Network Working Group Basavaraj. Patil Internet-Draft Nokia Intended status: Standards Track Frank. Xia Expires: April 26, 2007 Behcet. Sarikaya Huawei USA JH. Choi Samsung AIT Syam. Madanapalli LogicaCMG October 23, 2006 IPv6 Over IPv6 Convergence sublayer in 802.16 Networks draft-ietf-16ng-ipv6-over-ipv6cs-01 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 26, 2007. Copyright Notice Copyright (C) The Internet Society (2006). Abstract The IEEE 802.16d/e has specified several convergence sublayers which are a part of the MAC that can be used for carrying IPv6 packets. Patil, et al. Expires April 26, 2007 [Page 1] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 The IPv6 convergence sublayer enables transport of IPv6 packets directly over the MAC. Between the 802.16d/e host and the base station IPv6 packets are carried over a MAC layer transport connection which is a virtual point-to-point link. This document specifies the addressing and operation of IPv6 hosts served by a network that utilizes the 802.16d/e air interface. It recommends the assignment of a unique prefix to each host and allow the host to use multiple identifiers within that prefix, including support for randomly generated identifiers. Table of Contents 1. Conventions used in this document . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. IEEE 802.16d/e convergence sublayer support for IPv6 . . . . . 4 5. Generic network architecture using the 802.16d/e air interface . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. WiMAX network architecture and IPv6 support . . . . . . . 6 6. IPv6 link . . . . . . . . . . . . . . . . . . . . . . . . . . 7 6.1. IPv6 link in 802.16 . . . . . . . . . . . . . . . . . . . 8 6.1.1. IPv6 link in WiMAX . . . . . . . . . . . . . . . . . . 8 6.2. IPv6 link establishment in 802.16 . . . . . . . . . . . . 8 6.2.1. IPv6 link establishment in WiMAX . . . . . . . . . . . 9 6.3. Maximum transmission unit in 802.16 . . . . . . . . . . . 9 6.3.1. Maximum transmission unit in WiMAX . . . . . . . . . . 10 7. IPv6 prefix assignment . . . . . . . . . . . . . . . . . . . . 10 8. Router Discovery . . . . . . . . . . . . . . . . . . . . . . . 10 8.1. Router Solictation . . . . . . . . . . . . . . . . . . . . 10 8.2. Router Advertisement . . . . . . . . . . . . . . . . . . . 11 8.3. Router lifetime and periodic router advertisements . . . . 11 9. IPv6 addressing for hosts . . . . . . . . . . . . . . . . . . 11 9.1. Interface Identifier . . . . . . . . . . . . . . . . . . . 11 9.2. Duplicate address detection . . . . . . . . . . . . . . . 11 9.3. Stateless address autoconfiguration . . . . . . . . . . . 11 9.4. Stateful address autoconfiguration . . . . . . . . . . . . 12 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 11. Security Considerations . . . . . . . . . . . . . . . . . . . 12 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 13.1. Normative References . . . . . . . . . . . . . . . . . . . 12 13.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 Intellectual Property and Copyright Statements . . . . . . . . . . 15 Patil, et al. Expires April 26, 2007 [Page 2] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 1. Conventions used in this document In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, RFC 2119 [RFC2119] and indicate requirement levels for compliant implementations. 2. Introduction IPv6 transport over the IEEE 802.16d/e specified air interface can be accomplished via either the IPv6 convergence sublayer or the Ethernet convergence sublayer. The 802.16d/e [802.16e] specification includes the Phy and MAC details. The convergence sublayers are a part of the MAC. This document specifies IPv6 from the perspective of the IPv6 convergence sublayer. The mobile station/host is attached to an access router via a base station (BS). The host and the BS are conected via the 802.16d/e at the link and physical layers. The IPv6 layer terminates at an access router which may be a part of the BS or an entity beyond the BS. The base station is a layer 2 entity and relays the IPv6 packets between the AR and the host via a point-to- point connection over the air interface. The WiMAX (Worldwide Interoperability for Microwave Access) forum has defined a network architecture in which the air interface is based on the 802.16d/e standard. The addressing and operation of IPv6 described in this document is applicable to the WiMAX network as well. 3. Terminology The terminology is based on the definitions used in the network architecture specified by the WiMAX forum. BS - The Base Station (BS) is a logical entity that embodies a full instance of the 802.16d/e MAC and PHY in compliance with the IEEE 802.16 suite of applicable standards. It provides the layer 1/2 connectivity between the network and the MS. MS - The mobile