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What happened last night? BT Maintenance

RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

What happened last night? BT Maintenance

Morning guys,
Checked my graph this morning and saw something odd around 3:45 and 6am. Caused the DLM to kick in and increase my latency.
Checked others graphs, they also have issues around 6am.
So I'm guessing this is probably due to the BT Maintenance. I didn't think this would cause the DLM to start kicking my arse though.

Someone please tell me the DLM will step back down at some point, what is it, 14 day window?
40 REPLIES
Community Veteran
Posts: 6,824
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Registered: ‎27-10-2012

Re: What happened last night? BT Maintenance

I had the same blip, although never lost sync according to my router:

It was BTW network side so other ISPs were affected too (this is the BRAS for my exchange):

I checked the BT Service Status page and didn't notice any planned maintenance for my area.
Community Veteran
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Registered: ‎11-08-2007

Re: What happened last night? BT Maintenance

I saw that too -

Can someone please explain how a common network event which causes packet loss on multiple connections, can trigger individual customers line DLM to kick in like this ?.   I had always believed that DLM worked on the individual phone line electrical characteristics and the level of noise present in the wires.
My line which is nearly error free (less than 50 FEC errors per week) can easily hold maximum sync whilst on fastpath and an SNR of 13 to 15dB.
Recently, as in this case, my TBB graph sees the overnight BT network maintenance (yes I check the service status, and the other ping graphs) and see my line switch from clean fastpath over to interleaved with a depth of 64 ! (although today I'm still interleaved from the previous time).
This has happened three times in six weeks, requiring support tickets for having interleaving removed, after a widespread network glitch was seen.  
I had been wondering if this phenomenon was my imagination, but clearly not.
Any ideas ?
RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

Re: What happened last night? BT Maintenance

Since I'm a fairly new customer and only had my Fibre installed last week I can imagine the DLM will be more sensitive to interruptions.
That being said, I still would like to see it come back down though.
If I recall correctly the DLM is a rolling window that is something like 14 or 21 days. Does anybody know what that period actually is?
Community Veteran
Posts: 6,824
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Registered: ‎27-10-2012

Re: What happened last night? BT Maintenance

It's a bit of a flawed system if DLM kicks in when someone has a loss of internet connectivity (due to BT maintenance) but the PPP connection remains.
Looking at the PN graphs, most people have the red blips but their minimum pings remained the same as before.
Community Veteran
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Registered: ‎18-01-2013

Re: What happened last night? BT Maintenance

Not sure if it is related but I lost sync this morning :

Same connection but different tester and it shows a slightly different time of packet loss
RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

Re: What happened last night? BT Maintenance

@AndyH
Agreed, I seemed to have had a major loss of sync at 3:45am and that's when my DLM kicked in. Although to be fair, maybe they just re-routed me across some other routers.
@picbits
Certainly seems related to me.
Community Veteran
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Registered: ‎11-08-2007

Re: What happened last night? BT Maintenance

I didn't get a sync loss last night, but here is my router log the last time DLM kicked in -
Nov  8 03:44:55 Vigor: PPP Closed : Remote Terminating (PPPoA)
Nov  8 03:44:56 Vigor: Drop VPN ifno:9 because of WAN ifno:3 is down
Nov  8 03:45:17 Vigor: >>> Dial-up triggered by user : 192.168.xxx.xxx ; proto=UDP, to 204.2.134.162 port=ntp
Nov  8 03:45:20 Vigor: PPP Start (PPPoA)
Nov  8 03:45:20 Vigor: PPP Closed : Remote Terminating (PPPoA)
Nov  8 03:45:30 Vigor: >>> Dial-up triggered by user : 192.168.xxx.xxx ; proto=UDP, to 208.67.220.220 port=domain
Nov  8 03:45:33 Vigor: PPP Start (PPPoA)
Nov  8 03:45:41 Vigor: CHAP Login OK (PPPoA)
Nov  8 03:45:41 Vigor: IPCP Opening (PPPoA); Own IP Address : xxx.xxx.xxx.xxx  Peer IP Address : 195.166.128.196; Primary

