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Standard User drkdeath5000
(newbie) Sat 06-Aug-16 12:11:37
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ADSL 20CN Latency - is this normal?


[link to this post]
 
I have an ADSL 20CN connection syncing at 8000kbps down and 800kbps up. I'm experiencing highly varied latency which is noticeable when using VOIP services such as skype and online gaming is affected. I dont run anything heavy on the network. Bandwidth load is reported at roughly 30-50% and i purposely limit it to around 75% to prevent bufferbloat. My actual limited speeds are 5950 down and 593kbps up so i'm in no way maxing out my connection. I use an asus rt n66u running tomato qos which should be more than capable at handling my connection - cpu utlisation is reported at 5%.
I should also mention that i have ICMP and the thinkbroadband IP prioritised so this is not a case of the pings being (de)prioritised.

This is my bqm graph at idle 3AM - 8AM (no devices connected).
http://www.thinkbroadband.com/ping/share/c48f9d07c53...
I was under the impression it should be 5ms at most when idle and 10ms+ for overseas.

And a graph under a typical days useage - http://www.thinkbroadband.com/ping/share/87c5b6f16ef...

How do these graphs look, specifically is it normal for the latency to jump as much as 10ms+ at idle and 100ms under typical use (less than 75% bandwidth utilisation)?

Edited by drkdeath5000 (Sat 06-Aug-16 13:32:34)

Administrator MrSaffron
(staff) Sat 06-Aug-16 13:36:00
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Re: ADSL 20CN Latency - is this normal?


[re: drkdeath5000] [link to this post]
 
If your connection was dedicated between you and our BQM system we'd say no it was not normal, but given the shared nature of consumer connections and the more limited capacity inherent in 20CN backhaul it looks pretty normal.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User drkdeath5000
(newbie) Wed 10-Aug-16 01:10:34
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Re: ADSL 20CN Latency - is this normal?


[re: MrSaffron] [link to this post]
 
Are there any 20CN bqm's i can look at to confirm this?

I dont share my connection with anyone and its dedicated to 1 machine at a time so it just doesnt make sense to me how it can fluctuate so much. How can it be a stable 37-38ms at idle with the ping command only running (less than 100kbits up/down) but once i influence any traffic (500kbits+) it will fluctuate between 37-150ms.

I could understand it if i was close to maxing my bandwidth due to bufferbloat but at roughly 10% throughput and even up to 30-50% should it not be somewhat stable atleast within a few ms?

For example here is a quick ping command output while opening a simple web page it sends my latency spiking. Any amount of traffic seems to cause it to spike. As you can see its somewhat stable at idle but as soon as the web page is loaded its jumping up and back down. This just doesnt seem normal and with the highly varied latency i am finding it impossible to do anything that requires stable latency ie--gaming and voip.

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Reply from 80.249.99.130: bytes=32 time=37ms TTL=56
Reply from 80.249.99.130: bytes=32 time=41ms TTL=56Reply from 80.249.99.130: bytes=32 time=37ms TTL=56
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Reply from 80.249.99.130: bytes=32 time=42ms TTL=56Reply from 80.249.99.130: bytes=32 time=60ms TTL=56
Reply from 80.249.99.130: bytes=32 time=36ms TTL=56Reply from 80.249.99.130: bytes=32 time=41ms TTL=56
Reply from 80.249.99.130: bytes=32 time=38ms TTL=56Reply from 80.249.99.130: bytes=32 time=67ms TTL=56
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Reply from 80.249.99.130: bytes=32 time=45ms TTL=56Reply from 80.249.99.130: bytes=32 time=40ms TTL=56
Reply from 80.249.99.130: bytes=32 time=44ms TTL=56Reply from 80.249.99.130: bytes=32 time=61ms TTL=56
Reply from 80.249.99.130: bytes=32 time=38ms TTL=56Reply from 80.249.99.130: bytes=32 time=83ms TTL=56
Reply from 80.249.99.130: bytes=32 time=48ms TTL=56Reply from 80.249.99.130: bytes=32 time=73ms TTL=56
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Reply from 80.249.99.130: bytes=32 time=74ms TTL=56Reply from 80.249.99.130: bytes=32 time=56ms TTL=56
Reply from 80.249.99.130: bytes=32 time=39ms TTL=56Reply from 80.249.99.130: bytes=32 time=117ms TTL=56
Reply from 80.249.99.130: bytes=32 time=115ms TTL=56Reply from 80.249.99.130: bytes=32 time=104ms TTL=56
Reply from 80.249.99.130: bytes=32 time=54ms TTL=56Reply from 80.249.99.130: bytes=32 time=75ms TTL=56


