Network Working Group S. Kim Internet-Draft E. Paik Expires: December 26, 2006 J. Jin KT June 24, 2006 IP Deployment over IEEE 802.16 Networks draft-nam-ipv6-802-16e-01.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 December 26, 2006. Copyright Notice Copyright (C) The Internet Society (2006). Abstract This document introduces an WiBro, Wireless Broadband, network based on IEEE 802.16 technology. IEEE 802.16 are air interface specifiction for fixed and mobile broadband wireless system. WiBro is one of the profiles of IEEE 802.16. It depicts network architecture based on trial service and specifies frame format for reference point based on network architecture. It describes evolution of IPv6 deployment over IEEE 802.16 network with three Kim, et al. Expires December 26, 2006 [Page 1] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 phases. It lists issues of improvement for IP over IEEE 802.16 and IPv6 evolution. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology Used in This Document . . . . . . . . . . . . . . 4 3. WiBro Profile based on IEEE 802.16 . . . . . . . . . . . . . . 5 4. IP Deployment over IEEE 802.16 . . . . . . . . . . . . . . . . 6 4.1. Network Architecture . . . . . . . . . . . . . . . . . . . 6 4.1.1. ACR functions based on IEEE 802.16 . . . . . . . . . . 7 4.1.2. RAS functions based on IEEE 802.16 . . . . . . . . . . 7 4.2. IPv4 Deployment . . . . . . . . . . . . . . . . . . . . . 8 4.2.1. Frame format for reference point U . . . . . . . . . . 8 4.2.2. Frame format for reference point A . . . . . . . . . . 12 5. Evolution to IPv6 over IEEE 802.16 . . . . . . . . . . . . . . 12 5.1. IPv4 Service with IPv6 ready: Phase 1 . . . . . . . . . . 12 5.2. Partial Use of IPv6: Phase 2 . . . . . . . . . . . . . . . 13 5.3. Full dual stack: Phase 3 . . . . . . . . . . . . . . . . . 13 6. Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 6.1. Improvement for IP over IEEE 802.16 . . . . . . . . . . . 14 6.2. IPv6 evolution . . . . . . . . . . . . . . . . . . . . . . 14 7. Security considerations . . . . . . . . . . . . . . . . . . . 14 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 Intellectual Property and Copyright Statements . . . . . . . . . . 17 Kim, et al. Expires December 26, 2006 [Page 2] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 1. Introduction A public mobile services are provided based on circuit switched radio technology that enables mobility management, terminal status management. The major services are voice, however user's requirements are shifted to data service such as instant messaging, image transmission, video clip streaming and so on. It is difficult to satisfy emerging requirements by the advanced technology such as evolution of cdma2000 1x for data only (EV-DO), evolution of cdma2000 1x for both data and voice (EV-DV) and so on. The evolution of technologies for mobile network will be based on IP technologies. On the other hand, IP based networks are rapidly growing due to deployment of backbone network technologies and access network technologies. The backbone network technologies are 10 Gigabit Ethernet, 10 Gigabit Packet over SONET with dense wavelength division multiplexing (DWDM). The access network technologies for high speed Internet service are digital subscriber line (DSL), cable network and fiber to the home (FTTH) such as metro ethernet and combination of DSL and FTTH. However, wire-based high Internet access can not provide mobility requirement of the users. IEEE 802.11 technology is developed to cope with mobility issues on Internet. High speed mobile technologies evolved from voice network have excellent mobility management up to 120Km per hour, but it has to solve the high speed data rate to the user. An wired and Wireless LAN can provid excellent data rate compared with evolving mobile based voice network, but it has to solve mobility and cell coverage issues. IEEE 802.16 specifies a new air interface and medium access control (MAC) protocol to provide both high data rate and large cell coverage. In addition, IEEE 802.16e provides seamless mobility so that mobile users can use wireless Internet services while they are moving on vehicles. Broadband Wireless Access (BWA) is still in the early stage of its growth. WiBro, wireless broadband, is one of the profiles for IEEE 802.16 standards. It provides high-speed data rate more than IEEE 801.11 technology and mobility function as 3G networks. A third-generation capabilities from a network perspective implies packet switching, Internet access and IP connectivity capabilities. This document introduces an WiBro, Wireless Broadband, network based on IEEE 802.16 technology. IEEE 802.16 are air interface specifiction for fixed and mobile broadband wireless system. WiBro is one of the profiles of IEEE 802.16. It depicts network architecture based on ISP's experience of trial service and specifies frame format for reference point based on network architecture. It describes evolution of IPv6 deployment over IEEE 802.16 network with three phases. It lists issues of improvement for IP over IEEE 802.16 Kim, et al. Expires December 26, 2006 [Page 3] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 and IPv6 evolution. 