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From: tep@tots.UUCP (Tom Perrine)
Newsgroups: comp.protocols.tcp-ip
Subject: Mobile TCP/IP (was Re: Can subnets be separated by another net?)
Message-ID: <153@tots.UUCP>
Date: 12 Jul 90 21:08:53 GMT
References: <9007121332.AA02890@chiya.bellcore.com> <9007121800.AA01850@xap>
Reply-To: tep@tots.Logicon.COM (Tom Perrine)
Organization: Logicon, Inc., San Diego, California
Lines: 45
X-Local-Date: 12 Jul 90 14:08:53 PDT

In article <9007121800.AA01850@xap> stewart@xyplex.com (Bob Stewart) writes:
>Paul Tsuchiya writes:

>Seems to me that imbedding topological meaning in an address is not
>necessarily a good idea.  That implies that as I move my portable around the
>network (from hotel to hotel, or, worse yet, on a cross country trip with a
>mobile phone), its address has to change.  We have that problem now with SLIP
>connections.  A name service could track the change so you could always reach
>me by name, but the more I move the more I have to change the name mapping,
>and such mappings usually don't appreciate being changed very much.
>
>*I*n *M*y *H*umble *O*pinion, hierarchical administration for initial address
>assignment works nicely, such as with Domain Name Service or Ethernet global
>addresses, but should really be independent of routing.  Of course, flat
>addresses don't offer any built-in efficiencies for finding the right
>neighborhood, like IP addresses do now...
>
>Tradeoffs, tradeoffs, always tradeoffs.  Why can't there just be a right
>answer? 
>
>	Bob

But there is a right answer! Everyone will now use PPP over...
	cellular telephone dial-ups!! :-)

I hate to admit it, but the cell-phone (phone system) model of
addressing does have many advantages for the *user*. No matter where
you go, your logical address (phone number) follows you.

Of course, this puts all of the burden on the switching system, and
the routing can often be far from optimal for a roaming cell phone
user. I imagine that the main reason that this works for cell phones
is that there is enough "excess" capacity in the switching system to
handle the (hopefully) relatively rare, inefficient cases of roaming
cell phones, which are a very small part of the switching load.

Is there anything that we can learn (read "steal") from this example?


Tom Perrine (tep)                       |Internet: tep@tots.Logicon.COM
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