Network Working Group H. Jeon Internet-Draft J. Jee Expires: April 20, 2006 ETRI October 17, 2005 IPv6 NDP for Common Prefix Allocation in IEEE 802.16 draft-jeon-ipv6-ndp-ieee802.16-00.txt Status of this Memo 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. 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." 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 April 20, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract IEEE 802.16 is one of broadband wireless access technologies and will become a key technology for growing wireless IP network. However, connection-oriented feature of IEEE 802.16 introduces some issues in applying conventional standard IPv6 Neighbor Discovery Protocol (NDP). Following the previous 3GPP model [RFC 3314] for IPv6 NDP is not flexible in IPv6 link configuration since it assigns different network prefixes to each subscriber stations. We presents a mechanism which can allocate a common network prefix to all subscriber Jeon & Jee Expires April 20, 2006 [Page 1] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 stations under the same IPv6 link. Through this mechanism, the standard IPv6 NDP can be applied to IEEE 802.16 networks without modifying conventional host-side operation. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. General Terms . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Conventional Approaches . . . . . . . . . . . . . . . . . . . 4 4.1. Recommendations for IPv6 in 3GPP . . . . . . . . . . . . . 4 4.2. IPv6 over NBMA networks . . . . . . . . . . . . . . . . . 4 5. IPv6 Neighbor Discovery Issues over IEEE 802.16 . . . . . . . 5 5.1. IEEE 802.16 Deployment Architecture . . . . . . . . . . . 5 5.2. On-Link Issue . . . . . . . . . . . . . . . . . . . . . . 5 5.3. Multicast Issue . . . . . . . . . . . . . . . . . . . . . 6 6. IPv6 Neighbor Discovery Support over IEEE 802.16 . . . . . . . 6 6.1. Approach for On-Link Issue . . . . . . . . . . . . . . . . 6 6.2. Approach for Multicast Issue . . . . . . . . . . . . . . . 8 6.2.1. Multicast Emulation using Common CID . . . . . . . . . 8 6.2.2. Multicast Emulation using Multi-Unicast . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Normative References . . . . . . . . . . . . . . . . . . . 10 8.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12 Jeon & Jee Expires April 20, 2006 [Page 2] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 1. Introduction IPv6 Neighbor Discovery [RFC 2461] aims to solve problems due to the interaction between nodes attached on the same link. It is designed without dependence on a specific link layer technology, but assumes that the link layer technology support a native multicasting. IEEE 802.16 [IEEE 802.16][IEEE 802.16e] supports multicast and broadcast as well unicast. However, the aim of the multicast and broadcast is to transmit IEEE 802.16 MAC management messages for bandwidth allocation, not IP data. Thus, IPv6 Neighbor Discovery message on IEEE 802.16 cannot be delivered to neighboring hosts by means of multicast. IPv6 NDP messages have link-local scope address as IP destination address. It means those messages have to be delivered toward on-link hosts. However, if all Subscriber Station (SS) under same Base Station (BS) are configured with common IPv6 network prefix, IEEE 802.16 disagrees with IPv6 Neighbor Discovery on the definition of on-link host. Eventually, this discrepancy results in limitation of transmission coverage of IPv6 NDP messages with link-local scope address. We presents a mechanism which can allocate a common network prefix to all subscriber stations under the same IPv6 link. Through this mechanism, the standard IPv6 NDP can be applied to IEEE 802.16 networks without modifying conventional host-side operation. 2. Requirements The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. General Terms Description of following some terms is taken directly from [IEEE 802.16] and [IEEE 802.16e]. BS (Base Station) : A generalized equipment set providing connectivity, management, and control of the subscriber station. SS (Subscriber Station) : A generalized equipment set providing connectivity between subscriber equipment and a base station. CS (Service-specific Convergence Sublayer) : Sublayer in IEEE 802.16 MAC layer which classifier external network data and associates them Jeon & Jee Expires April 20, 2006 [Page 3] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 to the proper MAC service flow identifier and connection identifier. CID (Connection Identifier) : A 16 bit value that identifies a connection to equivalent peers in the MAC of the base station and subscriber station. DSA (Dynamic Service Addition) : The set of messages and protocols that allow the base station and subscriber station to add the characteristics of a service flow. MBS (Multicast and Broadcast Services) : Globally defined service flow that carries broadcast or multicast information towards a plurality of SS. MBS-CID (Multicast and Broadcast Services Connection ID) : Traffic CID for MBS. CCID (Common Connection Identifier) : CID shared by all SSs and BS for the purpose of transmitting IPv6 Neighbor Discovery messages. 