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latenecy doubled at 0700 Today speed drop of 20%

g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

latenecy doubled at 0700 Today speed drop of 20%

Had a stable (very) FTTC with IP profile of 23.8mps All of a sudden with no prior dropout latency increased and speed dropped at about 0700 this morning. Pings to bbc are now 25ms, double my ADSL2+ connection which is now as good at the FTTC
What would cause this, has the DLM added interleaving ?
Have raised a ticket but quite confused as to why this happened
Live think graph below and snapshot attached showing Latency doubling (did try to hop gateway and no difference)
http://www.thinkbroadband.com/ping/share/e0468ce186150eae5fbc63b40f21e1ca.html
48 REPLIES
Community Veteran
Posts: 1,293
Thanks: 30
Fixes: 4
Registered: 22-06-2012

Re: latenecy doubled at 0700 Today speed drop of 20%

Have you tried rebooting your router to obtain a change of gateway?
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Yep
Got a gateway change. No difference
Plusnet Staff
Plusnet Staff
Posts: 6,346
Thanks: 31
Fixes: 5
Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

Have things improved?
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

No change after the gateway switch, but last night the latency dropped slightly but no return of speed. I haven't re-established a PPP as I didn't want to confuse any tests

Tony
Plusnet Staff
Plusnet Staff
Posts: 6,346
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Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

It's probably worth keeping an eye on things, hopefully it'll settle down.
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Chris
Are you suggesting just wait for the DLM to readjust ? I have a ticket will that check for any actual lines issues. ?
Tony
Plusnet Staff
Plusnet Staff
Posts: 6,346
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Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

Tony
We don't have any control over what DLM does. The changes it makes are generally to better the overall performance of the connection. Our Faults Team will still be looking over your connection though, however, I've pretty much looked over what they would look over.
It's quite difficult because we don't get that much data (especially historical data) so it's sometimes difficult to see how your line has changed. I assume, given your line length that Interleaving has always been on Low.
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Chris
Not sure about interleaving.
But my sync speed has always been at 23.8. The top end of the range.
Tony
Plusnet Staff
Plusnet Staff
Posts: 6,346
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Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

I've attached your line details. Now you have them, it'd be interesting to see how they differ when the Faults Team your line. They will display the details on your ticket when it gets updated.
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Chris
Thanks that's really interesting. What's the period covered by the max and min downstream rate ?
Am I right if the line rate has recovered, I need to drop the PPP and re-establish to get the benefit of the slightly recovered rate.
In general not having access thru the BT modem to sync speeds how can I know if they increase again after the normal DLM process? What's shown on your portal under high speed broadband doesn't seem live info ?
Thanks for the info. Will compare stats when I get them.
Tony
Plusnet Staff
Plusnet Staff
Posts: 6,346
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Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

Hi Tony,
The min/max period is a continuous piece of data, so that is likely to stretch back to when your line was first installed. It's actually really good that it leaves that data there because it'll allow you to see how it's performed over a greater length of time.
If the line rate recovers, we get an update from our suppliers and we update the Speed Profile on our systems (automatically) which will force a drop of PPP which should update the speeds for you. There isn't really a way you'd know. You'd know if the profile has updated that I think you're referring to. Any changes to profiles are made between 3am-5am so if your line has been working flawlessly today and DLM is happy with things, it'll make a change tonight, so I could look tomorrow to see if there is an improvement for you if you'd prefer.
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Chris
That's really helpful thanks appreciate that. I did think the DLM took a minimum of 8 days but I might have that wrong.
They are small differences I know it's more a Tecnical interest. Unfortunately I have aluminium part way between the cabinet and my home. That's why my ADSL2 ( with you ) performs not far behind even though the exchange is still further away. !
Thanks again await your info tomorrow.
Tony
Plusnet Staff
Plusnet Staff
Posts: 6,346
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Registered: 26-11-2011

Re: latenecy doubled at 0700 Today speed drop of 20%

Tony,
DLM can take 9 days, it depends on the 'Barrier' as explained in this guide I wrote: http://community.plus.net/library/browsing/fttc-dlm-what-it-is-how-it-works/
Quite interesting how it works.
Chris Pettitt
Cloud Environments Engineer
g3uiss
Grafter
Posts: 102
Registered: 13-07-2013

Re: latenecy doubled at 0700 Today speed drop of 20%

Chris
Yes I read that, nice article. I come from a datacoms background where 1200bps was fast  Wink