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Throughput riddle

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  Throughput riddle Celejar <celejar@gmail.com> - 2016-03-18 17:50 +0100
    Re: Throughput riddle "John L. Ries" <jries@salford-systems.com> - 2016-03-18 19:50 +0100
      Re: Throughput riddle "John L. Ries" <jries@salford-systems.com> - 2016-03-18 20:30 +0100
        Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-18 20:40 +0100
      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-18 20:40 +0100
    Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-19 02:10 +0100
      Re: Throughput riddle Richard Hector <richard@walnut.gen.nz> - 2016-03-19 02:50 +0100
        Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-19 03:10 +0100
          Re: Throughput riddle Richard Hector <richard@walnut.gen.nz> - 2016-03-19 03:50 +0100
            Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-19 04:50 +0100
            Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-20 14:20 +0100
      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-20 14:20 +0100
        Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-20 17:40 +0100
          Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-20 19:10 +0100
            Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-20 21:50 +0100
              Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-21 03:20 +0100
                Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-21 06:00 +0100
                  Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-22 05:30 +0100
                    Re: Throughput riddle David Christensen <dpchrist@holgerdanske.com> - 2016-03-24 02:50 +0100
                      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-24 04:10 +0100
    Re: Throughput riddle arian <debian@semioptimal.net> - 2016-03-20 14:50 +0100
      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-20 15:50 +0100
        Re: Throughput riddle arian <debian@semioptimal.net> - 2016-03-20 16:30 +0100
          Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-20 18:40 +0100
          Re: Throughput riddle Andrew McGlashan <andrew.mcglashan@affinityvision.com.au> - 2016-03-20 19:50 +0100
    RE: Throughput riddle Bonno Bloksma <b.bloksma@tio.nl> - 2016-03-21 12:50 +0100
      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-22 05:40 +0100
    Re: Throughput riddle Dan Purgert <dan@djph.net> - 2016-03-21 13:30 +0100
      Re: Throughput riddle Celejar <celejar@gmail.com> - 2016-03-22 05:50 +0100
        Re: Throughput riddle David <david.g_jones@ntlworld.com> - 2016-03-22 11:20 +0100
          RE: Throughput riddle Bonno Bloksma <b.bloksma@tio.nl> - 2016-03-22 13:40 +0100

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#165684

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> Here's the part that baffles me - these are with the laptop connected
> to the router wirelessly:
> 
> Laptop - router:	~11.8 Mbps
> Laptop - NAS:		~14.7 Mbps
> 
> Once again, these numbers vary widely, but are in line with the laptop
> - router numbers.
> 
> But here's the kicker: Ookla's speedtest (run on the laptop with
> speedtest-cli) shows 29.01/5.89 (d/u), and this is fairly consistent.

Just checking: you're not runnging iperf bidriectional, right? WiFi is half duplex, in general for radio it's extremely difficult to achieve full duplex when you don't have separate uplink/downlink carriers.
In that case you need to double your figures, and you'd get something compatible with the speedtest results.

regards, arian

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#165694

On Sun, 20 Mar 2016 14:43:00 +0100
arian <debian@semioptimal.net> wrote:

> 
> > Here's the part that baffles me - these are with the laptop connected
> > to the router wirelessly:
> > 
> > Laptop - router:	~11.8 Mbps
> > Laptop - NAS:		~14.7 Mbps
> > 
> > Once again, these numbers vary widely, but are in line with the laptop
> > - router numbers.
> > 
> > But here's the kicker: Ookla's speedtest (run on the laptop with
> > speedtest-cli) shows 29.01/5.89 (d/u), and this is fairly consistent.
> 
> Just checking: you're not runnging iperf bidriectional, right? WiFi is half duplex, in general for radio it's extremely difficult to achieve full duplex when you don't have separate uplink/downlink carriers.
> In that case you need to double your figures, and you'd get something compatible with the speedtest results.

No - I've been using the default: 'iperf -c hostxxxx' on laptop, 'iperf
-sD' on router, NAS.

Actually, this morning I've been getting about 17-20 Mbps between the
laptop and NAS. I tried bidirectional testing ('iperf -d -c hostxxxx',
and the results actually remained constant.

I'm still getting only about 13 Mbps between the laptop and router.

