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Network Working Group                                        J. Jee, Ed.Request for Comments: 5154                                          ETRICategory: Informational                                   S. Madanapalli                                                      Ordyn Technologies                                                               J. Mandin                                                                  Runcom                                                              April 2008IP over IEEE 802.16 Problem Statement and GoalsStatus of This Memo   This memo provides information for the Internet community.  It does   not specify an Internet standard of any kind.  Distribution of this   memo is unlimited.Abstract   This document specifies problems in running IP over IEEE 802.16   networks by identifying specific gaps in the IEEE 802.16 Media Access   Control (MAC) for IPv4 and IPv6 support.  This document also provides   an overview of IEEE 802.16 network characteristics and convergence   sublayers.  Common terminology used for the base guideline while   defining the solution framework is also presented.Table of Contents1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .22.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .33.  Overview of the IEEE 802.16 MAC Layer  . . . . . . . . . . . .43.1.  Transport Connections  . . . . . . . . . . . . . . . . . .43.2.  IEEE 802.16 PDU Format . . . . . . . . . . . . . . . . . .53.3.  IEEE 802.16 Convergence Sublayer . . . . . . . . . . . . .54.  IP over IEEE 802.16 Problem Statement and Goals  . . . . . . .64.1.  Root Problem . . . . . . . . . . . . . . . . . . . . . . .64.2.  Point-to-Point Link Model for IP CS: Problems  . . . . . .84.3.  Ethernet-Like Link Model for Ethernet CS: Problems . . . .94.4.  IP over IEEE 802.16 Goals  . . . . . . . . . . . . . . . .105.  Security Considerations  . . . . . . . . . . . . . . . . . . .116.  Contributors . . . . . . . . . . . . . . . . . . . . . . . . .117.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . .118.  References . . . . . . . . . . . . . . . . . . . . . . . . . .128.1.  Normative References . . . . . . . . . . . . . . . . . . .128.2.  Informative References . . . . . . . . . . . . . . . . . .12Jee, et al.                  Informational                      [Page 1]

RFC 5154              IP over 802.16 PS and Goals             April 20081.  Introduction   Broadband Wireless Access networks address the inadequacies of low   bandwidth wireless communication for user requirements such as high   quality data/voice service, fast mobility, wide coverage, etc.  The   IEEE 802.16 Working Group on Broadband Wireless Access Standards   develops standards and recommended practices to support the   development and deployment of broadband Wireless Metropolitan Area   Networks [IEEE802.16].   Recently the WiMAX Forum, and in particular, its NWG (Network Working   Group) is defining the IEEE 802.16 network architecture (e.g., IPv4,   IPv6, Mobility, Interworking with different networks, AAA, etc.).   The NWG is thus taking on work at layers above those defined by the   IEEE 802 standards (typically limited to the physical and link-layers   only).  Similarly, WiBro (Wireless Broadband), a Korean effort, which   focuses on the 2.3 GHz spectrum band, is also based on the IEEE   802.16 specification [IEEE802.16].   IEEE 802.16 [IEEE802.16] is point-to-point and connection-oriented at   the MAC, physically arranged in a point-to-multipoint structure with   the Base Station (BS) terminating one end of each connection and an   individual Subscriber Station (SS) terminating the other end of each   connection.  The IEEE 802.16 convergence sublayer (CS) is at the   uppermost part of the MAC that is responsible for assigning transmit-   direction Service Data Units (originating from a higher layer   application, e.g., IP or Ethernet at the BS or SS) to a specific   outbound transport connection.  IEEE 802.16 defines two convergence   sublayer types, the ATM Convergence Sublayer (CS) and the Packet CS.   The IP Specific Subpart (IP CS) and the 802.3 Ethernet Specific   Subpart (Ethernet CS) of Packet CS are within the current scope of   IETF efforts.   There is complexity in configuring the IP Subnet over IEEE 802.16   network because of its point-to-point connection-oriented feature and   the existence of IP CS and Ethernet CS, which assume different   higher-layer functionality.  An IP Subnet is a topological area that   uses the same IP address prefix where that prefix is not further   subdivided except into individual addresses as specified in   [RFC4903].  The IP Subnet configuration is dependent on the   underlying link-layer's characteristic and decides the overall IP   operation on the network.  The IP CS and Ethernet CS of IEEE 802.16   assume different higher layer capabilities: IP routing functionality   in the case of IP CS and bridging functionality in the case of   Ethernet CS.  This means that the link-layer's characteristics   beneath IP can change according to the adopted convergence sublayers.Jee, et al.                  Informational                      [Page 2]