I presume that "PPP Closed : Remote Terminating (PPPoA)" indicates that my modem received a request from Plusnet/BT/exchange to end the current PPP session ?.
deathtrap
Grafter
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Registered: ‎23-04-2013

Re: What happened last night? BT Maintenance

@Russel: Looking at the ping graphs the 6am spike and packet loss  was due to BT OR The other packet loss at 3:45 looks like are loss of PPP rather than a resync due to DLM , When DLM strikes it is usually very quick under 30seconds, So the PPP session doesn't drop and the BT ip profile  can sometimes fail to update until you  Stop / re start the current PPP session , Has your IP profile changed as well as the base latency increasing @(3:45am) Also  from my basic  knowledge of DLM  it tends to strike between 5-6am.(FTTC) or that's what people have been reporting ,If no IP profile change (BTW side) as the pn profile can take longer sometimes to update
Then it maybe that  the gateway you where connected to terminated your PPP session ,and the gateway your connected to now is giving you a higher base latency as i have found there is variation of  6-7ms between some gateways
RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

Re: What happened last night? BT Maintenance

@deathtrap
I will have to check later when I get home as unfortunately I only noticed this issue once I got to work.
But you've certainly given me something else to think about.
To be fair my line has been very stable so possibly not DLM. I will have a look at the logs once I get back home.
thesawdust
Grafter
Posts: 384
Registered: ‎28-10-2013

Re: What happened last night? BT Maintenance

I also noticed the glitch, around 3:45am.
It's not increased my latency though?  Shocked
RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

Re: What happened last night? BT Maintenance

Well I checked on the TG582n router at home for the logs... That is some really tiny log space.
All the events have since lapsed and the most recent events are from 11:00am this morning - wow that doesn't help at all.
I'm on the PCL-AG03 gateway and if I remember correctly it's the same gateway I've always been on.
Anybody else on this same gateway noticed a latency increase?
Any of the PlusNet guys care to comment?
Community Veteran
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Registered: ‎27-10-2012

Re: What happened last night? BT Maintenance

@ Russel - are you anywhere near Nottingham, Sheffield or Birmingham? These were planned upgrades for last night/early this morning.
With FTTC, the ISP requests one of three DLM profiles:
Quote
Standard – best overall balance between speed and stability for general internet users
Stable – prioritise stability over speed for IPTV videoconferencing, home workers and businesses transferring data and IPTV
Speed – prioritise speed over stability for online gamers.

I would imagine PN provision people on standard, but it would be interesting to know which and whether there's much of a difference. Also, I would have thought online gamers would want stability over speed....
RCrozier
Grafter
Posts: 39
Registered: ‎29-10-2013

Re: What happened last night? BT Maintenance

@AndyH - I'm actually NorthWest of Manchester a bit.
Since I've been using the Fibre for almost 2 weeks I've been happy with the performance. The main question is what has changed now.
The cabinet and the exchange is quite close to me and I am fairly sure that my line is very stable. If something on PlusNet's side has changed then I could understand as several users have seen similar changes.
thesawdust
Grafter
Posts: 384
Registered: ‎28-10-2013

Re: What happened last night? BT Maintenance

You are currently connected to gateway ptn-ag03.
I don't notice anything different other than the small outage, Logs from the TG582n
Warning Nov 12 03:35:38 PPP link up (Internet) [81.1**.15*.*0]
Info Nov 12 03:35:28 PPP CHAP Chap receive success : authentication ok
Info Nov 12 03:35:26 PPP CHAP Receive challenge (rhost = PTN-AG03)
Info Nov 12 03:34:59 PPP CHAP Receive challenge (rhost = bras-red9.bs)
Info Nov 12 03:34:43 FIREWALL event (1 of 2): modified rules
Info Nov 12 03:34:43 FIREWALL event (1 of 1): created rules
Warning Nov 12 03:34:43 PPP link down (Internet) [81.1**.15*.*0]