> regards, arian

Celejar

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#165701

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> No - I've been using the default: 'iperf -c hostxxxx' on laptop, 'iperf
> -sD' on router, NAS.
> 
> Actually, this morning I've been getting about 17-20 Mbps between the
> laptop and NAS. I tried bidirectional testing ('iperf -d -c hostxxxx',
> and the results actually remained constant.

That sound weird. Can you check by means of tcpdump, wireshark or similar wether packages are actually only hitting the air once?

another simple bandwidth check:
# host1: nc -l 8090 > /dev/zero
# host2: dd if=/dev/zero | nc host1 8090

bidirectional version:
# host1: nc -l 8090 > /dev/zero
# host2: nc -l 8090 | nc host1 8090
# host1: dd if=/dev/zero | nc host2 8090

kill the last after a while

with that I get very consistent 2.7 MB/s unidirectional, 1.4 MB/s bidirectional

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#165705

On Sun, 20 Mar 2016 16:22:58 +0100
arian <debian@semioptimal.net> wrote:

> 
> > No - I've been using the default: 'iperf -c hostxxxx' on laptop, 'iperf
> > -sD' on router, NAS.
> > 
> > Actually, this morning I've been getting about 17-20 Mbps between the
> > laptop and NAS. I tried bidirectional testing ('iperf -d -c hostxxxx',
> > and the results actually remained constant.
> 
> That sound weird. Can you check by means of tcpdump, wireshark or similar wether packages are actually only hitting the air once?

I'm not very skilled with wireshark, but I tried it. I see lots of
packets with frame length 1514 (data length 1448) between the source
and destination, interspersed with many 66 byte frame length packets
between the dest and source (with no data). I suppose the former is the
iperf payload data, and the latter is just TCP/IP acknowledgments. What
should I be looking for, exactly?

Okay. More tests - currently the iperf tests are showing 17-20 Mbps
laptop - NAS, 14-16 Mbps laptop - router (even with '-d').

> another simple bandwidth check:
> # host1: nc -l 8090 > /dev/zero
> # host2: dd if=/dev/zero | nc host1 8090

2.0, 2.3, 2.4 and 2.5 Mbps laptop - NAS. Pretty much in line with the
ones above.

> bidirectional version:
> # host1: nc -l 8090 > /dev/zero
> # host2: nc -l 8090 | nc host1 8090
> # host1: dd if=/dev/zero | nc host2 8090
> 
> kill the last after a while
> 
> with that I get very consistent 2.7 MB/s unidirectional, 1.4 MB/s bidirectional

I must be doing something wrong with the last - it just exists
immediately, no error and no output. I think I understand the command
syntax, and it makes sense to me, but it just doesn't work. I feel like
I'm missing something obvious.

Sorry if I'm being dense, thanks for the help,

Celejar

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#165713

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Hi

On 21/03/2016 2:22 AM, arian wrote:
> another simple bandwidth check:
> # host1: nc -l 8090 > /dev/zero
> # host2: dd if=/dev/zero | nc host1 8090


Okay, I'm trying the following.

On host 1
# ssh -f name-in-config -L 18090:localhost:8090 'nc -l 8090 > /dev/zero'

The "name-in-config" is setup in ~/.ssh/config file with host and port,
direct login with the name works perfectly.



The remote end [host 2] is running nc, I can see it via a different login.

root 21335 21333 0 05:38 ? 00:00:00 bash -c nc -l 8090 > /dev/zero


Back to host 1....

# dd if=/dev/zero | nc localhost 18090
channel 3: open failed: connect failed: Connection refused

Why do I get a connect failed on this?


Kind Regards
AndrewM

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#165765

Hi,

Responding to one part of your mail. The other parts have been covered in other responses:

> I was originally using one of the common 1/6/11 channels, and I switched to 3 since I saw a lot of other stations on those channels.
> This may have resulted in some improvement, but I'm still stuck locally as above.

Be aware that by doing this you have created interference with even more wifi networks then before. See https://en.wikipedia.org/wiki/List_of_WLAN_channels
If you select just channel 1, 6 or 11 you will have only interference with other networks on that one channel. By selecting an "in between" channel 3 you now have interference from both the channel 1 and the channel 6 networks.
Usually best is to see where the weakest networks are, on 1, 6 or 11 and place your wifi there.  