4. Conventional Approaches This section shows existing approaches to adopt IPv6 over non- broadcast network or connection-oriented network. 4.1. Recommendations for IPv6 in 3GPP Following the 3GPP model for IPv6 neighbor discovery [RFC 3314], AR may assign distinct subnet to each SSs. In the case, IPv6 Neighbor Discovery can be deployed without any modification and some mechanisms using IPv6 Neighbor Discovery such as Address Resolution and Neighbor Unreachability Detection may be unnecessary. However, if BS configures one subnet for all SSs covered by the BS, IEEE 802.16 does not allow direct communication among SSs even though each SS knows that other SSs are neighboring ones at the IP level. It disallows the IPv6 Neighbor Discovery messages with link-local scope multicast destination address to be delivered to the intended receivers. 4.2. IPv6 over NBMA networks IPv6 over NBMA networks [RFC 2491] presents a general architecture for IPv6 over Non-Broadcast Multiple Access (NBMA) network. Specifically, IPv6 over NBMA networks focuses on an NBMA network with SVC mode which utilizes dynamically managed point to point and point to multipoint call and considers the NBMA network as core network Jeon & Jee Expires April 20, 2006 [Page 4] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 technology. IEEE 802.16 can be said to an NBMA network. However, IEEE 802.16 establishes administratively configured point-to-point link. That is, IEEE 802.16 can be referred to as NBMA network providing PVC support. Moreover, IEEE 802.16 is employed as access network technology in most cases. 5. IPv6 Neighbor Discovery Issues over IEEE 802.16 This section summarize issues when IPv6 Neighbor Discovery is employed over IEEE 802.16 under the condition all SSs are configured with common prefix address. 5.1. IEEE 802.16 Deployment Architecture Deployment architecture for IP network on IEEE 802.16 can be various according to the relationship between BS, Access Router (AR), and subnet. This document considers centralized architecture where AR assigns different prefixes to each BS and BS is connected to IP backbone via the AR as shown in Figure 1. /-------------------------------------\ | IP Backbone | \-------------------------------------/ | | /-----------\ /-----------\ | AR1 | | AR2 | \-----------/ \-----------/ / / | \ \ / / | \ \ / / | \ \ / / | \ \ / | | | \ / | | | \ BS1 BS2 BS3 BS4 BS5 BS6 BS7 BS8 BS9 BS10 Figure 1: Centralized Architecture 5.2. On-Link Issue IEEE 802.16 is a connection-oriented network. Even though all data in IEEE 802.16 are broadcasted to air shared to all SSs, only SS associated with the CID included in the data can receive the data. Thus, the connection between SS and BS can be seen direct one and thus only AR can be said to on-link for SS from the viewpoint of the IEEE 802.16. Jeon & Jee Expires April 20, 2006 [Page 5] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 However, IPv6 modules in each SS interpret on-link with prefix information. When SS sends data, it refers to destination cache for an entry matching the destination address. If no corresponding entry in the destination cache, SS matches the destination address with a prefix in prefix list in order to see whether or not the destination node is on-link. If the destination address matches a prefix, the destination cache is updated by setting next-hop address with the destination address and SS finds out link-layer address of the next- hop address using neighbor cache. Therefore, if all SSs covered by one BS can be configured with common prefix, all the SSs are on-link from the IPv6 point of view. Above different viewpoint of on-link causes inappropriate operations of IPv6 Neighbor Discovery because IPv6 Neighbor Discovery messages with local-scope multicast address are restricted in their transmission coverage. 