station is an IPv6 host that connects to the AR in the network via an 802.16d/e module. Transport Connection - 802.16 MAC is connection oriented. Several types of connections are defined and these include broadcast, unicast and multicast. Each connection is uniquely identified by a 16 bit connection identifier (CID). A transport connection is a unicast connection intended for user traffic. A transport connection is identified by an uplink and downlink CID. The scope of the transport Patil, et al. Expires April 26, 2007 [Page 3] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 connection is between the MS and the BS. Access Service Network (ASN) - The ASN is defined as a complete set of network functions needed to provide radio access to a WiMAX subscriber. The ASN is the access network to which the MS attaches. The IPv6 access router is an entity within the ASN. Access Router (AR) - The Access router is the 1st hop default IPv6 router from the perspective of the MS. The AR is an entity that can be an integral part of the BS or a separate entity within the access network. 4. IEEE 802.16d/e convergence sublayer support for IPv6 IEEE 802.16d/e has specified multiple convergence sublayers (CS) in the MAC. The convergence sublayers and MAC specifications are available in [802.16e]. IPv6 can be implemented in two ways: 1. Over the IPv6 convergence sublayer or 2. Over Ethernet (which runs over Ethernet CS). The figure below shows the options for IPv6 implementation in WiMAX: -------------- --------------- | IPv6 | | IPV6 | -------------- --------------- | IPv6 CS | | Ethernet | | .......... | --------------- | MAC | | Ethernet CS | -------------- | ........... | | PHY | | MAC | -------------- --------------- IPv6 over IPv6 CS | PHY | --------------- IPv6 over Ethernet Figure 1: IPv6 over IPv6 CS and over Ethernet The scope of this document is limited to IPv6 operation over IPv6 CS only. 5. Generic network architecture using the 802.16d/e air interface In a network that utilizes the 802.16d/e air interface the host/MS is attached to an IPv6 access router (AR) in the network. The BS is a Patil, et al. Expires April 26, 2007 [Page 4] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 layer 2 entity only. The AR can be an integral part of the BS or the AR could be an entity beyond the BS within the access network. IPv6 packets between the MS and BS are carried over a transport connection which has a unique connection identifier (CID). The transport connection is a MAC layer link between the MS and the BS. The figures below describe the possible network architectures and are generic in nature. More esoteric architectures are possible but not considered in the scope of this document. Option A: +-----+ CID1 +--------------+ | MS1 |------------/| BS/AR |-----[Internet] +-----+ / +--------------+ . /---/ . CIDn +-----+ / | MSn |---/ +-----+ Figure 2: The IPv6 AR as an integral part of the BS Option B: +-----+ CID1 +-----+ +-----------+ | MS1 |----------/| BS1 |----------| AR |-----[Internet] +-----+ / +-----+ +-----------+ . / ____________ . CIDn / ()__________() +-----+ / L2 Tunnel | MSn |-----/ +-----+ Figure 3: The IPv6 AR is separate from the BS, which acts as a bridge The above network models serve as examples and are shown to illustrate the point to point link between the MS and the AR. The next section shows a realization of the generic architecture by the WiMAX forum. Patil, et al. Expires April 26, 2007 [Page 5] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 5.1. WiMAX network architecture and IPv6 support The WiMAX network architecture consists of the Access Service Network (ASN) and the Connectivity Service Network (CSN). The ASN is the access network which includes the BS and the AR in addition to other functions such as AAA, Mobile IP Foreign agent, Paging controller, Location Register etc. The CSN is the entity that provides connectivity to the Internet and includes functions such as Mobile IP Home agent and AAA. The figure below shows the WiMAX reference model: ------------------- | ---- ASN | |----| ---- | |BS|\ R6 -------| |---------| | CSN| |MS|-----R1----| ---- \---|ASN-GW| R3 | CSN | R5 | | ---- | |R8 /--|------|----| |-----|Home| | ---- / | | visited| | NSP| | |BS|/ | | NSP | | | | ---- | |---------| | | | NAP | \ |----| ------------------- \---| / | | / | (--|------/----) |R4 ( ) | ( ASP network ) --------- ( or Internet ) | ASN | ( ) --------- (----------) Figure 4: WiMAX Network reference model Three different types of ASN realizations called profiles are defined by the architecture. ASNs of profile types A and C include BS' and ASN-gateway(s) which are connected to each other via an R6 interface. An ASN of profile type B is one in which the functionality of the BS and other ASN functions are merged together. No