2. Terminology Used in This Document Telecommunication Technology Association (TTA): The TTA is a standardization organization in Korea. The WiBro standard is one of the specifications developed by TTA. Subscriber station (SS): A generalized equipment set providing connectivity between subscriber equipment and a base station. It is generally accepted for fixed terminal with IEEE complient interface that defind by IEEE 802.16. The SS can be either fixed station or mobile station. Mobile Station (MS): A station in the mobile service intended to be used while in motion or during halts at unspecified points. An MS is always a subscriber station which must provide mobility function. Radio Access Station (RAS): A generalized equipment set providing connectivity between mobile station defined for WiBro in TTA. This is a part of base station in IEEE 802.16. Access Control Router (ACR): A generalized equipment set providing connectivity between RAS and IP network defined for WiBro in TTA. This is a part of base station in IEEE 802.16. Base Station (BS): A generalized equipment set providing connectivity, management, and control of the subscriber station is defined in IEEE 802.16. A BS is decomposed of RAS and ACR which is defined in TTA. Access Service Network (ASN): An ASN is a logical boundary and aggregation of functional entities defined in WiMAX Forum. An ASN is composed of BS and ASN gateway. It is clear relationship between TTA and WiMAX; what RAS is to WiBro, BS is to WiMAX. ACR is to WiBro as ASN gateway in to WiMAX. An ASN is the same architecture as BS defined by IEEE 802.16. Therefore, BS in terms of IEEE 802.16 includes RAS and ACR. Kim, et al. Expires December 26, 2006 [Page 4] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 Edge Router (ER): An edge router is a device that routes data packet between ASN and CSN. Connectivity Service Network (CSN): An CSN is a set of network functions that provide IP connectivity service to the subscriber station defined by WiMAX. Reference Point U: An U reference point is between SS and BS defined by TTA and IEEE 802.16. WiMAX defines R1 reference point between SS and BS. The U and R1 are the same reference point. Reference Point A: An A reference point is between RAS and ACR defined by TTA. IEEE 802.16 does not define for this reference point because one BS consists of RASs and ACR. WiMAX defines R6 reference point between BS and ASN gateway. The A and R6 are the same reference point. Reference Point I: An I reference point is between ACR and ER defined by TTA. WiMAX defines more detailed reference point that R3 for between ASN and CSN, R2 for between SS and CSN, R5 for between CSN and CSN. The I and R3 are the same reference point. The other reference point such as R2 and R5 are not general in terms of network architecture. Wireless Broadband (WiBro): An WiBro is one of the profiles for IEEE 802.16 standard developed by TTA. 3. WiBro Profile based on IEEE 802.16 IEEE 802.16 standard supports a wide range of frequencies upto 66GHz, channel size from 1.25MHz to 20MHz, radio characteristics both non- line-of-sight and line-of-sight and network configuration between SS and BS such as point to multipoint and mesh. The WiBro must comply with IEEE 802.16-2004 and IEEE 802.16e-2005. The profiles for WiBro are as following. Duplex Duplex is a bidirectional communication scheme between MS and RAS. It can be classified into half-duplex and full-duplex. A full- duplex method can achive either frequency division duplex (FDD) or time division duplex (TDD). FDD requires two channels, one for uplink and the other for downlink traffic. TDD network traffic Kim, et al. Expires December 26, 2006 [Page 5] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 uses a single channel with uplink and downlink traffic assigned to different time slots. WiBro uses time division duplex. Frequency Band and Channel Allocation The frequency bands for WiBro is from 2.3GHz to 2.4GHz that is divided into three bands for service provider (SP). A channel bandwidth is 9MHz and guard band between service provider is 4.5MHz. The frequency allocation as shown in Figure 1. +---------------+--------+----------------+--------+----------------+ | 1st band | guard | 2nd band (SP2) | guard | 3rd band (SP3) | | (SP1) | band | | band | | +---------------+--------+----------------+--------+----------------+ | 29MHz (3 CH) | 4.5MHz | 29MHz (3 CH) | 4.5MHz | 29MHz (3 CH) | +---------------+--------+----------------+--------+----------------+ Figure 1. Channel allocation in WiBro Multiple Access The IEEE 802.16 specifies multiple access methods: frequency division multiple access (FDMA), time division multiple access (TDMA), OFDM, OFDMA. A multiple access scheme between SS/MS and RAS is othogonal frequency division multiple access (OFDMA) in WiBro. Data Rate An uplink data rate per user is minimum 128Kbps and maximum 1Mbps for data traffic at the cell edge. A downlink traffic per user between 512Kbps and 3Mbps, respectively. A handover time is less than 150ms under the 60Km/hour condition. Frequency Reuse Factor An uplink data rate per user is minimum 128Kbps and maximum 1Mbps for data traffic at the cell edge. A downlink traffic per user between 512Kbps and 3Mbps, respectively. A frequency reuse factor is specified to 1. A maximum frequency efficiency is 6bps/Hz/Cell for downlink and 2bps/Hz/Cell for uplink respectively. Roaming among the Service Provider A service provider for WiBro should support roaming to the users. 4. IP Deployment over IEEE 802.16 4.1. Network Architecture The network architecture is shown in Figure 2. The WiBro network Kim, et al. Expires December 26, 2006 [Page 6] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 based on IEEE 802.16 is connected to the Internet via ER. +-----+ | --------- ASN --------- | ------ CSN ------ | | MS1 |----+ +-----+ | | +-----+ | +------+ +------+ +-----+ | MS2 |----+---| RAS1 |--+--| ACR1 |--+--| ER1 |-----[Internet] +-----+ | +------+ | +------+ | +-----+ . | . | . | . | . | . | +-----+ | +------+ | +------+ | | MSn |----+ | RASn |--+ | ACRn |--+ +-----+ +------+ +------+ Reference Point U A I Figure 2. Network Architecture for WiBro based on IEEE 802.16 4.1.1. ACR functions based on IEEE 802.16 Main functions of a ACR which is parts of ASN are as follow: - IP network interface function for both reference point I and reference point A. - DHCPv4 server and relay function for efficient IP address management. - Supporting session connection, continuity and disconnection with IEEE 802.16 management messages. - SS management function: Paging for idle mode SS with location management function. - Handover management and radio resource control function for MS. - Generating AAA information for user and sending them to Diameter server. 4.1.2. RAS functions based on IEEE 802.16 Main functions of a RAS which is parts of ASN are as follow: - IP network interface function for both reference point A and Kim, et al. Expires December 26, 2006 [Page 7] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 reference point U. - Supporting session connection, continuity and disconnection with IEEE 802.16 management messages. - Handover function and radio resource management for MS. - Radio resource management. 4.2. IPv4 Deployment The IEEE 802.16 MAC comprises of three sublayers; service specific convergence sublayer (CS), MAC common part sublayer, security sublayer. Multiple CSs are defined to use various protocols such as ATM CS and packet CS. Packet CS supports IEEE 802.3, IEEE 802.1Q, IPv4 and IPv6 via their own specific CS. There are three ways to use IPv4 packet CS at reference point U; IPv4 over IEEE 802.16, IPv4 over IEEE 802.3 over IEEE 802.16 and IPv4 over IEEE 802.1Q over IEEE 802.16. The WiBro uses IPv4 over IEEE 802.16 at reference point U. 4.2.1. Frame format for reference point U In Figure 3, L2 is the IEEE 802.16 header and trailer format.The L3 is the IPv4 header format. When the Ethernet CS is used, Ethernet header should be inserted between L2 header and L3 header in Figure 3[1-3]. H: Header Type (1 bit). Shall be set to zero indicating that it is a Generic MAC PDU. E: Encryption Control (1 bit). 0 = Payload is not encrypted; 1 = Payload is encrypted. Type (6 bit). This field indicates the subheaders and special payload types present in the message payload. The subheader types are mesh subheader, fragmentation subheader, packing subheader and FAST-FEEDBACK allocation subheader. The special payload is ARQ feedback payload. E: Extended subheader field (1 bit). 0 = the extended subheader is absent; 1 = the extended subheader is present. The ESF is applicable both in the downlink and in the uplink. C: CRC indicator (1 bit). 0 = CRC is not included; 1 = CRC is Kim, et al. Expires December 26, 2006 [Page 8] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 included in the PDU by appeding it. WiBro should be set to 1 because OFDMA is used in WiBro. