Affect on speeds of the Plusnet profile

[#1]

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

[#2]

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.

[#3]

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

[#4]

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.

[#5]

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.

[#6]

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

[#7]

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

[#8]

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.

[#9]

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.

[#10]

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

[#11]

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

[#12]

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.

[#13]

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

[#14]

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.

[#15]

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