ASN-GW is specifically defined in a profile B ASN. However all the functions of an ASN such as the MIP4 FA, AAA, AR exist within the scope of an ASN. The absence of the R6 interface is also a profile B specific characteristic. The MS at the IPv6 layer is associated with the AR in the ASN. The AR may be a function of the ASN-GW in the case of profiles A and C and is a function in the ASN in the case of profile B. When the BS and the AR are separate entities and linked via the R6 interface, IPv6 packets between the BS and the AR are carried over a Patil, et al. Expires April 26, 2007 [Page 6] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 GRE tunnel. The granularity of the GRE tunnel can be on a per flow basis, per MS basis or on a BS basis. The protocol stack in WiMAX for IPv6 is shown below: |-------| | App |- - - - - - - - - - - - - - - - - - - - - - - -(to app peer) | | |-------| /------ ------- | | / IPv6 | | | | IPv6 |- - - - - - - - - - - - - - - - / | | |--> | | --------------- -------/ | | IPv6| |-------| | \Relay/ | | | |- - - | | | | | \ / | | GRE | | | | | | | \ /GRE | - | | | | | | |- - - | |-----| |------| | | | | IPv6CS| |IPv6CS | IP | - | IP | | | | | ..... | |...... |-----| |------|--------| |-----| | MAC | | MAC | L2 | - | L2 | L2 |- - - | L2 | |-------| |------ |-----| |----- |--------| |-----| | PHY |- - - | PHY | L1 | - | L1 | L1 |- - - | L1 | -------- --------------- ----------------- ------- MS BS AR/ASN-GW CSN Rtr Figure 5: WiMAX protocol stack As can be seen from the protocol stack description, the IPv6 end- points are constituted in the MS and the AR. The BS provides lower layer connectivity for the IPv6 link. 6. IPv6 link RFC 2461 defines link as a communication facility or medium over which nodes can communicate at the link layer, i.e., the layer immediately below IP [RFC2461]. Usually a link is bounded by routers that decrement TTL. When an MS moves within a link, it can keep using its IP addresses. This is a layer 3 definition and note that the definition is not identical with the definition of the term '(L2) link' in IEEE 802 standards. This section presents a model for the last mile link, i.e. the link to which MSs attach themselves. Patil, et al. Expires April 26, 2007 [Page 7] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 6.1. IPv6 link in 802.16 For 802.16 network, following the 3GPP precedent [RFC3314], point-to- point link model is recommended. In 802.16, there exists L2 layer Transport Connection between an MS and a BS over which packets are transferred. A Transport Connection is represented by CID (Connection Identifier) and multiple Transport Connections can be assigned to an MS. When an AR and a BS is collocated, the collection of Transport Connections to an MS is defined as a single link. When an AR and a BS is separated, it is recommended that a tunnel is established between the AR and a BS whose granuality is no greater than 'per MS'. Then the tunnel(s) for an MS, in combination with the MS's Transport Connections, forms a single point-to-point link. 6.1.1. IPv6 link in WiMAX The MS and the AR are connected via a combination of : 1. The transport connection which is identified by a Connection Identifier (CID) over the air interface, i.e the MS and BS and, 2. A GRE tunnel between the BS and AR which transports the IPv6 packets From an IPv6 perspective the MS and the AR are connected by a point- to-point link. The combination of transport connection over the air interface and the GRE tunnel between the BS and AR creates a (point- to-point) tunnel at the layer below IPv6. The collection of service flows (tunnels) to an MS is defined as a single link. Each link has only an MS and an AR. Each MS belongs to a different link. No two MSs belong to the same link. A different prefix should be assigned to a different link. This link is fully consistent with a standard IP link, without exception and conforms with the definition of a point-to-point link in RFC2461 [RFC2461]. 6.2. IPv6 link establishment in 802.16 The MS goes through the network entry procedure as specified by 802.16d/e. At a high level the network entry procedure can be described as follows: 1. MS performs initial ranging with the BS. Ranging is a process by which an MS becomes time aligned with the BS. The MS is synchronized with the BS at the succesful completion of ranging and is ready to setup a connection. Patil, et al. Expires April 26, 2007 [Page 8] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 2. The MS does capability exchange with the BS. As part of this step, the MS indicates its capability which includes support for IPv6 convergence sublayer among others. 3. The MS now progresses to an authentication phase. Authentication is based on PKMv2 as defined in the 802.16e specification. 