Subject: RE: [seamoby] Some proposed changes to the requirements draft.

From: Nakhjiri Madjid-MNAKHJI1 <[email-masked]>
Date: Wed, 14 Nov 2001 17:09:22 -0600

Ok, It is clear that storage issue is out of scope. So I am 
not going to debate on central versus localized context, that
would be a specific issue for UMTS to solve if part of "context"
is at SGSN and part of it in GGSN (which are both edge routers essentially,
pointing at different edges of GPRS network, i.e. radio versus internet).

What troubles me is that although I don't know much about UMTS and PDP,
I have a feeling that PDP contexts are not quite the same as feature
contexts that we are talking about here in IETF. PDP contexts are more like
links than protocol states. You set up a virtual link, 
you activate a PDP context. You talk about prefix per PDP context and 
interface identifier per PDP context.... 

So we have an incompatibility in definition of "context" when we talk about
"context transfer" in IETF and 3GPP. and the concepts are not "transferable"!!
Am I not correct?

Regards,
Madjid

-----Original Message-----
From: Shahrier, Sharif M. [mailto:[email-masked]]
Sent: Wednesday, November 14, 2001 8:32 AM
To: 'Nakhjiri Madjid-MNAKHJI1'; [email-masked];
[email-masked]; Shahrier, Sharif M.; [email-masked]
Cc: Shahrier, Sharif M.
Subject: RE: [seamoby] Some proposed changes to the requirements draft.

The centralized approach to context transfer was dismissed
very early on. Is this still an issues?

For 5.6.2 I am not quite sure if some non-IETF protocols even
have the same definition for context as we do (PDP context is one
example), any idea??

Majid,

	The PDP context is used in the UMTS systems. A "global" PDP context
resides in the GGSN, and a "local" PDP context resides at each SGSN. The
context parameters at each SGSN is a subset of all those stored at the GGSN.
The MN's, of course, are attached to the SGSNs and send their datagrams to
the GGSN via the GTP (Generic Tunnel Protocol). 

Thus, the GGSN maintains a "central" context directory, while the SGSNs each
maintain a "local" context directory. 

The UMTS system is slated to use the IPv6 protocol, and hopefully, a lot of
the protocols that we develop in the IETF will find its way into this
architecture.

Aside from the UMTS, there are other wireless systems that will use context
transfer protocols with a combination of local/centralized directory
structure.

With this viewpoint, I strongly believe that the context transfer protocol
should support a combination of local and central context memory.

-Sharif.

---

From: "James Kempf" <[email-masked]>
Date: Wed, 14 Nov 2001 15:15:27 -0800

Madjid,

Yes. PDP context is like a PPP context. CT could apply, but we shouldn't
specifically engineer the CT protocol for it.

        jak

----- Original Message -----
From: "Nakhjiri Madjid-MNAKHJI1" <[email-masked]>
To: "'Shahrier, Sharif M.'" <[email-masked]>;
"Nakhjiri Madjid-MNAKHJI1" <[email-masked]>;
<[email-masked]>; <[email-masked]>;
<[email-masked]>
Sent: Wednesday, November 14, 2001 3:09 PM
Subject: RE: [seamoby] Some proposed changes to the requirements draft.