RE: Tanzanian ISPs move closer to establishing an Internet exchange

["Mark Tinka" <mtinka at africaonline.co.ug>]

About the OFDM, is it sustainable, in the long run? 2.4GHz and the ranges
within it have not been very successful in several parts of Africa, as a
long term WAN service strategy, from the mere fact that many service
providers, ISPs and private businesses/individuals will pretty much hook up
anything that runs on 2.4GHz. It is quite easy to get interference from
competing users, and even GSM networks that will over-power and flatten your
transmissions. Tanzania, Uganda, Kenya, Nigeria, are just a few of the
countries I can name that have experienced these kinds of problems with
wireless.

As for the 5GHz, yes, the issue about regulation can be a daunting one.
Needless to say, the range for both the 2.4GHz and the 5GHz is not very
inviting, when compared to fibre optic. When you compare the SNR and
attenuation properties each carry, over distance, fibre still looks like a
more scalable and sustainable solution.

Now, OFDM on telephone cables, as the research continues to grow, would be a
good idea, but there's quite a limitation amounts of copper in Africa, and
then again compared to fibre, copper may not have that wide a band even 100
years from now.

Now, with fibre, you can go the traditional SDH/SONET protocols that have
been used for a while now. But with DWDM, no need to change fibre cable,
just intelligent boxes at the cable ends and you go from 2.5Gbps to 200Gbps
plus. You can even have separate media formats such as ATM and SONET running
on the same fibre.

All in all, while Africa is trying to battle the digital divide, I don't
think we are in such a rush that we should go for technology that may not
support the user needs in the long run. Do it slow, do it right, would be
the better approach, don't you think?

Regards,

Mark Tinka - CCNA
Network Engineer
Africa Online Uganda
5th Floor, Commercial Plaza
7 Kampala Rd,
Tel:   +256-41-258143
Fax:   +256-41-258144
E-mail: mtinka at africaonline.co.ug
Web:     www.africaonline.co.ug
 

-----Original Message-----
From: owner-afnog at afnog.org [mailto:owner-afnog at afnog.org] On Behalf Of John
Tully
Sent: Tuesday, May 13, 2003 5:10 PM
To: afnog at afnog.org
Subject: Re: Tanzanian ISPs move closer to establishing an Internet exchange



>Against that must be weighed:
>- the cost of getting a circuit to the IX (especially if the local
>   infrastructure is poor-quality copper only, and local leased lines in
>   Africa can be very expensive)

Wireless is the way!  The new OFDM stuff is so fast that you could only 
consider fiber/laser as an alternative.  We will have OFDM (around 55Mb/s 
throughput is common) from 2.4GHz - 2.7GHz (2.5GHz to 2.7GHz are safe 
licensed frequencies) or all the 5GHz range for less than $1000 a side!  Of 
course it depends on the regulations in each country.

>- the cost of extra equipment at the IX

At the EAIF meeting last year it was pointed out that a CISCO for $2000 can 
do the job if you take some good advice on exactly what to buy (also a 
MikroTik router can do it cheaper).

>- the cost of IX administration (shared between members)

Of course you need some clever people like Brian working on it.

>which generally means that you have to get above a certain size before 
>it becomes economically feasible to join an IX.

I don't really know, but most likely the telecom lease line (for backhaul) 
are not coming down so quickly and the usage is surely growing in 
Africa.  So, everyday the economy should become more feasible.

>I don't dispute that IXes are good things. But you should beware 
>exaggeration, as it only weakens the argument. I imagine that if there 
>was $400m being poured down a drain every year, there would be people 
>ready to get their hands on it. Building an IX would be an attractive 
>commercial proposition.

How that was calculated is interesting.  As a former student of economics, 
I don't trust any statistics unless it is accompanied by a detailed 
description of the calculations.  Generally, you can see if you agree with 
the main idea and don't rely on vague statistics.

John
www.mikrotik.com


>Cheers,
>
>Brian.


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