CalmEddie
21-01-2010, 14:11
Hi! This looks like a great site. I've had an intermittent problem with my connection for over a year now. Because it's intermittent it's been so hard to diagnose, but now it's becoming more frequent. Sorry for the long post...
I have a VirginMedia 20Mbit connection (used to be NTL) with an VM branded Ambit 256 modem.
Connected to this via the WAN port is a Netgear blue-box wireless router: FWG114P with latest firmware version 2.0_18.
The router is configured to use openDNS, and shares these settings with the LAN using DHCP.
The LAN consists of:
1x Ubuntu 8.04 server.
1x Ubuntu 9.10 64bit high spec workstation client. Contains a number of virtual machines inc xin XP
1x Mac Mini client running dual boot Mac OS leapard and Ubuntu 9.10
1x Sony Vaio laptop client running dual boot windows XP and Ubuntu 9.10
1x NAS Storage
1x Netgear GS108 Switch
1x Playstation 3
None of the clients have firewalls, they rely on the NAT router. Obviously none of the linux machines have anti-virus software.
The cable modem and router are remote, located in a crawlspace in the loft next to the server / NAS. They are in this location to keep the noise down from the server. I switch them on/off using a remote device
Like this one: http://www.keene.co.uk/electronics/multi.php?mycode=RCS3
I can go and see the lights, but usually this is not practical enough to give valuable info while browsing.
I am experiencing web browsing dropouts. There are very strange, and appear to be consistent with cache / proxy problems at VM.
When there is a dropout, certain sites are unreachable. Others are perfectly reachable. The behaviour is consistent across all clients, and contacting friends at these times, they confirm the sites are not down.
Downloads are unaffected, but browsing is painful.
I can't see how any of my local equipment would arise a situation like this. IME, LAN either works or it doesn't and won't give strange routing problems like blocking certain web sites.
Power-cycling modem + router sometimes give an improvement which will last half a day. If I contact VM customer services, they reset the modem remotely and this makes a huge improvement. Browsing becomes faultless and much faster than usual, but this only lasts a week at most.
Swapping over to a direct ethernet connection to a single machine (the sony laptop in the crawlspace), the problem seems to go away. However, the problem also goes away if I power-cycle the modem. So this might be influencing this test.
But this means I still end up dis-trusting my set-up. Today I took the router back to factory settings, and re-uploaded the firmware. I've left it on vanilla settings as far as possible, but it's made no difference.
I've reset and rebuilt everything on the LAN. I've been over and over all the settings, used a tester on all the LAN cables. Swapped out LAN cables anyway.
Any help greatly appreciated.
I'm just starting to do ping and traceroute tests. Please bear with me as I have to mess about in the crawl-space to get the direct results. I will post back with values soon.
---------- Post added at 13:11 ---------- Previous post was at 12:26 ----------
The info here is 4 years old...,
http://www.cableforum.co.uk/board/12/26006-cable-modem-signal-levels.html
but I assume is still current. :) I should expect:
Downstream Receive Power Level: Ideally -6dBmV to +15dBmV
Downstream SNR: Minimum is 33dB.
Upstream Transmit Power: Anything between 28dB and 53dB is fine.
I'm getting:
Downstream Receive Power Level : 5.9 dBmV
Downstream SNR : 40.5 dB
Upstream transmit Power Level : 40.5 dBmV
Which seems OK.
I have a VirginMedia 20Mbit connection (used to be NTL) with an VM branded Ambit 256 modem.
Connected to this via the WAN port is a Netgear blue-box wireless router: FWG114P with latest firmware version 2.0_18.
The router is configured to use openDNS, and shares these settings with the LAN using DHCP.
The LAN consists of:
1x Ubuntu 8.04 server.
1x Ubuntu 9.10 64bit high spec workstation client. Contains a number of virtual machines inc xin XP
1x Mac Mini client running dual boot Mac OS leapard and Ubuntu 9.10
1x Sony Vaio laptop client running dual boot windows XP and Ubuntu 9.10
1x NAS Storage
1x Netgear GS108 Switch
1x Playstation 3
None of the clients have firewalls, they rely on the NAT router. Obviously none of the linux machines have anti-virus software.
The cable modem and router are remote, located in a crawlspace in the loft next to the server / NAS. They are in this location to keep the noise down from the server. I switch them on/off using a remote device
Like this one: http://www.keene.co.uk/electronics/multi.php?mycode=RCS3
I can go and see the lights, but usually this is not practical enough to give valuable info while browsing.
I am experiencing web browsing dropouts. There are very strange, and appear to be consistent with cache / proxy problems at VM.
When there is a dropout, certain sites are unreachable. Others are perfectly reachable. The behaviour is consistent across all clients, and contacting friends at these times, they confirm the sites are not down.
Downloads are unaffected, but browsing is painful.
I can't see how any of my local equipment would arise a situation like this. IME, LAN either works or it doesn't and won't give strange routing problems like blocking certain web sites.
Power-cycling modem + router sometimes give an improvement which will last half a day. If I contact VM customer services, they reset the modem remotely and this makes a huge improvement. Browsing becomes faultless and much faster than usual, but this only lasts a week at most.
Swapping over to a direct ethernet connection to a single machine (the sony laptop in the crawlspace), the problem seems to go away. However, the problem also goes away if I power-cycle the modem. So this might be influencing this test.
But this means I still end up dis-trusting my set-up. Today I took the router back to factory settings, and re-uploaded the firmware. I've left it on vanilla settings as far as possible, but it's made no difference.
I've reset and rebuilt everything on the LAN. I've been over and over all the settings, used a tester on all the LAN cables. Swapped out LAN cables anyway.
Any help greatly appreciated.
I'm just starting to do ping and traceroute tests. Please bear with me as I have to mess about in the crawl-space to get the direct results. I will post back with values soon.
---------- Post added at 13:11 ---------- Previous post was at 12:26 ----------
The info here is 4 years old...,
http://www.cableforum.co.uk/board/12/26006-cable-modem-signal-levels.html
but I assume is still current. :) I should expect:
Downstream Receive Power Level: Ideally -6dBmV to +15dBmV
Downstream SNR: Minimum is 33dB.
Upstream Transmit Power: Anything between 28dB and 53dB is fine.
I'm getting:
Downstream Receive Power Level : 5.9 dBmV
Downstream SNR : 40.5 dB
Upstream transmit Power Level : 40.5 dBmV
Which seems OK.