On Tue, January 13, 2009 8:57 pm, Joe Abley wrote:
The fact that I choose to stick 701 in an AS_PATH attribute on a prefix I advertise in order to stop that prefix from propagating into 701 is entirely my own business, and it's a practice which, although apparently not commonplace, has been a well-known part of the IDTE toolbox for many years.
This does seem to be an interesting question. I'm AS X, I have no contractual relationship with AS Y, or indeed any informal peering relationship with them. All of my connectivity with AS Y is via at least one other AS. For whatever reason, technical, political, or pure whim, I don't want AS Y to receive any of my announcements. What's the correct tool to do this? Other than AS-PATH, I can't see a reliable way to do this currently. Lots of my peers or transits may have communities I can set to request that they don't announce my routes in particular regions, at particular peering points etc, but they almost certainly don't have one to restrict announcements to a specific AS. Do we need a set of well-known communities XXXXX:AS that can be recognised everywhere as "do not announce to AS"? Regards, Tim.