4. On succesfull completion of authentication, the MS performs 802.16e registration with the network. 5. The MS can request the establishment of a service flow over the IPv6 convergence sublayer. The service flow can also be triggered by the network as a result of pre-provisioning. The service flow establishes a link between the MS and the AR over which IPv6 packets can be sent and received. 6. The AR sends a router advertisement to the MS. The above flow does not show the actual 802.16e messages that are used for ranging, capability exchange or service flow establishment. Details of these are in [802.16e]. 6.2.1. IPv6 link establishment in WiMAX The mobile station performs initial network entry as specified in 802.16e. On succesful completion of the network entry procedure the ASN gateway/AR triggers the establishment of the initial service flow (ISF) for IPv6 towards the MS. The ISF is a GRE tunnel between the ASN-GW/AR and the BS. The BS in turn requests the MS to establish a transport connection over the air interface. The end result is a transport connection over the air interface for carrying IPv6 packets and a GRE tunnel between the BS and AR for relaying the IPv6 packets. On succesful completion of the establishment of the ISF, IPv6 packets can be sent and received between the MS and AR. The ISF enables the MS to communicate with the AR for host configuration procedures. After the establishment of the ISF, the AR can send a router advertisement to the MS. An MS can establish multiple service flows with different QoS characteristics. The ISF can be considered as the primary service flow. The ASN GW/ AR treats each ISF, along with the other service flows to the same MS, as a unique link which is managed as a (virtual) interface. 6.3. Maximum transmission unit in 802.16 The MAC PDU is of the format shown in the figure below: |--------------------------//----------------| |Generic MAC HDR | Payload | CRC | |-------------------------//-----------------| Patil, et al. Expires April 26, 2007 [Page 9] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 Figure 6: MAC PDU Format The MAC HDR is a 6 byte header followed by the payload and a 4 byte CRC which covers the whole PDU. The length of the PDU is indicated by the Len parameter in the Generic MAC HDR. The Len parameter has a size of 11 bits. Hence the total PDU size is 2048 bytes. The IPv6 payload can be a max value of 2038 bytes (MAC HDR - CRC). IPv6 MTU for 802.16 may be a value which is less than 2038 bytes. 6.3.1. Maximum transmission unit in WiMAX The WiMAX forum [WMF] has specified the SDU size as 1522 octets. Hence the IPv6 path MTU can be 1500 octets. However because of the overhead of the GRE tunnel used to transport IPv6 packets between the BS and AR and the 6 byte MAC header over the air interface, using a value of 1500 would result in fragmentation of packets. It is recommended that the default MTU for IPv6 be set to 1400 octets for the MS. Note that the 1522 octet specification is a WiMAX forum specification and not the size of the SDU that can be transmitted over 802.16d/e, which is higher. RFC2461 [RFC2461] recommends that IPv6 nodes implement Path MTU discovery. In such cases the default value can be over-ridden. Additionally if the 802.16d/e MAC layer can provide an indication of the MTU size to be used, the MS can use that as the default MTU. 7. IPv6 prefix assignment Each MS can be considered to be on a separate subnet as a result of the point-to-point connection. A CPE type of device which serves multiple IPv6 hosts, may be the end point of the connection. Hence one or more /64 prefixes should be assigned to a link. The prefixes are advertised with the on-link (L-bit) flag set to facilitate Detecting Network Attachment (DNA) operation [RFC4135]. 8. Router Discovery 8.1. Router Solictation On completion of the establishment of the IPv6 link, the MS may send a router solicitation message to solicit a Router Advertisement message from the AR to acquire necessary information as specified in RFC2461 [RFC2461]. An MS that is network attached may also send router solicitations at any time. Patil, et al. Expires April 26, 2007 [Page 10] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 8.2. Router Advertisement The AR should send a number of router advertisements as soon as the IPv6 link is established to the MS [FRD]. The AR may send unsolicited router advertisements periodically as specified in RFC2461 [RFC2461]. However to conserve the battery lifetime of hosts and to conserve radio resources over the air interface, unsolicited router advertisement transmission are not recommended. 8.3. Router lifetime and periodic router advertisements The router lifetime should be set to a large value, preferably in hours. 