Thanks McTim. This is helpful.

On Fri, Feb 18, 2011 at 7:17 AM, McTim <dogwallah@gmail.com> wrote:
Hi,

On Wed, Feb 16, 2011 at 12:41 PM, warigia bowman <warigia@gmail.com> wrote:
> Here is a good article on shutdown of net in Egypt.
>
> http://www.nytimes.com/2011/02/16/technology/16internet.html?ref=world
>
> However, I still find it technically confusing. Can the engineers among us
> again please review for the social scientists what happened here precisely?


I can try.

There are 7 layers in the OSI model:

http://www.novell.com/info/primer/art/prim02.gif


>
> Quoting
>
> "One of the government’s strongest levers is Telecom Egypt, a state-owned
> company that engineers say owns virtually all the country’s fiber-optic
> cables; other Internet service providers are forced to lease bandwidth on
> those cables in order to do business.".[ . . . .]


To get access to the rest of the Internet, Egyptian ISPs need a
physical link to other ISPs outside of Egypt.

AFAICS (walu: this means As Far As I Can See), Egypt gov said shut
down at layer 3 or we will shut you down at layers 1 or 2.

>
> "Yet despite this decentralized design, the reality is that most traffic
> passes through vast centralized exchanges — potential choke points that
> allow many nations to monitor, filter or in dire cases completely stop the
> flow of Internet data." .[ .. . . ]


There must be places for ISPs to meet each other to exchange traffic.
these are often called Internet eXchange Points or NAPS, (Network
Access Points).  Shutting down an IXP does not necessarily sever all
connectivity in that country, as providers have international links.
Shutting down an IXP just severs intra-country connections.


>
> "There has been intense debate both inside and outside Egypt on whether the
> cutoff at 26 Ramses Street was accomplished by surgically tampering with the
> software mechanism that defines how networks at the core of the Internet
> communicate with one another, or by a blunt approach: simply cutting off the
> power to the router computers that connect Egypt to the outside world." [ .
> . . . ]

We may never know, as the effect is similar, but some more data here:

http://labs.ripe.net/Members/csquarce/three-case-studies-egyptian-disconnection

--
Cheers,

McTim
"A name indicates what we seek. An address indicates where it is. A
route indicates how we get there."  Jon Postel



--
Dr. Warigia Bowman
Visiting Assistant Professor
American University in Cairo
Global Affairs and Public Policy