Re: [Idr] draft-rosen-idr-aigp-00

[Robert Raszuk <[e-mail]>]

Hi Jeff,

>> * I think that making new attribute is clean indeed, but a bit risky to 
>> touch your best path selection algorithm each time new attribute is 
>> invented to influence best path decision.
 >
> How do you propose to make the algorithm aware of future attributes that
> have not been invented yet?  If I want to do bestpath decision based on
> who has the coolest ASCII-art in their advertisement, just assuming that
> I have an army of stick-man art critics in my basement, how can you
> write spec or software to anticipate that need until I thought of it?

http://tools.ietf.org/html/draft-retana-bgp-custom-decision-00

    This document defines a new Extended Community [EXT_COMM], called the
    Cost Community, which may be used in tie breaking during the best
    path selection process.  The end result is a local custom decision
    process.

...

    The network administrator may use the Cost Community to assign a
    value to a path originated or learned by a peer in any part of the
    local domain. The Point of Insertion may also be specified using the
    values defined in the IANA registry [BGP_PAR] or this document.

    If a BGP speaker receives a path that contains the Cost Community, it
    MUST consider its value at the Point of Insertion specified, when
    calculating the best path [RFC1771].

R.