Could it not possibly be an issue with the line, perhaps a poorly configured or failing DSLAM, QoS or something related at the exchange? Would it be worth pursuing as a fault with the ISP?

In the event it shows anything of importance my live bqm graph is available here-- http://www.thinkbroadband.com/ping/share/80d502d9725... Note my idle periods are early morning 2am-8am.

Edited by drkdeath5000 (Wed 10-Aug-16 01:20:10)


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Administrator MrSaffron
(staff) Wed 10-Aug-16 11:01:44
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Re: ADSL 20CN Latency - is this normal?


[re: drkdeath5000] [link to this post]
 
Your idea that the latency should be as low as 5 ms at offpeak times is wrong, the green area should be fairly consistent 24/7

And yes any download activity will raise the latency, until you have a connection fast enough that some activities don't saturate the line. If constituent latency is important then you need to run QoS i.e. limit services so that ping is given a guaranteed response.

IPStream is more constrained too as the backhaul capacity is getting old and not scaled well for the amount of video streaming, so impact of others further down the network can have an impact.

In short for gaming and voip, you need to make sure no one does anything on your line if you can avoid it.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User drkdeath5000
(newbie) Wed 10-Aug-16 12:04:43
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Re: ADSL 20CN Latency - is this normal?


[re: MrSaffron] [link to this post]
 
@MrSaffron My theory is that it should be a stable 36-38ms at idle with 1ms typical jitter and with light load it should increase by at most 5ms so around 43ms. My idle results are fairly consistent with this theory as not only is the green area stable but the yellow area is too but the issue i am having is as soon as i influence light traffic, lets say 500kbits of data that jitter is suddenly 100ms+.

I realise saturating the line will cause bufferbloat and hence raise the latency but i am only using roughly 10% of my connection here. I have 8000kbits (down) and 800 (up) to work with and i am using roughly 10% of this-- again i have purposely limited the connection to prevent saturation. I also run a comprehensive QoS system to limit services and guarantee ICMP priority above all else. It may not be a firebrick but it is a proved and working system (Tomato QoS on an asus rt n66u). Many ADSL users use tomato over at the linksys forum and have great success with it-- many i have discussed the issue with have stable pings up to 75% saturation before pings start to go wild.

Again my connection is dedicated to 1 machine only and not shared with anyone, all i have running during VOIP or gaming is the ICMP ping command and the qbm running 24/7. Connection is limited to 1000kbits (down) 100 (up) yet i am still receiving severe ping spikes of 100ms+.

Some pingplotter graphs might help show my issue more clearly. I started my tests at idle and slowly influenced traffic in 1000kbit steps. All tests are done at a constant rate using FileZilla to rate limit the traffic. Clearly you can see my pings start of at idle somewhat stable but as soon as i start to influence traffic the pings are erratic. Even at 1000kbits which is roughly 10% saturation there are frequent ping spikes.

https://s9.postimg.org/cwowo7tov/pings.png

Would you not agree that something is not quite right here?

Edited by drkdeath5000 (Wed 10-Aug-16 13:42:51)

Administrator MrSaffron
(staff) Wed 10-Aug-16 14:00:25
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Re: ADSL 20CN Latency - is this normal?


