Deaggregation Disease

Fri Jul 21 15:38:19 UTC 2006

On 21-Jul-2006, at 11:20, Saku Ytti wrote:

> On (2006-07-21 10:48 -0400), Joe Abley wrote:
>
>> As it happens, Tony Li, Rex Fernando and I wrote up a proposal for a
>> new attribute which might help in some of these situations. (It's a
>> crude mechanism, but not as crude as NO_EXPORT).
>>
>>    http://www.ietf.org/internet-drafts/draft-ietf-idr-as-
>> pathlimit-02.txt
>
>  I'm sure I'm not first one to to think about 'TTL' to AS hops
> (http://www.merit.edu/mail.archives/nanog/2002-10/msg00394.html),
> of course different reason at that time :). Other thing I was thinking
> about was ability to have include/exclude AS#'s community/attribute.

That seems to me like another perfectly valid approach, and one that  
already exists to some extent (e.g. by pre-poisoning AS_PATH  
attributes with AS numbers of remote networks that you don't want to  
accept particular routes). I'm told that IDRP has inclusion and  
exclusion lists which provide more exhaustive implementation of this  
kind of idea, too.

However, for some applications those mechanisms rely on knowing the  
topology one or more AS hops away from your network; AS_PATHLIMIT  
doesn't. To my eye the two approaches seem complementary.

[To be clear, incidentally, Tomy, Rex and I made no claim to be the  
original authors of the idea we were documenting in this draft:

8.  Acknowledgements

    The editors would like to acknowledge that they are not the original
    initiators of this concept.  Over the years, many similar proposals
    have come our way, and we had hoped that self-discipline would cause
    this type of mechanism to be unnecessary.  We were overly  
optimistic.

    The names of those who originally proposed this are now lost to the
    mists of time.  This should rightfully be their document.  We would
    like to thank them for the opportunity to steward their concept to
    fruition.]

Joe