nanog mailing list archives

Re: Selfish routing


From: alex () yuriev com
Date: Sun, 27 Apr 2003 18:22:49 -0400 (EDT)


alex () yuriev com wrote:
But curiously, adding some 
incremental capacity to a network can, under some conditions, actually 
make it worse!

Oh, rubbish.

To alex:  It's not necessary to add a tiny link to the network
to make things worse.  In fact, the actual Braess Paradox example
that roughgarden uses arises from the addition of a high-capacity,
low-latency link in the wrong place.  It presumes the existence of
a smaller capacity path through the network somewhere, but are you
arguing that those paths don't exist?  I can show you a lot of them,
since it's what my software (the aforementioned MIT RON project) is
designed to exploit.  The Internet is full of weird, unexpected paths
when you start routing in ways that the network designers didn't  intend.
And that's what selfish routing _does_.

To those who really dont get what I am saying:


If you do not have enough capacity, the selfish or non-selfish routing does
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                                not matter.
                                ^^^^^^^^^^


99.99999% of network problems are caused by CAPACITY issues be that packet
loss, or routers incapable of dealing with the traffic.


Addressing 0.00001% of problems caused by selfish routing is not going to
make it better. Address the issues that cause 99.99999% of the problems
before addressing 0.00001%


Alex


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