RFC 5154              IP over 802.16 PS and Goals             April 2008   This document provides the feasible IP Subnet model for each IP CS   and Ethernet CS and specifies the problems in running IP for each   case.  This document also presents an overview of IEEE 802.16 network   characteristics specifically focusing on the convergence sublayers   and the common terminology to be used for the base guideline while   defining solution frameworks.2.  Terminology   Subscriber Station (SS): An end-user equipment that provides   connectivity to the IEEE 802.16 networks.  It can be either fixed/   nomadic or mobile equipment.  In mobile environment, SS represents   the Mobile Subscriber Station (MS) introduced in [IEEE802.16e].   Base Station (BS): A generalized equipment set that provides   connectivity, management, and control between the subscriber station   and the IEEE 802.16 networks.   Access Router (AR): An entity that performs an IP routing function to   provide IP connectivity for the subscriber station (SS or MS).   Protocol Data Unit (PDU): This refers to the data format passed from   the lower edge of the MAC to the PHY, which typically contains SDU   data after fragmentation/packing, encryption, etc.   Service Data Unit (SDU): This refers to the data format passed to the   upper edge of the MAC   IP Subnet: Topological area that uses the same IP address prefix   where that prefix is not further subdivided except into individual   addresses as specified from [RFC4903].   Link: Topological area bounded by routers, which decrement the IPv4   TTL or IPv6 Hop Limit when forwarding the packet as specified from   [RFC4903].   Transport Connection: The MAC layer connection in IEEE 802.16 between   an SS (MS) and BS with a specific Quality of Service (QoS)   attributes.  Several types of connections are defined and these   include broadcast, unicast, and multicast.  Each transport connection   is uniquely identified by a 16-bit connection identifier (CID).  A   transport connection is a unique connection intended for user   traffic.  The scope of the transport connection is between the SS   (MS) and the BS.   Connection Identifier (CID): A 16-bit value that identifies a   connection to equivalent peers in the IEEE 802.16 MAC of the SS (MS)   and BS.Jee, et al.                  Informational                      [Page 3]

RFC 5154              IP over 802.16 PS and Goals             April 2008   Ethernet CS: The 802.3/Ethernet CS specific part of the Packet CS   defined in [IEEE802.16].   802.1Q CS: The 802.1Q (VLAN) specific part of the Packet CS defined   in [IEEE802.16].   IP CS: The IP specific subpart of the Packet CS defined in   [IEEE802.16].   IPv4 CS: The IP specific subpart of the Packet CS, Classifier 1   (Packet, IPv4)   IPv6 CS: The IP specific subpart of the Packet CS, Classifier 2   (Packet, IPv6).3.  Overview of the IEEE 802.16 MAC Layer   IEEE 802.16 [IEEE802.16] is point-to-point and connection-oriented at   the MAC, physically arranged in a point-to-multipoint structure with   the BS terminating one end of each connection and an individual SS   terminating the other end of each connection.  Each SS in the network   possesses a 48-bit MAC address.  The BS possesses a 48-bit unique   identifier called "BSId".  The BS and SS learn each others' MAC   Address/BSId during the SS's entry into the network.  Additionally,   the BS may possess a 48-bit MAC address, but this is only known to   the SS if using the Ethernet CS.3.1.  Transport Connections   User data traffic in both the BS-bound (uplink) and SS-bound   (downlink) directions is carried on unidirectional "transport   connections".  Each transport connection has a particular set of   associated parameters indicating characteristics such as   cryptographic suite and quality of service.   After successful entry of an SS to the IEEE 802.16 network, no data   traffic is possible as there are no transport connections between the   BS and the SS yet.  Transport connections are established by a   3-message signaling sequence within the MAC layer (usually initiated   by the BS).   A downlink-direction transport connection is regarded as "multicast"   if it has been made available (via MAC signaling) to more than one   SS.  Uplink-direction connections are always unicast.Jee, et al.                  Informational                      [Page 4]

