[Ict4d] Moving Network Research group meeting to Wednesday 17June 2:30PM ICT4D meeting room
Brian DeRenzi
bderenzi at cs.uct.ac.za
Mon Jun 15 08:28:31 SAST 2015
Ok, great, I stand corrected. Thanks guys.
Brian
On Mon, Jun 15, 2015 at 8:26 AM Thomas Reitmaier <treitmaier at gmail.com>
wrote:
> Hi networking group,
> The co design group has switched to a fortnightly schedule for the vac, so
> it won't be meeting this week. So as long as we don't run over an hour,
> there won't be any conflict.
>
> Thomas
> ------------------------------
> From: Brian DeRenzi <bderenzi at cs.uct.ac.za>
> Sent: 6/15/2015 8:17 AM
> To: Alette Schoon <A.Schoon at ru.ac.za>; ict4d at cs.uct.ac.za
> Subject: Re: [Ict4d] Moving Network Research group meeting to Wednesday
> 17June 2:30PM ICT4D meeting room
>
> David,
>
> There will be a bit of a space conflict. The codesign meeting runs 2-3p on
> Wednesday and health from 330-430p.
>
> Brian
>
> On Sun, Jun 14, 2015 at 11:18 PM Alette Schoon <A.Schoon at ru.ac.za> wrote:
>
>> Hi David
>>
>> Yes that's better for me too.
>>
>> Alette
>>
>>
>> Quoting David Johnson <djohnson at csir.co.za>:
>>
>> > Hi all
>> >
>> > I only found out today that my kids are also off school on Monday 15
>> > June and I want to move the network research group meeting to
>> > Wednesday 17 June at the same time so I can take some leave tomorrow.
>> >
>> > Would this day and time work for everyone that wanted to attend?
>> >
>> >
>> >
>> > Thanks
>> > David
>> >
>> > ___________________________
>> >
>> > David Johnson
>> > Principal Researcher
>> > Networks and Media group
>> > Meraka, CSIR
>> > Adjunct Senior Lecturer
>> > ICT4D, Computer Science Department
>> > University of Cape Town
>> >
>> >
>> > On Wed, Jun 10, 2015 at 10:21 AM, David Johnson <djohnson at csir.co.za>
>> wrote:
>> >> Hi all
>> >>
>> >> Our next Network Research group meeting should be a pretty lively one.
>> >> We are going to be discussing this very interesting email thread we've
>> >> been having on
>> >>
>> >> - Is DTN dead
>> >> - How to make applications / TCP stacks / operating systems / servers
>> >> developing-world network friendly ... well that was my take on the
>> >> topic of the discsussion
>> >>
>> >> Alette Schoon has been having problems with uploads of audio/video
>> >> from hip-hop artists timing out over mobile networks which resonated
>> >> with some of our current discussions on poor performance of TCP on
>> >> certain operating systems ... so all this is tying together nicely
>> >>
>> >> Alette will be skyping in from Rhodes
>> >>
>> >> Any suggestions for a specific paper(s) to read - Melissa had some
>> >> interesting paper suggestions from Marshini Chetty ... I vote for "Why
>> >> is my internet slow?: making network speeds visible"
>> >>
>> >> All suggestions welcome
>> >>
>> >> David
>> >>
>> >> ___________________________
>> >>
>> >> David Johnson
>> >> Principal Researcher
>> >> Networks and Media group
>> >> Meraka, CSIR
>> >> Adjunct Senior Lecturer
>> >> ICT4D, Computer Science Department
>> >> University of Cape Town
>> >>
>> >>
>> >>
>> >> ---------- Forwarded message ----------
>> >> From: Alette Schoon <A.Schoon at ru.ac.za>
>> >> Date: Wed, Jun 10, 2015 at 9:47 AM
>> >> Subject: Re: [Ict4d] Fwd: Is DTN dead?
