View Full Version : Intermittent access / loss of sync
Wonder if anybody on here may agree with me, have some clues or general advice here.
Company: NTL
Area: CM16 / 01992
UBR: Walt-cmts-15 (pop ~160)
Modem: Ambit ("lima")
Package: Broadband "M" upgraded to 10Mbit
Usage profile : low
Downstream : 35.7 dB SNR @0.2 dBmV
Upstream: 39.0 dBmV
It all started on thursday, irregular and unpredictable loss of sync, modem logged bunches of T3 timeout errors and ranging would start again, most annoying.
Called up VM and (after much arguing about how it was not my equipment and me having to make an official complaint) they suggested modem was at fault and dispatched a tech with a new one, so I could at least have some internet access this weekend and get some work done.
Tech replaced modem, checked signal in the house, said all was fine and then left. Guess what happened 20 mins later :)
Extremely difficult to convince any of the people the other end of the phone that they need to take a proper look at the cable, perhaps put it on 24hr monitoring (it is very irregular when it happens).
Since replacement of the modem I've only had two outages so far (in the past three hours) which is better than before where I would get around 8 an hour.
Following my internal cabling from the spitter to the internal and external faceplates, all I can really see is that the external box is full of cobwebs but otherwise, the kit and junction look in good condition.
Any pointers appreciated.
PS: I've written a perl script to provide a unix "tail" for the ambit logs if anybody is interested, the source can be found here:
http://www.convergence.cx/scripts/cmtail.pl
webcrawler2050
15-08-2009, 15:06
http://www.cableforum.co.uk/board/94/33653957-simple-self-test-steps-will-assist.html This will help, follow the steps and post them up here.
Bigfootedfred
15-08-2009, 15:08
one of the other guys will know this better but your upstream sounds a bit low
Up 39.0 dBmV
it might slip a little lower sometimes, and may be causing it to lose sync i rekon.
The engineers can set it higher i believe.
webcrawler2050
15-08-2009, 15:11
one of the other guys will know this better but your upstream sounds a bit low
Up 39.0 dBmV
it might slip a little lower sometimes, and may be causing it to lose sync i rekon.
The engineers can set it higher i believe.
A little high - could be one of the causes..
moaningmags
15-08-2009, 15:12
Your upstream power level is spot on as is your downstream power level and SNR.
If it was me you were talking to I'd be checking the UBR for SNR issues or FEC errors and not finding any I'd be speaking to 2nd line.
Bigfootedfred
15-08-2009, 15:13
A little high - could be one of the causes..
hmm, well the guys on the support line tell me 46 is normal, so there you go, im trusting those guys less and less.
webcrawler2050
15-08-2009, 15:17
hmm, well the guys on the support line tell me 46 is normal, so there you go, im trusting those guys less and less.
My mistake..
hmm, well the guys on the support line tell me 46 is normal, so there you go, im trusting those guys less and less.
Your power level is as Mags said absolutely spot on for your connection so any issue must be elsewhere.
Also check here as well http://www.cableforum.co.uk/board/12/26006-cable-modem-signal-levels.html
Check below you will see that I am one of those support guys.
Bigfootedfred
15-08-2009, 15:30
Your power level is as Mags said absolutely spot on for your connection so any issue must be elsewhere.
Also check here as well http://www.cableforum.co.uk/board/12/26006-cable-modem-signal-levels.html
Check below you will see that I am one of those support guys.
lol mate, no offense and nothing personal but its been going on for bloody ages now, i dont wanna bring it all into someone else thread though.
il take your word for it 46 is good. honestly though i have nothing agaisnt you or virgin, the BB is ussaly damn near perfect.
webcrawler2050
15-08-2009, 15:32
There must be something else..
How contended is the UBR in your area? All of these steps, will give some clarity http://www.cableforum.co.uk/board/94/33653957-simple-self-test-steps-will-assist.html
lol mate, no offense and nothing personal but its been going on for bloody ages now, i dont wanna bring it all into someone else thread though.
il take your word for it 46 is good. honestly though i have nothing agaisnt you or virgin, the BB is ussaly damn near perfect.
No need to take my word just click that link I provided.
Also here is my own Upstream and high is above 55.
Upstream transmit Power Level : 45.0 dBmV
Er, not quite sure how , but here you go:
Step 1] Reboot Virgin Media Modem & Router
It's been changed!
Step 2] How – are you connected from your PC to Virgin Media.
directly connected , PC to modem
Step 3] Timing
Yes, problem occurs irregularly
Step 4] We need to see, PING results.
