Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!cica!tut.cis.ohio-state.edu!cheops.cis.ohio-state.edu!karl From: karl@cheops.cis.ohio-state.edu (Karl Kleinpaste) Newsgroups: comp.mail.misc Subject: Re: sigh (was Re: Short-circuiting a route) Message-ID: Date: 19 Jul 89 19:59:02 GMT References: <562@daitc.daitc.mil> <12167@polyslo.CalPoly.EDU> <1888@prune.bbn.com> <423@cwjcc.CWRU.Edu> <425@cwjcc.CWRU.Edu> <432 Sender: news@tut.cis.ohio-state.edu Organization: Ohio State Computer Science Lines: 49 In-reply-to: edguer@alpha.ces.cwru.edu's message of 19 Jul 89 19:10:17 GMT [Sorry I haven't been able to get you on the phone, Aydin; I've tried 3 times without success...] edguer@alpha.ces.cwru.edu writes: > Hmm. Yes, the RFC974 algorithm may require a reroute of the first > hop at each relay point along the path to the destination. Note, > however this is only a reroute of THE FIRST HOP and thus would be > the same as passive rerouting, not active (rabid) rerouting. > RFC974 does not say to look down the list trying to find known > hosts, it merely says to look at the first domain (host) in the > path and try to reach it. If: I have a connection to system aaaaa; I advertise the connection to aaaaa as _very_ expensive so that it doesn't get used by others as a relay much, in fact, so expensive that my own paths file contains the line aaaaa bbbbb!ccccc!aaaaa!%s I nonetheless expect and accept that the occasional piece of mail bound for aaaaa should still go straight there, because it's known to my Systems file... Then: An incoming piece of mail specifying aaaaa!user will have to be rerouted: bbbbb!ccccc!aaaaa!user because of the requirement, with pathalias as MX, that I reroute the first hop, _before_ a direct attempt. This is morally incorrect. Maintaining the equivalence of Systems = A records and pathalias = MX records (and CNAMEs, agreed), I _must_ reroute that first hop. Making such a reroute into a requirement is Wrong. (Making it optional is my business and no one else's, as the link may be genuinely of high cost.) I have advertised it as expensive for any of a wide variety of reasons; perhaps I just find it politically inconvenient to let people know that I exchange mail with aaaaa. Whatever the reason, I want the connection to be available and used on demand, without most people actually putting it to such use. Say, just for my pals, who are "in the know" about the connection. If someone is truly and honestly bright enough to figure out that the connection from myself to aaaaa is there, and he routes specifically to me for just that reason, I should be allowed to respect it. MXing (first hop rerouting) will prevent that, because it is a requirement. Therefore I still maintain that !-paths are not source routes. --Karl