5.3. Multicast Issue IPv6 Neighbor Discovery messages excepting Redirect are destined for local-scope multicast address such as all-router multicast address, all-node multicast address, and solicited-node multicast address. However, there is no dedicated CIDs for multicasting IPv6 packet in IEEE 802.16. Thus, any available traffic CID value needs to be allocated for multicasting IPv6 packet. From this, all SSs involved same multicast group can share the CID for common use. 6. IPv6 Neighbor Discovery Support over IEEE 802.16 In the previous section, we discussed issues when IPv6 Neighbor Discovery is deployed over IEEE 802.16. Following subsections handle the mentioned respective issues in order to support IPv6 Neighbor Discovery over IEEE 802.16. 6.1. Approach for On-Link Issue As mentioned before, the disagreement of on-link definition between IEEE 802.16 and IPv6 Neighbor Discovery restricts the transmission of link-local scope multicast addressed IPv6 Neighbor Discovery messages. Therefore, it is necessary to relay the restricted messages as an approach for on-link issue. Multicast Relaying Part (MRP) serves as packets relayer and is located in SS and AR. MRP can be positioned to IP layer (or Ethernet if IEEE 802.16 CS supports Ethernet) in order to receive packets from IEEE 802.16 CS first of all. Figure 2 shows a protocol stack on Jeon & Jee Expires April 20, 2006 [Page 6] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 centralized architecture including MRP where IEEE 802.16 CS supports only IPv6 and Ethernet is used between BS and AR. +-------------+ ~ ~ +-------------+ +-----------+ | IPv6 | | IPv6 | + +-------+ +------------------------+ + +-----+ | | MRP | | Bridge | | | MRP | +-------------+ +------------+-----------+ +-----------+ | 802.16 MAC | | 802.16 MAC | 802.3 MAC | | 802.3 MAC | +-------------+ +------------+-----------+ +-----------+ | 802.16 PHY |------| 802.16 PHY | 802.3 PHY |-------| 802.3 PHY | +-------------+ +------------+-----------+ +-----------+ SS BS AR Figure 2: Protocol Stack on Centralized Architecture including MRP MRP over AR intercepts packets destined for the multicast addresses from IEEE 802.16 CS and then prepares packet relaying while passing those to upper layer. Intercepting rule of MRP is different according to the case when IEEE 802.16 CS supports IPv6 over Ethernet or native IPv6. In case of IPv6 over Ethernet, MRP intercepts packets, which begin with 33-33 in Ethernet address. If IEEE 802.16 CS supports only IPv6, MRP holds packets, which begin with FF02 in IPv6 address. Note that MRP over AR does not intercept packets addressed FF02::2 (or 33-33-00-00-00-02). This is due to the assumption AR serves as default router and there is no other router in the subnet. Figure 3 shows multicast address types used in IPv6 Neighbor Discovery. Jeon & Jee Expires April 20, 2006 [Page 7] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 +----------------------+--------------+---------------------+ | Type |IP Addr. Type | Ethernet Addr. Type | +----------------------+--------------+---------------------+ |Link-local all-nodes | FF02::1 | 33-33-00-00-00-01 | |multicast address | | | +----------------------+--------------+---------------------+ |Link-local all-routers| FF02::2 | 33-33-00-00-00-02 | |multicast address | | | +----------------------+--------------+---------------------+ |Solicited-node |FF02::1:FFxx:x| 33-33-FF-xx-xx-xx | |multicast address | | | +----------------------+--------------+---------------------+ In Solicited-node multicast address, xx:x (xx-xx-xx) is last 24 bits of a unicast IPv6 address. Figure 3: Multicast Address Type in IPv6 Neighbor Discovery In addition to above function, MRP over AR may redirect packets destined for on-link host. In PMP mode of IEEE 802.16, all data from SS have to pass through the its serving BS. Among the data, those addressing neighboring SSs must be transmitted again via the incoming interface. In such a situation, AR can transmit Redirect message to sender. This problem can be issue in implementation of IEEE 802.16 CS. However, if IEEE 802.16 CS does not handle this point, MRP can treat the problem by redirecting such packets. 6.2. Approach for Multicast Issue This section describes how to transmit the packets with link-local scope multicast address into IEEE 802.16 network. We suggest following two different approaches for the purpose of multicast emulation. 