Subject: [eap] RE: The EAP GPRS protocol (fwd)

From: [email-masked] (Bernard Aboba)
Date: Tue, 21 Jan 2003 13:59:20 -0800 (PST)

---------- Forwarded message ----------
Date: Wed, 15 Jan 2003 19:11:06 +0200
From: Salkintzis Apostolis-Y1026C <[email-masked]>
To: "'Mark Grayson (mgrayson)'" <[email-masked]>
Cc: [email-masked]
Subject: RE: The EAP GPRS protocol

Mark,

Thanks for your response.

EAP GPRS is virtually a simple encapsulating scheme tailored for UMTS/GPRS terminals, which, in addition to UTRAN/GPRS interfaces, they support an 802.11 radio interface. Note that these terminals already implement the GMM protocol, hence EAP GPRS assumes that GMM is already there. Note also that, UMTS/GPRS terminals already implement L2 protocols (in particular the RRC in UMTS and the LLC in GPRS), which provide a L2 transport for GMM messages. EAP GPRS does not encapsulate directly the GMM messages but rather it encapsulates the corresponding RRC/LLC messages. This way, we exploit the data link services of RRC/LLC, which include sequence control, re-transmissions, enciphering, integrity checking, etc. In other words, EAP GRPS operates right below RRC (in UTRAN mode) or LLC (in GPRS mode).

The goal of EAP GPRS is to allow UMTS terminals to move between UTRAN and WLAN access. Our assumption is that the WLAN is "tightly-coupled" to UMTS core network. In this scenario, EAP GPRS acts as a scheme that allows RRC/LLC packets to pass through WLAN devices that enforce 802.1x access control. One of the benefits of using EAP GPRS is that it is very simple.

In theory, EAP GPRS can carry any type of traffic, not only RRC/LLC.

I agree that RRC/LLC operation or even GMM operation is coupled to some parameters broadcast on UTRAN/GPRS radio interface. We are seeing this as a separate issue and we deliberately left it outside the scope of EAP GPRS.

Best regards,
Apostolis
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-----Original Message-----
From: Mark Grayson (mgrayson) [mailto:[email-masked]]
Sent: Wednesday, January 15, 2003 5:20 PM
To: Salkintzis Apostolis-Y1026C; [email-masked]
Subject: RE: The EAP GPRS protocol

Apostolis

Can you explain the differences between your proposal and
http://www.ietf.org/internet-drafts/draft-buckley-pppext-eap-sim-gmm-00.
txt. Do you propose to transport more than GMM messages between the peer
and EAP server? If so how are Radio Resource messages processed - since
these relate specifically to GSM/GPRS/UMTS radio bearers.

Keeping my comments to GMM, I would say that the GMM state machine is
quite complex for WLAN authentication: according to 24.008, 115 pages of
mobility management elementary procedures, 27 pages of GMM messages and
22 pages of GMM information elements. Hence, the limited appeal to those
interested in tight coupling, although even for tight coupling,
alternative techniques exist, e.g., EAP-SIM.

In addition, some of these GMM procedures require interaction with Radio
Specific information, e.g., using GSM broadcast information to trigger
transitioning between different values of GPRS Update Status, which are
not defined for WLAN.

Best regards,
Mark
___________________________________________________
Mark Grayson
Consulting Engineer
World Wide Mobile Service Providers
Cisco Systems

IP Phone: +33 (0)1.58.04.31.24
GSM: +33 (0)6.19.98.40.99

-----Original Message-----
From: Salkintzis Apostolis-Y1026C [mailto:[email-masked]]
Sent: 15 January 2003 15:29
To: [email-masked]
Subject: The EAP GPRS protocol

Dear all,

The following I-D has recently been submitted and relates to PPPEXT
area. I would appreciate your comments.

Title : The EAP GPRS Protocol (EAP-GPRS)
Author(s) : A. Salkintzis
Filename : draft-salki-pppext-eap-gprs-00.txt
Pages : 21
Date : 2003-1-6

This document specifies an extension to the Extensible Authentication
Protocol (EAP) [2], referred to as EAP-GPRS, which allows GPRS clients
to perform signaling procedures with a core GPRS network through devices
that enforce EAP-based access control. For example, a GPRS client can
use EAP-GPRS to attach to a GPRS network through an access point that
enforces IEEE 802.1X [3] access control. In this case, the GPRS attach
signaling is performed in the context of the underlying 802.1X procedure
and the GPRS messages are encapsulated into EAP-GPRS packets. If the
GPRS client is permitted to attach to the GPRS network, then the 802.1X
procedure ends successfully and the client is authorized access to the
access point. In general, EAP-GPRS allows any type of signaling to take
place during the EAP authentication as an embedded signaling procedure.
However, in this documents we particularly focus on GPRS specific
signaling.

A URL for this Internet-Draft is:
<http://www.ietf.org/internet-drafts/draft-salki-pppext-eap-gprs-00.txt>

---
Dr. Apostolis Salkintzis
Motorola
Tel: +30-210-8172335
Fax: +30-210-6810168
E-mail: [email-masked]