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Originally Posted by qasdfdsaq
You've both gone off on a tangent and completely missed the point it seems.
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Have we? Everything was pretty clear until you came along and started nitpicking.
Quote:
Originally Posted by qasdfdsaq
Yes, 8 channels is double the capacity of 4 channels. But no single user can even fill 3 channels let alone 4, plus simply because one person has a 4 channel modem does not reduce the entire network down to a 4 channel bottleneck. The maximum any user can use right now is about 2.5 channels anyway. 2.5 out of 4 is exactly the same as 2.5 out of 8 - it's still 2.5.
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I've highlighted the bit that's most obviously wrong here, from a simple maths point of view.
2.5 out of 4 leaves 1.5
2.5 out of 8 leaves 5.5
Not "exactly the same" at all. IF two Ambit users have 120mbit and happen to be on the same 4 channels, then it's impossible for them both to achieve 120Mbit down at the same time (2.5 + 2.5 = 5). This is a scenario with just 2 users, obviously there's a lot more users on the local network than that. Can the CMTS switch one of those two users "on-the-fly"? Can it do that as soon as channels 1 and 2 become maxed out? (or rather, once channels 1-4 go above 50% capacity).
Quote:
Originally Posted by qasdfdsaq
Taking your scenario, while hypothetically several Ambit users are demanding full speed from their 120Mbit services simultaneously via the same 4 channels of an 8 channel set, while presumably the other 4 channels remain empty, then that just means the CMTS' load balancing setup is broken. Getting a million channel modem won't unbreak it.
---------- Post added at 15:02 ---------- Previous post was at 14:57 ----------
What exactly do you see as the problem here?
Say the network has 8 channels.
You're on channels 1-4. Someone else is on channels 1-4. Channels 1-4 get heavily loaded.
You get load balanced onto channels 5-8. Problem solved.
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Right, someone who's a bit more qualified than me will have to come along and answer this, but how dynamic IS that load balancing on the CMTS?
What I mean is, how quickly can the CMTS tell the modem that it needs to jump channels? I thought it was only during the initial sync that the modem does, i.e. roughly every reboot (and presumably there's a kind of resync that happens occasionally - again, I need to stress that I'm not an expert here at all and I would like someone to clarify). So yes, the CMTS load balances but can it load balance usage down to the minute, such as when one user starts downloading a large file versus overall usage in the area?
There's another scenario as well. Assume the CMTS is load balancing effectively, but the area has heavy use. If load balancing is working as it should, it's reasonable to assume that all available channels have roughly the same amount of utilisation. Say all channels are regularly on 75% utilisation - quite high but quite a lot of capacity to spare. You've got 4 channels, what does that leave you with? On 4 channels, that leaves you with approximately 2 channels worth of bandwidth - not enough for your 120Mbit. However, if you have 8 channels? You've got effectively 4 channels worth of bandwidth, so still plenty to go around.