RFC 5154              IP over 802.16 PS and Goals             April 20083.2.  IEEE 802.16 PDU Format   An IEEE 802.16 PDU (i.e., the format that is transmitted over the   airlink) consists of a Generic MAC header, various optional   subheaders, and a data payload.   The IEEE 802.16 Generic MAC header carries the Connection Identifier   (CID) of the connection with which the PDU is associated.  We should   observe that there is no source or destination address present in the   raw IEEE 802.16 MAC header.3.3.  IEEE 802.16 Convergence Sublayer   The IEEE 802.16 convergence sublayer (CS) is the component of the MAC   that is responsible for mapping between the MAC service and the   internal connection oriented service of the MAC CPS (Common Part   Sublayer), through classification and encapsulation.  The   classification process assigns transmit-direction Service Data Units   (originating from a higher layer application, e.g., an IP stack at   the BS or SS) to a specific outbound transport connection.  The   convergence sublayer maintains an ordered "classifier table".  Each   entry in the classifier table includes a classifier and a target CID.   A classifier, in turn, consists of a conjunction of one or more   subclassifiers -- where each subclassifier specifies a packet field   (e.g., the destination MAC address in an Ethernet frame, or the Type   of Service (TOS) field of an IP datagram contained in an Ethernet   frame) together with a particular value or range of values for the   field.  To perform classification on an outbound Service Data Unit,   the convergence sublayer proceeds from the first entry of the   classifier table to the last, and evaluates the fields of the Service   Data Unit for a match with the table entry's classifier.  When a   match is found, the convergence sublayer associates the Service Data   Unit with the target CID (for eventual transmission), and the   remainder of the IEEE 802.16 MAC and PHY processing can take place.   IEEE 802.16 defines two convergence sublayer types, the ATM CS and   the Packet CS.  The ATM CS supports ATM directly.  The Packet CS is   subdivided into three specific subparts.   o  "The IP Specific Subpart" carries IP packets over a point-to-point      connection.   o  "The 802.3 Ethernet Specific Subpart" carries packets encoded in      the 802.3/Ethernet packet format with 802.3 style headers.   o  "The 802.1Q VLAN Specific Subpart" carries 802 style packets that      contain 802.1Q VLAN Tags.Jee, et al.                  Informational                      [Page 5]

RFC 5154              IP over 802.16 PS and Goals             April 2008   Classifiers applied to connections at the time of connection   establishment further classify and subdivide the nature of the   traffic over a connection.   The classifications that apply to the Ethernet CS include packet over   the 802.3/Ethernet CS, IPv4 over the 802.3/Ethernet CS, IPv6 over the   802.3/Ethernet CS, 802.3/Ethernet CS with RObust Header Compression   (ROHC) header compression and 802.3/Ethernet with Enhanced Compressed   Real-Time Protocol (ECRTP) header compression.   The classifications that apply to the 802.1Q/VLAN CS include IPv4   over 802.1Q/VLAN and IPv6 over 802.1Q/VLAN.   It should be noted that while the 802.3/Ethernet CS has a packet   classification that does not restrict the IP version (packet over the   802.3/Ethernet CS), the IP CS and 802.1Q/VLAN CS do.  All the IP   classifiers for those CSs are either IPv4 or IPv6.   The classifiers enable the MAC to be sure of the presence of fields   in the headers and so to be able to apply the payload header   suppression (PHS) feature of IEEE 802.16 to those headers.   For the sake of brevity in this document, the following naming   conventions will be used for particular classifications of particular   subparts of particular CSs.   o  IPv4 CS: Packet CS, IP Specific Subpart, Classifier 1 (Packet,      IPv4)   o  IPv6 CS: Packet CS, IP Specific Subpart, Classifier 2 (Packet,      IPv6)   o  Ethernet CS: Packet CS, 802.3/Ethernet Subpart, Classifier 3      (Packet, 802.3/Ethernet)   An implementation of IEEE 802.16 can support multiple CS types.   We can observe that the CS type, subpart, and classification actually   defines the type of data interface (e.g., IPv4/IPv6 or 802.3) that is   presented by IEEE 802.16 to the higher layer application.4.  IP over IEEE 802.16 Problem Statement and Goals4.1.  Root Problem   The key issue when deploying IP over IEEE 802.16 networks is how to   configure an IP Subnet over that link, which is connection-oriented   and point-to-point in the MAC level.  IP Subnet is a topological areaJee, et al.                  Informational                      [Page 6]

