cancel
Showing results for 
Search instead for 
Did you mean: 

random slow tcp connections

FIXED
legume
Rising Star
Posts: 179
Thanks: 13
Registered: 21-07-2013

random slow tcp connections

By repeatedly testing can anyone else get a tbb speed test that looks like this?

https://www.thinkbroadband.com/speedtest/1513334509787411755

For a couple of weeks now I've had an issue where some single thread tcp downloads will be limited by packet loss specific to that connection. For a close server it equates to 1-3mbit speed wise, slower for a more distant server.

My tbb line monitor shows zero loss.

When a slow connection is running I can start another to the same place and get line speed.

It's just like every nth connection is slow, n being a bit variable but doing some automated netperf tests it's usually between 3 and 8 ish.

I've reproduced with different PCs + OSes and am testing wired.

The fact that while a bad tcp is running I can max with another seems to suggest that it's not my line, when the issue started I had been connected for months, so nothing changed there. Everything has now been power cycled in an attempt to make it go away and I am now on a different ip range.

The nature of the issue means that multiple other users in the house have not even noticed, "normal" internet use is unaffected as pretty much all big downloads multi thread and one out of many tcps running at 2mbit isn't really noticeable when browsing.

It could be some thing my end, I use a little DC PC as a router + ECI modem but the "per tcp" aspect makes it seem like there is some round robin routing going on elsewhere.

 

 

25 REPLIES
Browni
Aspiring Hero
Posts: 2,257
Thanks: 768
Fixes: 45
Registered: 02-03-2016

Re: random slow tcp connections

Have a look at

https://community.plus.net/t5/Fibre-Broadband/Odd-TBB-test/m-p/1393324#M52010

I must have been really bad in a previous life as this was my 3rd ISP in a row that used lithium.
Now you're stuck with me because my new ISP doesn't run a forum Cheesy
legume
Rising Star
Posts: 179
Thanks: 13
Registered: 21-07-2013

Re: random slow tcp connections

Thanks, I recall that very long thread from when it was active. Some results may match, but many seem different. At the time I couldn't reproduce any issue - maybe it's just my turn :-)

 

More detail - it's not just tbb, I can reproduce with netperf to several flent servers in various places.

flent-london.bufferbloat.net

flent-eu.bufferbloat.net

flent-newark.bufferbloat.net

Also downloading eg a linux kernel from local cdn will reproduce.

If a connection is bad, it stays bad, with only slight variation in speed.

Community Veteran
Posts: 2,285
Thanks: 109
Fixes: 4
Registered: 18-02-2013

Re: random slow tcp connections

@legume

I've had a few problems with my uploads dropping to Zero in the last few weeks but I put that down to my Firmware so I thought (?) nothing seen on the single thread uploads though at present. I'll keep on an eye out for it though.

legume
Rising Star
Posts: 179
Thanks: 13
Registered: 21-07-2013

Re: random slow tcp connections

I don't seem have any problem with upload, this is testing to the flent servers that are problematic for downloads.

 

Community Veteran
Posts: 2,285
Thanks: 109
Fixes: 4
Registered: 18-02-2013

Re: random slow tcp connections

I'll have another look a bit later as I'm bogged-down with the kids smashing it atm!

 

Community Veteran
Posts: 2,285
Thanks: 109
Fixes: 4
Registered: 18-02-2013

Re: random slow tcp connections

So just re-visit this, it seems my firmware was the cause of my slight loss to some sites. it was after all a dip of a few mb/s which seemed to be the same if I was testing to Europe of closer so I had to be carefull not to point a finger where not needed.

@legume are you still seeing the same issues ?

legume
Rising Star
Posts: 179
Thanks: 13
Registered: 21-07-2013

Re: random slow tcp connections

Yea I can still reproduce this. It's not bad enough for anyone to have noticed as such, we only really stream youtube which seems to be immune. Other large downloads like game updates are multi threaded and one out of many tcps being slow when browsing is only slightly noticeable.

I did think that recent posts on here WRT streaming issues could be related, but some seem to have other explanations.

My issue is not just peak time.

Testing today with 3 runs of 20x5 second netperf  "hits" on a London server  came back with 0, 3 and 4 out of the 20 bad connections.

We haven't played much over Xmas, but when we have with 3 xboxes all has been OK - maybe UDP is immune - or maybe luck. I notice that using a VPN in another thread solved a streaming speed issue.

On my side of things, I've tested with a direct pppoe from a laptop into my usual ECI modem and then repeated with a Huawei, the issue is unchanged.

