[broadbandbug]

Originally Posted by popper

this lack of tested upstream bonding "silver" or "Full" D3 seems to be true at the moment, however 2009/2010 seems far to long a commercial availablility timescale given the new push to the new (Euro-)D3 spec worldwide.

while its not really a viable option as far as i can tell,(does anyone have experience of this kit?) they could go for a limited "Full" D3 Speced "Casa Systems" device or 3 in each headend as a limited trial/test on the "Full" D3 certified spec, if matched up with one of the "Full" D3 CPE (probably Ambit on past experience)due out in full production in around 3 months i think....

also,there are several more "waves" to come this year, so there is also a potential to get a silver or even a full 'Cisco or Motorola' card through and into commercial production this year....

http://www.lightreading.com/document...53441&site=cdn
"CableLabs also awarded “full” qualification status for Cable Modem Termination Systems (CMTS) to Casa Systems for two devices. This is the first qualification of a DOCSIS 3.0 CMTS representing “full” or complete compliance with all requirements of the DOCSIS 3.0 specification for headends. Motorola received bronze qualification for its CMTS."

---------- Post added at 19:50 ---------- Previous post was at 19:16 ----------



i was under the impression the No.s your quoting are the average US non Euro D1.0 No.s

and the majority of kit in VM network was infact Euro D1.1 kit ? and so has both more freq and speed to play with on average....

and thats not even allowing for the far improved speeds/freq per single channel of the new (Euro-)Docsis2.0B spec that the (Euro-)D3 will be using as its base....

also , i cant find the link i put up on the other thread that showed the recommended "(US)industry best practice" slides, was to in effect re-seg/shuffle the available total currently used freqs around, so as to allow far for scope in improved larger blocks of freqs to play with later,to get ready for the up and coming D3 rollouts worldwide....and other future options etc.

sure its on a company by company basis, but it seems only wise of VM with its massive UK market share, to have at least started , or at least got a plan ready for the recommended re-shuffle of the total used freq plans over the whole VM network.

and thats not even considering the turning off of the old analogue sometime in the future (2010/1012 was it?).

The majority (Two Thirds) of VM Network is US DoCSIS, only the Bromley Platform is EuroDoCSIS. For Upstream Bandwidth they are both the same with regards to channel width and capacity availability etc.

---------- Post added at 21:54 ---------- Previous post was at 21:50 ----------

Originally Posted by TraxData

Err...but they used upstream bonding when the trial first started.

They had 6mbit upload (1.5mbit per channel) at the start of the trials, it was only recently (well 5+ months) that they changed it down to 1.5mbit.

Propriatary non standard CMTS and Modems from Arris.. As you know they didn't win through the vendor selection (too expensive?).
Motorola and Cisco do not have an upstream channel bonding capability currently available.

---------- Post added at 21:56 ---------- Previous post was at 21:54 ----------

Originally Posted by foddy

That DOES sound a bit simple ... at what layer were you measuring this bandwidth? From 1:46, I'd assume you're just measuring IP packets (40/1500 would be 1.15:46).

But, you probably performed this test over ethernet. On top of your IP packet, you have an ethernet frame plus additional protocol overheads. This would normally add up to 38 bytes (ethernet addresses, packet length, checksum, guard space, etc.)

38 bytes on top of a 1500 byte data packet is 2.5% extra. 38 bytes on top of a 40 byte ack packet is 95% extra, almost double.

So, for ethernet your measured ratio would be 1.95:49.025, assuming everything above; that's close enough to 2:50.

Now, there are two BIG caveats, and one little one.

Firstly, the cable modem is NOT ethernet. I really don't know enough about it to know what sort of overheads there are, but you can be sure there's a source and destination address. The fact that the cable side has MAC addresses which look just like ethernet addresses would suggest that they could be comparable.

Secondly, I've no idea at which protocol level the bandwidth limit is at. If it's discarding the lower-layer protocols before calculating the speed, then 1.33Mbps would be sufficient (although NOT enough to you to make best use of the bandwidth).

If the bandwidth limit INCLUDES the additional overheads (whatever they may be) then it's unlikely that 1.33Mbps would be enough: even 12 bytes (two mac addresses) is enough to increase the bandwidth requirement to 1.77M.

Thirdly, delayed-ack could reduce the ack traffic by half. It will for some people ... but from your calculations above, not you.

Of course, this is all academic if you want to do anything except downloading large files. Most people will be want do to things like check for e-mails, send e-mails, read web pages, have Windows doing updates, NTP updates, weather updates, RSS feeds.

More upload would be beneficial, but then again it's more than you'd get with 20Mbps so it's a move forward.

Would any reduction in Upstream bandwidth requirements be gained from use of things like Ack Suppression?