Bufferbloat - is it bad?
 

I consider my broadband to be working perfectly, it gives me full speed for what i pay for and currently no congestion since moving to an upgraded CMTS.

However after running the DSLreports speedtest i have been getting readings of C,D and F for bufferbloat, is this bad as based on my other graphs below everything appears to be fine apart from the TBB graph, although this is only like that as i am running on 16 downstream channels on my Hub3 since moving to an Arris CMTS and everyone experiences the same result, and i am not sure if it is really causing a problem, unless it is causing the bufferbloat?

https://www.cableforum.co.uk/images/...2016/01/26.png
https://www.cableforum.co.uk/images/...2016/01/28.png
http://www.pingtest.net/result/137917465.png
http://www.thinkbroadband.com/ping/s...14-01-2016.png

Re: Bufferbloat - is it bad?
 

My Sky 80mb fibre has been suffering lately ;) imagine gaming with your kind of connection, must be awful. I'm quite literally amazing at Black Ops 3 I put most of it down to my connection with its 20mb upload.


http://www.thinkbroadband.com/ping/s...16-01-2016.png

Re: Bufferbloat - is it bad?
 

As i said my connection is great, gaming is not an issue, so as in the OP is bufferbloat bad for the technical minded folk here who know the answer? :)

Re: Bufferbloat - is it bad?
 

Bufferbloat increases download and upload speeds (by a minute amount) at the expense of poor responsiveness while maxing out the connection.

If you try gaming or browsing while also downloading or uploading at full speed, you'll notice a lot of lag. If you only ever do one thing at a time on your connection, you won't notice the effect at all.

Bufferbloat has always been bad on VM's network, it's intentional and by design.

Re: Bufferbloat - is it bad?
 

Thanks

Re: Bufferbloat - is it bad?
 

All fine here with VM including bufferbloat

https://www.cableforum.co.uk/images/...2016/01/27.png

Re: Bufferbloat - is it bad?
 

Maybe it is the Hub3 doing it, but the connection itself currently seems 100% fine.

Re: Bufferbloat - is it bad?
 

Mine was same on sh2, sh2ac and the sh3

Re: Bufferbloat - is it bad?
 

No idea here then, atleast the connection seems fine.

Re: Bufferbloat - is it bad?
 

Fine here on the SH3 too https://www.cableforum.co.uk/images/...2016/01/25.png

Re: Bufferbloat - is it bad?
 

All i know is the bufferbloat is on my downstream, upstream is fine, the connection appears perfect though on 16 downstreams, however i was congested when on a different CMTS on 8 downstreams.

Re: Bufferbloat - is it bad?
 

I can only comment on the TBB graph as Bufferbloat is not something that appears to affect my son's gaming while I'm busy doing other stuff.

The TBB graph on the SH2ac in modem mode to an ASUS router showed very low maximum latency. On the other hand, with the SH3 I see the same as Snoopz; perfect performance but higher maximum latency and the same as before low average latency. I'm told by VM that they are looking at this phenomenon.

Re: Bufferbloat - is it bad?
 

My downstream seems to be iffy but upstream tests just tank it massively


https://www.cableforum.co.uk/images/...2016/01/21.png

Re: Bufferbloat - is it bad?
 

Odd. The cable networks usually have bloat on upstream, not downstream.

Re: Bufferbloat - is it bad?
 

When i do that speedtest the bufferbloat can shoot right upto 1200ms by the end of the test for download, however when doing upload it stays lowish at around 20ms if i remember, not at home so cant check.

Re: Bufferbloat - is it bad?
 

https://www.youtube.com/watch?v=F1a-eMF9xdY

http://www.cablelabs.com/how-docsis-...ue-management/

http://www.cablelabs.com/wp-content/...QM_May2014.pdf

Re: Bufferbloat - is it bad?
 

I've never understood the concept of downstream buffer bloat. The data arriving is passed straight to the destination device.

Maybe something to do with e.g. A 200 meg circuit but a 100 meg link to the device - there would be some buffering if the arrival rate is 200 meg but then in TCP, semaphores between destination & source would start/stop data flow. Something like that.

Re: Bufferbloat - is it bad?
 

Just done another test, the connection gave me full speed at 156mbit, download bufferbloat rose to +1100ms, upload bufferbloat stays between +3ms to +23ms although right at the very end for a split second it did rise to +239ms but this doesn't always happen.

But as already said, i think my connection works perfectly since i was moved to 16 downstream channels on a new Arris CMTS, i am not sure if i was getting bufferbloat on my old CMTS.

It would be nice to know why some people see bufferbloat on VM and others don't though. I was originally Cambridge Cable before NTL/VM took it over if that makes any difference.

Re: Bufferbloat - is it bad?
 

Snoopz, I think that DSLReports are confusing the hell out of customeers.

Your downstream is VM's upstream. It seems to me that any bufferbloat they claim to detect when testing downstream speed (how do they detect it?) is in VM's transmission path.

Re: Bufferbloat - is it bad?
 

The bloat's tested by monitoring latency during the upload and download sections of the tests and comparing to baseline, Seph.

Re: Bufferbloat - is it bad?
 

Are we saying the DSLreorts are miss reporting my connection bloat? Are there any alternatives to a bloat test i can do?

Re: Bufferbloat - is it bad?
 

So it's simply latency re-branded as bufferbloat to scare the hell out of peops.

Re: Bufferbloat - is it bad?
 

It's measuring how latency changes under load. That is the definition of buffer bloat. How long a ping can spend stuck behind the other traffic, in a buffer, before it gets dropped.

Re: Bufferbloat - is it bad?
 

To what end? Is there any VOIP problem in your circuit? Any gaming difficulty? If not, I think you're chasing shadows. I'm open to stand corrected, of course.