>> >> To: Thomas Reitmaier <treitmaier at gmail.com>
>> >> Cc: Melissa Densmore <melissa.r.densmore at gmail.com>, David Johnson
>> >> <djohnson at csir.co.za>, Marion Walton <the.marion.walton at gmail.com>,
>> >> Richard Maliwatu <richardmaliwatu at hotmail.com>
>> >>
>> >>
>> >> Very interesting, Thomas, but I'm afraid I have no idea what it means
>> >> and how this affects the upload. I somehow assumed that the internet
>> >> is totally immaterial, and that as your signal bounces around in
>> >> cyberspace it doesn't really matter where it goes, it's all the same
>> >> for the network. Hopefully you will enlighten me on Monday.
>> >>
>> >>
>> >> Quoting Thomas Reitmaier <treitmaier at gmail.com>:
>> >>
>> >>> Hi Alette,
>> >>> look at the following traceroute, which prints out at the steps (hops
>> in
>> >>> networking speak) and time it takes in milliseconds for me to reach
>> the
>> >>> servers of kasimp3.co.za from my internet access point at home.
>> Don't worry
>> >>> too much about the various numbers, just focus on the domain names.
>> Steps
>> >>> 1-3 show my home router and how it is connected to apartment complex's
>> >>> internet connection. In Steps 4 - 10, you'll notice that my apartment
>> >>> complex is connected to the internet through MTN business. All pretty
>> >>> standard so far. Then it gets interesting: The next hops (11) are in
>> >>> Amsterdam and (12-14) in Phoenix, Arizona (USA).
>> >>>
>> >>> » traceroute kasimp3.co.za
>> >>> traceroute to kasimp3.co.za (69.64.85.104), 64 hops max, 52 byte
>> packets
>> >>> 1 10.0.0.4 (10.0.0.4) 1.731 ms 1.386 ms 1.112 ms
>> >>> 2 hotspot.albionnet.co.za (192.168.1.254) 4.193 ms 35.796 ms
>> 15.092 ms
>> >>> 3 * * *
>> >>> 4 41.181.53.149 (41.181.53.149) 119.075 ms 169.156 ms 140.773 ms
>> >>> 5 ipc-recieve-tb-1a.mtnbusiness.net (41.181.53.150) 86.456 ms
>> 24.188
>> >>> ms 16.527 ms
>> >>> 6 tb-dca-2.za--qux-i.za.mtnbusiness.net (66.8.11.186) 28.924 ms
>> >>> tb-dca-2.za--qux-a.za.mtnbusiness.net (41.181.184.28) 74.133 ms
>> >>> 32.935 ms
>> >>> 7 compj-cpt-1.mtnns.net (196.44.18.2) 23.149 ms 24.591 ms
>> 12.113 ms
>> >>> 8 ls-cr-2--tb-cr-1.uk-b.mtnns.net (196.44.31.113) 159.815 ms
>> 196.263
>> >>> ms 168.846 ms
>> >>> 9 am-cr-1.nl--ls-cr-2.uk-a.mtnns.net (196.44.31.183) 182.104 ms
>> 192.057
>> >>> ms 260.215 ms
>> >>> 10 am-tpr-1.nl--am-cr-1.nl-a.mtn.net (209.212.111.141) 194.530 ms
>> >>> 172.623 ms 213.045 ms
>> >>> 11 xe-4-1-0-135.edge5.amsterdam1.level3.net (212.72.41.89) 172.244
>> ms
>> >>> 201.675 ms 194.240 ms
>> >>> 12 ae-0-11.bar2.phoenix1.level3.net (4.69.148.114) 351.307 ms
>> 325.790 ms
>> >>> *
>> >>> 13 aph-inc.dba.bar2.phoenix1.level3.net (4.28.82.158) 355.671 ms
>> 335.862
>> >>> ms 516.751 ms
>> >>> 14 edge1_cr1.phx.codero.com (216.55.184.98) 370.878 ms 310.218 ms
>> >>> 303.125 ms
>> >>> 15 69.64.66.26 (69.64.66.26) 358.165 ms 342.422 ms 339.437 ms
>> >>> 16 kasimp3.co.za (69.64.85.104) 323.978 ms 395.737 ms 319.839 ms
>> >>>
>> >>>
>> >>> So in effect your participants are uploading their stuff to, and
>> >>> downloading it from, a datacenter in Arizona.
