In reply to a post by gary333:

Here is my Virgin Media results for today.

https://www.thinkbroadband.com/broadband/monitoring/...

yours is so much better than mine, during periods of use and periods of non-use.

Jitter due to the shared nature of DOCSIS, combined with the performance issues of the CPE

Dreadful would be https://www.thinkbroadband.com/assets/guides/faq-bqm...

so even a connection that isn't get used (for example overnight), it would still be normal to have yellow spikes all over the place?

between midnight and 9am the house was "asleep"
https://www.thinkbroadband.com/broadband/monitoring/...

Edited by spgray (Fri 06-Nov-20 13:16:59)

In reply to a post by spgray:

so even a connection that isn't get used (for example overnight), it would still be normal to have yellow spikes all over the place?

Can be because the cable from your house goes to other homes before it goes to VM data centre. Different to the Openreach networks (ADSL, VDSL/FTTC and Openreach FTTP). If some other homes are maxing out their connection, this will impact people on the same coax cable segment.

Depending on where you are, whcih of the 28+ companies built your area, the number of homes per coax cable segment can be different. (Remember VM historically was many companies).

maxing out the connection at 4am in the morning? possible i suppose but unlikely.
they'd also need to be maxing it out every day 24/7 - again possible, but unlikely?

the street cab is 3 feet away from my house (6 feet away from the entry point to the house), the cable goes direct from the external wall of the house to the cabinet (it doesn't go to a T-Point on the pavement). it's also a small cabinet compared to the larger ones elsewhere in the area.

i am in area 28 (johnstone), however these houses are around 10 years old so the virgin infrastucture for this particular group of houses didn't exist until the houses were built.

whether the cable from the cab goes to other housse en-route to the headend, i don't know.
it's still a DOCSIS 3.0 network with upgrade to 3.1 happening soon apparently.

Jitter even when you are not using the connection is fairly normal for cable.

i.e. you won't see the pure green type graphs that DSL users post.

In reply to a post by spgray:

maxing out the connection at 4am in the morning? possible i suppose but unlikely. they'd also need to be maxing it out every day 24/7 - again possible, but unlikely?

Average that over say 100 to 250 homes passed in a segment, and the impacts of people on lockdown / furlough. Worse if you have a typical student house where computers may be set up to download 24x7.

the street cab is 3 feet away from my house (6 feet away from the entry point to the house), the cable goes direct from the external wall of the house to the cabinet (it doesn't go to a T-Point on the pavement). it's also a small cabinet compared to the larger ones elsewhere in the area.

Passive cabinet, similar to those outside mine. Links your cable to others, as if it was point to point to each home.

i am in area 28 (johnstone), however these houses are around 10 years old so the virgin infrastucture for this particular group of houses didn't exist until the houses were built.

whether the cable from the cab goes to other housse en-route to the headend, i don't know.
it's still a DOCSIS 3.0 network with upgrade to 3.1 happening soon apparently.

Same as the rest of the nation, you have no idea if you were coax connected to an existing section, or connected to new fibre going direct to the UBR / Head end.

Contrast with the traditional openreach network (until FTTP) which was point to point to the DSLAM, and then shared from the DSLAM. The openreach FTTP uses GPON which is shared between 32 homes.

If you forget the graph, how is the connection in use?

In reply to a post by spgray:

the street cab is 3 feet away from my house (6 feet away from the entry point to the house), the cable goes direct from the external wall of the house to the cabinet (it doesn't go to a T-Point on the pavement). it's also a small cabinet compared to the larger ones elsewhere in the area.

Being so close to the cabinet what are your power levels like? I lived next door to a cabinet in my last house and the power levels could be problematic especially on the upstream. This would lead to intermittent “freezing” of the connection and other gremlins. Virgin Media struggled to keep them in spec as even the lowest tap points in the cabinet were all setup to provide the right levels to houses that were all further away.

You mention there is no Tee (Toby). How does the cable get to the house as you’d still expect an underground shared duct? The area i live in (which I believe is the more common setup) has each house on its own cable. Some areas appear to be a kind of communal shared cable, i imagine in this instance that it would be more common for the connection to be flakier. Although, even on individual cables to the cabinet, the cabinet just acts as a big splitter and there is just a much higher quality coax cable that links it back to the node.

sorry for the late reply.
these are my line stats.

i know a T-point is how it's supposed to work, but if i look at the cable that comes out the wall, it goes in the direction of the cabinet, not in the direct of where the t-point is.

see linked image showing a drawing of what is there (C is cabinet, T points on the pavement at front of the houses on the street). cabinet and entry point are at side of the house and cabinet is a few feet away from the entry point.

https://i.ibb.co/fN9yr5C/Screenshot-2020-11-18-13533...

Downstream bonded channels
Channel Frequency (Hz) Power (dBmV) SNR (dB) Modulation Channel ID
1 323000000 4.9 37 256 qam 24
2 187000000 6.1 37 256 qam 7
3 195000000 5.8 37 256 qam 8
4 203000000 5.5 37 256 qam 9
5 211000000 5.6 37 256 qam 10
6 219000000 5.4 38 256 qam 11
7 227000000 4.8 37 256 qam 12
8 235000000 3.9 37 256 qam 13
9 243000000 3.7 38 256 qam 14
10 251000000 3.7 38 256 qam 15
11 259000000 3.5 37 256 qam 16
12 267000000 3.5 37 256 qam 17
13 275000000 3.9 37 256 qam 18
14 283000000 4.5 38 256 qam 19
15 291000000 4.5 37 256 qam 20
16 299000000 4.9 37 256 qam 21
17 307000000 4.6 38 256 qam 22
18 315000000 5.3 38 256 qam 23
19 443000000 3.7 37 256 qam 25
20 451000000 3.2 37 256 qam 26
21 459000000 2.7 37 256 qam 27
22 467000000 2.5 37 256 qam 28
23 475000000 3 37 256 qam 29
24 483000000 2.7 37 256 qam 30


Downstream bonded channels
Channel Locked Status RxMER (dB) Pre RS Errors Post RS Errors
1 Locked 37.6 179 1
2 Locked 37.6 91 0
3 Locked 37.6 471 0
4 Locked 37.6 146 0
5 Locked 37.6 130 0
6 Locked 38.9 409 0
7 Locked 37.6 115 0
8 Locked 37.6 283 0
9 Locked 38.6 259 0
10 Locked 38.6 206 0
11 Locked 37.6 184 0
12 Locked 37.6 232 0
13 Locked 37.6 266 0
14 Locked 38.6 115 0
15 Locked 37.6 202 0
16 Locked 37.6 176 0
17 Locked 38.6 185 0
18 Locked 38.6 124 0
19 Locked 37.6 124 0
20 Locked 37.6 203 0
21 Locked 37.6 197 0
22 Locked 37.6 434 0
23 Locked 37.6 172 0
24 Locked 37.6 213 0