Subject: [MOBILE-IP] PPP support in 3Gwireless

From: Qiang Zhang <[email-masked]>
Date: Tue, 16 Nov 1999 10:22:05 -0500

I have questions regarding the PPP support in the 3G wireless network,
please clarify.

Would the PPP support tend to be very automatic? Thus, being transparent to
the user, the device will be able to initiate PPP session whenever it enters
a new network, is this true?    If it is true, we know this will have impact
on the applications because if there is a "release IP" and "obtain new IP"
procedure, a lot applications  basically just chicken out.

Is there solution out there already it is left to the implementations? Where
can I find corresponding document if any. Thank you!

-Qiang

1100 Warnings!
--Line 100000: 3 cokes shut down your immune system for 24 hours, so stay
away from sodas!

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From: Tom Hiller <[email-masked]>
Date: Tue, 16 Nov 1999 11:18:04 -0600

Quiang,

PPP at this stage of cdma2000 standards is "automatic" in the sense we have no
other link protocol to the user: The user must run PPP. In a future version
cdma2000 may have an alternate data link. This is uncertain at the moment.

Generally cdma2000 supports two access mechanisms. (1) PPP access (2) Mobile IP

When the mobile moves to a new Packet Data Service Node (PDSN -- contains a NAS
and FA), the PDSN will restart PPP to the mobile automatically. It is a
requirement that that a PPP implementation not reset the entire IP stack above
it for Mobile IP.

A given PDSN will have moderately wide coverage (e.g. a large city) for a couple
of reasons: (1) there is an Radio Access Networks (RAN) to PDSN interface that
supports mobility between multiple RANs while maintaining connectivity to the
same PDSN so that PPP needs to restart less frequently (2) Some deployed Radio
Access Networks are really quite large and cover much of a large city.

Thus, Mobile IP provides a persistent addresses with very wide mobility, but PPP
implementations need to be "enhanced" to not reset the rest of the IP stack for
Mobile IP users. For those users in which PPP is not "enhanced" and no Mobile IP
client exists on their device, cdma2000 users will still have a some mobility
that is not as extensive as supported by Mobile IP.

Tom Hiller

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From: Jim Willkie <[email-masked]>
Date: Wed, 17 Nov 1999 09:05:14 -0800

Folks:
Below I'd like to add a bit to Tom's comments...

>that is not as extensive as supported by Mobile IP.

There are actually 2 means available to avoid the 'resetting the IP stack':
1) get Microsoft to make their PPP implementation(s) to behave correctly or
2) implement the IS-707* Packet Network model in the mobile.

For a MobileIP solution the Network model method is viewed (here at QC at
least) as required anyway in order to perform Mobile Node registration at
the mobile. So this would make the poorly behaving Msoft PPP a mute point,
at least for the MobileIP case.

Jim Willkie

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From: Marcello Lioy <[email-masked]>
Date: Wed, 17 Nov 1999 09:27:24 -0800

At 09:18 AM 11/16/1999 , Tom Hiller wrote:
>
>Thus, Mobile IP provides a persistent addresses with very wide mobility,
>but PPP implementations need to be "enhanced" to not reset the rest of the
>IP stack for Mobile IP users. For those users in which PPP is not
>"enhanced" and no Mobile IP client exists on their device, cdma2000 users
>will still have a some mobility that is not as extensive as supported by
>Mobile IP.
>

I would like to add my voice behind Tom's here.  I have been expounding for
a couple of years about poorly behaving PPP stacks.  Unfortunately my words
seem to fall on deaf ears as the stack in question is still broken in the
exact same way.  I recently gave a presentation outlining PPP related
inter-operability issues related to cdma2000 packet data.  There are
several issues that relate to this particular stack, and resetting the
upper layers is not the only one.  I am hoping that pressure from a bunch
of different places will force our friends in Redmond to get it together
and fix their stack.

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