Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!unmvax!pprg.unm.edu!hc!ames!amdahl!pyramid!prls!philabs!ttidca!alter
From: alter@ttidca.TTI.COM (Steve Alter)
Newsgroups: comp.mail.uucp
Subject: Re: map wizardry - terminal links
Message-ID: <3528@ttidca.TTI.COM>
Date: 8 Dec 88 21:32:37 GMT
References: <571@comdesign.CDI.COM> <810@mailrus.cc.umich.edu> <513@ditka.UUCP> <4109@mailgw.cc.umich.edu>
Organization: Citicorp/TTI, Santa Monica
Lines: 58

In article <4109@mailgw.cc.umich.edu> emv@mailgw.cc.umich.edu (Ed Vielmetti) writes:
} Try this:
} 
} formtek	sunpitt(DEMAND)
} sunpitt	(DEMAND+HOURLY),sun(DEAD)
} 
} in your paths.local file.  That should have the same impact as your
} proposed syntax.  

I was planning to post the same suggestion, but saw a problem in it.
I mailed Karl Swartz a different suggestion; I didn't post it as I
wasn't sure about its validity.

Currently, there is no map-entry for sunpitt at my site; it sounds
like Sun Microsystems at Pittsburg but does not appear in any of the
Pennsylvania files.  A couple of sites talk to sunpitt, but sunpitt
doesn't talk to anybody?  AS LONG AS THIS IS TRUE, the above
suggestion will work, but if sunpitt decides to submit a map-entry...
(read on.)

The following is based, hypothetically, on the assumption that
sunpitt submits a map-entry with this cost in it:

sunpitt		sun(HOURLY)

The problem with the above suggestion (please correct me if I'm
wrong!) is that pathalias would see two unrestricted costs for the
sunpitt!sun link and will use the cheaper one in building the routing
tables.

The following line:
sunpitt		(DEMAND+HOURLY)
only means that the specified cost can enter the competition for routes
from formtek TO sun, but that link becomes very costly for routes
THROUGH sun to points beyond.

Now, we still have two unrestricted costs for the same link:
sunpitt		sun(HOURLY)		! sunpitt's entry
sunpitt		sun(DEAD)		! formtek's paths.local

Pathalias will use the cheaper one and will probably still end up
generating some routes through sunpitt!sun to other sites.

What is missing is the ability for formtek's paths.local to OVERRIDE
other costs for the same links, i.e. if the
sunpitt		sun(DEAD)
can override the
sunpitt		sun(HOURLY)
then no routes through that link to other sites will be generated, but
that link will still be used for mail directly to sun, because of the
sunpitt		(DEMAND+HOURLY)	! what a wierd cost!
line.

This make sense to anyone?
-- 
Steve Alter        
{csun,philabs,psivax,pyramid,quad1,rdlvax,retix}!ttidca!alter
Citicorp/TTI, Santa Monica CA  (213) 452-9191 x2541