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- |H|E| Type |E|C|EKS|R| Length | CID MSB | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L2 | CID LSB | HCS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- |Version| IHL |Type of Service| Total Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identification |Flags| Fragment Offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time to Live | Protocol | Header Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L3 | Source Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- | | +- -+ / payload ... / +- -+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- | CRC (optional) | L2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- Figure 3. Frame Format for IPv4 CS over IEEE 802.16 EKS: Encryption Key Sequence (2 bit). The index of the traffic encryption key and initialization vector used to encrypt the payload. This field is only meaningful if the EC field is set to 1. R: Reserved (1 bit). Shall be set to zero. Length (11 bit). The length in bytes of the MAC PDU including MAC header and the CRC. CID: Connection identifier (16 bit). A CID identifies a connection to equivalent peers in the MAC of the BS and SS. A BS composes of RAS and ACR in WiBro. An SS's peer is an ACR in terms of CID information. There are several CIDs defined in IEEE 802.16 for the purpose of well-known address as shown in Figure 4 [2]. Kim, et al. Expires December 26, 2006 [Page 9] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 +--------------------+--------+-------------------------------------+ | CID | Value | Description | +--------------------+--------+-------------------------------------+ | Initial ranging | 0x0000 | Used by SS and BS during initial | | | | ranging process. | | Basic CID | 0x0001 | The same value is assigned to both | | | - m | the DL and UL connection. | | Primary management | m+1 - | The same value is assigned to both | | | 2m | the DL and UL connection. | | Transport CIDs, | 2m+1 - | For the secondary management | | Secondary Mgt CIDs | FE9F | connection, the same value is | | | | assigned to both the DL and UL | | | | connection. | | Multicast CIDs | 0xFEA0 | For the downlink multicast service, | | | - | the same value is assigned to all | | | 0xFEFE | MSs on the same channel that | | | | participate in this connection. | | AAS initial | 0xFEFF | A BS supporting AAS shall use this | | ranging CID | | CID when allocating an AAS Ranging | | | | period (using AAS Ranging | | | | Allocation IE). | | Multicast polling | 0xFF00 | A BS may be included in one or more | | CIDs | - | multicast polling groups for the | | | 0xFFF9 | purposes of obtaining bandwidth via | | | | polling. These connections have no | | | | associated service flow. | | Normal mode | 0xFFFA | Used in DL-MAP to denote bursts for | | multicast CID | | transmission of DL broadcast | | | | information to normal mode MS. | | | | Sleep mode multicast | | Sleep mode | 0xFFFB | Used in DL-MAP to denote bursts for | | multicast CID | | transmission of DL broadcast | | | | information to Sleep mode MS. May | | | | also be used in MOB_TRF-IND | | | | messages. | | Idle mode | 0xFFFC | Used in DL-MAP to denote bursts for | | multicast CID | | transmission of DL broadcast | | | | information to Idle mode MS. May | | | | also be used in MOB_PAG-ADV | | | | messages. | | Fragmentable | 0xFFFD | Used by the BS for transmission of | | Broadcast CID | | management broadcast information | | | | with fragmentation. The fragment | | | | sub header shall use 11-bit long | | | | FSN on this connection. | | Padding CID | 0xFFFE | Used for transmission of padding | | | | information by SS and BS. | Kim, et al. Expires December 26, 2006 [Page 10] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 | Broadcast CID | 0xFFFF | Used for broadcast information that | | | | is transmitted on a downlink to all | | | | SS. | +--------------------+--------+-------------------------------------+ Figure 4. well-known CID for IEEE 802.16 HCS: Header Check Sequence (8 bit). This field is used to detect errors in the header. The transmitter shall calculate the HCS value for the first 40 bits of the IEEE 802.16 MAC header, and insert the result into this field. The HCS value is the remainder of the division by the generator polynomial that is g(x) = X8 + X2 + X + 1. CRC: Cyclic Redundancy Check (32 bit). As the CRC indicator bit is set to 1 in WiBro, the sender shall calculate the CRC value for the entire IEEE 802.16 frame. The generator polynomial is g(x) = X32 + X26 + X23 + X22 + X16 + X12 + X11 + X10 + X8 + X7 + X5 + X4 + X2 + X + 1. Kim, et al. Expires December 26, 2006 [Page 11] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 4.2.2. Frame format for reference point A 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- | Destination Ethernet Address | + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + L2 | Source Ethernet Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- |Version| IHL |Type of Service| Total Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Identification |Flags| Fragment Offset | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Time to Live | Protocol | Header Checksum | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L3 | Source Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Destination Address | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Options | Padding | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- | | +- -+ / payload ... / +- -+ | | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- | FCS | L2 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ --- Figure 5. Frame Format for reference point A 5. Evolution to IPv6 over IEEE 802.16 IPv6 service should be provided without affecting IPv4 service. An ISP can prepare IPv6 deployment by following three phases. 