however they did that 20 years before. The little bit of work that they had to do to make it bi-directional and digital pales in comparison. Perhaps. But 20/20 will be a loss leader if people run this 7x24 no mater if it is FTTH or HFC. The regional and national costs to deliver continuous content at these speeds is not $50 / month... commercially it is more like $50 / meg (average costs for 50Mb small biz service). | | |
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 espaethDigital PlumberPremium,MVM
join:2001-04-21
Minneapolis, MN
kudos:2
 ·Clear Wireless
| said by telcolackey:said by funchords:The market is demonstrating that the problem has a lot to do with HFC and, in particular, its upload constraint. Cablelabs is behind the competitive ball, and FIOS is taking Cable Internet customers as a result. Cable can't touch a 20/2 tier -- soon to be a 20/20 tier. DOCSIS actually does not have the upstream constraint people think. Most CMTS cards offer equal bandwidth (combined ports) for both upstream and downstream. Actually, there are upstream constraints to both FiOS and DOCSIS cable systems. They both share the same "multiple speaker" problem; within a shared access segment only one device can be transmitting at any given time. The downstream is easy because the head-end has monopolistic control over the downstream channel with no competition for "air time"; it broadcasts out and every device on the segment listens for traffic destined to them. The return path requires more technical finesse to work out how to get every device to transmit in an orderly fashion so that transmissions don't get garbled and lost. It's like being on a conference call -- if multiple people talk at the same time all conversations are lost until it gets down to the point where just one person is talking. Multiplexing technologies like TDMA work well at solving this problem, but it requires additional overhead which steals your upstream efficiency. On current DOCSIS systems that's why you have a 38mbps downstream to 10mbps upstream (DOCSIS 1.x) or 30mbps upstream (DOCSIS 2.0).
FiOS has similar limits; their current deployed configuration is limited to 622mbps downstream and 155mbps upstream. The big difference is that while cable operators have 200-500 homes per HFC node, FiOS is only divided out so 32 homes share a head-end port. It'll be interesting to watch how things work out for Verizon with the 15/15 and 20/20 symmetrical rollouts, because even if you ignore bandwidth reservations for voice services 155mbps / 32 homes is still ~4.8mbps per home. There's also that problem of selling $150 - $200 of wholesale bandwidth for $50-70/mo. If people really start using their connections as people in these forums suggest, that's going to be a big problem.
Cable could match FiOS for service with DOCSIS 3.0, but it would require much smaller node segments than what they have now. | |
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