Subject: "mobile" orthogonal to wide-area wireless

From: "James P. Salsman" <[email-masked]>
Date: Wed, 18 Oct 2000 00:42:01 -0700 (PDT)

The prevailing view seems to be that wide-area wireless 
devices need to be "mobile" in the sense that they are 
able to move from one network to another.  This is not 
the case, and maybe not even desirable.  I believe that 
this view has led to easily avoidable delays in wireless 
internet services.

There are a few wireless companies that provide proxied 
web and email services over existing cellular telephone 
networks.  For example, Omnisky, popular with Palm users:

  http://www.omnisky.com/images/newCoverageMap.jpg

Those coverage patterns are probably typical, and 
suggest that it would be much easier for them to provide 
a local gateway in each non-overlapping coverage area 
than to implement protocols such as "Mobile IP" which 
perform hand-offs from one subnet to another, without 
any noticeable degradation in performance.

Of course, this can be taken too far.  I've mentioned 
that Metricom/Ricochet packets sent from California make 
their next IP hop in New Jersey, with 0.75 s latency.

Is there any compelling reason why wireless IP needs to 
be "mobile" in the sense of traversing networks?

Cheers,
James

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From: Klaas Wierenga <[email-masked]>
Date: Wed, 18 Oct 2000 10:38:11 +0200

James,

> be "mobile" in the sense of traversing networks?

yes, I don't want to pay my expensive cellular operator when near a
wireless LAN access point.

Klaas

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From: Harald Alvestrand <[email-masked]>
Date: Wed, 18 Oct 2000 11:33:32 +0200

>this view has led to easily avoidable delays in wireless

the foot is in the other mouth; it is not the wireless device that needs to 
be mobile, it is the mobile device that neeeds to be wireless.

The mobile device (that is not limited to being a telephone) needs to move 
from one network to another, under the dual constraints of budget and 
performance (minimize first, maximize second).

For Palm 8 class devices, very low bandwidth in the "WAN" space and quite 
high bandwidth in the "IR" space (when syncing) seem sufficient variants.
For PC+headset class devices, the requirements are different; for 
PC+videocamera class devices, different again.
All of them roam.

IMHO, of course.

--
Harald Tveit Alvestrand, [email-masked]
+47 41 44 29 94
Personal email: [email-masked]

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From: "James P. Salsman" <[email-masked]>
Date: Wed, 18 Oct 2000 10:47:26 -0700 (PDT)

Klass,

> wireless LAN access point.

That's a good reason, but it doesn't require such a drastic solution.

I would rather have one address for a wireless WAN interface and 
another address for a wireless LAN interface -- which seems to be 
doable today -- much more than I want to wait for the solution 
with "Mobile IP" address traversal to become commercially available.

Cheers,
James

---

From: Daryl Bunce <[email-masked]>
Date: Wed, 18 Oct 2000 12:29:58 PDT

> be "mobile" in the sense of traversing networks?

My opinion is yes, just so others can reach you/your server.
                                            ^^^

If you are running services on your portable (c'mon, my
portable is pretty powerfull, especially compared to the
old VAX I used) and you want others to consistently have
the ability to use them, I suspect MobileIP is the way
to go.  I'm still wondering about this.

- R/db                ( [email-masked] )
    The Moon is Waning Gibbous (68% of Full)

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From: John Day <[email-masked]>
Date: Wed, 18 Oct 2000 16:26:40 -0400

>with "Mobile IP" address traversal to become commercially available.

No, what you want is a serial number. Or at least what you describe 
is a serial number.  An address is very different.

Take care,
John

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From: Masataka Ohta <[email-masked]>
Date: Thu, 19 Oct 2000 11:05:48 +0859 ()

James;

> this view has led to easily avoidable delays in wireless 

Why do you think "mobile" delays wireless Internet services?

IP mobility protocol is out there and AAA is a problem of
wireless, not mobile, Internet services.

					Masataka Ohta

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From: Keith Moore <[email-masked]>
Date: Wed, 18 Oct 2000 23:04:39 -0400

> is a serial number.  An address is very different.

the word "address" is used in so many different ways that any
argument of the form "x is/is not an address" tends to be 
nothing more than an argument about which definition of the
word "will be master" (to quote Humpty Dumpty)

users don't care about whether their mobile device has one address
that follows it everywhere or whether it changes addresses as
it moves.  however, depending on their needs, they might care about
their applications continuing to stay connected while they're mobile.
they might also care about running applications that are both mobile
and "always on".

any network stack that supports the latter two kinds of applications
will almost certainly employ (at least) two different sets of 
things that could be called "addresses" - one which is stable
even while the device is mobile, and another which is less stable.
whether those two addresses look alike or different, whether
the technology used is "mobile IP" or something else , and
the level of the protocol stack at which the indirection occurs
- these are implementation choices.

of course, some implementation choices work better than others,
especially when it comes to interoperating with the wired Internet,
or in being able to support existing applications, or in being 
able to switch from one communications medium to another.  but 
the implementation choice can quite reasonably be different
depending on the particular characteristics of the device and
its communications media, and also on the needs of its users.

Ketih

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From: Mohsen BANAN-Public <[email-masked]>
Date: Wed, 18 Oct 2000 22:08:49 -0700 (PDT)

All of this and a great deal more is discussed in various old books,
such as:

- Internetwork Mobility - The CDPD Approach
  Taylor, Waung and Banan
  Prentice Hall
  1996
  ISBN: 0-13-209693-5

Hope this helps.

...Mohsen

>>>>> On Wed, 18 Oct 2000 23:04:39 -0400, Keith Moore <[email-masked]> said:

  >> is a serial number.  An address is very different.

  Keith> the word "address" is used in so many different ways that any
  Keith> argument of the form "x is/is not an address" tends to be 
  Keith> nothing more than an argument about which definition of the
  Keith> word "will be master" (to quote Humpty Dumpty)

  Keith> users don't care about whether their mobile device has one address
  Keith> that follows it everywhere or whether it changes addresses as
  Keith> it moves.  however, depending on their needs, they might care about
  Keith> their applications continuing to stay connected while they're mobile.
  Keith> they might also care about running applications that are both mobile
  Keith> and "always on".

  Keith> any network stack that supports the latter two kinds of applications
  Keith> will almost certainly employ (at least) two different sets of 
  Keith> things that could be called "addresses" - one which is stable
  Keith> even while the device is mobile, and another which is less stable.
  Keith> whether those two addresses look alike or different, whether
  Keith> the technology used is "mobile IP" or something else , and
  Keith> the level of the protocol stack at which the indirection occurs
  Keith> - these are implementation choices.

  Keith> of course, some implementation choices work better than others,
  Keith> especially when it comes to interoperating with the wired Internet,
  Keith> or in being able to support existing applications, or in being 
  Keith> able to switch from one communications medium to another.  but 
  Keith> the implementation choice can quite reasonably be different
  Keith> depending on the particular characteristics of the device and
  Keith> its communications media, and also on the needs of its users.

  Keith> Ketih