RFC 5154              IP over 802.16 PS and Goals             April 2008   that uses the same IP address prefix where that prefix is not further   subdivided except into individual addresses.  [RFC4903] There are   three different IP Subnet models [RFC4968] that are possible for IEEE   802.16 network:   1) Point-to-point Link Model   2) Ethernet-like Link Model   3) Shared IPv6 Prefix Link Model   The specific problems and issues when adopting the above IP Subnet   models to the IEEE 802.16 network are as below:   In the point-to-point link model, each SS under a BS resides on a   different IP Subnet.  Therefore, only a certain SS and an AR exist   under an IP Subnet, and IP packets with destination address of link   local scope are delivered only within the point-to-point link between   a SS and an AR.  PPP [RFC1661] has been widely used for this kind of   point-to-point link.  However, the direct use of PPP is not possible   on the IEEE 802.16 network because IEEE 802.16 does not define a   convergence sublayer, which can encapsulate and decapsulate PPP   frames.  Therefore, there needs to be a mechanism to provide a point-   to-point link between an SS and an AR in case of IP CS.  The other   alternative is to utilize PPP over Ethernet by using the Ethernet CS.   However, Ethernet CS assumes the upper layer's bridging functionality   to realize the Ethernet-like link model.   In the Ethernet-like link model, all SSs under an AR reside on the   same IP Subnet.  This also applies when SSs are connected with   different BSs.  This Ethernet-like link model assumes that underlying   link-layer provides the equivalent functionality like Ethernet, for   example, native broadcast and multicast.  It seems feasible to apply   IEEE 802.16's Ethernet CS to configure this link model.  However,   IEEE 802.16's MAC feature is still connection-oriented, and does not   provide multicast and broadcast connection for IP packet transfer.   Therefore, we need a mechanism like IEEE 802.1D to realize multicast   and broadcast.  Moreover, frequent IP multicast and broadcast   signaling should be avoided so as not to wake up the SSs that are in   sleep/idle mode [IEEE802.16e].   The shared IPv6 prefix link model eventually results in multi-link   subnet problems [RFC4903].  In IEEE 802.16, the BS assigns separate   IEEE 802.16 connections for SSs.  Therefore, SSs are placed on   different links.  In this situation, distributing shared IPv6 prefix   for SSs, which are placed on different links causes multi-link subnetJee, et al.                  Informational                      [Page 7]

RFC 5154              IP over 802.16 PS and Goals             April 2008   problems.  This applies to IP CS and even to Ethernet CS if no   bridging functionality is implemented on top of the BS or between the   BS and the AR.   We identified the feasible IP Subnet models for IEEE 802.16 networks   depending on the convergence sublayers.  At the current stage, only   the IP CS and Ethernet CS of IEEE 802.16 are within the scope of   ongoing IETF work.  Following are the feasible IP Subnet models for   each convergence sublayer used.   1.  Point-to-Point Link model for IP CS.   2.  Ethernet-like Link Model for Ethernet CS.   According to the point-to-point feature of the IEEE 802.16 MAC, the   Point-to-Point link model is the feasible IP Subnet model in the case   of IP CS.  For the Ethernet CS, the Ethernet-like link model is the   feasible IP Subnet model.  However, in this model unnecessary   multicast and broadcast packets within an IP Subnet should be   minimized.4.2.  Point-to-Point Link Model for IP CS: Problems   - Address Resolution:   Address Resolution is the process by which IP nodes determine the   link-layer address of a destination node on the same IP Subnet given   only the destination's IP address.  In the case of IP CS, the IEEE   802.16 MAC address is not used as part of the IEEE 802.16 frame so   typical usage of the Address Resolution Protocol (ARP) or Neighbor   cache does not apply.  Thus, performing the address resolution may be   redundant in the case of IP CS.  For IPv4, ARP cannot be carried by   the IP CS, so is not used either by the SS or by the BS.  For IPv6,   address resolution is the function of IP layer, and IP reachability   state is maintained through neighbor discovery packets.  Therefore,   blocking neighbor discovery packets would break the neighbor   unreachability detection model.   - Router Discovery:   The BS needs to send the Router Advertisement (RA) with separate IP   prefix in unicast manner for each SS explicitly to send periodic   router advertisements in IEEE 802.16 Networks.Jee, et al.                  Informational                      [Page 8]

RFC 5154              IP over 802.16 PS and Goals             April 2008   - Prefix Assignment:   Separate IP prefix should be distributed for each SS to locate them   on different IP Subnets.  When an SS moves between BSs under the same   AR, the AR needs to redistribute the same IP Subnet prefix, which the   SS used at the previous BS.   - Next-Hop:   SS's next-hop always needs to be the AR that provides the IP   connectivity at that access network.   - Neighbor Unreachability Detection (NUD):   Because the SS always sees an AR as the next hop, the NUD is required   only for that AR.  Also the requirement of NUD may depend on the   existence of a connection to the BS for that particular destination.   - Address Autoconfiguration:   Because a unique prefix is assigned to each SS, the IP Subnet   consists of only one SS and an AR.  Therefore, duplicate address   detection (DAD) is trivial.4.3.  Ethernet-Like Link Model for Ethernet CS: Problems   - Address Resolution:   For Ethernet CS, the sender needs to perform an address resolution to   fill the destination Ethernet address field even though that address   is not used for transmitting an IEEE 802.16 frame on the air.  That   Ethernet destination address is used for a BS or bridge to decide   where to forward that Ethernet frame after decapsulating the IEEE   802.16 frame.  When the destination's IP address has the same address   prefix with its own, the sender should set the Ethernet frame's   destination address as the destination itself.  To acquire that   address, the address resolution should be performed throughout   conventional broadcast- and multicast-based ARP or Neighbor Discovery   Protocol (NDP).  However, if not filtered (e.g., [RFC4541]), these   multicast and broadcast packets result in the problem of waking up   the SSs that are in sleep/idle mode [IEEE802.16e].   - Router Discovery:   All SSs under the AR are located in the same broadcast domain in the   Ethernet-like link model.  In this environment, sending periodic   Router Advertisements with the destination of all-nodes multicastJee, et al.                  Informational                      [Page 9]

