lots of packet loss

llamatronic · 07-09-2008, 19:08

Hello folks,

I've been getting lots of packetloss off and on over the past week or two. I finally gave up and called the support number, who arranged to send out an engineer.

Two questions I guess - I'm in twickenham - is this a known problem in the area at the moment? I didn't see anything on the support site. Second question; the engineer who's coming. Will the engineer be a network person who understands the words "packet loss," or will he be someone who looks at the three lights on the front of the modem, and declares everything to be fine? I'm worried because from time to time it IS fine, but most of the time it's a mess. If it's fine when he arrives, is that it?

(I'm actually not entirely confident this post will make it, but might as well have a try...)

Ah, I'm including a traceroute to this site as an example of how bad things are from time to time. (It's below - I was going to attach a file, but that doesn't seem to work.)

cheers,
lt

C:\Documents and Settings\user>tracert www.cableforum.co.uk

Tracing route to www.cableforum.co.uk [87.106.129.133]
over a maximum of 30 hops:

1 1 ms 353 ms 348 ms 192.168.1.1
2 * * * Request timed out.
3 369 ms * 11 ms osr01mort-v15.network.virginmedia.net [62.30.242.129]
4 4294966961 ms 361 ms 359 ms osr02croy-tenge73.network.virginmedia.net [62.30.242.57]
5 4294966960 ms * * pop-bb-b-ge-210-0.network.virginmedia.net [195.182.178.86]
6 * 357 ms 362 ms pop-bb-a-ae0-0.network.virginmedia.net [213.105.174.229]
7 363 ms 14 ms * bre-bb-b-so-320-0.network.virginmedia.net [62.255.81.238]
8 37 ms * * telc-ic-1-as0-0.network.virginmedia.net [62.253.185.74]
9 18 ms * 359 ms te1-3.ccr01.lon04.atlas.cogentco.com [130.117.15.69]
10 372 ms 359 ms 359 ms te4-3.mpd01.lon01.atlas.cogentco.com [130.117.3.189]
11 38 ms 14 ms 15 ms te2-1.3493.mpd02.lon01.atlas.cogentco.com [130.117.2.18]
12 14 ms 362 ms 360 ms te4-2.mpd01.lon02.atlas.cogentco.com [130.117.1.18]
13 361 ms * * schlund_and_partner.demarc.cogentco.com [130.117.240.170]
14 * 359 ms * ge-2-1.bb-c.the.lon.gb.oneandone.net [212.227.120.25]
15 375 ms 385 ms * te-1-3.bb-c.bap.rhr.de.oneandone.net [212.227.120.49]
16 54 ms 69 ms 49 ms ae-8.gw-distp-b.bad.oneandone.net [212.227.121.221]
17 * * 379 ms ae-1.gw-prtr-r211-b.bad.oneandone.net [195.20.247.45]
18 * * * Request timed out.
19 380 ms * 57 ms server3.cableforum.co.uk [87.106.129.133]

Trace complete.

C:\Documents and Settings\user>

Axegrinder · 07-09-2008, 19:14

Could you post your modem power levels

http://192.168.100.1/

Username and password both "root" without quotes.

Do not post your MAC address or serial number.

llamatronic · 07-09-2008, 19:34

Quote:

Originally Posted by Axegrinder

Could you post your modem power levels

http://192.168.100.1/

Username and password both "root" without quotes.

Do not post your MAC address or serial number.

Hey, thanks for the reply. Shoot, I was going say all I was getting an error from FireFox when trying that URL, but it occurred to me to try IE, and now have actual results. Am I right in thinking that my upstream power is a bit low?