>> >>>
>> >>> Thomas
>> >>>
>> >>>
>> >>>
>> >>> On Tue, Jun 9, 2015 at 5:43 PM, Alette Schoon <A.Schoon at ru.ac.za>
>> wrote:
>> >>>
>> >>>> I would love to write up something, Melissa, especially as our
>> university
>> >>>> now recognizes ComSci conferences in its points system. CHI or
>> AfriCHI
>> >>>> sound like the best option to get it out before anyone scoops me. Any
>> >>>> chance that we could have a 'How to write a ComSci conference paper'
>> >>>> workshop during my next visit in July? What do you think, Marion?
>> >>>>
>> >>>>
>> >>>>
>> >>>> Quoting Melissa Densmore <melissa.r.densmore at gmail.com>:
>> >>>>
>> >>>> I love it - Alette you should write a paper on p2p pedestrian
>> >>>> networks! I
>> >>>>>
>> >>>>> think it's widely understood as something that happens, but there
>> really
>> >>>>> isn't a lot written about it, and it's important that it gets
>> documented
>> >>>>> as
>> >>>>> a phenomenon! It's related to some of the work on intermediaries
>> (of
>> >>>>> which
>> >>>>> there is also not a lot), and as David mentioned there hasn't been
>> a lot
>> >>>>> of
>> >>>>> work on DTNs recently. Would you be interested in writing up
>> something
>> >>>>> for
>> >>>>> CHI2016 (due this september) or CSCW2017 (due probably May next
>> >>>>> year)? Or
>> >>>>> maybe ICTD2016 (due september?) or AfriCHI2016 (due 5 october)
>> >>>>>
>> >>>>> Also related - and in response to David's last email, I've been
>> thinking
>> >>>>> for a while about a paper on appropriate design paradigms for
>> >>>>> applications
>> >>>>> to be developing-world-network friendly. I sort of think of it as
>> POP3 vs
>> >>>>> AJAX mail. It's not that complicated - longer timeouts, no chatty
>> >>>>> mechanism, forgiving of network drops, but I'm not sure how to
>> frame an
>> >>>>> investigation around it. Is the answer really to push everything
>> to a
>> >>>>> gateway rather than getting software developers to be aware of
>> parts of
>> >>>>> the
>> >>>>> Internet that aren't always on and bandwidth unlimited?
>> >>>>>
>> >>>>> Melissa
>> >>>>>
>> >>>>> On Tue, Jun 9, 2015 at 4:20 PM, Thomas Reitmaier <
>> treitmaier at gmail.com>
>> >>>>> wrote:
>> >>>>>
>> >>>>> Thanks Everyone for the interesting questions and discussions!
>> >>>>>>
>> >>>>>>
>> >>>>>> Alette, I think it might be helpful if you could give a few more
>> details
>> >>>>>> on the problems your participants are having. Off the top of my
>> head,
>> >>>>>> these
>> >>>>>> questions will help us direct our discussions:
>> >>>>>>
>> >>>>>> What types of phones are they using? And, if possible, what
>> Operating
>> >>>>>> System version are they running?
>> >>>>>>
>> >>>>>> What cell phone network are they using (e.g. MTN, vodacom)? I'm
>> assuming
>> >>>>>> pre-paid? Are they purchasing data-bundles?
>> >>>>>>
>> >>>>>> What type of network are they connecting to (e.g. 2G, 3G)?
>> >>>>>>
>> >>>>>> What service are they trying to upload to?
>> >>>>>>
>> >>>>>> Are they uploading through an App or through the web browser?
>> >>>>>>
>> >>>>>> What type of content and file sizes?
>> >>>>>>
>> >>>>>>
>> >>>>>> And please do let us know if you'd like to skype into our
>> >>>>>> meeting. I'd be
>> >>>>>> more than happy to set that up.
>> >>>>>>
>> >>>>>> Thomas
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>>
>> >>>>>> On Tue, Jun 9, 2015 at 4:02 PM, David Johnson <djohnson at csir.co.za
>> >
>> >>>>>> wrote:
>> >>>>>>
>> >>>>>> These are great discussions for our next network research group
>> >>>>>>>
>> >>>>>>> meeting - I'll schedule one for Monday 15 June now that our Masi
>> trip
>> >>>>>>> will be moved to Friday 19 June.