In the 5GHz band there a lot more non overlapping channels and because of the lower reach the chance of interference is lower as well. However, because of that you might need more transmitters as well.

Bonno Bloksma

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#165812

On Mon, 21 Mar 2016 11:41:05 +0000
Bonno Bloksma <b.bloksma@tio.nl> wrote:

> Hi,
> 
> Responding to one part of your mail. The other parts have been covered in other responses:
> 
> > I was originally using one of the common 1/6/11 channels, and I switched to 3 since I saw a lot of other stations on those channels.
> > This may have resulted in some improvement, but I'm still stuck locally as above.
> 
> Be aware that by doing this you have created interference with even more wifi networks then before. See https://en.wikipedia.org/wiki/List_of_WLAN_channels
> If you select just channel 1, 6 or 11 you will have only interference with other networks on that one channel. By selecting an "in between" channel 3 you now have interference from both the channel 1 and the channel 6 networks.
> Usually best is to see where the weakest networks are, on 1, 6 or 11 and place your wifi there.  
> 
> In the 5GHz band there a lot more non overlapping channels and because of the lower reach the chance of interference is lower as well. However, because of that you might need more transmitters as well.

I'm curious about this. I see that lots of sites claim this to be the
correct approach to channel selection, apparently based largely on a
Cisco articlef rom 2004:

http://web.archive.org/web/20150502223736/http://www.cisco.com/c/en/us/td/docs/wireless/technology/channel/deployment/guide/Channel.html

OTOH, some argue that these results are mainly relevant to enterprise
contexts, but less so to typical consumer environments:

http://superuser.com/questions/443178/is-it-better-to-use-a-crowded-2-4ghz-wi-fi-channel-1-6-11-or-unused-3-4-8

Everyone explains the theory as you've given it, and I suppose it makes
sense, but theory is no substitute for actual empirical evidence. I
suppose that for best results, I would have to benchmark throughput
across my links while on different channels. And even if I get better
throughput on 3, I'd still have to consider whether it's worth it, in
light of possible negative effects to my neighbors.

Thanks,

> Bonno Bloksma

Celejar

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#165766

On 2016-03-18, Celejar <celejar@gmail.com> wrote:
> Hi,
>
> I'm trying to understand the throughput across the different links of
> my little home network, and am perplexed by the measured wireless
> throughput.
>
> The three main devices I'm interested in:
>
> Router: Buffalo WZR-HP-G300NH running OpenWrt (Chaos Calmer 15.05).
> Gigabit WAN and LAN, 802.11bgn wireless.

I know I'm coming to the party a bit late, and it's probably been
answered somewhere else in the posts here, but what channel width are
you running here?

If you're running 40 MHz, you WILL be getting combined Co-channel
contention from all other devices on channels 1 and 6 (or 6 and 11).
With 2.4 GHz connections, it's advisable to stick to 20 MHz channels, to
limit the amount of contention you're getting.

>
> [...]
>
> Here's the part that baffles me - these are with the laptop connected
> to the router wirelessly:
>
> Laptop - router:	~11.8 Mbps
>
> These numbers actually exhibit significant variance, but they're
> generally at least this much, and at most about 15-20 Mbps.
>
> Laptop - NAS:		~14.7 Mbps
>
> Once again, these numbers vary widely, but are in line with the laptop
> - router numbers.
>
> But here's the kicker: Ookla's speedtest (run on the laptop with
> speedtest-cli) shows 29.01/5.89 (d/u), and this is fairly consistent.
>
> [...]
>
> So the wireless link can apparently push at least 30 Mbps or so, so why
> are my local wireless throughput numbers so much lower?

Given that the router is a 2x2 device, have you tried sending multiple
streams with iperf (with the "-P" client option)?  As I (likely,
incorrectly) recall, iperf defaults to one stream, whereas speedtest
will run multiple streams.

>
> I was originally using one of the common 1/6/11 channels, and I switched
> to 3 since I saw a lot of other stations on those channels. This may
> have resulted in some improvement, but I'm still stuck locally as
> above. What's the explanation for this - how can I possibly be getting
> much better throughput to servers tens of miles away than to my local
> stations? Does iperf somehow work fundamentally differently from
> speedtest? If so, which is a better representation of actual throughput?

