topic Re: Affect on speeds of the Plusnet profile in Plusnet Feedback

Affect on speeds of the Plusnet profile

Oldjim — Mon, 15 Apr 2013 11:11:00 GMT

Why does the Plusnet profile knock so much off the line speed
Example
Sync 4,000kbps BT IP profile 3,528kbps Plusnet profile 4,100kbps

Sync 4,000kbps BT IP profile 3,528kbps Plusnet profile 3,500kbps

I don't want some anodyne answer I want a proper explanation and a reason why it can't be fixed

Re: Affect on speeds of the Plusnet profile

dave — Mon, 15 Apr 2013 11:46:23 GMT

Is that repeatable on other speedtests? And have you ever seen a throughput speed higher than the BT profile?
Seems odd though, almost implies that the BT profile was higher than 3528kbps at the time of the first test (which is possible as I'm assuming the speed has decreased recently). I'll see if I can replicate it and I'll ask the question to our suppliers (network kit and BT) and get back to you.

Re: Affect on speeds of the Plusnet profile

Oldjim — Mon, 15 Apr 2013 11:55:43 GMT

It is repeatable and has been discussed before http://community.plus.net/forum/index.php/topic,111019.0.html/

Quote from: spraxyt
In my opinion delayed line profile tracking is the main problem and making that "instant" would remove the major cause for complaint. However my perception by comparing measured speeds from the Thinkbroadband tester (at non-busy times) is that download speed reduces by around 150kbps when Current line speed drops from "too high" to the "correct" (21CN) value. (Which I think ties in with what Oldjim said.)
From that I infer that the bRAS is able to fit more packets onto the copper line than it is given when Current line speed is set "correctly". That is traffic prioritisation is too conservative. Perhaps if a bit more was allowed down the line, occasionally a "titanium packet" might be dropped by the bRAS but is that completely unacceptable? My suspicion is that happens anyway in a real data stream.

Nothing to do with BT profile being high
If you want to manually increase my profile on your side I will do the test again

Re: Affect on speeds of the Plusnet profile

ReedRichards — Mon, 15 Apr 2013 12:22:55 GMT

Quote from: Oldjim
It is repeatable and has been discussed before http://community.plus.net/forum/index.php/topic,111019.0.html/

I started that poll way back in January and the idea got a good few votes; more, I suspect, than would ever have voted for the Pro Option. But the point is that it is three months later and STILL Plusnet haven't taken any action. All talk and no trousers.

Re: Affect on speeds of the Plusnet profile

spraxyt — Tue, 16 Apr 2013 16:48:22 GMT

In my experience the 150-200kbps speed loss from a "correctly set" Plusnet profile occurred on 20CN too. So it's not something new. Again it was most visible on Thinkbroadband speed tests in circumstances similar to those mentioned in that January quote.
I have raised this with Plusnet but the inference was it doesn't routinely happen, must have been an isolated glitch (or I was mistaken).
For 21CN a temporary solution might be to round-up the BT profile so that (using Oldjim's example) 3.528Mbps becomes 3.6Mbps rather than 3.5Mbps.

Re: Affect on speeds of the Plusnet profile

Anotherone — Tue, 16 Apr 2013 16:56:22 GMT

On his connection only please, I'd rather not have random packet drops.

Re: Affect on speeds of the Plusnet profile

Oldjim — Tue, 16 Apr 2013 17:48:59 GMT

Why should there be random packet drops if the Plusnet speed restriction is still below the BT one in practical terms

Re: Affect on speeds of the Plusnet profile

ejs — Tue, 16 Apr 2013 18:45:38 GMT

Does the BT profile not actually enforce any speed limit?

Quote from: Page
The maximum possible IP throughput rate is limited to the actual line rate achieved through
rate adaptation (i.e. approx 90- 95% of the current DSL line rate is the maximum possible IP
throughput, irrespective of the upper limit shown in the table). This figure can only be achieved
under multiple TCP sessions.

Re: Affect on speeds of the Plusnet profile

dave — Thu, 25 Apr 2013 15:52:50 GMT

Oldjim - you available to do some testing on Tuesday? The answer back from our supplier is that the profiles are correctly configured so would be useful to do some testing and see what it shows. I've done some testing here on a 5700kbps profile and getting a constant throughput of 5500kbps but the LNS reports a throughput rate of 5651176bps so it may be that it's including the L2TP overhead in the rate but need to check.

