Title:	The possible improvement image for PDP activation for supporting Terminating PPP at ADP/MS
Date:	99-05/1-4
Source:	NTT DoCoMo
Related to:	PDP Activation procedure (SM and GTP)
1.	The purpose of this contribution
This contribution is the companion contribution of N1-99503, which propose an improvement for the efficient
support of IP communication terminating PPP at ADP/MS. This contribution expresses NTT DoCoMo’s idea for the principle of the solution and two possible images for the solution as the basis of the discussion.
2.	The basic principles for the Solution of the improvement of the PDP activation
This chapter proposes the following principle and sub-principles for the solution mainly considering the tight schedule for the Release99. But this contribution does not stick to the proposal and would like to hear comments for the proposal.
3.1 The principles and sub-principles
Principle1:  The impact on the current GPRS specification and the coming GPRS network should be minimized.
Principle2:  The solution should be generalized, not only aim to PPP but also aim to other user interface e.g. DHCP
This can be achieved by taking the following sub-principles.

Sub-principle1: The new messages to be added in the PDP activation should be exchanged between MS and GGSN. The parameters in the messages should be routed to GGSN by SGSN transparently. SGSN does not have to look into parameters in the messages. This way of solution will cause the minimal impact on the SGSN.
Sub-principle2: The sequence syntax composed by the new messages to be added in the PDP activation don’t have to be recognized by SGSN. This means the mapping among PPP sequence and the new messages with current PDP activation request/response messages and ISP-GGSN e.g RADIUS, DHCP messages are up to implementation and out of scope of the specification. The reason for this is considering tight schedule of the Release99 and freedom for  implementation.
Sub-principle3: The necessary elements for the interface protocol (at this time PPP) are carried in the protocol configuration option field of the new messages and current PDP activation request/response messages.
3.2 The two possible images for the solution
The following images roughly shows examples of the solution. It should be noted that according to sub-principle 2, the mapping among PPP sequence, PDP activation (with new messages) and e.g Radius is one example in these images.

The following is the first image for the solution. The main characteristic is that the proposed new messages are between current PDP activation request/response messages.
First Example for the Solution

ADP/MS

SGSN

GGSN

ISP

Activate PDP
context  Request

Create PDP
context  Request

ＴＥ

AT command

LCP

e.g. Radius
　　 sequence

Point1:transparent to SGSN.
           SGSN performs only massage routing

Point2: Actual procedures consist of new messages and PDP activate
            request and response and mapping between the procedure and
            PPP sequence/AT command may be out of scope for the
            specification of UMTS phase1.

Ｃｒｅａｔｅ PDP
context  Response

Activate PDP
context  Response

PPP
sequence

Authentication

IPCP

New message for downward (standalone)

New message for  upward (standalone)

The following is the second image for the solution. The main characteristic is that the proposed new messages are after current PDP activation request/response messages.
The second Example for the Solution

ADP/MS

SGSN

GGSN

ISP

Activate PDP
context  Request

Create PDP
context  Request

ＴＥ

AT command

LCP

e.g. Radious
　　 sequence

Point1:Transparent to SGSN. SGSN will only massage routing

Ｃｒｅａｔｅ PDP
context  Response

Activate PDP
context  Response

PPP
sequence

Authentication

IPCP

New message for downward (standalone)

New message for  upward (standalone)

Point2: Actual procedures consist of new messages and PDP activate
            request and response may be out of scope for the specification
            and mapping between the procedure and PPP sequence/AT
            command may be out of scope for the specification of UMTS
            phase1.

The expected impact on the current specification will be as follows.
(1)	Defining one message for the downward with having message ID, TI, length of the “protocol configuration option field” and “protocol configuration option field”
(2)	Defining one message for the upward with having message ID, TI, length of the “protocol configuration option field”     and “protocol option field”
(3)	The proposed new messages are defined as “standalone” messages. So the timer for these messages are not necessary to be defined.
These (1) and (2) will be defined in 03.60,04.08,09.60.
07.60, 09.61 likely to have no impact since no mapping would be specified in the Release99.

3.	Discussing points in the solution
Discussing points for the solution are listed up as follows. The author of this contribution would like to hear the opinion for each item.
(a)	Any comments for the principles and  sub-principles
(b)	Which example is more preferable? Or are there any other solution for the terminating PPP at ADP/MS?
(c)	The necessary specification for Release99 is only defining new standalone messages one for uplink and one for downlink. Should we specify more?
4.	Conclusion
This contribution shows NTT DoCoMo’s idea for the images of the possible solution. For Release99 work, two standalone messages are necessary for the improvement and the impact for the improvement can be considered as limited.

5.	PROPOSAL
TSG CN WG1 should start for the work for the improvement of PDP activation procedure for the efficient(Real) support of PPP termination at ADP(MS). NTT DoCoMo (and supporting companies if there are) would like to contribute to the work and also hear other companies comments.