>> >>>>>>>
>> >>>>>>> I've been having some conversations about performance issues with
>> some
>> >>>>>>> of my colleagues at CSIR on other devices like XBOX that don't
>> like
>> >>>>>>> high-delay links and even androids apps that have issues ... I
>> sense
>> >>>>>>> there is a lot to uncover at various layers of the stack to really
>> >>>>>>> understand why apps / various browser-based services perform
>> poorly
>> >>>>>>> when the network isn't perfect .. see conversation below...
>> >>>>>>>
>> >>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>
>> >>>>>>>
>> >>>>>>> Hi Kobus - that's interesting. I checked my Android TCP settings
>> and
>> >>>>>>> the TCP receive window is fairly generous
>> >>>>>>>
>> >>>>>>> cat /proc/sys/net/core/rmem_max = 2,097,152 so basically 2MB ...
>> this
>> >>>>>>> would mean on your 5 Mbps link the receive window of your android
>> >>>>>>> phone would only become a bottleneck when your delay is higher
>> than
>> >>>>>>> about 4s.
>> >>>>>>>
>> >>>>>>> Apps sometimes have their own statically defined internal flow
>> >>>>>>> control buffers that don't like high delay - for example you will
>> >>>>>>> notice ssh often has different performance to iperf with high
>> delay
>> >>>>>>> nets - that's because its not very well tuned to high delay ..
>> some of
>> >>>>>>> the phone apps are probably the same. In addition servers also
>> don't
>> >>>>>>> like lots of hanging sockets (they consider a few seconds as a
>> long
>> >>>>>>> time) and kick you off. This was something that was really
>> frustrating
>> >>>>>>> in Zambia - servers would kick you off and you would have to keep
>> >>>>>>> retrying a download with no differential recovery - The TCP
>> connection
>> >>>>>>> actually was surviving but the server threw you off.
>> >>>>>>>
>> >>>>>>> Of course your Microsoft box will suffer from the above + a TCP
>> stack
>> >>>>>>> (I assume it is the same as Windows) not well tuned to the
>> occasional
>> >>>>>>> high delay when the mesh is congested.
>> >>>>>>>
>> >>>>>>> My sense is that every home and village could do with an
>> intelligent
>> >>>>>>> box (connected to your 3G / ADSL ... modem) with the kind of TCP
>> >>>>>>> acceleration and network optimization we see in satellite modems +
>> >>>>>>> local cloud (like our VillageShare/owncloud) for sync which then
>> >>>>>>> intelligently syncs to your favourite cloud service like Dropbox
>> when
>> >>>>>>> your net is not used + allows some level of priority on which
>> folders
>> >>>>>>> must sync immediately (like work docs) or can wait for periods of
>> low
>> >>>>>>> use (e.g. photos / videos etc.) + detecting OS queries for
>> updates /
>> >>>>>>> virus updates triggering a sync to the intelligent box at low
>> usage
>> >>>>>>> period (e.g. night) which then are synced to your device later.
>> >>>>>>>
>> >>>>>>> Something many people also don't know is the importance of
>> throttling
>> >>>>>>> their outbound link to around 90% of the known capacity of the
>> link.
>> >>>>>>> This prevents the outbound being driven to congestion when
>> uploading
>> >>>>>>> (e.g. dropbox sync) and dropping ACKS for web / file downloads -
>> which
>> >>>>>>> can have a massive impact on your incoming capacity. This is
>> >>>>>>> particularly vital on ADSL modems.
>> >>>>>>>
>> >>>>>>> I think there is a business opportunity in an intelligent box
>> like the
>> >>>>>>> one above that will have a place in every home in places in the
>> world
>> >>>>>>> where home connections are not fibre yet and the device could
>> also be
>> >>>>>>> used at a rural village level in the case where connectivity is
>> spread
>> >>>>>>> from a shared gateway.
>> >>>>>>>
>> >>>>>>> There are products for windows e.g. SpeedConnect Internet
>> Accelerator
>> >>>>>>> -
>
>
> [The entire original message is not included.]
>
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