On Thu, Apr 10, 2008 at 5:49 PM, Brian E Carpenter <[EMAIL PROTECTED]> wrote: > I would suggest turning this into a concrete goal, such as: > > <strawman> > The update rate in the mapping system should be at least > two orders of magnitude less than the update rate in > the BGP4 system, at any point in time. > </strawman>
Brian, Depending on the character of the map system, this is either absolutely critical or blithering nonsense. Before pushing similar concrete goals, I'd ask you glance through TRRP for an example of a system in which constraints on the system-wide map update rate appear unwarranted. TRRP isn't a push-based system. That difference may prove significant when considering permissible map update rates and that significance shouldn't be overlooked by the specified goals. Anyway, while I think the idea of a map system that doesn't convey reachability information is interesting at a conceptual level, I don't see how you can implement it without making the system at least hybrid-pull. Just because a particular service provider (BGP AS) can usually reach a particular endpoint doesn't mean they always can. That holds true regardless of whether the service provider itself is reachable. And as we see every time Cogent gets in a spat with someone, just because you can reach either of two ISPs doesn't necessarily mean they can reach each other. If you don't convey reachability information in the map, then the ITR will have to ask its selected ETR whether a particular endpoint is currently reachable and it will have to keep verifying that reachability throughout the session. If you're going to do all that, why not use a pull system from the beginning and gain all of its advantages? Remember, you can't rely on the ETR to tell the ITR that a destination is no longer reachable. There are common, trivial cases in which that will fail as discussed here: http://bill.herrin.us/network/statechange.html Regards, Bill Herrin -- William D. Herrin ................ [EMAIL PROTECTED] [EMAIL PROTECTED] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 -- to unsubscribe send a message to [EMAIL PROTECTED] with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg
