Network Working Group Satish Jamadagni INTERNET-DRAFT Vidhya R Category: Informational August 5 2006 Expires: January 5, 2007 An IAPP-Mobile IP reference interworking protocol Status of this Memo Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 5, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Satish, Vidhya Expires January, 2007 [Page 1] Internet-Draft IAPP-Mobile IP reference protocol august 2006 Abstract With WLAN hotspots becoming more wide spread, there is growing interest among cellular service providers in WLAN-Cellular interworking/roaming architectures. Service providers are looking at deployment of interworking heterogeneous wireless access points. There is also a growing breed of terminals trying to build a capability to roam between 3G and 802.xx technologies. Working groups within IETF and IEEE 802.21 are involved in defining seamless roaming standards. 802.21 is attempting to define roaming standards not just from one 802-based network to another, but also between 802-based networks and 3G cellular network. Support for handoff between heterogeneous wireless networks is becoming vital. Mobile IP has always been the macro network mobility protocol of choice where as the IAPP - Inter Access Point Protocol (802.11f) has been recommended as the roaming protocol between 802.11 access points. This draft suggests a mechanism of supporting handoff between IAPP supported 802.xx devices and 3G packet core networks. 1. Introduction The combination of 3G and WLAN wireless technologies offers the possibility of achieving anywhere, anytime Internet access, which benefits both end users and service providers. In this draft we discuss one interworking architecture for providing integrated service capability across widely deployed 3G CDMA2000-based and 802.11-based networks. Two well known design choices for 3G-WLAN integration haven been proposed in [1] namely the tightly coupled and loosely coupled architectures. The proposed MIP-IAPP handoff mechanism can be used in either configuration depending on where the interworking function is implemented. The discussed interactions between the IAPP protocol and the Mobile IP stack can also be in a gateway. Such a gateway can facilitate fast handoff needs typical of intertechnology handovers. For a mobile device with interfaces to both technologies, an interworking gateway with IAPP & Mobile IP interactions will support seamless handoff in the presence of overlapping radio coverage. 1.1. Terminology This document uses the following terms: Intertechnology Handover Gateway: An gateway entity that facilitates signaling and seamless handover between a 3GPP core and a WLAN accesspoint. Satish, Vidhya Expires January, 2007 [Page 2] Internet-Draft IAPP-Mobile IP reference protocol august 2006 Loosely coupled architecture An Authentication Server is an entity that provides an Authentication Service to an Authenticator. This service verifies from the credentials provided by the Supplicant, the claim of identity made by the Supplicant. Tightly coupled architecture The protocol entity associated with a physical or virtual (802.11) Port. A given PAE may support the protocol functionality associated with the Authenticator, Supplicant or both. 2. 802.11f – THE INTER ACCESS POINT PROTOCOL (IAPP) The 802.11f recommended practice for WLAN access points [8] describes a set of services that allows the wireless LAN Access Points (APs) to interoperate on a common Distribution System (DS), using the TCP over IP (TCP/IP) or User Datagram Protocol over IP (UDP/IP) to carry IAPP packets between APs. It also describes the use of the Remote Authentication Dial-in User Service (RADIUS) Protocol, so APs may obtain information about one another. The IAPP specification also provides a proactive caching mechanism to accomodate faster roaming concerns by sending a Station context to neighboring APs. The devices in a network that use the IAPP are typically 802.11 APs. Other layer 2 networking devices, such as bridges and switches are also affected by the operation of the IAPP. The IAPP protocol primiarly allows for a single AP connectivity for WLAN terminals at any point in time. A notion of a single access point connectivity is very valid under a WLAN-3G roaming scenario as well. 3. Fast Handoff drafts for mobile IP Mobile IP handoffs have been shown to have latencies that are not suited for the wireless domains. This has led to the study of fast handoff techniques between wireless access points [7]. Fast handoff techniques are more relevant to an inter technology handoff. In [7] three techniques are suggested to achieve low latency handovers: Pre registration, Post registration and a combined registration method. The PRE-REGISTRATION handoff method allows the a mobile terminal to be involved in an anticipated IP-layer handoff. The MN is assisted by the network in performing an L3 handoff before it completes the L2 handoff. The POST-REGISTRATION handoff method allows the oFA (old FA) and nFA (new FA) to utilize L2 triggers to set up a bi-directional tunnel between oFA and nFA that allows the MN to continue using its oFA while on nFA's subnet. Satish, Vidhya Expires January, 2007 [Page 3] Internet-Draft IAPP-Mobile IP reference protocol August 2006 This minimizes the impact on real-time applications. The combined method involves both the methods mentioned above. If the PRE-REGISTRATION handoff can be performed before the L2 handoff completes, the combined method resolves to a PRE-REGISTRATION handoff. In this draft we map IAPP signals to the fast handoff messages as described in [7]. 4. 3G-WLAN INTERWORKING SCENARIOs Two approaches have been discussed in [1] [5] for WLAN and CDMA 2000 networks.The rationale behind the tightly coupled approach is to make the WLAN network appear to the 3G core network as another 3G access network. The WLAN network would then have to fake functions that are part of a 3G radio access networks. In this architecture, the WLAN gateway network element appears as a 3G core or a packet control function (PCF) to a CDMA2000 core network. The loosely coupled approach introduces a new element in the WLAN network, the WLAN gateway which connects to the Internet and does not have any direct link to 3G network elements such as a PDSN. We call this approach loosely coupled interworking because it completely separates the data paths in WLAN and 3G networks. The high-speed WLAN data traffic is never injected into the 3G core network, but the end user still experiences seamless access. The mentioned IAPP-MIP mapping functions can be accommodated within the scope of both approaches with the only requirement of a fast handoff primitives being available as described in [7]. A 3GPP2 compliant PDSN implements the foreign agent (FA) functionality defined in Mobile IP [3], allowing cross-PDSN mobility. The 3GPP2 standards for CDMA 2000 also support a fast handoff method where in a tunnel is established between the source and the target PDSNs. This tunnel helps in faster signaling as well as act as a bi-casting tunnel for data. Additional caching functionality would be requiredto accommodate the IAPP-MIP signaling. 5. IAPP triggers for fast Mobile IP Interworking In this draft we suggest the MIP-IAPP coupling architecture within the context of a handover between WLAN and 3GPP2 network. The architecture proposed in this paper suggests handoff notifications between the IAPP demon and the Foreign Agent (FA) either in a WLAN-CDMA gateway or in a CDMA 2000 PDSN which implements an IAPP demon. Though we recommend that the PDSN implement an IAPP entity the WLAN and CDMA2000 data paths will remain distinct and as such our approach could be termed a loosely coupled architecture approach. Both IAPP as well as Mobile IP fast handoff drafts support caching of a mobile terminals handover context in possible targets. Satish, Vidhya Expires January, 2007 [Page 4] Internet-Draft IAPP-Mobile IP reference protocol August 2006 This similarity between the IAPP design and fast handoff pre-registration support in MIP has led us to suggest a mapping function between the two protocols at either the WLAN & CDMA gateway or at the CDMA2000 PDSN. This supports fast handoff between WLAN and a CDMA 2000 network by means of mutual notification between the IAPP and the Mobile IP protocols. The rest of the draft will focus on the specifics of the IAPP and Mobile IP interactions within a WLAN gateway architecture. A WLAN distributed network supports fast handoff through IAPP interactions and specifically proactive context caching. Therefore, a natural way to implement inter technology handoff between CDMA2000 and WLAN networks is to implement Mobile IP extensions, specifically the FA to interact with the IAPP entity. The following sections show a few of the IAPP and Mobile IP interaction points in a WLAN gateway architecture. A close interaction between the IAPP and a FA helps in achieving two goals: 1. Discovery of WLAN network by a CDMA 2000 wireless network and vice versa. 