Virgin Media - poor latency same period every evening

stormknight · 12-03-2010, 01:03

Hey there,

I spotted this thread which seems to be a similar issue to what I am experiencing and was hoping someone might be able to shed some light on the issue.

I've been with Virgin since they took over the Telewest service in the Birmingham area. Never had any real issues with the service in about 10 years. Until recently, I am experiencing higher than usual latency.

During the daytime, it's not so bad, however in the evening, latency goes up and up, to the point where online gaming is almost impossible.

I've been using a couple of tools for measuring latency and I get roughly the following latency from 8pm through to midnight.

18:00 - 60 ms
19:00 - 120 ms
20:00 - 200 ms
21:00 - 350 ms
21:30 - 550 ms
21:45 - 820 ms
22:00 - 300 ms
22:30 - 200 ms
23:00 - 150 ms
23:30 - 120 ms
00:00 - 100 ms

Here's the stats off my cable modem

Cable Modem Information
Cable Modem : DOCSIS 1.0/1.1/2.0 Compliant
Boot Code Version : 1.1.2c
Software Version : 2.111.1002
Hardware Version : 1.9

Cable Modem Downstream
Downstream Lock : Locked
Downstream Channel Id : 30
Downstream Frequency : 299000000 Hz
Downstream Modulation : QAM256
Downstream Symbol Rate : 6952 Ksym/sec
Downstream Interleave Depth : taps12Increment17
Downstream Receive Power Level : 4.9 dBmV
Downstream SNR : 38.3 dB

Cable Modem Upstream
Upstream Lock : Locked
Upstream Channel ID : 3
Upstream Frequency : 37500000 Hz
Upstream Modulation : QAM16
Upstream Symbol Rate : 2560 Ksym/sec
Upstream transmit Power Level : 37.0 dBmV
Upstream Mini-Slot Size : 2

Cable Modem Upstream Burst
Modulation Type QPSK QPSK QPSK 16QAM 16QAM
Differential Encoding Off Off Off Off Off
Preamble Length 36 232 232 128 128
Preamble Value Offset 244 6 6 504 504
FEC Error Correction (T) 0 5 5 4 9
FEC Codeword Information Bytes (k) 16 34 34 76 232
Scrambler Seed 338 338 338 338 338
Maximum Burst Size 0 0 0 7 0
Guard Time Size 22 48 48 22 22
Last Codeword Length Fixed Fixed Fixed Short Short
Scrambler on/off On On On On On

Cable Modem Operation Configuration
Network Access : Allowed
Maximum Downstream Data Rate : 20480000
Maximum Upstream Data Rate : 768000
Maximum Upstream Channel Burst : 3044
Maximum Number of CPEs : 1
Modem Capability : Concatenation Enabled, Fragametation Enabled, PHS Enabled

Does anyone have any clever ideas what could cause this?

Everything was fine up until a week ago, and now I get the same experience every evening. None of my equipment has changed, nor have any of my configuration.

Sephiroth · 12-03-2010, 01:17

usually when your modem stats are as exemplary as you've shown it's due to upstream congestion during peak time. There may be some clues in the event log like T3 timeouts.

Why would this happen? Could be anything from other users uploading heavily in your area; could be something VM did to shift customers around their server estate.

Best to report it to 2nd line support on the newsgroup.

stormknight · 12-03-2010, 02:27

Thanks for the rapid response and especially for pointing me in the direction of that newsgroup.

I just couldn't face the whole spectacle of phoning the support line and going through half an hour of answering basic questions on stuff I have already eliminated.