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Re: 4-Byte AS Number soon to come?

  • From: Iljitsch van Beijnum
  • Date: Wed Aug 24 02:59:08 2005 
On 24-aug-2005, at 5:50, Susan Hares wrote:


This is the first of many steps.  And to be fair to the authors, the
process got held up due to the base draft being re-written.



So, the key discussion points are (as Yakov has indicated as well):
    a) Are there any technical problems with the specification
    b) Does the specification cause operational problems?
    c) General concerns about the design of the additions to BGP
        (scaling, etc).




I find the design less robust than it could be.



What it does is define that toward a neighbor that also supports wide
AS numbers it will send the AS path with 32-bit AS numbers, and
toward a neighbor that doesn't support wide AS numbers it sends the
AS path with 16-bit AS numbers and a "new AS path" with 32-bit AS
numbers.



I think it makes more sense to ALWAYS send the old 16-bit AS path and
the new 32-bit AS path attribute. This makes the code path identical
for the two types of peers, which is less likely to lead to new bugs
and makes for easier (operational) debugging.




Implementation reports give us the opinion of those who have already
implemented the protocol.  That's usually worth hearing about.




As an operator, I'm sorry to say I don't always have the highest
possible opinion of the people implementing the protocols. (I always
say: never ask the people who built the thing what it can do.)
Obviously implementing a specification is a crucial step, and an
illuminating one because it brings out bugs and hidden assumptions in
the specification. It can also uncover a broken design, but I hope
and believe this is relatively rare. (And it's not like a broken
design is automatically unimplementable, so implementation is
certainly not guaranteed to bring out design problems.) So yes, it's
worth hearing about, but not worth delaying publication for. And
since the IETF only has one way to publish documents for periods
extending six months...