[ppml] geo addressing

Rich Emmings rich at nic.umass.edu
Wed Nov 23 10:17:30 EST 2005

On Wed, 23 Nov 2005, Michael.Dillon at btradianz.com wrote:

> I can't understand the benefits to a company of having a
> single prefix as opposed to half a dozen. It's all inside
> their own network anyway.

A number of reasons.  Example: You can more easily recognize your own 
traffic from 'foreign' when applying policy, and router configurations are a 
lot shorter when you only have one or two prefixes to deal with as opposed 
to 15.  A lesser config leads to lesser chance of configuration errors, so 
improves overall reliability.  The usefulness of this depends from org to org.

That said, I tend to prefer two medium chunks to one large one, as when 
things go off base globally with one, a portion of your space stays 
reachable. But in saying I want 2, doesn't mean I want more.

Now, the tension between size of the global tables, and efficient allocation 
to LIR's may vary from being mutually beneficial, to being polar opposites, 
hence existing policy concerning not issuing of address space only for 
administrative convenience.


Since we're still beating Dobbin the deceased, when it comes to multihoming 
for diversity purpose, I want the 2nd system to be as separate as possible. 
2nd city, 2nd routing block, 2nd provider, etc.  More recently Katrina and 
less recently NYC provides some lessons in business continuity over a large 
geo area disaster.  Level 3 and Cogent's little dance speak of the need for 
[true] provider diversity.  Geo based systems provide that 2nd prefix, but 
so does multiple allocation of _any_ kind without the attempt to maintain a 
an optional, secondary hierarchy.  I also catch a strong whiff for the 
possibility of a geo based system making censorship much easier.


That said, your goals concern intra geo area routing, to attempt keep it 
close.  There have been, and are some models which of this.  Example the old 
educational NEARNet and the phoenix of that, the current Boston Gigapop. The 
gigapop is part of I2/Abilene so there are barriers to admission, Traffic in 
the gigapop between member institutions remains local to the area.  Traffic 
outside of the area, but on I2, heads off to other I2 gigapops (or the 
member institution routes it out I1)   It doesn't use geo addressing. 
there's more than another way to solve the problem you want to solve.

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