Will save you the actual data:
When it works:
$ ping -c 10 www.bbc.co.uk | grep -A999 stat
--- www.bbc.net.uk ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9003ms
rtt min/avg/max/mdev = 10.377/20.318/75.140/19.263 ms
When it doesn't work:
$ ping -c 10 www.bbc.co.uk | grep -A999 stat
--- www.bbc.net.uk ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 126028ms
Step 5] – We need to see a trace route
sure thing:
when it works:
$ traceroute -q 1 -w 1 www.bbc.co.uk
traceroute to www.bbc.net.uk (212.58.251.195), 64 hops max, 28 byte packets
1 10.14.152.1 (10.14.152.1) 16 ms
2 popl-core-1b-ge-500-671.network.virginmedia.net (62.255.161.125) 15 ms
3 pop-bb-b-as2-0.network.virginmedia.net (213.105.174.238) 16 ms
4 gfd-bb-a-so-010-0.network.virginmedia.net (213.105.172.137) 21 ms
5 gfd-bb-b-ae0-0.network.virginmedia.net (213.105.172.6) 18 ms
6 redb-ic-1-as0-0.network.virginmedia.net (62.253.185.78) 17 ms
7 212.58.239.249 (212.58.239.249) 29 ms
8 212.58.238.133 (212.58.238.133) 21 ms
9 212.58.239.58 (212.58.239.58) 13 ms
10 www-vip.telhc.bbc.co.uk (212.58.251.195) 16 ms
when it doesn't work:
$ traceroute -q 1 -w 1 www.bbc.co.uk
traceroute to www.bbc.net.uk (212.58.251.195), 64 hops max, 28 byte packets
1 *
2 *
3 *
Step 6] Power levels
When working , downstream is at 0.2 dBmV, upstream tx is at 39.0 dBmV
when not working, downstream is at 0.0 dBmV, upstream tx is at 39.0 dBmV
Step 7] Speed Test / Downloading
Get about 6 mbit/sec download, i'm happy with this.
Step 8] Anti Virus / Spyware / Malware
I don't have any such things installed, as far as I am aware + looking at my netstat, I'm not infected with any malware.
webcrawler2050
15-08-2009, 15:44
Er, not quite sure how , but here you go:
Step 1] Reboot Virgin Media Modem & Router
It's been changed!
Step 2] How – are you connected from your PC to Virgin Media.
directly connected , PC to modem
Step 3] Timing
Yes, problem occurs irregularly
Step 4] We need to see, PING results.
Will save you the actual data:
When it works:
$ ping -c 10 www.bbc.co.uk | grep -A999 stat
--- www.bbc.net.uk ping statistics ---
10 packets transmitted, 10 received, 0% packet loss, time 9003ms
rtt min/avg/max/mdev = 10.377/20.318/75.140/19.263 ms
When it doesn't work:
$ ping -c 10 www.bbc.co.uk | grep -A999 stat
--- www.bbc.net.uk ping statistics ---
10 packets transmitted, 0 received, 100% packet loss, time 126028ms
Step 5] – We need to see a trace route
sure thing:
when it works:
$ traceroute -q 1 -w 1 www.bbc.co.uk
traceroute to www.bbc.net.uk (212.58.251.195), 64 hops max, 28 byte packets
1 10.14.152.1 (10.14.152.1) 16 ms
2 popl-core-1b-ge-500-671.network.virginmedia.net (62.255.161.125) 15 ms
3 pop-bb-b-as2-0.network.virginmedia.net (213.105.174.238) 16 ms
4 gfd-bb-a-so-010-0.network.virginmedia.net (213.105.172.137) 21 ms
5 gfd-bb-b-ae0-0.network.virginmedia.net (213.105.172.6) 18 ms
6 redb-ic-1-as0-0.network.virginmedia.net (62.253.185.78) 17 ms
7 212.58.239.249 (212.58.239.249) 29 ms
8 212.58.238.133 (212.58.238.133) 21 ms
9 212.58.239.58 (212.58.239.58) 13 ms
10 www-vip.telhc.bbc.co.uk (212.58.251.195) 16 ms
when it doesn't work:
$ traceroute -q 1 -w 1 www.bbc.co.uk
traceroute to www.bbc.net.uk (212.58.251.195), 64 hops max, 28 byte packets
1 *
2 *
3 *
Step 6] Power levels
When working , downstream is at 0.2 dBmV, upstream tx is at 39.0 dBmV
when not working, downstream is at 0.0 dBmV, upstream tx is at 39.0 dBmV
Step 7] Speed Test / Downloading
Get about 6 mbit/sec download, i'm happy with this.
