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BiggA

join:2005-11-23
EARTH
reply to rradina

Re: Just curious

I don't think there is any way to reliably run an uncapped system. One user could use up all the bandwidth on it.

Fiber is expensive, and while telcos have to do it, or else fail (U-Verse), because copper pair wire has so little bandwidth left in it, cable operators don't, as they would be much wiser to push 8-channel bonding, new versions of DOCSIS, 1ghz plants, SDV, and all-digital before they need a new medium to deliver their service.

The constraints on DOCSIS are all in the RF plant. Backhaul is easy to add. They can, and will, add DOCSIS speed and capacity as competition makes it necessary (as it has with FIOS).

The takeaway is that Comcast is much more comfortable pushing more bandwidth, more channels of DOCSIS, and more fiber farther out into the last mile than they are competing with price, and they want to keep it that way.

rradina

join:2000-08-08
Chesterfield, MO
".. no reliable way to run an uncapped system. One user could use up all the bandwidth..."

That statement doesn't make sense to me. What do you mean by this? DOCSIS 2 is only capable of around ~40Mbps. The current crop of D3 modems are only capable of about 300Mbps but only if current chipsets maximum channels are exploited. Surely FTTN that serves 300 houses with a 50% penetration rate (150 customers) isn't going to be exhausted by one user even if everyone is configured with 100Mbps capability. 1) It's doubtful even a heavy user will be able to max out such a connection on one site because the other end is governed. They would have to use a multi-site download or some other kind of other file transfer mechanism that specializes in using multiple sockets to maximize throughput. 2) If the 150 customers are served by bonding different sets of some 20 channels, it's statistically unlikely that multiple exceptional customers such as this will collide.

cramer
Premium
join:2007-04-10
Raleigh, NC
kudos:9

... isn't going to be exhausted by one user even if everyone is configured with 100Mbps capability.

By definition, that's A CAP. Uncapped means zero obstruction to using the full bandwidth of the system. If it's capable of 40, you can use all 40. If it's capable of 300, you can use all 300.

If you don't think this is bad, or even possible, please stop by my office and I'll show you just how bad it can get thanks to ONE user! The *ONLY* thing that will put a limit in such a system is the speed of the remote side of the connection. (or connections) ISPs limit per user connection speeds and deploy queing methods to more evenly/fairly divide their finite bandwidth.

rradina

join:2000-08-08
Chesterfield, MO
You misunderstood what I meant by removing the throttle. We're also both probably using the wrong term for CAP since that's usually associated with a quantity of bytes over a period of time and not the speed at which they are transferred.

If one user can jeopardize the system, there are deep, deep issues that go beyond what we can discuss here.

BiggA

join:2005-11-23
EARTH
reply to cramer
Exactly. People used to uncap modems, and the cable companies cracked down on it, as if it became more widespread, it could have really screwed cable systems up... And yeah, one user could screw with a system if they were sucking the full bandwidth of all the channels.

rradina

join:2000-08-08
Chesterfield, MO
But that's in the past, isn't it? Isn't all that stuff now controlled by the CMTS? (i.e. PowerBoost?) If so, that means there's no excuse, other than poor management, for one user to lay waste to the "system" (whatever that means). At worst they can impact a node but if properly managed, the CMTS should be able to use pretty basic algorithms to balance what's available across all the node's active users. I say let them have it all...unless, as I've been postulating, the last mile is, for the moment, capable enough that if they did this, the problem would reveal itself upstream.

BiggA

join:2005-11-23
EARTH
Yes, Comcast does it farther upstream, but it's still a form of capping. It's necessary for a stable system.