randomdude
25-02-2007, 21:53
OK, I'm confused here.
Back story is that I live in a 5-person student house. I'm in charge of the net access. A couple (or three) of the guys in the house torrent fairly heavily. We have a Telewest cable line, live somewhere around Leeds, and use a surfBoard cable modem. Haven't called tech support. Home network setup is a linux router but this was unplugged for most of the testing (see below text) and I was mainly using an XP laptop and another XP box for testing. No firewalls are in effect other than the Linux machine.
A few weeks ago we started having network congestion (2+ minutes to load a web page, etc). This has steadily been getting worse, and recently I hassled the torrenters and eventually removed them from the network, which eased the problem, but didn't get rid of it totally. I got annoyed tonight and unplugged the lot, jacked my Xp laptop into the cable modem and rebooted it. I get around 5% packet loss pinging bbc.co.uk (is this an acceptable level?), but I still take over 30 seconds to load, for example, my LJ friends page, although most sites are responsive. I tried a nearby other machine (also running XP) as well.
So I do a packet dump and find (a substantial amount of) 'TCP Retransmission' and 'DUP ACK' packets. The page takes 30 seconds to load. netstat tells me I have had 8% packet loss during the http get.
This makes me suspect packet loss, so I go to my cable modem's stats page and it tells me my snr is 39dB, downstream power level is 5dB and the upstream power level is 39dBmV. This is in line with what I've read on the subject. I've unplugged everything else (cable box, reception is OK) from the coax line.
Now I'm really at a loss. Surely any problem that 'isn't my problem' would be reflected in the cable modem stats? Or is it likely that my modem has snuffed it? Or have I/my housemates annoyed someone at Telewest with their torrenting, who have promptly banhammered us, causing what I see?
I'm really confused. I've got all my housemates screaming at me to 'fix it' and I'm wondering if its time to call support - but don't really know what to say and really dont want to get an engineer out only to find its my problem and not his.
Any pointers, ideas, or anything? I'm all out of ideas :(
You say you like bbc.co.uk traceroutes, so here's one.
C:\Documents and Settings\a>tracert bbc.co.uk
Tracing route to bbc.co.uk [212.58.224.131]
over a maximum of 30 hops:
1 <1 ms 2 ms <1 ms 10.xx.xx.xx
2 13 ms 21 ms <1 ms 80.xx.xx.xx
3 <1 ms 1 ms 1 ms 62.30.252.26
4 1 ms 1 ms 1 ms 194.117.136.166
5 3 ms 1 ms 1 ms 194.117.136.173
6 <1 ms 1 ms 1 ms 194.117.136.146
7 2 ms 1 ms 1 ms bbc-gw0-linx.prt0.thdoe.bbc.co.uk [195.66.224.103]
8 2 ms 2 ms 10 ms 212.58.238.153
9 5 ms 3 ms 3 ms rdirwww-vip.thdo.bbc.co.uk [212.58.224.131]
Trace complete.
This is one of the things that confuses me - all that gets through fine, as does the pinging (with slight packetloss) but a TCP sesh really breaks things.
As I say, I'm all out of ideas. Can anyone see anything I've missed, or any issues I should phone Telewest about? I suppose a good deal of what I'm asking can be summed up as 'is this all normal'.
Thanks.
Back story is that I live in a 5-person student house. I'm in charge of the net access. A couple (or three) of the guys in the house torrent fairly heavily. We have a Telewest cable line, live somewhere around Leeds, and use a surfBoard cable modem. Haven't called tech support. Home network setup is a linux router but this was unplugged for most of the testing (see below text) and I was mainly using an XP laptop and another XP box for testing. No firewalls are in effect other than the Linux machine.
A few weeks ago we started having network congestion (2+ minutes to load a web page, etc). This has steadily been getting worse, and recently I hassled the torrenters and eventually removed them from the network, which eased the problem, but didn't get rid of it totally. I got annoyed tonight and unplugged the lot, jacked my Xp laptop into the cable modem and rebooted it. I get around 5% packet loss pinging bbc.co.uk (is this an acceptable level?), but I still take over 30 seconds to load, for example, my LJ friends page, although most sites are responsive. I tried a nearby other machine (also running XP) as well.
So I do a packet dump and find (a substantial amount of) 'TCP Retransmission' and 'DUP ACK' packets. The page takes 30 seconds to load. netstat tells me I have had 8% packet loss during the http get.
This makes me suspect packet loss, so I go to my cable modem's stats page and it tells me my snr is 39dB, downstream power level is 5dB and the upstream power level is 39dBmV. This is in line with what I've read on the subject. I've unplugged everything else (cable box, reception is OK) from the coax line.
Now I'm really at a loss. Surely any problem that 'isn't my problem' would be reflected in the cable modem stats? Or is it likely that my modem has snuffed it? Or have I/my housemates annoyed someone at Telewest with their torrenting, who have promptly banhammered us, causing what I see?
I'm really confused. I've got all my housemates screaming at me to 'fix it' and I'm wondering if its time to call support - but don't really know what to say and really dont want to get an engineer out only to find its my problem and not his.
Any pointers, ideas, or anything? I'm all out of ideas :(
You say you like bbc.co.uk traceroutes, so here's one.
C:\Documents and Settings\a>tracert bbc.co.uk
Tracing route to bbc.co.uk [212.58.224.131]
over a maximum of 30 hops:
1 <1 ms 2 ms <1 ms 10.xx.xx.xx
2 13 ms 21 ms <1 ms 80.xx.xx.xx
3 <1 ms 1 ms 1 ms 62.30.252.26
4 1 ms 1 ms 1 ms 194.117.136.166
5 3 ms 1 ms 1 ms 194.117.136.173
6 <1 ms 1 ms 1 ms 194.117.136.146
7 2 ms 1 ms 1 ms bbc-gw0-linx.prt0.thdoe.bbc.co.uk [195.66.224.103]
8 2 ms 2 ms 10 ms 212.58.238.153
9 5 ms 3 ms 3 ms rdirwww-vip.thdo.bbc.co.uk [212.58.224.131]
Trace complete.
This is one of the things that confuses me - all that gets through fine, as does the pinging (with slight packetloss) but a TCP sesh really breaks things.
As I say, I'm all out of ideas. Can anyone see anything I've missed, or any issues I should phone Telewest about? I suppose a good deal of what I'm asking can be summed up as 'is this all normal'.
Thanks.