Which is the virgin street cabinet? - Page 2

Sephiroth · 26-05-2011, 08:24

Quote:

Originally Posted by kwikbreaks

Would I be right in guessing that this is the situation which takes ages to get fixed? I'm guessing the way out would be to add another optical node or at least an additional fibre back to the CMTS.
SEPH: It depends where the contention lies. If it's at the line card, then resegmentation makes sense, failing which an additional or more powerful line card. If the contention is at the optical node, maybe an additional fibre. But usually the contention is due to the swamping of channel capacity due to oversubscription and thus peak time demand. Also the number of upstream channels is crucial to the avoidance of contention for gaming. The optical circuit itself, IMO, is unlikely to be the weakness. Only the number of channels it carries.
---------- Post added at 07:49 ---------- Previous post was at 07:46 ----------

well just look at that - a website dedicated to cab spotters

SEPH: Ha ha. I mapped the whole of Winnersh last year and that enabled me to work out the number of homes passed per cabinet and optical node. I did it first on Google Street View and then walked the streets for confirmation. The odd cabinet door was open as a photo opportunity but sadly no optical nodes had their doors open.

kwikbreaks · 26-05-2011, 09:11

Quote:

Originally Posted by Sephiroth

The odd cabinet door was open as a photo opportunity but sadly no optical nodes had their doors open.

Bit of street cab soft porn I hunted down for you then...
http://www.broadband-finder.co.uk/bl...et-cabinet.jpg

http://skuds.org/wordpress/wp-conten...ox-254x300.jpg

===

I had to turn off safe search to find this one...

http://www.nbr.co.nz/files/0cabinet.jpg

Sephiroth · 26-05-2011, 09:25

Thanks kwiky. They're not optical nodes though. I think I've got a photy of at least one on the home machine that I'll post together with my nerdy map of Winnersh and it's street cabinets.

kwikbreaks · 26-05-2011, 09:29

Most of the pictures on google seem to be just the equipment rather than open cabinets so maybe that VM gaffer tape holding so many shut is stronger than I thought

This looks like it's probably an optical node as it's right next to a standard looking cab. Terrible picture unfortunately - long lens paparazzi no doubt... http://news.bbcimg.co.uk/media/image...3_rutland2.jpg

TJS · 26-05-2011, 10:03

How do the ones that don't have an optical node in work? do they just link up to one that does?

Sephiroth · 26-05-2011, 10:34

They combine and amplify the individual circuits (taps) in the big Magnavox box which then combines with the incoming coax from the street box further up and produce a single amplified coax to the next street box, and so on until it reaches the optical node where it's all remodulated to fibre optics.

Something like that. In other words, your supposition is correct. There is a clue on kwik's phot if you study it.

zekeisaszekedoes · 26-05-2011, 16:41

This turned into an interesting thread. Geeky, but good. Wish I'd gone and had a poke around when the tech adjusted the levels yesterday, maybe snapped a pic to see how many houses the cabinet covers.

qasdfdsaq · 27-05-2011, 14:42

Threads like these are why I still visit CF (occasionally)

7031 · 27-05-2011, 15:15

Quote:

Originally Posted by qasdfdsaq

Threads like these are why I still visit CF (occasionally)

Seconded. I find it pretty interesting actually.

TJS · 27-05-2011, 16:29

Does anyone know what sort of the speed the fiberoptic nodes connect to the street cabs at?

---------- Post added at 16:29 ---------- Previous post was at 16:29 ----------

Also is it the fiberoptic node thats limiting areas from being upgraded to the 100 mb package sooner; or do they need to upgrade the CMTS things?

7031 · 27-05-2011, 17:32

Quote:

Originally Posted by TJS

Does anyone know what sort of the speed the fiberoptic nodes connect to the street cabs at?

---------- Post added at 16:29 ---------- Previous post was at 16:29 ----------

Also is it the fiberoptic node thats limiting areas from being upgraded to the 100 mb package sooner; or do they need to upgrade the CMTS things?

Not sure. I saw an engineer working on the cabinet the same day that 100Mbit became available in my area, and I'm pretty sure it's not a fibre node, but it could have been a separate thing.

TJS · 27-05-2011, 18:46

Hmm; Looking at the 100 mb roll out schedule then comparing to the CMTS sttus website; it seems that the areas that are being upgraded for 100 mb first seem to have only about 3 - 4 CMTS' when the larger areas like stoke on trent e.t.c with upwards of 15 CMTS' Only show 'being planned' it seems strange to upgrade smaller areas first :s

http://shop.virginmedia.com/content/...t_16_03_11.pdf

http://ukinternetreport.co.uk/cmts/

Sephiroth · 27-05-2011, 19:23

Quote:

Originally Posted by TJS

Does anyone know what sort of the speed the fiberoptic nodes connect to the street cabs at?

---------- Post added at 16:29 ---------- Previous post was at 16:29 ----------

Also is it the fiberoptic node thats limiting areas from being upgraded to the 100 mb package sooner; or do they need to upgrade the CMTS things?

The speed of light! The downstream is pumped out for your modem at the configured rate and likewise from your modem for the upstream.

Have a read of this.

The fibre capacity question is not intuitive. The article I've pointed to might help you understand. It's all about Msyms/second, QAM modulation (bit density) and how many channels are shared between how many users. A single channel at 256QAM (8 bits/symbol) at 6.952 MegaSysms/sec allows 55 Mbits per channel (you see that on the modem stats). There are 4 bonded channels on each of which you get your slice. If you were working at 50 meg, you'd get 13.9 meg/channel and if more than 4 users are fully stretching their link, anyone else coming onto that channel will face congestions (as then will the others). So it's the maths of DOCSIS that governs what happens, not the speed of light.

Does that help?

Tazz · 27-05-2011, 20:28

Quote:

Originally Posted by Sephiroth

The data centres aren't advertised for security reasons. The one in Reading is absolutely non-descript. It'll be as place on an industrial estate (of sorts) with VM vans parked on the hard standing. VM phones have nothing to do with BT phones. Totally separate.

If your village is a long way from anywhere else (like more than half a mile), I'd say that the box you pictured was an optical node. It looks large enough given that it serves only 40 homes.

Ooo near a certain wholesale supplier by any chance?

7031 · 27-05-2011, 22:18

Quote:

Originally Posted by Sephiroth

The speed of light! The downstream is pumped out for your modem at the configured rate and likewise from your modem for the upstream.

Have a read of this.

Thanks for that. Very informative read.