5.1. IPv4 Service with IPv6 ready: Phase 1 In phase 1, Internet Service is launched based on IPv4 with network architecture shown in Figure 2. While Internet still support IPv4-only, ER can support IPv4/IPv6 dual Kim, et al. Expires December 26, 2006 [Page 12] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 stacks. An ASN equipment that comply with IEEE 802.16 may support IPv6 with dual stack. However dual stack in ASN equipment is not enabled during phase 1. Tunneling protocol among ERs is defined but not be used. In this phase, the network delivers IPv4 traffic only. And MSs are based on IPv4. Figure 6 shows IP functionalities among the network elements based on network architecture. +----------------------+----------+----------+----------+----------+ | Phase 1 | SS/MS | ASN | ER | Internet | +----------------------+----------+----------+----------+----------+ | IPv4 only | O | | | O | | IPv4/IPv6 dual stack | | O | O | | +----------------------+----------+----------+----------+----------+ Figure 6. Phase 1 scenarion for evolution IPv6 over IEEE 802.16 5.2. Partial Use of IPv6: Phase 2 In phase 2, the ISP starts offering IPv6 service over IEEE 802.16 partially. An ASN equipment and ERs enable IPv4/IPv6 dualstack. IPv4 and IPv6 traffic is delivered independantly. IPv4 traffic is delivered as same as in phase 1. IPv6 traffic is delivered through tunnels between ERs in Internet. Because, the Internet does not support full IPv6. +----------------------+----------+----------+----------+----------+ | Phase 2 | SS/MS | ASN | ER | Internet | +----------------------+----------+----------+----------+----------+ | IPv4 only | | | | O | | IPv4/IPv6 dual stack | O | O | O | | +----------------------+----------+----------+----------+----------+ Figure 7. Phase 2 scenarion for evolution IPv6 over IEEE 802.16 Figure 7 shows IP functionalities among the network elements based on network architecture. 5.3. Full dual stack: Phase 3 In phase 3, the ISP provides stable IPv6 service due to whole networks can operate dual stack. The Internet can deliver IPv6 traffic without IPv4-IPv6 tunneling protocol. The IPv4/IPv6 dual stack is enabled not only in ASN but also in CSN including Internet. Kim, et al. Expires December 26, 2006 [Page 13] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 However, there are IPv4-only MSs, IPv4/IPv6 dual stack MSs and IPv6- olny MSs. An IPv4-only MSs use IPv4. The IPv4/IPv6 dual stack MSs and IPv6-olny MSs use IPv6. +-----+ | --------- ASN --------- | ------ CSN ------ | | MS1 |----+ +-----+ | IPv4/IPv6 dual stack | IPv4/IPv6 dual stack +-----+ | +------+ +------+ +-----+ | MS2 |----+---| RAS1 |--+--| ACR1 |--+--| ER1 |-----[Internet] +-----+ | +------+ | +------+ | +-----+ . | . | . | . | . | . | +-----+ | +------+ | +------+ | | MSn |----+ | RASn |--+ | ACRn |--+ +-----+ +------+ +------+ IPv4/IPv6 dual stack Figure 8. Phase 3 scenarion for evolution IPv6 over IEEE 802.16 6. Issues Some issues arise to improve IPv4 and to evolve IPv6 over IEEE 802.16. 6.1. Improvement for IP over IEEE 802.16 - TCP Performance - QoS 6.2. IPv6 evolution - IPv6 address allocation to MS 7. Security considerations We do not consider any security issues in this draft. 8. References [1] IEEE 802.16, "IEEE Standard for Local and metropolitan area networks Part16: Air Interface for Fixed Broadband Wireless Kim, et al. Expires December 26, 2006 [Page 14] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 Access System", October 2004. [2] IEEE 802.16e, "IEEE Standard for Local and metropolitan area networks Part16: Air Interface for Fixed Broadband Wireless Access System Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands", February 2006. [3] Postel, J., "Internet Protocol", RFC 791, September 1981. [4] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998. Kim, et al. Expires December 26, 2006 [Page 15] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 Authors' Addresses Sang-Eon Kim Network Infra Lab., KT 17 Woomyeon-dong, Seocho-gu Seoul, 137-791 Korea Phone: +82 2 526 6117 Fax: +82 2 526 5200 Email: sekim@kt.co.kr Eunkyoung Paik Advanced Technology Lab., KT 17 Woomyeon-dong, Seocho-gu Seoul, 137-791 Korea Phone: +82 2 526 5233 Fax: +82 2 526 5200 Email: euna@kt.co.kr Jong Sam Jin Network Infra Lab., KT 17 Woomyeon-dong, Seocho-gu Seoul, 137-791 Korea Phone: +82 2 526 6113 Fax: +82 2 526 5200 Email: jongsam@kt.co.kr Kim, et al. Expires December 26, 2006 [Page 16] Internet-Draft IP Deployment over IEEE 802.16 Networks June 2006 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 (2006). 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. Kim, et al. Expires December 26, 2006 [Page 17]