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Re: [RRG] yetAnotherProposal: AS-number forwarding

Hi Geoff,
 
>Dunno how much all this helps the world other than illustrate (a) that
>AS-based routing is probably too coarse and you may want a finer level
>of granularity in terms of division of forwarding elements and (b) all
>of this is well covered ground.

I think AS-based routing does not necessarily imply that
we have to use just a locator per AS, but the locators'
structure will have to be based on the AS number.
 
(I will use 2-byte AS numbers to better explain this).
 
Let's suppose we want to send traffic to a server A having
an IP address within the "identifier prefix" of a stub AS
connected to a transit provider whose ASN=1. Let's also
suppose that we use the "locator prefix" 240.0.1.0/24 to
send tunneled traffic towards AS1 (second and third bytes
are the AS number). It means that the outer IP address
would be 240.0.1.0.
 
For server B having an IP address in a different "identifier
prefix", AS1 could announce a second "locator prefix", for
example 240.0.1.128/25, so that traffic sent to server B
would be tunneled with the outer IP address 240.0.1.128.
 
And AS1 would announce these two "locator prefixes", namely
240.0.1.0/24 and 240.0.1.128/25, in different ways to the
rest of the Internet.
 
And this exercise can be made finer and finer so that an
"identifier prefix" could be assigned a "locator prefix"
such as 240.0.1.77/32.
 
Therefore AS-based routing can be used with a very fine
level of granularity I think.
 
Regards,
Juanjo
 
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