Re: Affect on speeds of the Plusnet profile

Oldjim — Thu, 25 Apr 2013 16:47:18 GMT

Just give me a shout - either via the forum or by phone

Re: Affect on speeds of the Plusnet profile

Oldjim — Fri, 26 Apr 2013 09:12:21 GMT

I don't know if it is relevant but using the TBB speedtest the burst speed matches the IP profile but the average is the lower figure

Re: Affect on speeds of the Plusnet profile

dave — Tue, 30 Apr 2013 11:51:09 GMT

It might be, I'm looking at a couple of things at the moment to see if I can see what's going on.
I've got a couple of tests in mind to do. Download something and max your line out and do a ping -t to somewhere (DNS should be fine).
I'll think increase the speed profile 100kbps and see what that does to the download and ping, then do it again.
On my line the first step was fine but 2nd the latency increased all over the shop on the ping as the traffic was now being policed by BT not us.

Re: Affect on speeds of the Plusnet profile

Oldjim — Tue, 30 Apr 2013 12:00:31 GMT

As requested
C:\Users\Jim>ping -t ntp.plus.net
Pinging ntp.plus.net [212.159.13.50] with 32 bytes of data:
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Started download
Reply from 212.159.13.50: bytes=32 time=40ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=40ms TTL=250
Reply from 212.159.13.50: bytes=32 time=40ms TTL=250
Reply from 212.159.13.50: bytes=32 time=44ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Download finished - it must have been cached
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=34ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=55ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=38ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Started download
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=56ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=43ms TTL=250
Reply from 212.159.13.50: bytes=32 time=39ms TTL=250
Reply from 212.159.13.50: bytes=32 time=43ms TTL=250
Reply from 212.159.13.50: bytes=32 time=39ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=40ms TTL=250
Reply from 212.159.13.50: bytes=32 time=40ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=45ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=37ms TTL=250
Reply from 212.159.13.50: bytes=32 time=45ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=43ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=38ms TTL=250
Reply from 212.159.13.50: bytes=32 time=37ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=43ms TTL=250
Reply from 212.159.13.50: bytes=32 time=38ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250

Re: Affect on speeds of the Plusnet profile

dave — Tue, 30 Apr 2013 13:46:45 GMT

Ta, I've increased your profile by 100kbps and kicked the PPP session, let's see if you see a little bit more speed but similar latency.

Re: Affect on speeds of the Plusnet profile

Oldjim — Tue, 30 Apr 2013 14:19:21 GMT

Ping test
Download started about when the ping jumped to 64ms
C:\Users\Jim>ping -t ntp.plus.net
Pinging ntp.plus.net [212.159.13.50] with 32 bytes of data:
Reply from 212.159.13.50: bytes=32 time=37ms TTL=250
Reply from 212.159.13.50: bytes=32 time=35ms TTL=250
Reply from 212.159.13.50: bytes=32 time=38ms TTL=250
Reply from 212.159.13.50: bytes=32 time=64ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=70ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=43ms TTL=250
Reply from 212.159.13.50: bytes=32 time=47ms TTL=250
Reply from 212.159.13.50: bytes=32 time=60ms TTL=250
Reply from 212.159.13.50: bytes=32 time=86ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=66ms TTL=250
Reply from 212.159.13.50: bytes=32 time=64ms TTL=250
Reply from 212.159.13.50: bytes=32 time=36ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=77ms TTL=250
Reply from 212.159.13.50: bytes=32 time=48ms TTL=250
Reply from 212.159.13.50: bytes=32 time=44ms TTL=250
Reply from 212.159.13.50: bytes=32 time=44ms TTL=250
Reply from 212.159.13.50: bytes=32 time=73ms TTL=250
Reply from 212.159.13.50: bytes=32 time=47ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=55ms TTL=250
Reply from 212.159.13.50: bytes=32 time=67ms TTL=250
Reply from 212.159.13.50: bytes=32 time=46ms TTL=250
Reply from 212.159.13.50: bytes=32 time=41ms TTL=250
Reply from 212.159.13.50: bytes=32 time=59ms TTL=250
Reply from 212.159.13.50: bytes=32 time=60ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=45ms TTL=250
Reply from 212.159.13.50: bytes=32 time=44ms TTL=250
Reply from 212.159.13.50: bytes=32 time=61ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Reply from 212.159.13.50: bytes=32 time=42ms TTL=250
Speed test results
Today 15:13 3426 kbps (428kB/s) 653 kbps (81.6kB/s)
Today 13:01 3345 kbps (418kB/s) 675 kbps (84.4kB/s)
TBB result with high profile
Previous with normal profile

Re: Affect on speeds of the Plusnet profile

dave — Tue, 30 Apr 2013 14:42:25 GMT

I'll try it at 3700kbps but it may already be set too high at 3600kbps, you've gained a bit of speed on the average but looks like it's hitting the BT policer. Let's see if this is the same as the one at 3600kbps (my line's profile BT side was something like 5798kbps which may explain why I went up two steps before seeing the latency increase).
I think I know what's happening though and the burst seems to be the biggest clue, let's check the result of the next one and I'll explain.

