Path: utzoo!utgpu!water!watmath!clyde!att!pacbell!ames!mailrus!uflorida!gatech!psuvax1!psuhcx!wcf
From: wcf@psuhcx.psu.edu (William C. Fenner)
Newsgroups: news.sysadmin
Subject: Re: How does "routing" responsibility work? (.US Domain)
Message-ID: <273@psuhcx.psu.edu>
Date: 22 Jul 88 15:05:15 GMT
References: <8576@ihlpa.ATT.COM> <397@comdesign.UUCP> <309@clout.Jhereg.MN.ORG>
Reply-To: wcf@psuhcx (William C. Fenner)
Organization: Penn State University
Lines: 46

In article <309@clout.Jhereg.MN.ORG> mark@clout.Jhereg.MN.ORG (Mark H. Colburn) writes:
|In article <397@comdesign.UUCP> pst@comdesign.uucp (Paul Traina) writes:
|>I may be wrong about this,  but I was under the impression that any
|>gateway into a domain is responsible for being able to connect to (or at
|>least route to) any other host in that domain.
|>
|>How does one take (the simplest example) mail from:
|>	foo.la.ca.us to bar.la.ca.us
|>
|>Assuming foo does not know about bar?  Do we then pass the mail back
|>up to the "ca" router and it finds & computes a new path to bar?
|
|Given the following example, 
|
|	foo.sf.ca.us to bar.la.ca.us
|
|The mail would have to take the following route (assuming, of course, that 
|foo and bar do not have a direct connection, and that bar and sf.ca.us 
|don't have a direct connection):
|
|    foo.sf.ca.us -> sf.ca.us -> ca.us -> la.ca.us -> bar.la.ca.us
|
|This is the beauty of hierarchical namespace, connections to lower
|level domains are gaurenteed (well, assuming machines are up :-).  The 
|difficulties come in when you branch across top level domains (i.e. mail 
|from foo.la.ca.us to jhereg.mn.org).  In this case, all top level servers
|know how to get to all other top level servers.  So in the example
|above, us knows how to get mail to org, who then passes it down to
|mn.org and finally to jhereg.mn.org.
|

But the problem is, who is going to be sf.ca.us, ca.us, and la.ca.us?
I would think that most of the machines in .us would be personal machines,
because those are the ones that mostly don't fit.  Let's say I decided to
register my machine under .us.  I would be hogbbs.SCL.PA.US or something
like that.  Now, let's say I'm the only machine in PA under .US, let alone
State College.  So who do I pass to?  I have to be scl.pa.us as well as
pa.us.  And is there (going to be?) a US machine that is at the top of
the .US domain?

  Bill
-- 
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