[Bloat] T-Mobile LTE buffer bloat

[Dave Taht]

On Thu, Oct 31, 2013 at 03:04:23AM +0100, Stefan Alfredsson wrote:
> Hi, Stephen, the list,
> 
> We're running a 3G/4G measurement site at Karlstad university, with
> mobile broadband subscriptions from the four major telecom operators
> in Sweden. I was curious to see how measurements in our network
> would compare to yours, so I did a measurement run with netalyzer.

Groovy!

Can I ask that you try something that can more likely stress
out that bus than netanlyzer? The netperf-wrappers tools 
(notably the tcp_bidirectional and rrul test), use C, rather than java.

There is a reasonably local-to-you netperf rrul server at demo.tohojo.dk. You 
can also easily setup a local one....

netanlyzer doesn't work well above 12Mbits, in particular. Netperf-wrappers
works to 10GigE speeds.

apt-get install python-matplotlib
for that ubuntu version you will need to build netperf 2.6 from scratch,
pulling it down from svn or it's website
compiling with ./configure --enable-demo && make install

git clone https://github.com/tohojo/netperf-wrapper.git
cd netperf-wrapper
sudo python setup.py install

sample command line:

netperf-wrapper -H demo.tohojo.dk -p all_scaled -o mymodem_name.svg \
-t "the modem I'm testing" --disable-log rrul


> 
> To summarize, the measured buffering is well below one second for
> all tests, although the results are not directly comparable since we
> are using directly attached USB modems (Huawei E392 with Ubuntu
> 12.04) 

ubuntu has backported fq_codel as far as 12.04. What kernel are you using?

> instead of a separate router box. However, the numbers might
> be interesting in a more general perspective.

Yes, they are. These are repeatable?

I don't consider "less than 1 second" to be "good". 5ms is good. 
At 250ms seems to be where stuff starts to break...

> 
> Tele2 LTE: Upload 12 Mbit/s, 240 ms buffering, Download > 20
> Mbit/s, buffering not measurable
> http://n1.netalyzr.icsi.berkeley.edu/summary/id=43ca253f-6593-7f837e62-5321-488e-b480
> 
> Tele2 HSPA+: Upload 1.1 Mbit/s, 630 ms buffering, Download > 20
> Mbit/s, 509 ms buffering
> http://n2.netalyzr.icsi.berkeley.edu/summary/id=43ca208a-23052-a0e80cbb-9a7c-44e0-ba88

You'll note here that the buffering goes up as the bandwidth goes down.
This is the inverse of the desired result.

> 
> Telenor LTE: Upload 16  Mbit/s, 190  ms buffering, Download >20
> Mbit/s, 470 ms buffering
> http://n3.netalyzr.icsi.berkeley.edu/summary/id=36ea240d-31617-45bca5e3-53ef-450e-a9bf
> 
> Telenor HSPA+: Upload 3.4 Mbit/s,  200 ms buffering, Download > 14
> Mbit/s, 490 ms buffering
> http://n3.netalyzr.icsi.berkeley.edu/summary/id=36ea240d-31612-c6d0d98d-8bcf-4a03-832d
> 
> Telia LTE: Upload 18 Mbit/s, 140 ms buffering, Download > 20 Mbit/s,
> buffering not measurable
> http://n3.netalyzr.icsi.berkeley.edu/summary/id=36ea240d-31599-1ebc684e-c164-4786-832a
> 
> Telia HSPA+: Upload 1.1 Mbit/s, 630  ms buffering, Download > 20
> Mbit/s, 640 ms buffering
> http://n2.netalyzr.icsi.berkeley.edu/summary/id=43ca208a-22984-40c59ae2-0c36-4e67-9039
> (note similarity with Tele2 HSPA+ - IIUC Tele2 and Telia share the
> 3G network infrastructure)
> 
> Tre LTE: Upload 19 Mbit/s, 150 ms buffering, Download > 20 Mbit/s,
> 98 ms buffering
> http://n3.netalyzr.icsi.berkeley.edu/summary/id=36ea240d-31648-86a273a5-82ae-4929-a634
> 
> Tre HSPA+: Upload 3.5 Mbit/s, 190 ms buffering, Download > 8.6
> Mbit/s, 780 ms buffering
> http://n1.netalyzr.icsi.berkeley.edu/summary/id=43ca253f-6609-3316da33-9ea6-41ca-a8ac
> 
> 
> For reference, I also made a measurement from the same host, but
> using a wired connection over the Swedish university network: Upload
> was measured to > 20 Mbit/s and download to 15 Mbit/s, with no
> measurable buffering.
> http://n1.netalyzr.icsi.berkeley.edu/summary/id=43ca253f-6563-078896ce-dc0a-4333-9119

That was kind of my point. Netanyzler has issues at higher speeds.

Please give the rrul test a shot.

> 
> 
> Regards,
>   Stefan Alfredsson
> 
> 
> 
> On 10/31/13 00:25 , Stephen Hemminger wrote:
> >I got one of these Samsung LTE hotspot.
> >Not surprisingly it has huge bloat and a stupid http proxy
> >that netalyzer claims rewrites images.
> >Bandwidth: Up 1.6 Mbit/sec Down 4.3Mbit/sec
> >Latency: 140ms 0% loss
> >Buffering: Uplink 5100ms Down 1800ms
> >
> >How can the uplink side be so bad! 5 seconds???
> >
> >Might even return it as defective. You can't even add a review on their
> >website. Probably they would end taking down like Apple.
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> >Bloat at lists.bufferbloat.net
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> 
> 
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