My UBR and Ping Graph

[garmcqui]

Hi all,

When I go to the my UBR site, I get:

http://img507.imageshack.us/img507/829/32498343.png

And the UKInternetreport site shows:

http://img43.imageshack.us/img43/1896/60744940.png

So what is my UBR? Acto 1? Acto 12? Which?

Also, the ping graph above shows no significant disturbance for the Acto UBR's last night, yet my thinkbroadband graph says significantly different:

Download Failed (1)

Any ideas why?

Thanks

[kwikbreaks]

I believe the congestion point is usually your local optical node and the UBR serves umpteen of them. If that isn't correct somebody will be along to say so....

[garmcqui]

I believe the congestion point is usually your local optical node and the UBR serves umpteen of them. If that isn't correct somebody will be along to say so....

So this street cabinet which is about 20 feet from my door, is this the local optical node?

http://img254.imageshack.us/img254/9800/photoicw.jpg

[kwikbreaks]

Most probably not. You get simple distribution cabinets like that feeding a street and several cabinets are linked together going back to the optical node which converts all the signals on the coax into signals on fibre which goes back to one of the ports on the UBR. (I think).

Oh and I'd assume you are on ACTO1 although the graph says ACTO01for some reason.

I'm on NRTE25 - my hostname is cpc5-nrte25-2-0-custnnn.n-n.cable.virginmedia.com

[Skie]

Interesting how the hostnames are different for some areas:

cpc11-live19-2-0-***.know.cable.virginmedia.com

[qasdfdsaq]

One of the two refers to the DHCP pool you're on. Can't remember which.

[Chrysalis]

when you ping the ubr externally the traffic goes over a fairly fat pipe which isnt congested, as far as I know no areas are congested at that point. However the congestion issue is your side of the ubr on a much thinner pipe.

[Sephiroth]

I posted this in answer to a similar question on the VM forum:

It works like this (but can vary in different parts of the country according to who was the original cable supplier):

1/
A small street cabinet connects either 16 or 32 customers. A larger street cabinet connects 48.

2/
The cable from a cabinet passes along to another cabinet configured as above.

3/
5 or 6 cabinets go to an optical node and it's fibre from there.

4/
In high density population areas, you might get 20 coax cabinet feeding the optical node.

5/
The optical node originally would have supported only 2 upstream channels and these might have been split between two nodes at the VM end line card. So that's a heck of a lot of users who think they're getting, say 5 meg upstream sharing just 40 meg upstream capacity.

6/
A bonding group currently has 4 downstream channels with c. 200 meg capacity to share across one or two optical nodes.

So that explains how overutilisation can occur.

The current infrastructure upgrade programme should double all the capacities I've mentioned. For high contention areas, VM should be adding more optical nodes and line cards and CMTS devices at their end to cope with the additional channels allocated. That's what they say they're doing.

So there you have it. The full explanation. I might get corrected on some piece of detail, but that's basically it.

I hope that helps you somewhat.

[qasdfdsaq]

1/
A small street cabinet connects either 16 or 32 customers. A larger street cabinet connects 48.
Or in Ex-TW areas they can connect hundreds!

[Sephiroth]

Got a picture of one, Qasi?

[Chrysalis]

I be surprised if its only 48 seph, my cabinet serves multiple streets which amount to probably 100s of seperate properties (including houses converted to flats).

[Sephiroth]

Yeah, Chrys. You're right. I've just looked at one of my photo collection and I can see capacity for 96 with possibility of expansion to 144. That's a double door cabinet.

[Chrysalis]

Yeah, Chrys. You're right. I've just looked at one of my photo collection and I can see capacity for 96 with possibility of expansion to 144. That's a double door cabinet.

interesting, can you share these pics :D

thanks for checking.

I assume with splitters that 144 can be multiplied.

[Sephiroth]

Splitters on tap points, can play havoc with attenuation or noise (if unterminated). But I've seen them in an open cabinet in a University town dahn saarf.

Anyway, here's a schematic I made from a photo of a large cabinet.

You'll note the 15 dB/18/22/29 tap points.

[qasdfdsaq]

Got a picture of one, Qasi?
Not the insides, no. But remember we have shared drops here, so they're not unusually big.

(Oddly, I just had a nap this afternoon and ended up dreaming of VM street cabs... >_<)

[General Maximus]

5/
The optical node originally would have supported only 2 upstream channels and these might have been split between two nodes at the VM end line card. So that's a heck of a lot of users who think they're getting, say 5 meg upstream sharing just 40 meg upstream capacity.

6/
A bonding group currently has 4 downstream channels with c. 200 meg capacity to share across one or two optical nodes

Great, so when they wang thousands (if not hundreds of thousands) of customers up to 100mbit to share a 400mbit line we are all royally screwed

[garmcqui]

Do VM utilise BT's optical network at all?

[Sephiroth]

Great, so when they wang thousands (if not hundreds of thousands) of customers up to 100mbit to share a 400mbit line we are all royally screwed
And Igni has posted many times on the subject in that vein. (BVut the numbers won't be as high as you suggest).

In my area its just under 500 homes passed per optical node. The uptake is prolly less than 30%. In urban areas, that's gonna be 2,000 per optical node (uptake will be higher) hence my suggestion in another post of up to 20 cabinets per optical node. Then it's down to VM to provide enough fibre and spread channels across the 20 cabinets so that contention is kept to a minimum.

[qasdfdsaq]

Great, so when they wang thousands (if not hundreds of thousands) of customers up to 100mbit to share a 400mbit line we are all royally screwed
Just wait till they wang up to 400mbit customers to share a 400mbit line.

---------- Post added at 11:47 ---------- Previous post was at 11:46 ----------

Do VM utilise BT's optical network at all?
No