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

From: Patrice Calhoun <[email-masked]>
Date: Wed, 17 Nov 1999 09:38:31 -0800

Of course, one could always simply do away with PPP, which btw is not required
in CDMA2000 (for mobile ip service), and make use of PPP's framing, which is
HDLC. This would simplify the whole network, reduce the number of bits over the
air, eliminate a huge potential for mis-configuration on the mobile, etc.

PatC
>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.
>
>
>
>----------------------------------------------------------------------
>Marcello Lioy                                          Voice:   x18220
>AA-318A                                                Pager: 635-0867

---

From: Marcello Lioy <[email-masked]>
Date: Wed, 17 Nov 1999 09:57:13 -0800

At 09:38 AM 11/17/1999 , Patrice Calhoun wrote:
>Of course, one could always simply do away with PPP, which btw is not
>required in CDMA2000 (for mobile ip service), and make use of PPP's
>framing, which is HDLC. This would simplify the whole network, reduce the
>number of bits over the air, eliminate a huge potential for
>mis-configuration on the mobile, etc.

This in theory is true, but I have a couple of problems with this.

1) One of the worst things about PPP (in this context) is the
   asynchronous HDLC framing - this imposes a hefty overhead due to
   the escaping.

2) PPP is everywhere.  People get PPP for free with their OS's
   (granted there are problems with the MS implementation) but who is
   going to pay money for software that (from a consumer perspective)
   does exactly the same thing as PPP, when PPP is free?  It also has
   the potential of complicating the mobile (which is far too
   complicated as it is because of call processing issues - another
   discussion that) as it may have to implement BOTH PPP and the HDLC
   derivative.  One of the great advantages off (a properly behaving
   PPP) is that the mobile can operate in Relay Model mode (which
   makes it essentially a byte pipe) and this SIGNIFICANTLY improves
   the performance of the mobile.

I think an alternative is only truly useful/worthwhile if:
1) IETF standard protocol
2) Commonly implemented, and distributed with relevant OS's
3) Does not use escaping

Granted the third issue is not as key as there are ways of dealing with the
framing.

>>of different places will force our friends in Redmond to get it together

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Marcello Lioy                                 Voice: (619)651-8220
Qualcomm Inc.                                 PGR:   (619)635-0867