Name
WebSTAR EPC2100r2
Hardware Version
2.0
Software Version
v1.0.2r1244-050225h
Receive Power Level
10.2 dBmV
Transmit Power Level
24.0 dBmV
Cable Modem Status
Operational

Downstream Status
Operational
Channel ID
1
Downstream Frequency
339000000 Hz
Modulation
256QAM
Bit Rate
20480000 bits/sec
Power Level
10.4 dBmV
Signal to Noise Ratio
39.4 dB

Upstream Status
Operational
Channel ID
2
Upstream Frequency
22200000 Hz
Modulation
16QAM
Bit Rate
768000 bits/sec
Power Level
24.0 dBmV

Axegrinder · 07-09-2008, 19:48

Your upstream power is quite low and your downstream power is fairly high, but guessing by the modem your Ex telewest. Ideally you want your upsream highger that 30db (i think anyway..), and your D/S power to be near to 0 as possible.

HTH

llamatronic · 07-09-2008, 22:29

Thanks for that Axegrinder - much appreciated.

Incidentally, my modem had no username and password at all - it let me straight in. Not exactly impressive security...

07-09-2008, 22:38

Quote:

Originally Posted by llamatronic

Thanks for that Axegrinder - much appreciated.

Incidentally, my modem had no username and password at all - it let me straight in. Not exactly impressive security...

The username and password used to be primarily for NTL modems not Telewest modems and was just an anamoly on their modems as the is no requirement for security on a modem.

Your Downstream is well within normal operational parameters for a Telewest connection but your Upstream is way to low and you need to call Tech Support, as the may be a fault on the UBR you are connected to.

I can see that you are on a 20meg connection as well.

LaineY · 09-09-2008, 13:59

yeah its defo a power level issue..

ur street box needs adjusted

09-09-2008, 19:42

I suspect a possible SNR issue on the UBR to be honest.

Ignitionnet · 09-09-2008, 22:00

You've read the threads on Digital Spy / Newsgroups from people in this post code which were responded to by VM support as SNR issues then

Just FYI low upstream transmit power isn't usually indicative of upstream noise, modems usually increase their Tx power in response to noise as periodic station maintenance messages are dropped.

Actually I wonder if there's a malfunctioning or badly lined up amp cascade that's overcooking the return path. That'd both cause noise and poor SNR, over-amplification = distortion and laser clipping = bad SNR.

*Ponders*

Sorry OP. There's an area fault in bits of TW1, ETA for fix is apparently 15th...

09-09-2008, 22:07

Quote:

Originally Posted by Broadbandings

You've read the threads on Digital Spy / Newsgroups from people in this post code which were responded to by VM support as SNR issues then

Just FYI low upstream transmit power isn't usually indicative of upstream noise, modems usually increase their Tx power in response to noise as periodic station maintenance messages are dropped.

Actually I wonder if there's a malfunctioning or badly lined up amp cascade that's overcooking the return path. That'd both cause noise and poor SNR, over-amplification = distortion and laser clipping = bad SNR.

*Ponders*

Sorry OP. There's an area fault in bits of TW1, ETA for fix is apparently 15th...

What is the issue then.

Ignitionnet · 09-09-2008, 22:17

Hmm they don't seem to know. Noise was mentioned, as were low Rx levels at uBR neither of which fit together unless there's an amp/laser problem. Take your pick really, won't know until it's fixed I suspect.

You know how apparent 'noise' issues are troubleshot on the HFC right?

09-09-2008, 22:20

Quote:

Originally Posted by Broadbandings

Hmm they don't seem to know. Noise was mentioned, as were low Rx levels at uBR neither of which fit together unless there's an amp/laser problem. Take your pick really, won't know until it's fixed I suspect.

You know how apparent 'noise' issues are troubleshot on the HFC right?

I said SNR on the uBR because it seemed to fit the symptoms from previous calls, but without sitting in front of a screen with the OP's details I am unable to be certain.

Ignitionnet · 09-09-2008, 22:25

Understand. In any case 24dBmV is not acceptable transmit power for 16QAM and it's likely that signals from the cable modem are getting torn to bits before they get near the lasers if the modem thinks that that's a reasonable transmit power.

EDIT: Ah yeah to answer you, yep it would show up on the uBR as bad SNR. I wasn't disagreeing with you there I think you're spot on, I was just contemplating why the SNR was bad as it didn't look like the 'usual' suspects.