Re: Affect on speeds of the Plusnet profile

Oldjim — Tue, 30 Apr 2013 15:29:22 GMT

C:\Users\Jim>ping -t ntp.plus.net
Pinging ntp.plus.net [212.159.6.9] with 32 bytes of data:
Reply from 212.159.6.9: bytes=32 time=36ms TTL=250
Reply from 212.159.6.9: bytes=32 time=35ms TTL=250
Reply from 212.159.6.9: bytes=32 time=37ms TTL=250
Download started about here
Reply from 212.159.6.9: bytes=32 time=49ms TTL=250
Reply from 212.159.6.9: bytes=32 time=42ms TTL=250
Reply from 212.159.6.9: bytes=32 time=45ms TTL=250
Reply from 212.159.6.9: bytes=32 time=36ms TTL=250
Reply from 212.159.6.9: bytes=32 time=47ms TTL=250
Reply from 212.159.6.9: bytes=32 time=50ms TTL=250
Reply from 212.159.6.9: bytes=32 time=53ms TTL=250
Reply from 212.159.6.9: bytes=32 time=57ms TTL=250
Reply from 212.159.6.9: bytes=32 time=69ms TTL=250
Reply from 212.159.6.9: bytes=32 time=78ms TTL=250
Reply from 212.159.6.9: bytes=32 time=69ms TTL=250
Reply from 212.159.6.9: bytes=32 time=69ms TTL=250
Reply from 212.159.6.9: bytes=32 time=76ms TTL=250
Reply from 212.159.6.9: bytes=32 time=69ms TTL=250
Reply from 212.159.6.9: bytes=32 time=72ms TTL=250
Reply from 212.159.6.9: bytes=32 time=92ms TTL=250
Reply from 212.159.6.9: bytes=32 time=82ms TTL=250
Reply from 212.159.6.9: bytes=32 time=88ms TTL=250
Reply from 212.159.6.9: bytes=32 time=92ms TTL=250
Reply from 212.159.6.9: bytes=32 time=91ms TTL=250
Reply from 212.159.6.9: bytes=32 time=88ms TTL=250
Reply from 212.159.6.9: bytes=32 time=88ms TTL=250
Reply from 212.159.6.9: bytes=32 time=88ms TTL=250
Reply from 212.159.6.9: bytes=32 time=88ms TTL=250
Reply from 212.159.6.9: bytes=32 time=89ms TTL=250
Reply from 212.159.6.9: bytes=32 time=86ms TTL=250

Re: Affect on speeds of the Plusnet profile

dave — Tue, 30 Apr 2013 16:08:13 GMT

Pretty much what I expected.
So here's what I think happens.
1. When the Plusnet profile is equal to or lower than the BT profile
When you download at line speed and max your line out the first pinch point is the profile on the Juniper LNS. This profile is a shaper so when your throughput reaches the shaper rate it will start to buffer some of the packets. It buffers using the priority we've set to the traffic so when you're downloading something (in gold) and pinging (in titanium) it will buffer some of the download but not the ping.
I think the effect of the buffering is making the speed test show a reduction in the result (hence why you get the burst rate at 3.7Mbps on the TBB test).
2. When the Plusnet profile is higher than the BT profile
When you download at line speed and max your line out the first pinch point is the profile on the BT BRAS. The BT BRAS has no concept of what traffic you are doing and so you see the increase in latency on the ping when you're downloading at the same time as it will need to buffer/drop traffic when you get to the line rate but it's indiscriminate as to which it will buffer or drop.
The buffer size is small on the Plusnet network but when I was testing on my line I could see it increasing, and then it continues to release the traffic even after you stop the download if TCP doesn't naturally back off the rate. We tested this out in the lab and the result was that you first got a smoother data rate coming through as TCP would try and match the line rate and the buffer would ensure it came down steadily at that rate but the very buffering to the speed test makes the speed test result look lower because of the way it gets measured.
I've put your profile back to 3500kbps. I'll do a bit more testing to be sure but I'm 99% certain that this is down to how it measures it now because it's being buffered and that's the same thing that our vendor says. I'll see if I can see what the buffer size limits are as that should help explain the maths behind it.

Re: Affect on speeds of the Plusnet profile

Oldjim — Tue, 30 Apr 2013 16:24:52 GMT

Thanks Dave

Re: Affect on speeds of the Plusnet profile

dave — Tue, 30 Apr 2013 16:38:54 GMT

No prob, thanks for helping testing it's that burst result that convinced me.