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From: guy@rlgvax.UUCP (Guy Harris)
Newsgroups: net.mail
Subject: Re: definitions for LOCAL, DEMAND, DAILY
Message-ID: <396@rlgvax.UUCP>
Date: Sun, 27-Jan-85 17:54:44 EST
Article-I.D.: rlgvax.396
Posted: Sun Jan 27 17:54:44 1985
Date-Received: Wed, 30-Jan-85 06:05:59 EST
References: <700@cbosgd.UUCP> <14000006@smu.UUCP>
Organization: CCI Office Systems Group, Reston, VA
Lines: 28

> The first problem is that pathalias assumes the cost of a link
> is the same in both directions (at least I think it does).  This
> is often not correct since site A may call site B on demand but
> site B calls site A only once a day.

Wouldn't

	A	B(DEMAND)
	B	A(DAILY)

do here?  From the PATHALIAS(1) manual:

	"Pathalias" expects as input a sequence of host-to-host
	connectivity information, with a host name in column 1,
	followed by white space, followed by a comma-separated
	list of links (also host names), denoting a connection
	from the host to the links.  *Connections are assumed to
	be unidirectional.* ("italics" mine)

So the first line declares that messages are passed from A to B on
demand, but says nothing about the passage of messages from B to A.
The second line says that messages are passed from B to A at least once
a day.  (The fact that messages will be passed from B to A as soon as
a message is shipped from A to B should not be taken into consideration
in determining path costs, since this is not normally under B's control.)

	Guy Harris
	{seismo,ihnp4,allegra}!rlgvax!guy