120M : Can someone explain why cable suffers on upload?

[MaverickJesus]

Originally Posted by qasdfdsaq

To be fair he's not entirely far off. The implication is TV uses a large, and static amount of bandwidth on every cable, even for those many customers who don't have TV. By delivering only the TV channels that are being watched (essentially making all channels "on demand") a huge amount of capacity could be freed up.

Say 75 channels are in use for TV delivery, vs. somewhere around 16 for broadband, no single user is ever going to be watching 75 channels (plus radio) at the same time! So if the point was ever reached that all the current passive splitter cabinets ended up having mini-CMTS' put in them, with dedicated coax to each subscriber, then the vast majority of that coax's capacity would be going to waste delivering traffic that is literally being ignored when it could be used for faster broadband delivery.

Even if we never got close to one node per customer, a node with 50 subs on it are still unlikely to ever get close to consuming all 75 TV channels simultaneously, meaning most of the capacity is *still* going to waste when compared to, e.g. an efficient IP-multicast system.

Personally I'd like for VM to eradicate all broadcast TV channels and re-purpose the spectrum for broadband, because I don't watch TV and want faster internet. But even that wouldn't solve the issue of crippled upstream, since almost all the upstream is already being used for internet services anyway; in fact it'd even further skew the upload/download ratios on offer.

Yes, this is pretty much what I was getting at - I don't have a great working knowledge of how DOCSIS works apart from the high level aspects, so I wasn't sure if it was actually a feasible option to do an IP-multicast style delivery method or not.

[horseman]

Originally Posted by MaverickJesus

Yes, this is pretty much what I was getting at - I don't have a great working knowledge of how DOCSIS works apart from the high level aspects, so I wasn't sure if it was actually a feasible option to do an IP-multicast style delivery method or not.

I think what your both actually alluding to is SDV ?

Although I 'm still a tad confused about the "future part and the obscene additional bandwidth"?

Unfortunately as stated previously VM don't seem to have gone the MTA chipset route which must mean they don't feel an immediate (as in next 3-5yrs) need to free up any downstream TV frequencies using that method?

[qasdfdsaq]

VM also don't feel the "need" to upgrade some congested areas until users can barely get 0.1Mbps on their 10Mbps connections. Just because they don't feel an immediate need doesn't mean it shouldn't be investigated for the medium-distant future

[kwikbreaks]

There is no need to upgrade such areas. Doing so would be very very expensive I imagine so letting those fool enough to continue paying pay is clearly the way to higher profits which is all that matters. Apparently.

[telfordcable]

Downstream DS-1 DS-2 DS-3 DS-4 DS-5 DS-6 DS-7 DS-8
Frequency (Hz) 299000000 283000000 291000000 307000000 315000000 323000000 N/A N/A
Lock Status(QAM Lock/FEC Sync/MPEG Lock) Locked Locked Locked Locked Locked Locked Unlocked Unlocked
Channel ID 195 193 194 196 197 198 N/A N/A
Modulation 256QAM 256QAM 256QAM 256QAM 256QAM 256QAM Unknown Unknown
Symbol Rate (Msym/sec) 6.952000 6.952000 6.952000 6.952000 6.952000 6.952000 N/A N/A
Interleave Depth I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 I=12
J=17 N/A N/A
Power Level (dBmV) 0.27 0.97 0.48 0.42 0.36 0.36 N/A N/A
RxMER (dB) 34.17 34.78 34.08 34.84 34.36 37.94 N/A N/A



Upstream US-1 US-2 US-3 US-4
Channel Type 2.0 N/A N/A 2.0
Channel ID 33 N/A N/A 34
Frequency (Hz) 46200000 N/A N/A 39400000
Ranging Status Success Other Other Success
Modulation 64QAM N/A N/A 64QAM
Symbol Rate (Sym/sec) 1024000 N/A N/A 1024000
Mini-Slot Size 4 N/A N/A 4
Power Level (dBmV) 47.80 N/A N/A 47.50


General Configuration Network Access Allowed
Maximum Number of CPEs 1
Baseline Privacy Enabled
DOCSIS Mode EuroDOCSIS 3.0
Config File
Primary Downstream Service Flow SFID 21931
Max Traffic Rate 135000000 bps
Max Traffic Burst 10000 bytes
Min Traffic Rate 0 bps
Primary Upstream Service Flow SFID 21930
Max Traffic Rate 15000000 bps
Max Traffic Burst 16320 bytes
Min Traffic Rate 0 bps
Max Concatenated Burst 16320 bytes
Scheduling Type Best Effort


© 2010 Virgin Media. All rights reserved.




Been downtime all day for the last 4 days. It's now working but I notice massive change in downstream and upstream. Are these look ok?

[Kabaal]

Originally Posted by telfordcable

Upstream US-1 US-2 US-3 US-4
Modulation 64QAM N/A N/A 64QAM
Symbol Rate (Sym/sec) 1024000 N/A N/A 1024000

Primary Downstream Service Flow SFID 21931
Max Traffic Rate 135000000 bps

Primary Upstream Service Flow SFID 21930
Max Traffic Rate 15000000 bps

Been downtime all day for the last 4 days. It's now working but I notice massive change in downstream and upstream. Are these look ok?

Interesting, if you haven't tampered with that config then you have a different one than normal. 15mb upstream instead of 12, provisioned for 135mb instead of 133mb on download, 64QAM instead of 16QAM (although everyone is getting that at some point i think) and a Symbol Rate of 1024000 instead of 5120000 on the upstream.

[telfordcable]

128.67Mb download and 13.48Mb upload

[craigj2k12]

A TBB monitor would be interesting

[telfordcable]

I will upload later when I get home.

[Sephiroth]

Originally Posted by Kabaal

Interesting, if you haven't tampered with that config then you have a different one than normal. 15mb upstream instead of 12, provisioned for 135mb instead of 133mb on download, 64QAM instead of 16QAM (although everyone is getting that at some point i think) and a Symbol Rate of 1024000 instead of 5120000 on the upstream.

That answers a question I've put a couple of months ago: What will VM do with 64QAM upstream? Increase speed or ease congestion using the 50% extra bit density? It looks like one of each in equal measure if my maths is right.

[General Maximus]

oh please don't tell me you believe him

[telfordcable]

Originally Posted by craigj2k12

A TBB monitor would be interesting

There u go

[qasdfdsaq]

Originally Posted by General Maximus

oh please don't tell me you believe him

Hahahaha

[Kushan]

I wouldn't mind a screenshot of your operational config screen, Telford.

[qasdfdsaq]

Careful, he knows mspaint.