Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Author Topic: PCP Change - 20% Drop in FTTC Speed  (Read 1241 times)

art37

  • Member
  • **
  • Posts: 32
PCP Change - 20% Drop in FTTC Speed
« on: March 01, 2017, 12:40:43 PM »

I would be grateful for some advice. My FTTC line has been 100% stable at 85 Max down and 24 up for the past 2 years on an 80/20 profile. Over the past couple of months, BTOR has been installing a second PCP box. Last Friday, I walked past the site and three guys were working in the 2 PCP boxes and on an underground cable. When I got home, I found that my FTTC had suffered a brief disconnect and it was showing a DSL carrier but no internet connection. I walked back to the PCP and one of the guys offered to take a look. Twenty minurtes later, I got a call to say that he had reversed a jumper and everything should be OK. Yes and no - I got the internet connection back but at a max speed of 68Mbps with a downstream SNR of 4 and lots of errors.

This morning, I powered down my Fritz!Box. The FTTC speed has fallen to 66 but the downstream SNR has increased to 6. I have called Zen and they have run quote an invasive line test unquote and everything tests OK. They now want me to do the usual test from the Test Socket. I have 'no' for the moment as I have no reason to suspect that anything is wrong with my in house set up.

I am hoping now that the SNR has downstream increased to 6 that the profile will recover in  time. My connection is currently showing 66581/18507, Latency FAST/FAST, G.INP OFF, INP OFF, SNR 6/6, Bitswap ON/ON and Line Attenuation 13/13.

The error rate is beginning to fall. After 3 hours it is showing:

Fritz!Box      22ES 0 Many Errors(SES), CRC 0.12/min Last 15 Mins 1
Central Exc   14ES 10 Many Errors(SES), CRC 0.31/min  Last 15 Mins 0

Is there anything else that I should be doing/checking other than being patient?

Logged

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #1 on: March 14, 2017, 02:35:29 PM »

Update:

The change of PCP seems to have been completed. Since 1 March, my router log shows 44 disconnections/re-synchs: no further loss of synchronisation since the work was completed last Friday. I think that the contractors got rather fed up of people complaining about the loss of their broadband. They put it down to aluminium in the old PCP.

Not surprisingly, DLM has kicked in and I am now on a profile with max speeds of 67.4 down and 23.3 up (Profile 67.3/20). The max attainable downstream speed is still 20% below what my line was achieving a month ago (held steady for over 3 years). More worryingly, 10 days ago, my line started showing considerable packet loss on the TBB QM.

I confess that I am not sure how significant it is? No matter what I do in terms of turning things off, nothing changes.

[Moderator edited to fix the broken link.]

Further Update:

Thanks for fixing the broken link.

Well after 3 weeks of issues, I see that Zen has moved my line to their GEA backhaul overnight. DLM has been removed, and whilst my max attainable speed is still down by about 5Mbps, i am now on a 77/23 profile. Downstream SNR is 6 and Upstream 10. My BQM is still showing 40% packet loss and some single thread speed issues. It is a now a question of seeing how things settle down.
« Last Edit: March 15, 2017, 10:00:10 AM by art37 »
Logged

Chrysalis

  • Content Team
  • Kitizen
  • *
  • Posts: 4790
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #2 on: March 16, 2017, 11:16:34 PM »

there is no 77mbit profile, you may be confusing sync speed with profile's.

My speculation is at the moment with the new PCP installation they may have moved some cross tie connections around which effectively is reentering the crosstalk lottery and you may have lost out.

The packet loss report as a fault, clearly shouldnt be happening, but of course you should rule out the fritz box first as the fritz box "does" rate limit icmp by default. When I used my firztbox it caused packetloss on tbb ping tests until I adjusted the settings.
Logged
Sky Fiber Pro - Billion 8800NL bridge & PFSense BOX running PFSense 2.4 - ECI Cab

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #3 on: March 17, 2017, 10:08:34 AM »

there is no 77mbit profile, you may be confusing sync speed with profile's.

My speculation is at the moment with the new PCP installation they may have moved some cross tie connections around which effectively is reentering the crosstalk lottery and you may have lost out.

The packet loss report as a fault, clearly shouldnt be happening, but of course you should rule out the fritz box first as the fritz box "does" rate limit icmp by default. When I used my firztbox it caused packetloss on tbb ping tests until I adjusted the settings.


My current stats are:

                                                       Receive Direction             Send Direction
Max. DSLAM throughput   kbit/s   80000                             20000
Min. DSLAM throughput   kbit/s   128                                    128
Attainable throughput   kbit/s           77961                            25796
Current throughput   kbit/s           77961                            20000
Seamless rate adaptation             off                                    off
          
Latency      fast   fast
Impulse Noise Protection (INP)      0   0
G.INP      off   off
          
Signal-to-noise ratio   dB   5   9
Bitswap      on   on
Line attenuation   dB   13   12
          
Profile   17a      
G.Vector      off   off
          
Carrier record      A43   A43

Which settings did you adjust on the Fritz!Box to stop packet loss on BQM? It just appeared a couple of weeks ago: about two weeks after I installed firmware 6.80.

When I first set up my Fritz!Box 7390 on FTTC, I was getting 105Mbps max attainable downstream; how times have changed.
Logged

Chrysalis

  • Content Team
  • Kitizen
  • *
  • Posts: 4790
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #4 on: March 18, 2017, 12:42:05 AM »

Sorry I cannot remember the exact placing of it as I last used my fritzbox years ago, but its most likely to be in the firewall settings somewhere.