6.2.1. Multicast Emulation using Common CID IEEE 802.16e proposes Multicast and Broadcast Service (MBS), which presents media service to SSs using multicast or broadcast. Under MBS architecture, each SS selects MBS contents and then configures a corresponding CID using DSA procedure. Such a CID for MBS is referred to as MBS-CID. MBS-CID is one of transport CIDs and is shared by all SSs requesting same media content. This document defines Common CID (CCID)as a special case of MBS-CID. CCID is allocated to BS and all SSs served by the BS utilizing a general DSA procedure in MBS for the purpose of transmitting IPv6 Neighbor Discovery messages. For the assigning the CCID, we assume Jeon & Jee Expires April 20, 2006 [Page 8] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 that service flow for IPv6 Neighbor Discovery is globally defined and the service flow is known to BS and all SSs. Once initialization between BS and SS is completed, they perform DSA procedure for creating the IPv6 Neighbor Discovery service flow. The detailed process creating new service flow and updating CS for mapping of the service flow to CCID is outside scope of this document. BS transmits IPv6 Neighbor Discovery messages relayed by AR towards all SSs via the CCID. 6.2.2. Multicast Emulation using Multi-Unicast The transmission using CCID allows IPv6 Neighbor Discovery messages to be delivered only once per transmission. However, it requires some modification to IEEE 802.16. This section shows how to transmit IPv6 Neighbor Discovery messages without an additional aid from IEEE 802.16. IPv6 Neighbor Discovery message is delivered by repeated unicast transmissions towards SSs involved the multicast address of the IPv6 Neighbor Discovery message. MRP over AR must manage mapping table which matches solicited-node multicast address with corresponding link-local address prior to relaying. Followings shows the total procedures: 1)MRP on SS constructs its own solicited-node multicast address with last 24 bits in its interface identifier based on IEEE EUI-64 Address. 2)MRP on SS informs BS of the solicited-node multicast address and its link-local address. Note that the link-local address has not yet been confirmed by Duplicate Address Detection (DAD) procedure. (MRP may extend MLD [RFC 2710] to notify the information) 3)MRP on AR checks the uniqueness of the link-local address informed by each SS without sending Neighbor Solicitation. If the link-local address is not valid, stop this procedures. Otherwise, go to Step 4. 4)MRP over AR manages mapping table which matches solicited-node multicast address with a corresponding valid link-local address. 5)When MRP over BS relays the IPv6 Neighbor Discovery messages, it refer the mapping table and swap the destination address of the messages with corresponding link-local address. Note that IPv6 Neighbor Discovery messages with link-local all node multicast address is sent to all SS. Jeon & Jee Expires April 20, 2006 [Page 9] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 7. Security Considerations IEEE 802.16e architecture supports a number of mandatory authorization mechanisms such as EAP-TTLS, EAP-SIM and EAP-AKA. RFC 3971 specifies security mechanisms for NDP and defines securing NDP messages. Applicability of SEND for IEEE 802.16 networks will be further investigated. 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 8.2. Informative References [IEEE802.16] IEEE Std 802.16-2004, "IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems", October 2004. [IEEE802.16e] IEEE P802.16e/D10, "Draft IEEE Standard for Local and metropolitan area networks, Amendment for Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands", Auguest 2005. [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) Specification", RFC 2460, December 1998. [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998. [RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6 over Non-Broadcast Multiple Access (NBMA) networks", RFC 2491, January 1999. [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast Listener Discovery (MLD) for IPv6", RFC 2710, October 1999. [RFC3314] Wasserman, M., "Recommendations for IPv6 in Third Generation Partnership Project (3GPP) Standards", RFC 3314, September 2002. Jeon & Jee Expires April 20, 2006 [Page 10] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 Authors' Addresses Hongseok Jeon Electronics Telecommunications Research Institute 161 Gajeong-dong, Yuseong-gu Daejeon, 305-350 KOREA Phone: +82-42-860-3892 Email: jeonhs@etri.re.kr Junghoon Jee Electronics Telecommunications Research Institute 161 Gajeong-dong, Yuseong-gu Daejeon, 305-350 KOREA Phone: +82-42-860-5126 Email: jhjee@etri.re.kr Jeon & Jee Expires April 20, 2006 [Page 11] Internet-Draft IPv6 NDP for CPA in IEEE 802.16 October 2005 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. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Disclaimer of Validity This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement Copyright (C) The Internet Society (2005). 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Jeon & Jee Expires April 20, 2006 [Page 12]