Re: [tcmtf] Community Neworks: any idea about them?

Mirko Sužnjević <Mirko.Suznjevic@fer.hr> Fri, 11 October 2013 13:31 UTC

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From: =?iso-8859-2?Q?Mirko_Su=BEnjevi=E6?= <Mirko.Suznjevic@fer.hr>
To: "jsaldana@unizar.es" <jsaldana@unizar.es>, 'Arjuna Sathiaseelan' <arjuna@erg.abdn.ac.uk>
Thread-Topic: [tcmtf] Community Neworks: any idea about them?
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Date: Fri, 11 Oct 2013 13:31:12 +0000
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Subject: Re: [tcmtf] Community Neworks: any idea about them?
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Hello everyone,
While we did get negative feedback on TCP on the IETF meeting in Berlin, I am not sure we should completely discard TCP, especially in the cases in which the Internet connection is very poor and in which many devices/users are using a single connection. Benefits of providing extra bandwidth in these conditions could outweigh the downsides of messing up TCP sometimes. One of the major drawbacks of TCM-TFing TCP was that if we lose a packet comprising multiple TCP flows, all of them will reduce their sending rate at the same time. Maybe in the conditions of relatively poor Internet connectivity which occurs in such networks (especially ones which could be designed for very poor districts aiming to provide basic connectivity) the benefit of providing extra bandwidth would outweigh the downside of messing up TCP sometimes. 
Therefore, I would really like that when we create an implementation of TCM-TF we include TCP as well! In this way we could (presuming that we know the characteristics of the traffic in such networks and characteristics of such links) performs simulations with and without usage of TCM-TF and see whether the results would increase or decrease QoE of the users of such networks.
TCM-TF was created in mind to be reactive and react to congestion in certain parts of the network. In those cases where users require high QoE at the start I concur using TCM-TF on TCP could be problematic. On the other hand, in networks with such bad links it could be employed constantly. As I said with proper implementation and simulation and using proper QoE models we could see how much benefit or degradation we get. Using it only for UDP might yield too little bandwidth savings. Again, it all boils to simulation with proper realistic traffic mixes and seeing how much gain can we get with using only UDP, using both UDP and TCP, and  how much does it impact the QoE of the users. 
To sum it up, I would like us to implement these algorithms and perform simulations on realistic traffic mixes.
Is anyone aware of any available traffic traces from such community networks?
Cheers!
Mirko

-----Original Message-----
From: tcmtf-bounces@ietf.org [mailto:tcmtf-bounces@ietf.org] On Behalf Of Jose Saldana
Sent: Tuesday, October 8, 2013 1:44 PM
To: 'Arjuna Sathiaseelan'
Cc: tcmtf@ietf.org; tsv-area@ietf.org
Subject: Re: [tcmtf] Community Neworks: any idea about them?

Hi, Arjuna,

The idea of multipath TCP sounds interesting. It consists of "inverse multiplexing" with TCP. However, TCM-TF does "multiplexing" with UDP.

What I was thinking is: can these scenarios also fit with TCM-TF? The idea is to compress small-packet flows (VoIP, online games) in order to save bandwidth, when a number of flows share a common path. We have discarded the multiplexing of TCP, because the additional delay may modify the dynamics of TCP.

TCM-TF combines header compression, multiplexing and tunneling, in order to aggregate a number of flows, when a low-bandwidth link is in the path. Thus, bandwidth can be saved and pps can be reduced, at the cost of processing power.

Do you think this case can be found in these kind of networks? In the discussion of TCM-TF in Berlin this summer, some people from Africa were interested, since they think that low-bandwidth links have to be better used.

Thanks!

Jose

> -----Mensaje original-----
> De: tcmtf-bounces@ietf.org [mailto:tcmtf-bounces@ietf.org] En nombre 
> de Arjuna Sathiaseelan Enviado el: martes, 08 de octubre de 2013 11:42
> Para: jsaldana@unizar.es
> CC: tcmtf@ietf.org; tsv-area@ietf.org
> Asunto: Re: [tcmtf] Community Neworks: any idea about them?
> 
> Dear Jose,
>   I would like to take this opportunity to present some of the work we 
> are doing here at Cambridge -
> 
> We are trying to solve the universal service problem in urban areas 
> (where people cannot afford to access the Internet) using existing 
> home broadband networks - home owners who have Internet connections 
> share their Internet connection for free with those who dont have.
> 
> We are currently doing deployments in a deprived area in Nottingham ( 
> see www.publicaccesswifi.org )
> 
> More on the LCDNet initiative is here:
> http://www.cl.cam.ac.uk/~as2330/lcd/index.html
> 
> There are interesting possibilities to do multi-path TCP between
aggregating
> multiple access points and we are exploring that option too.
> 
> The TIER group in berkeley have done quite a lot of nice work with
wireless
> for developing countries:
> tier.cs.berkeley.edu/
> 
> Happy to discuss more :)
> 
> Regards
> Arjuna
> 
> On 8 October 2013 10:24, Jose Saldana <jsaldana@unizar.es> wrote:
> > Hi all.
> >
> >
> >
> > I have recently "discovered" the concept of Community Networks. They 
> > are "large scale, self-organized and decentralized networks, built 
> > and operated by citizens for citizens." They are "also self-owned 
> > and self-managed by community members, self-growing in links, 
> > capacity and
> services provided."
> >
> >
> >
> > A paper explaining them can be found here:
> > http://www.sigcomm.org/ccr/papers/2013/July/2500098.2500108
> >
> >
> >
> > Some examples:
> >
> > http://funkfeuer.at/
> >
> > https://wlan-si.net/
> >
> > http://www.bogota-mesh.org/en
> >
> >
> >
> > I would like to know your opinion about this:
> >
> >
> >
> > do you think this is a good idea?
> >
> >
> >
> > Can they be a good place for developing experiments?
> >
> >
> >
> > I think this can be a good solution for developing countries.
> >
> >
> >
> > In addition, regarding TCM-TF, can they be a new scenario where 
> > traffic optimization could be interesting? I mean, they do not have 
> > too much bandwidth, and they connect to the Internet through a 
> > single link in many cases (a bottleneck). One of the services 
> > considered is
VoIP.
> >
> >
> >
> > Thanks a lot!
> >
> >
> >
> > Jose
> >
> >
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