Affect on speeds of the Plusnet profile

[#1]

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.

[#2]

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

[#3]

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.

[#4]

Thanks Dave

[#5]

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

[#6]

I actually had to disable Kaspersky to get a sensible result otherwise the http x 6 test came out significantly above my sync speed

[#7]

I agree with oldjim in the first post. See thread here: http://forums.thinkbroadband.com/plusnet/f/4315755-are-plusnet-limit-cap-on-fttc.html?fpart=all
Plusnet should do something about it. The VDSL are worse than ADSL2+ knocked off five meg while the ADSL/ADSL2+ is knocked off one meg

[#8]

No issues here:

Quote

Estimated line speed: There's no speed estimate currently held on your account. Current line speed: 92 Mb

[#9]

^^ That speed is about right 2Meg less than IP Profile for your throughput but your is FTTP. My FTTC is worse 5Meg less than IP Profile for throughput. Something is not right. It should be 2Meg less than IP Profile.

[#10]

AndyH's speed profiles seem to be mismatched (Plusnet 92 / BT 96.54) and the BT speedtest result is higher than the Plusnet profile, which is supposed to be impossible.
In my experience on ADSL, the Plusnet profile reduces the maximum sustainable download speed by about 5%.

[#11]

But FTTP/FTTC should be no different.
What I am trying to show is that I can match my Plusnet Line Speed - I am sure if they increased it to match my IP Profile, I will be able to match that.

[#12]

We know we can match our Plusnet profile - the whole point of this thread is that we can exceed our Plusnet profile.

[#13]

I thought goldenfibre is trying to say that his Plusnet line speed (77.4Mb) matches the BT IP Profile (77.42Mb), but he thinks the Plusnet line speed is actually lower than it displays because he can only get around 72Mb?

[#14]

77.4Mb to get my speed throughput of 72Mb is a massive 5Mb gap lower. It's shouldn't be as it should be around 75Mb (2Mb less than BT IP Profile is accepted but 5Mb less is not accepted)
I got email alert from watch that page on BTW Checker is changed my line estimated speed below:
Changed:
-       FTTC Range A (Clean)    80  79.9  20   19.9 --          Available
-       FTTC Range B (Impacted) 80  71.3  20   17.9 --          Available
... into:
+       FTTC Range A (Clean)    80  77    20   19.9 --          Available
+       FTTC Range B (Impacted) 80  67.3  20   17.9 --          Available
Also Plusnet changed my estimated speed too: before was 79.9Mb but now down to 77Mb
High-speed Broadband
Telephone number:
    **************
Phone exchange:
    CUCKOO OAK
Estimated line speed:
    77Mb (Download speed could vary depending on line conditions. Estimates are the maximum speeds that your phone line can support. These speeds are dependent on the package you choose.) - Checked on 2014-03-22 14:04:28
Current line speed:
    77.4 Mb

[#15]

Just to be 100% clear here.
Are you saying you think the Plusnet Line Speed Limit/Cap is actually lower than it shows?