Switch back to 1, 6, or 11 (and a 20 MHz channel).  As others have
explained, being on an "in-between" channel will result in you getting
actual interference (rather than simply co-channel contention) ... not
to mention causing interference for your neighbors.

It might be a good idea to upgrade to a dual-band access point, so that
you can use 5 GHz, which is typically has much cleaner channels.

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#165813

On Mon, 21 Mar 2016 12:15:56 -0000 (UTC)
Dan Purgert <dan@djph.net> wrote:

> On 2016-03-18, Celejar <celejar@gmail.com> wrote:
> > Hi,
> >
> > I'm trying to understand the throughput across the different links of
> > my little home network, and am perplexed by the measured wireless
> > throughput.
> >
> > The three main devices I'm interested in:
> >
> > Router: Buffalo WZR-HP-G300NH running OpenWrt (Chaos Calmer 15.05).
> > Gigabit WAN and LAN, 802.11bgn wireless.
> 
> I know I'm coming to the party a bit late, and it's probably been
> answered somewhere else in the posts here, but what channel width are
> you running here?
> 
> If you're running 40 MHz, you WILL be getting combined Co-channel
> contention from all other devices on channels 1 and 6 (or 6 and 11).
> With 2.4 GHz connections, it's advisable to stick to 20 MHz channels, to
> limit the amount of contention you're getting.

Running at 20 MHz.

> > [...]
> >
> > Here's the part that baffles me - these are with the laptop connected
> > to the router wirelessly:
> >
> > Laptop - router:	~11.8 Mbps
> >
> > These numbers actually exhibit significant variance, but they're
> > generally at least this much, and at most about 15-20 Mbps.
> >
> > Laptop - NAS:		~14.7 Mbps
> >
> > Once again, these numbers vary widely, but are in line with the laptop
> > - router numbers.
> >
> > But here's the kicker: Ookla's speedtest (run on the laptop with
> > speedtest-cli) shows 29.01/5.89 (d/u), and this is fairly consistent.
> >
> > [...]
> >
> > So the wireless link can apparently push at least 30 Mbps or so, so why
> > are my local wireless throughput numbers so much lower?
> 
> Given that the router is a 2x2 device, have you tried sending multiple
> streams with iperf (with the "-P" client option)?  As I (likely,
> incorrectly) recall, iperf defaults to one stream, whereas speedtest
> will run multiple streams.

Just tried a few runs with "-P 2" - no difference.

> > I was originally using one of the common 1/6/11 channels, and I switched
> > to 3 since I saw a lot of other stations on those channels. This may
> > have resulted in some improvement, but I'm still stuck locally as
> > above. What's the explanation for this - how can I possibly be getting
> > much better throughput to servers tens of miles away than to my local
> > stations? Does iperf somehow work fundamentally differently from
> > speedtest? If so, which is a better representation of actual throughput?
> 
> Switch back to 1, 6, or 11 (and a 20 MHz channel).  As others have
> explained, being on an "in-between" channel will result in you getting
> actual interference (rather than simply co-channel contention) ... not
> to mention causing interference for your neighbors.
> 
> It might be a good idea to upgrade to a dual-band access point, so that
> you can use 5 GHz, which is typically has much cleaner channels.

Thanks. See my other response in the thread regarding channel selection.

