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CRCs spike on incoming call

alanj
Grafter
Posts: 227
Thanks: 7
Registered: 02-08-2013

CRCs spike on incoming call

Hi there
Sorry for the somewhat lengthy explanation below… There are a couple of questions at the end if you can manage to get that far – and I’d be really grateful for any advice!  Grin
Until a few days ago I had a very stable connection which had been up for 49 days with bandwith 888/6561 and total CRC errors over the 7 weeks of 498 up / 12666 down. Then the connection went down (several times in short succession), and reconnected at 312/6262 (a very much lower upstream sync), and SN margin 14.5/6.5.
I had a further drop yesterday afternoon, and when the router reconnected it was at an all-time low of 32/4803 with SN margin of 29.2/12.9.  I had routerstats running at the time and noticed there had been a spike in upstream CRC errors (from 50ish to 22Cool just before the connection dropped, possibly related to an incoming call.  I restarted the router and managed to get back to pretty well normal speeds for my line: 888/6346.
I then tried ringing my landline and noticed that an incoming call results is a sudden increase in upstream CRC errors – anything between 10-20 and 80-100+, and twice calling my line caused the connection to drop.  I rang technical support, explained everything but didn’t manage to make any progress – he just told me my line stats were currently fine and to try a different filter (I already had, and was plugged into the test socket) and to try moving the router to a different socket in case it was a power surge (I’m not sure how many sockets he thinks I have within a meter of my phone socket… And do you really get power surges on one socket but not others on the same ring mainHuh?)
Anyway… Having looked in this and a few other forums I am now confused as to whether this spike in CRC errors on receiving a call is (a) perfectly normal, or (b) an indication of a possible fault on the line. Does anyone have an opinion on this?  I should add that when my connection does drop, it very often does come back up with a much reduced upstream sync – often in the 200s.
If this is indicative of a possible problem – how on earth do I persuade the technical support team to do something more than looking at my current line stats and declaring everything is fine?
I have restarted my router today and everything looks good again at the moment – router stats are:
Uptime: 0 days, 2:47:22
DSL Type: ITU-T G.992.3
Bandwidth (Up/Down) [kbps/kbps]: 888 / 6,587
Data Transferred (Sent/Received) [MB/MB]: 22.74 / 170.54
Output Power (Up/Down) [dBm]: 12.8 / 0.0
Line Attenuation (Up/Down) [dB]: 25.3 / 41.5
SN Margin (Up/Down) [dB]: 9.3 / 6.1
System Vendor ID (Local/Remote): TMMB / ----
Chipset Vendor ID (Local/Remote): BDCM / IFTN
Loss of Framing (Local/Remote): 0 / 0
Loss of Signal (Local/Remote): 0 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): -
Error Seconds (Local/Remote): 5 / 0
FEC Errors (Up/Down): 389 / 1,218
CRC Errors (Up/Down): 0 / 8
HEC Errors (Up/Down): 0 / 56
Thanks in advance!
Alan
3 REPLIES
Plusnet Help Team
Plusnet Help Team
Posts: 4,782
Thanks: 364
Fixes: 136
Registered: 01-01-2012

Re: CRCs spike on incoming call

Hi there.
I'd recommend keeping a eye on your connection as it could be a intermittent issue.
If it occurs again the best course of action would be to raise a fault online. I've included the link below for you.
http://faults.plus.net
If you have any further issues please let us know.
If this post resolved your issue please click the 'This fixed my problem' button
 Matthew Wheeler
 Plusnet Help Team
Community Veteran
Posts: 38,431
Thanks: 1,008
Fixes: 59
Registered: 15-06-2007

Re: CRCs spike on incoming call

A couple of things to check - I had the same problem
Connect the router to the test socket with no phones connected - try a different filter if possible
Phone your number using a mobile and leave it ringing - do you get the same spike/connection drop
Is the line quiet - dial 17070 Option 2
If the line is quiet and you see the problem then you need to raise an intermittent connection fault explaining why in the notes at the end
There are two possible causes - a line card fault or a line fault
In my case changing the line card didn't help and they needed to change my connection from the cab to the exchange (it took several visits in my case as it was a bit complicated due to being served from an auxiliary cab off the main cab and the problem was between the main cab and the exchange)
alanj
Grafter
Posts: 227
Thanks: 7
Registered: 02-08-2013

Re: CRCs spike on incoming call

Thanks, both.  Always good to have such quick support from this forum  Smiley
@ Oldjim
Thanks for the suggestion. I tried ringing from a mobile with new filter and no phones plugged in as suggested - still had a burst of CRC errors, though not a vast number. Quiet line test seems not to have any obvious noise.  Will let the connection run without any further messing around for a day or so, then try again and raise a fault if still having issues
Cheers
Alan