The stats you posted confirm you still on a open 80/20 profile.
Logged
Sky Fiber Pro - Billion 8800NL bridge & PFSense BOX running PFSense 2.4 - ECI Cab

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #5 on: March 19, 2017, 09:20:33 AM »

Sorry I cannot remember the exact placing of it as I last used my fritzbox years ago, but its most likely to be in the firewall settings somewhere.

The stats you posted confirm you still on a open 80/20 profile.

Thanks. Any idea how long an open profile will last on a GEA line?  I thought that it was only 2 days on WMBC? I have now been on my GEA line for 4 1/2 days.
Logged

Chrysalis

  • Content Team
  • Kitizen
  • *
  • Posts: 4790
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #6 on: March 19, 2017, 09:57:56 AM »

It will last forever if the line is stable.
Logged
Sky Fiber Pro - Billion 8800NL bridge & PFSense BOX running PFSense 2.4 - ECI Cab

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #7 on: March 19, 2017, 10:30:29 AM »

It will last forever if the line is stable.

Thanks - I didn't know that. My line is now very stable now that BTOR's guys have stopped grabbing handfuls of old wiring to find a particular line.
Logged

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #8 on: April 01, 2017, 01:00:46 PM »

Sorry to post again on this issue but I am still confused about what is happening to my line. Six weeks ago, I was on a full 80/20 profile (held steady for over two years) with max attainable speeds of 84D/24U.

After an early morning re-synch on the 24th Feb, max attainable speed fell into the mid 60s. There then followed two weeks of PCP work as lines were moved to a new PCP. Multiple disconnections later, my speed held fallen to 55D with interleaving etc.

On the 25th March, Zen carried out a change of backhaul with a DLM re-set. My speeds were 79D/25U. Over the past 2 or so weeks, my max attainable down speed has matched the profile speed with varying SNR (sometimes 5 and 4). There have been 3 re-sysnchs with the down speed falling to 73. After each re-synch the line has held steady for a couple of days and then SNR has fallen to 5/4. Last night, with a SNR of 6 and no errors showing, there was a further re-synch and POP change resulting in a slightly higher down speed.

My present stats are:


Receive Direction   Send Direction
Max. DSLAM throughput   kbit/s   80000   20000
Min. DSLAM throughput   kbit/s   128   128
Attainable throughput   kbit/s   74161   26260
Current throughput   kbit/s   74161   20000
Seamless rate adaptation      off   off
          
Latency      fast   fast
Impulse Noise Protection (INP)      0   0
G.INP      off   off
          
Signal-to-noise ratio   dB   6   10
Bitswap      on   off
Line attenuation   dB   13   12
          
Profile   17a      
G.Vector      off   off
          
Carrier record      J43   J43

Error Counter
Seconds With   Not Remediable Errors (CRC)
Errors (ES)   Many
Errors (SES)   per
Minute   Last
15 Minutes
FRITZ!Box                  37   0   0.04   3
Central exchange   6   0   0   0

My carrier has changed from A43 to J43.

I haven't a clue what is going on. My line is on an ECI cabinet.
Logged

ejs

  • Kitizen
  • ****
  • Posts: 1317
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #9 on: April 01, 2017, 02:09:39 PM »

My carrier has changed from A43 to J43.

I think this must be because FritzBoxes cycle through different handshaking carrier sets, and so ends up displaying whichever happened to be used at the time it connected. Things are supposed to be configured to only use A43 (it's one of the requirements of Modem Conformance Testing as described in BT SIN 498).

----

There doesn't really seem to be anything going on. It'll be what Chrysalis said, the new cabinet changed the crosstalk levels, and you've lost a small amount of speed as a result.
Logged

art37

  • Member
  • **
  • Posts: 32
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #10 on: April 02, 2017, 09:23:53 AM »

I think this must be because FritzBoxes cycle through different handshaking carrier sets, and so ends up displaying whichever happened to be used at the time it connected. Things are supposed to be configured to only use A43 (it's one of the requirements of Modem Conformance Testing as described in BT SIN 498).

----

There doesn't really seem to be anything going on. It'll be what Chrysalis said, the new cabinet changed the crosstalk levels, and you've lost a small amount of speed as a result.

Thanks. I have actually lost about 12% of the max attainable speed that I had 5 weeks ago. Not significant for me in real terms but I would be a v.unhappy customer if my max speed wasn't as high as it is. It seems daft that a cabinet full of bundled and tangled wires )with aluminium wires according to the engineers)  can produce less crosstalk interference than a new cabinet with racks of wired connectors.
Logged

ejs

  • Kitizen
  • ****
  • Posts: 1317
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #11 on: April 02, 2017, 09:33:45 AM »

It's not really surprising though, a mess of jumbled wires vs. all the wires lined up a bit neater perhaps running parallel closer together for longer and connected to racks.
Logged

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 30086
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: PCP Change - 20% Drop in FTTC Speed
« Reply #12 on: April 02, 2017, 11:35:37 AM »

Your downstream attenuation (13db) is similar to mine (12.8db).   

For years I held 80Mbps with plenty to spare.  Then last Oct I think they changed something at the cab as my line went down for about 15 mins.   When it came back up it was 76Mbps. 

Since that time Ive also had some sort of fluctuating fault which causes errors. The DLM kicked in which caused me to go below the line threshold and I called out Openreach.   They supposedly fixed the fault which was causing the errors by swapping me to another pair.  My sync is now 73.7 Mbps on open profile.

What Im trying to say is that exactly the same cable between the joint box at the end of my drive to my BT66, yet a different pair within that same cable syncs lower.  Sometimes its a lottery.    :(
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker