Heads up: Long AS-sets announced in the next few days

David Schwartz davids at webmaster.com
Fri Mar 4 01:26:41 UTC 2005



> >>So, given these considerations, is everyone announcing an AS-set
> >>announcing "routes that falsely claim to have passed through another
> >>autonymous system"?
> >
> > 	Yes. From RFC1771:

> Ok, so if everyone announcing an AS-set is announcing "routes that
> falsely claim to have passed through another autonymous system", and you
> are saying this shouldn't be done, then why aren't you complaining with
> everyone who is announcing an AS-set?

	I never said that this shouldn't be done. I said it shouldn't be done
without the consent of the owners of the ASes you wish to include. In
addition, the things I don't complain about don't constitute a defense to
the things I do complain about.

> > [Quote of section 5.1.2 almost in its entirety]
> >
> > 	So you are violating RFC1771, plain and simple. To then go
> > and cite one
> > small section of RFC1771 in your defense is hypocritical.
>
> You quote Section 5.1.2, but you don't mention that if you follow
> Section 5.1.2 to the letter there is no way that an AS-path may contain
> an AS-set. To summarize the whole of section 5.1.2, the various cases are:
>
> Propagating a route learned from an UPDATE message:
>
>   a) To another router in same AS: don't modify AS-path
>   b) To a neighboring AS:
>      1. Path starts with AS_SEQUENCE: prepend own ASn
>      2. Path starts with AS_SET: prepend new AS_SEQUENCE with own AS in it
>
> Originating a route:
>
>    a) To neighboring AS: announce own ASn as only element in path
>    b) To another router in same AS: announce empty AS-path
>
> If you follow this to the letter, you must rule out both prepending "(In
> this case, the AS number of the originating speaker's autonomous system
> will be the only entry in the AS_PATH attribute)" and any form of
> AS-set, since there is no way, following these rules, that an AS-set may
> enter the AS-path in the first place.

	Section 9.2.4.2 documents how an AS-set can enter the AS-path as part of
aggregating routes. As far as I can tell, the use of AS-sets is permitted
only to aggregate routes.

> If we are violating this section, then everyone else announcing an
> AS-set, and - at least the way I read it - anyone doing prepending, is
> doing so too. But nobody is suggesting that these things
> shouldn't be done.

	Lovely straw man. I complained about the lack of *consent* and you talk
about people prepending their *own* AS numbers? Are you suggesting they lack
their own consent?!

	DS





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