802.16d/e hosts have the capability to transition to an idle mode in which case the radio link between the BS and MS is torn down. Paging is required in case the network needs to deliver packets to the MS. In order to avoid waking a mobile which is in idle mode and consuming resources on the air interface, the interval between periodic router advertisements should be set quite high. The MaxRtrAdvInterval should be configurable to a value which is greater than 1800 seconds. 9. IPv6 addressing for hosts The addressing scheme for IPv6 hosts in 802.16 network follows the IETFs recommendation for hosts specified in RFC 4294. The IPv6 node requirements RFC RFC4294 [RFC4294] specifies a set of RFCs that are applicable for addressing. 9.1. Interface Identifier The MS has a 48-bit MAC address as specified in 802.16e [802.16e]. This MAC address is used to generate the 64 bit interface identifier which is used by the MS for address autoconfiguration. The IID is generated by the MS as specified in RFC2464 [RFC2464]. For addresses that are based on privacy extensions, the MS may generate random IIDs as specified in RFC3041 [RFC3041]. 9.2. Duplicate address detection DAD is performed as per RFC2461 [RFC2461] and, RFC2462 [RFC2462]. 9.3. Stateless address autoconfiguration If the A-bit in the prefix information option (PIO) are set, the MS performs stateless address autoconfiguration as per RFC 2461, 2462. The AR is the default router that advertises a unique /64 prefix (or prefixes) that is used by the MS to configure an address. Patil, et al. Expires April 26, 2007 [Page 11] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 9.4. Stateful address autoconfiguration The Stateful Address Autoconfiguration is invoked if the M-flag is set in the Router Advertisement. Obtaining the IPv6 address through stateful address autoconfiguration method is specified in the RFC3315 [RFC3315]. 10. IANA Considerations This draft does not require any actions from IANA. 11. Security Considerations This document does not introduce any new vulnerabilities to IPv6 specifications or operation as a result of the 802.16d/e air interface or the WiMAX network architecture. 12. Acknowledgments TBD. 13. References 13.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", RFC 2119, March 1997, . [RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery for IP Version 6 (IPv6)", RFC 2461, December 1998, . [RFC2462] Thomson, S. and T. Narten, "IPv6 Stateless Address Autoconfiguration", RFC 2462, December 1998, . [RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet Networks", RFC 2464, December 1998, . [RFC3041] Narten, T. and R. Draves, "Privacy Extensions for Stateless Address Autoconfiguration in IPv6", RFC 3041, January 2001, . Patil, et al. Expires April 26, 2007 [Page 12] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 [RFC3314] Wasserman, Ed., M., "Recommendations for IPv6 in Third Generation Partnership Project (3GPP) Standards", RFC 3314, September 2002, . [RFC3315] Droms, Ed., R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, July 2003, . [RFC3756] Nikander, P., Kempf, J., and E. Nordmark, "IPv6 Neighbor Discovery (ND) Trust Models and Threats", RFC 3756, May 2004, . [RFC4135] Choi, JH. and G. Daley, "Goals of Detecting Network Attachment in IPv6", RFC 4135, August 2005, . [RFC4294] Loughney, Ed., J., "IPv6 Node requirements", RFC 4294, April 2006, . [RFC4921] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4921, February 2006, . 13.2. Informative References [802.16e] "IEEE Std 802.16e: 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", October 2005. [FRD] Choi, JH., Shin, DongYun., and W. Haddad, "Fast Router Discovery with L2 support", August 2006, . [WMF] "http://www.wimaxforum.org". [WiMAXArch] "WiMAX End-to-End Network Systems Architecture http://www.wimaxforum.org/technology/documents", August 2006. Patil, et al. Expires April 26, 2007 [Page 13] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 Authors' Addresses Basavaraj Patil Nokia 6000 Connection Drive Irving, TX 75039 USA Email: basavaraj.patil@nokia.com Frank Xia Huawei USA 1700 Alma Dr. Suite 100 Plano, TX 75075 Email: xiayangsong@huawei.com Behcet Sarikaya Huawei USA 1700 Alma Dr. Suite 100 Plano, TX 75075 Email: sarikaya@ieee.org JinHyeock Choi Samsung AIT Networking Technology Lab P.O.Box 111 Suwon, Korea 440-600 Email: jinchoe@samsung.com Syam Madanapalli LogicaCMG 125 Yemlur P.O. Off Airport Road Bangalore, India 560037 Email: smadanapalli@gmail.com Patil, et al. Expires April 26, 2007 [Page 14] Internet-Draft IPv6 over IPv6 CS in 802.16 October 2006 Full 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. 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. Intellectual Property 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. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Patil, et al. Expires April 26, 2007 [Page 15]