Path: utzoo!utgpu!watmath!clyde!ima!cfisun!lakart!dg
From: dg@lakart.UUCP (David Goodenough)
Newsgroups: comp.mail.misc
Subject: Re: Another example why not to re-route
Message-ID: <360@lakart.UUCP>
Date: 1 Dec 88 17:32:28 GMT
References: <989@tank.uchicago.edu>
Organization: Lakart Corporation, Newton, MA
Lines: 102

From article <989@tank.uchicago.edu>, by matt@oddjob.uchicago.edu (Matt Crawford):
> More opinion:
> 
> Anyone who even attempts to use the news-path as a mail address should
> question their own sanity.

For us who know better, Mr. Crawford's comments hold up. But even I have sent
E-mail using a news path in the days before I knew better. Just today,
I received mail from New Jersey (lakart is in Mass) that went from Jersey
to Ohio to Mass to California to Indiana to California to Mass to me.
I just wonder how much that letter cost to reach me - I estimate it
travelled 12000 miles across 20 sites before reaching me, from a site that
is no more than 400 miles away.

> Anyone who attempts to have their news system preserve the validity of
> the news-path as a mail address should receive a pat on the head and a
> kick in the pants.
> 				Matt Crawford

We know better, but THERE ARE STILL IDIOTS OUT THERE WHO WILL TRY IT.

I agree that totally agressive rerouting is not clever, but I ask comments
on the (re-)routing done here.

(N.B. lakart has four neighbours: cfisun, xait, mirror and pallio)

    Step 1. if lakart appears "further down" the path, ditch the intervening
portion:

	xait!harvard!adelie!cfisun!lakart!mirror!.....

becomes:

	mirror!.....

    Step 2. if any of my immediate neighbours appear further down, then
ditch the intervening portion:

	xait!harvard!adelie!cfisun!ima!....

becomes:

	cfisun!ima!....

OK SO FAR. (?)

		THIS IS THE IMPORTANT STEP

vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
>>>>>>>>IF I CAN REACH THE FIRST HOP, SEND IT THERE.<<<<<<<<
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	If I can't (and here is where Mr Vixie & others will disagree)
find the LAST hop I can get to, and send it there with the tail intact:

	snarf!harvard!foo!portal!blurf!decwrl!hiccup!user

becomes:

	xait!garp!decvax!decwrl!hiccup!user

For people who say I should route from the other end (i.e. try to find a route
to snarf, if that fails try for harvard etc.) I ask the following. In either
case I have to add some routing information (either to harvard to decwrl)
from my local idea of what the maps look like. THESE TWO ROUTES ARE EQUALLY
LIKELY TO BE INCORRECT, so what is the advantage of sending to harvard
as opposed to decwrl. In both cases, since I've rerouted, I may have
introduced an error into the route. As an aside, if my route to decwrl IS
bad, but the site (say garp) that "can't" do the uucp (i.e. garp!decvax is
down) applies this same methodology the message will get thru, AS LONG AS
THEY APPLY THE "IF I CAN GET IT TO A NEIGHBOUR, DON'T MESS WITH IT" bit.

N.B. Just in case the message DOES start looping (e.g. garp thinks the cheapest
way to decwrl is thru lakart, with a broken path out of here) I keep a check
on message ID's for all letters passing thru, on the fourth time of seeing,
they are returned to sender, along the reply path that came in originally.
i.e. the data file looks like:

	XX00010030@pallio.UUCP	1	pallio!dg

where the 1 is the count of times I've seen the message.

Note that if the message path was garp!harvard!xait!lakart!cfisun!.....
(which will be cfisun!..... by the time I see it) then I'm not going to
mess with it, because I can just give it to cfisun and let them send it
on, hence the risk of "looping" is almost nil.

The point of this system is that a valid (even if hand-crafted) path is
left alone, which is basically what everyone is screaming about, but it
still allows me to use lakart as a router for pallio. This I have to do,
because I can't ever see fitting pathalias onto a CP/M machine :-). Of
course, as soon as we all follow killer's lead, and lakart becomes
lakart.boston.ma.us, and pallio becomes pallio.lakart.boston.ma.us then
bang paths become a thing of the past. Now if someone could tell me
how to do this .....
-- 
	dg@lakart.UUCP - David Goodenough		+---+
							| +-+-+
	....... !harvard!xait!lakart!dg			+-+-+ |
AKA:	dg%lakart.uucp@harvard.harvard.edu	  	  +---+