Re: Bufferbloat - is it bad?
 

As far as i know i have no problem.

Re: Bufferbloat - is it bad?
 

Since it is non-ping traffic that matters, the low priority ping has to wait. What's the big deal here? Of course latency changes under load. Realms of ...

Re: Bufferbloat - is it bad?
 

Re: Bufferbloat - is it bad?
 

The downstream bloat test is totally meaningless, the way I see it. As load grows (towards all destinations from the CMTS), so does latency and pings get relegated. What's the big deal?

Re: Bufferbloat - is it bad?
 

On things like Superhubs and the CMTS that feed them the ping doesn't have any priority, low or otherwise. Everything is treated equally.

CMTS sending pings to end users treats it with the same priority as other traffic. The big routers only prioritise traffic that has them as the destination unless told otherwise.

Control plane versus forwarding plane. Traffic for router takes control plane, traffic passing through router forwarding plane.

Re: Bufferbloat - is it bad?
 

How would these result be impacted by Weighted Fair Queuing though?

In that case I'd guess the bloat measurement would start high and then reduce as the data payload packets get deprioritised.

Re: Bufferbloat - is it bad?
 

As far as I know they wouldn't. The queueing is simple FIFO on the CMTS cards.

Re: Bufferbloat - is it bad?
 

Both the DSLReports and TBB graphs agree. You're seeing big lag/latency from time to time. This is Bufferbloat - the undesirable latency that comes from a router or other network equipment buffering too much data.

Bufferbloat makes VoIP calls get bad, gaming gets laggy, and general web browsing gets sticky. You'll see it whenever there's traffic competing to be sent on the link. If your home router is buffering too much data, you'll see upload bloat, and if your ISP's headend/equipment is buffering too much data you'll see it on the download.

Most people think, "Oh yes, someone else is using the internet now, so things will be slow."

But it doesn't have to be - this is a solved problem. The fq_codel algorithm in OpenWrt, Linux kernels, and many commercial routers means that you can upload and download files while gaming and doing VoIP without any bad effect. (DOCSIS 3.1 cable modems also offer an effective anti-bloat system.)

As for measuring Bufferbloat, the DSLReports system uses websocket request/responses to measure the latency *during* the transfers to see how much lag is induced when transferring files. If DSLReports says there's latency, it's there.

The Bufferbloat team has a short article, "What to do about Bufferbloat?" at http://www.bufferbloat.net/projects/...ut_Bufferbloat

Re: Bufferbloat - is it bad?
 

Run a comparison between the single-threaded and multi-threaded TBB tests over ethernet.

Single threaded: http://labs.thinkbroadband.com/speed...gaUEKWiwklw392

Multi-threaded: http://labs.thinkbroadband.com/speedtest/

My bufferbloat results below for the Hub 3.0.

Single-threaded:

https://www.cableforum.co.uk/images/local/2016/01/4.jpg

Multi-threaded:

https://www.cableforum.co.uk/images/local/2016/01/5.jpg

As you can see, a big difference in downstream bufferbloat depending on number of threads/connections utilised, as expected.

You may want/need to run the tests several times, as these flash tests can suffer from spikes in data coming from the network card.

Re: Bufferbloat - is it bad?
 

These results are with HUB3 and 16 downstreams, what do you make of it and do you think my upstream looks strange, maybe it is the wrong time of the day to do it? I did speedtest.net too and it gave a far smoother download.

Single threaded.
http://www.cableforum.co.uk/board/at...1&d=1454011132

Multi threaded.
http://www.cableforum.co.uk/board/at...1&d=1454011132

Re: Bufferbloat - is it bad?
 

I don't see anything strange in the upload.

What you're seeing in the upload is the buffering in your router. On my speed test, it peaks/bursts at 14.4 meg - so that has to be into a buffer en route to TBB.

Re: Bufferbloat - is it bad?
 

I just want to leave this here. My "200mbit" connection:

https://www.cableforum.co.uk/images/local/2016/01/8.png

:(

Re: Bufferbloat - is it bad?
 

Yes, there are a few other tests.

• MUD_Wizard suggests trying single or multiple streams.
  
• You could post the link to your DSLReports tests - there's a lot of info there...
  
• For a "down in the details" test, you could run a ping test while using any of the other speed tests. Just start a ping to a well-connected host (say, google.com), then start the speed test.

Re: Bufferbloat - is it bad?
 

Re: Bufferbloat - is it bad?
 

I agree. These tests don't really mean anything except maybe for braggin' rights. The primary question is whether your network performance is good enough.

Do you get the speed you're paying for? Does it let you do anything you want, anytime you want? Does gaming work great (no lag) and do your voice calls sound OK? Is that true even when someone else is up/downloading files? If so, then you're golden. Your network is doing fine.

But... If high traffic (streaming/torrenting) screws up your connection - you get lagged out, browsing feels sticky, voip is terrible - then you need to find out why.

Most speed tests only tell about... speed. They give a quick ping time measurement, but only when the line's idle. They don't measure latency *during* the download and upload. That's why the Bufferbloat test at www.dslreports.com/speedtest is so cool. It can put numbers to the lag: if it's OK, then you can look elsewhere.

I know how to fix it - my net at home works great. It's simple, but needs a little attention.

Re: Bufferbloat - is it bad?
 

Shouldn't be. Absolutely no reason for the Hub to hold onto anything downstream, it should be getting shot of packets as soon as processing is done. Exception to that being where wireless connection is slower than broadband connection.

If the Hub is holding onto TCP traffic for excessive periods WoW and Starcraft 2 players are going to be very upset by it. If it's trying to be too clever with TCP likewise they aren't going to be happy.