 

 

Community Gaffer
Community Gaffer
Posts: 13,289
Thanks: 1,063
Fixes: 86
Registered: 04-04-2007

Re: random slow tcp connections

Managed to replicate this from a line in the office. 

output-tbb-20:2018-01-02 15:54:30 (318 KB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 15:54:47 (4.41 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 15:55:19 (4.42 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 15:55:36 (4.41 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 15:59:00 (4.40 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:01:05 (259 KB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:01:22 (4.41 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:01:39 (4.42 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:05:45 (268 KB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:08:36 (4.41 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:09:10 (4.42 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:09:27 (4.42 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:09:44 (4.40 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-20:2018-01-02 16:12:48 (4.41 MB/s) - '20MB.zip' saved [20971520/20971520]
output-tbb-5:2018-01-02 15:53:25 (4.31 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 15:54:43 (4.29 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 15:55:14 (333 KB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 15:55:31 (4.22 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 15:58:55 (294 KB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 15:59:45 (282 KB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:01:17 (4.22 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:01:35 (4.24 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:04:29 (4.31 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:08:32 (4.31 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:09:05 (301 KB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:09:22 (4.27 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:09:40 (4.27 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-5:2018-01-02 16:12:43 (4.23 MB/s) - '5MB.zip' saved [5242880/5242880]
output-tbb-50:2018-01-02 15:54:41 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 15:54:59 (4.45 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 15:55:30 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 15:58:37 (283 KB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 15:59:27 (1.82 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:01:16 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:01:33 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:04:27 (305 KB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:08:31 (310 KB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:08:48 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:09:21 (4.44 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:09:38 (4.45 MB/s) - '50MB.zip' saved [52428800/52428800]
output-tbb-50:2018-01-02 16:12:42 (288 KB/s) - '50MB.zip' saved [52428800/52428800]


Interestingly, I can't replicate the issue using another line that's routed slightly differently.

Going to do some digging...

Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵

Terranova667
Pro
Posts: 1,277
Thanks: 70
Fixes: 3
Registered: 19-02-2014

Re: random slow tcp connections

I have been noticing this to, when i first run a TBB speed test i get 1-2Mb on single thread if I run it again it will go to the full 40Mb+ that it should be showing, same results for their test files the first time i tried it wouldn't go beyond 1Mbps then when i did it again it jumped to the 5Mbps it should be doing, it's not just TBB that i get this result same goes for other testers and downloads like steam and Playstation downloads.

something weird going on with throughput, hope Bob can spot something it's becoming annoying having to stop and start downloads to get the speed to be where it should be.

 

TBB Test first time run.

 

1514930661688818455-mini

 

 

 

 

 

 

TBB test run again

1514931035728337455-mini

 

 

Browni
Aspiring Hero
Posts: 2,257
Thanks: 768
Fixes: 45
Registered: 02-03-2016

Re: random slow tcp connections

Hmmm...

My Broadband Speed TestMy Broadband Speed TestMy Broadband Speed Test

Classic example of congestion on my line Sad

I must have been really bad in a previous life as this was my 3rd ISP in a row that used lithium.
Now you're stuck with me because my new ISP doesn't run a forum Cheesy
Browni
Aspiring Hero
Posts: 2,257
Thanks: 768
Fixes: 45
Registered: 02-03-2016

Re: random slow tcp connections

Something up somewhere...

 

My Broadband Speed Test

I must have been really bad in a previous life as this was my 3rd ISP in a row that used lithium.
Now you're stuck with me because my new ISP doesn't run a forum Cheesy
Community Gaffer
Community Gaffer
Posts: 13,289
Thanks: 1,063
Fixes: 86
Registered: 04-04-2007

Re: random slow tcp connections

Fix

Right, think we've spotted something.

Couple of links in one of our data centres don't look to be behaving. They've been taken out of service.

@Browni @legume, how do things look now?

Bob Pullen
Plusnet Product Team
If I've been helpful then please give thanks ⤵

legume
Rising Star
Posts: 179
Thanks: 13
Registered: 21-07-2013

Re: random slow tcp connections

Looking good for me now, thanks.

Browni
Aspiring Hero
Posts: 2,257
Thanks: 768
Fixes: 45
Registered: 02-03-2016

Re: random slow tcp connections

Not much difference here

 My Broadband Speed Test

I must have been really bad in a previous life as this was my 3rd ISP in a row that used lithium.
Now you're stuck with me because my new ISP doesn't run a forum Cheesy