Step 8] Anti Virus / Spyware / Malware
I don't have any such things installed, as far as I am aware + looking at my netstat, I'm not infected with any malware.
Can you post the full response from the pings please and the trace route?
Sure:
$ ping -c 10 www.bbc.co.uk
PING www.bbc.net.uk (212.58.251.195) 56(84) bytes of data.
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=1 ttl=117 time=16 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=2 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=3 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=4 ttl=117 time=24 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=5 ttl=117 time=30 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=6 ttl=117 time=16 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=7 ttl=117 time=10 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=8 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=9 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=10 ttl=117 time=14 ms
Not sure what you mean about the traceroute, no more information available there?
---------- Post added at 16:06 ---------- Previous post was at 15:58 ----------
Oh, and if anybody is interested in the ambit logs, here they are:
Sat Aug 15 14:31:45 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:43 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:49 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:52 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:31:53 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:12 2009 - Critical (3) - SYNC Timing Synchronization failure - Failed to acquire QAM/Q...
Sat Aug 15 14:32:10 2009 - Critical (3) - Unicast Ranging Received Abort Response - Re- initializing MAC
Sat Aug 15 14:32:17 2009 - Critical (3) - SYNC Timing Synchronization failure - Failed to acquire QAM/Q...
Sat Aug 15 14:32:23 2009 - Information (7) - Locked on the downstream. Waiting for UCDs...
Sat Aug 15 14:32:29 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:27 2009 - Information (7) - starting ds time sync acquisition...
Sat Aug 15 14:32:28 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:32:30 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:32:33 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:34 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:40 2009 - Information (7) - MAP w/initial maintenance region received.
Just got off the phone with them, they are still pestering me about my equipment, managed to convince them to send a tech out, they appear to be offshore (india?) and hence find that I'm having communication difficulties here. (they were asking me what time it was "over there"?)
moaningmags
15-08-2009, 16:07
That's a lot of T3 timeouts in a short space of time.
webcrawler2050
15-08-2009, 16:08
Sure:
$ ping -c 10 www.bbc.co.uk
PING www.bbc.net.uk (212.58.251.195) 56(84) bytes of data.
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=1 ttl=117 time=16 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=2 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=3 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=4 ttl=117 time=24 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=5 ttl=117 time=30 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=6 ttl=117 time=16 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=7 ttl=117 time=10 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=8 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=9 ttl=117 time=14 ms
64 bytes from www-vip.telhc.bbc.co.uk (212.58.251.195): icmp_seq=10 ttl=117 time=14 ms
Not sure what you mean about the traceroute, no more information available there?
---------- Post added at 16:06 ---------- Previous post was at 15:58 ----------
Oh, and if anybody is interested in the ambit logs, here they are:
Sat Aug 15 14:31:45 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:43 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:49 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:31:52 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:31:53 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:12 2009 - Critical (3) - SYNC Timing Synchronization failure - Failed to acquire QAM/Q...
Sat Aug 15 14:32:10 2009 - Critical (3) - Unicast Ranging Received Abort Response - Re- initializing MAC
Sat Aug 15 14:32:17 2009 - Critical (3) - SYNC Timing Synchronization failure - Failed to acquire QAM/Q...
Sat Aug 15 14:32:23 2009 - Information (7) - Locked on the downstream. Waiting for UCDs...
Sat Aug 15 14:32:29 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:27 2009 - Information (7) - starting ds time sync acquisition...
Sat Aug 15 14:32:28 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:32:30 2009 - Critical (3) - No Ranging Response received - T3 time-out
Sat Aug 15 14:32:33 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:34 2009 - Information (7) - MAP w/initial maintenance region received
Sat Aug 15 14:32:40 2009 - Information (7) - MAP w/initial maintenance region received.
Just got off the phone with them, they are still pestering me about my equipment, managed to convince them to send a tech out, they appear to be offshore (india?) and hence find that I'm having communication difficulties here. (they were asking me what time it was "over there"?)
Yep - look slike routing issues - speak to TS again..
Spoken to them again, they appear to not have a clue what they are doing and say they can't escalate it, have to remain stuck without stable internet for the weekend.
vBulletin® v3.8.11, Copyright ©2000-2024, vBulletin Solutions Inc.