Possible addition tag for the aut-sys object.

[Tony Bates <Tony.Bates@localhost]

Please find enclosed a small propsed additional tag that I would like
to get put into the next and perhaps final round of the documet due out
early next. Also note that so far I have had little feedback on the paper
as it stands. I have already made some changes in terms of cosmetics and 
some of the remaining holes but would still be interested in any comments.

--Tony.

Addition of a "default: " tag to the Proposed "aut-sys" database object.
------------------------------------------------------------------------

Currently, in the paper the method for detailing default routing is by
use of the KEYWORD "DEFAULT" as I call it in the routing policy expression.
However, upon reflection we feel it may be useful to to express this is 
terms of a tag itself. Basically, this details which AS neighbor you choose
to select default routing to.

So the format of the default tag would be.

default: <as-num> <preference>, multiple lines, optional

So for example if you are AS1 with two connections to the outside world,
AS 2 and AS 4.
And generally you take some transit networks in on both paths but select
default for one (say AS 4) and if this goes away use AS 2 as backup this you 
would express it something like this.


                               AS 3
                                 |
                                 |                ---------------
		AS 1------------AS 2-------------(   Global      )
                   |                             (               )
                   |                             ( Internet      )
                   +------------AS 4-------------(_______________) 
                                 |
                                 |
                                 |
                               AS 5

The routing policy description would be as follows:

aut-sys:	AS1
as-in:          AS2 100 AS2 AS3
as-out:		AS2 AS1
as-in:		AS4 100 AS4 AS5
as-out:		AS4 AS1
default:	AS4 100
default:	AS2 150
<administrative stuff >

If equal preferences are given this is also fine but of course the matter is 
purely local as to how this may be implemented. We also make distinction as to
how default is reached (i.e. by  a given network or use of 0.0.0.0, etc) as 
again this is purely a local bi-lateral matter and very much implementation 
dependent.