Celejar

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#165817

On Tue, 2016-03-22 at 00:45 -0400, Celejar wrote:
> On Mon, 21 Mar 2016 12:15:56 -0000 (UTC)
> Dan Purgert <dan@djph.net> wrote:
> 
> > On 2016-03-18, Celejar <celejar@gmail.com> wrote:
> > > Hi,
> > >
> > > I'm trying to understand the throughput across the different links of
> > > my little home network, and am perplexed by the measured wireless
> > > throughput.
> > >
> > > The three main devices I'm interested in:
> > >
> > > Router: Buffalo WZR-HP-G300NH running OpenWrt (Chaos Calmer 15.05).
> > > Gigabit WAN and LAN, 802.11bgn wireless.
> > 
> > I know I'm coming to the party a bit late, and it's probably been
> > answered somewhere else in the posts here, but what channel width are
> > you running here?
> > 
> > If you're running 40 MHz, you WILL be getting combined Co-channel
> > contention from all other devices on channels 1 and 6 (or 6 and 11).
> > With 2.4 GHz connections, it's advisable to stick to 20 MHz channels, to
> > limit the amount of contention you're getting.
> 
> Running at 20 MHz.
> 
> > > [...]
> > >
> > > Here's the part that baffles me - these are with the laptop connected
> > > to the router wirelessly:
> > >
> > > Laptop - router:	~11.8 Mbps
> > >
> > > These numbers actually exhibit significant variance, but they're
> > > generally at least this much, and at most about 15-20 Mbps.
> > >
> > > Laptop - NAS:		~14.7 Mbps
> > >
> > > Once again, these numbers vary widely, but are in line with the laptop
> > > - router numbers.
> > >
> > > But here's the kicker: Ookla's speedtest (run on the laptop with
> > > speedtest-cli) shows 29.01/5.89 (d/u), and this is fairly consistent.
> > >
> > > [...]
> > >
> > > So the wireless link can apparently push at least 30 Mbps or so, so why
> > > are my local wireless throughput numbers so much lower?
> > 
> > Given that the router is a 2x2 device, have you tried sending multiple
> > streams with iperf (with the "-P" client option)?  As I (likely,
> > incorrectly) recall, iperf defaults to one stream, whereas speedtest
> > will run multiple streams.
> 
> Just tried a few runs with "-P 2" - no difference.
> 
> > > I was originally using one of the common 1/6/11 channels, and I switched
> > > to 3 since I saw a lot of other stations on those channels. This may
> > > have resulted in some improvement, but I'm still stuck locally as
> > > above. What's the explanation for this - how can I possibly be getting
> > > much better throughput to servers tens of miles away than to my local
> > > stations? Does iperf somehow work fundamentally differently from
> > > speedtest? If so, which is a better representation of actual throughput?
> > 
> > Switch back to 1, 6, or 11 (and a 20 MHz channel).  As others have
> > explained, being on an "in-between" channel will result in you getting
> > actual interference (rather than simply co-channel contention) ... not
> > to mention causing interference for your neighbors.
> > 
> > It might be a good idea to upgrade to a dual-band access point, so that
> > you can use 5 GHz, which is typically has much cleaner channels.
> 
> Thanks. See my other response in the thread regarding channel selection.
> 
> Celejar
> 
Also remember you can have too much RF power in your transmitter, as
well as your neighbours overloading your system, you could be
overloading your own.

Try turning down the transmitters power.

David.

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#165825

Hi,

[...]
>>> It might be a good idea to upgrade to a dual-band access point, so 
>>> that you can use 5 GHz, which is typically has much cleaner channels.
>>
>> Thanks. See my other response in the thread regarding channel selection.
>> 
>> Celejar
>> 
> Also remember you can have too much RF power in your transmitter, as well
> as your neighbours overloading your system, you could be overloading your own.
> 
> Try turning down the transmitters power.

That might indeed be a good idea because....
Another misconception that people do not take into account when increasing the power on the WiFi transmitter.... Although the transmitter can use a higher power setting and the clients can see the WiFi base tramsmitter, that does not mean the clients will use a higher setting. Therefore the base station might not hear the client.
A lot of WiFi networks had to be "redesigned" when taking into account that a mobile phone uses a lot less power, usually aroud 60% of a laptop. Before the redesign a lot of times there would be failed communications a.k.a. noise when the WiFi base did not correctly hear the client, the client resending creating more noise, etc., degrading WiFi performance for all nearby devices.

This can happen at home too. There is not really a difference in "Enterprise WiFi" and "SOHO WiFi" when you look at those parts. In just means that in Enterprise WiFi there is interference inside the corporate building, so it is the same company who is having the problems as the one that is causing them. With SOHO WiFi there is interference between you and your neighbours. Whether you care depends on whether you like them or if maybe because of your interference they are getting bigger / better WiFi transmitters as well and THEN bother you? ;-)
It is best to adhere to "researched best practices" I think.

Bonno Bloksma

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