2. A subsequent fast handoff or layer 2 trigger transportation between WLAN and a CDMA network. 5.1. Network discovery & proactive caching The fact that an IAPP agent resides on the CDMA 2000 PDSN and a FA resides on the WLAN gateway allows the CDMA network to be WLAN mesh aware. For inter-technology handoff, discovery should always precede any exchange of signaling information. Such a discovery is facilitated by the IAPP CACHE notify The IAPP CACHE notify message from the IAPP to the MIP FA is treated as a MIP Pre-Registration indication. The following diagram shows the IAPP CACHE notify mapping in an FA. The CACHE primitive also helps in the discovery of a neighbouring WLAN entity in a 3G network. It should be mentioned at this stage that such a message can be restricted to a set of mobiles that support both WLAN and 3G services. Satish, Vidhya Expires January, 2007 [Page 5] Internet-Draft IAPP-Mobile IP reference protocol august 2006 Local APME Local IAPP Local FA | | | | | | | | Start | | | Confirmation | | | timeout | |IAPP-ADO.request| ____ | |--------------->|-------\__/ Start | | | /__\ Confirm | | | | timeout | |IAPP-CACHE | | ___ | |--------------->|---------|------\__/ | |Notify .request | | /__\ | | | Send | Layer2 | | | |---------|------->| | | | Up date |Frame | | | | |(confirm)| | | |<------- |--------|---- | | | Send |ADD-notify| | | |---------|---------|---------|-------------> | | | packet | | IAPP | | |(confirm)| | | |<--------|---------|---------|----- specific |IAPP-ADD.confirm| \|/ | | |<--- -----------|<-------/ \ | | |(Status=SUCCESSFUL)| | | | | | | | | Send CACHE | notify | | |------------- -----|-------->| | |packet to neighbours| |MIP Fast handoff | | | |--> | | | |Pre-Registration | | confirm | | request | |<------------------|---------| | | | | | | | | 5.2 Trigger notifications between IAPP and Mobile IP IAPP is not a layer 2 mechanism. It uses layer 2 association and re-association triggers from the MLME of the AP to facilitate mobility whereas Mobile IP uses layer 3 advertisements to initiate layer 3 handovers. The L2 indications both at WLAN AP and the CDMA 2000 AP during a WLAN CDMA handover will have to be transported. The FA association will have to be notified to the IAPP as IAPP MOVE indication. The following figure illustrates the mapping the IAPP MOVE primitive to the FA registration request message from a mobile. Satish, Vidhya Expires January, 2007 [Page 6] Internet-Draft IAPP-Mobile IP reference protocol august 2006 Local MLME Local APME Local IAPP | | | | MLME - | On cache hit | | REASSOCIATE | for | |--------------------->| reassociating | | .indication | STA | | | IAPP- CACHE- | | |--------------------> | | | NOTIFY .request | | | | | | | | | | | | | | | IAPP-CACHE- | | |<-------------------- | | | NOTIFY .confirm | | | | | | | | | IAPP-MOVE |Notify CDMA FA of a | |-------------------->|move to a CDMA network | | .request |-------------------> | | |The FA responds with | | |notification to HA | | | 6. ACKNOWLEDGEMENTS: We acknowledge all people who helped review this draft. 7. REFERENCES 1. Milind M. Buddhikot, Girish Chandranmenon, Seungjae Han, Yui-Wah Lee, Scott Miller, and Luca Salgarelli, Design and implementation of a LAN/CDMA 2000 Interworking architecture, IEEE communications magazine, November 2003. 2. “TIA/EIA/IS-835B cdma2000 Wireless IP Network Standard,” 3GPP2, 2000. 3. C. Perkins, Ed., “IP Mobility Support for IPv4,” IETF RFC 3344, Aug. 2002. 4. A. Salkintzis, C. Fors, and R. Pazhyannur, “WLAN-GPRS Integration for Next-generation Mobile Data Networks,” IEEE Wireless Commun., Oct. 2002. 5. 3GPP2-WLAN interworking, Stage 1 Requirements, S-R0087-0 V1.0, 3GPP2, 2004. 6. Jin Xiaohui, Li Jiandong, IAPP enhancement protocol, IEEE 0-7803-7010-4, IEEE 2001. Satish, Vidhya Expires January, 2007 [Page 7] Internet-Draft IAPP-Mobile IP reference protocol august 2006 7. K. El Malki, et al, Low Latency Handoffs in Mobile IPv4, draft-ietf-mobileip-lowlatency-handoffs-v4-09.txt, IETF, work in progress 8. Recommended Practice for Multi-Vendor Access Point Interoperability via an Inter-Access Point Protocol Across Distribution Systems Supporting IEEE 802.11 Operation, IEEE P802.11F, IEEE 2003. 7. Author's Contacts Satish Jamadagni Bangalore - 560078 e-mail: sjamadagni@yahoo.com Vidhya R Bangalore - 560078 email: vjamadagni@yahoo.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. 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