[re: drkdeath5000] [link to this post]
 
Without much more extensive analysis (and verification of the hardware used) I'd say that 4 ms variation in average is not a problem. Guaranteeing stable latency is very difficult to do.

If you want to pursue the 'there is a fault' probably best to recourse to people like Adrian Kennard AAISP who will have more experience of IPStream and ping performance via their customer base.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User drkdeath5000
(newbie) Wed 10-Aug-16 16:14:19
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Re: ADSL 20CN Latency - is this normal?


[re: MrSaffron] [link to this post]
 
Respectfully the average is not a good indication of how the connection is performing. Whilst i may have an average of 38-42ms the spikes are 100ms+ apart and very brief so of course the average is going to be lower.

I'm positive something is wrong somewhere as i have had ADSL for 15 years prior to this and dont recall having any such issues i am having here. Okay it was a 21CN service but the latency should be much the same between 20CN and 21CN. So at this stage i am pretty sure i want to pursue this as a fault unless someone can convince me otherwise.

How would you recommend bringing this to the attention of the ISP or Adrian Kennard? Bare in mind i have tried to sign up to AAISP prior to this but found out that they cannot offer a service in my area due to it being a market 1 classed area (owned entirely by BT). I have read great things about Adrian and what he has done for broadband services over the years but somehow i cannot see him wanting to help unless i am a paying customer.
Standard User jchamier
(eat-sleep-adslguide) Wed 10-Aug-16 16:33:29
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Re: ADSL 20CN Latency - is this normal?


[re: drkdeath5000] [link to this post]
 
In reply to a post by drkdeath5000:
How would you recommend bringing this to the attention of the ISP or Adrian Kennard? Bare in mind i have tried to sign up to AAISP prior to this but found out that they cannot offer a service in my area due to it being a market 1 classed area (owned entirely by BT). I have read great things about Adrian and what he has done for broadband services over the years but somehow i cannot see him wanting to help unless i am a paying customer.


Market 1 means Ofcom classification, and those have changed, think its letters now - and it means nobody else supplies wholesale services to that exchange. Its a shame BT haven't upgraded to 21CN however.

plusnet unlimited fibre 80/20 since 2 Jun 14 - Sync as of 7th Aug 16: 55,355/10,291 kbps with G.INP
17 years of UK broadband since 1999 ntl:cable modem trial -Router: Asus RT-AC68U with HG612 - BQM
Administrator MrSaffron
(staff) Wed 10-Aug-16 16:46:33
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Re: ADSL 20CN Latency - is this normal?


[re: drkdeath5000] [link to this post]
 
Do you really mean the spikes are 0.1 second apart, that is so close the average should rise, how often are you running a ping then?

For a start IPStream is a lot older and no-one expects sterling latency performance from it, so a spike every so often might be down to the network, some other noise burst or an odd interaction with your hardware/software combination.

Getting to the bottom of what it is will be a long costly affair, and first step would be dragging all your kit to a similar speed on LLU or 21CN line and testing it there and comparing to their normal performance.

As for AAISP refusing service, was not aware they refused to provide a service on IPStream only exchanges, remember while its not offering TalkTalk LLU, there is a wholesale service available.

Take a read through www.sinet.bt.com and the documents describing the BT IPStream service which will define latency performance criteria, and you will find it is best efforts so.

The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.
Standard User jchamier
(eat-sleep-adslguide) Wed 10-Aug-16 16:52:33
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Re: ADSL 20CN Latency - is this normal?


[re: MrSaffron] [link to this post]
 
In reply to a post by MrSaffron:
Take a read through www.sinet.bt.com and the documents describing the BT IPStream service which will define latency performance criteria, and you will find it is best efforts so.

And each ISP has a latency criteria for its network from the "tail" termination out to the transit.

plusnet unlimited fibre 80/20 since 2 Jun 14 - Sync as of 7th Aug 16: 55,355/10,291 kbps with G.INP
17 years of UK broadband since 1999 ntl:cable modem trial -Router: Asus RT-AC68U with HG612 - BQM
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