RFC 5154              IP over 802.16 PS and Goals             April 2008   address results in the problem of waking up the SSs that are in   sleep/idle mode [IEEE802.16e].   - Prefix Assignment:   Because the same IP prefix is shared with multiple SSs, an IP Subnet   consists of multiple SSs and an AR.  The SS assumes that there exist   on-link neighbors and tries to resolve the L2 address for the on-link   prefixes.  However, direct communication using link-layer address   between two SSs is not possible with Ethernet CS alone; bridging   functionality must be added on top of the BS or between the BS and   AR.   - Next-Hop:   When Ethernet CS is used and the accompanying Ethernet capability   emulation is implemented, the next-hop for the destination IP with   the same global prefix with the sender or link local address type   should be the destination itself not an AR.   - Neighbor Unreachability Detection (NUD):   All SSs under the same AR are all the neighbors.  Therefore, the NUD   is required for all the SSs and AR.   - Address Autoconfiguration:   Duplicate Address Detection (DAD) should be performed among multiple   SSs and an AR, which use the same IP prefix.  The previous multicast-   based DAD causes the problem of waking up the SSs that are in sleep/   idle mode [IEEE802.16e].4.4.  IP over IEEE 802.16 Goals   The following are the goals in no particular order that point at   relevant work to be done in IETF.   Goal #1.  Define the way to provide the point-to-point link model for             IP CS.   Goal #2.  Reduce the power consumption caused by waking up sleep/idle             [IEEE802.16e] terminals for Ethernet-like link model.   Goal #3.  Avoid multi-link subnet problems.   Goal #4.  Allow applicability of security schemes such as SEcure             Neighbor Discovery (SEND) [RFC3971].Jee, et al.                  Informational                     [Page 10]

RFC 5154              IP over 802.16 PS and Goals             April 2008   Goal #5.  Do not introduce any new security threats.   Goal #6.  Review management requirements and specifically the             interfaces and specific management model (objects) for IP             over IEEE 802.16 in collaboration with IEEE 802.16 working             group.5.  Security Considerations   This documents describes the problem statement and goals for IP over   IEEE 802.16 networks and does not introduce any new security threats.   The IEEE 802.16 link-layer employs cryptographic security mechanisms   as specified in [IEEE802.16][IEEE802.16e].6.  Contributors   This document is a joint effort of the problem statement team of the   IETF 16ng Working Group.  The team members include Junghoon Jee, Syam   Madanapalli, Jeff Mandin, Gabriel Montenegro, Soohong Daniel Park,   and Maximilian Riegel.   The problem statement team members can be reached at:      Junghoon Jee, jhjee@etri.re.kr      Syam Madanapalli, smadanapalli@gmail.com      Jeff Mandin, j_mandin@yahoo.com      Gabriel Montenegro, g_e_montenegro@yahoo.com      Soohong Daniel Park, soohong.park@samsung.com      Maximilian Riegel, maximilian.riegel@nsn.com7.  Acknowledgments   The authors would like to express special thank to David Johnston for   his help withSection 3, "Overview of the IEEE 802.16 MAC Layer", and   for carefully reviewing the entire document, and also to Phil Roberts   for suggesting the reorganization of the document depending on the   baseline IP subnet models.   The authors also would like to thank Jari Arkko, HeeYoung Jung,   Myung-Ki Shin, Eun-Kyoung Paik, Jaesun Cha, and the KWISF (Korea   Wireless Internet Standardization Forum) for their comments and   contributions.Jee, et al.                  Informational                     [Page 11]

RFC 5154              IP over 802.16 PS and Goals             April 20088.  References8.1.  Normative References   [RFC1661]      Simpson, W., "The Point-to-Point Protocol (PPP)",                  STD 51,RFC 1661, July 1994.   [RFC3971]      Arkko, J., Kempf, J., Zill, B., and P. Nikander,                  "SEcure Neighbor Discovery (SEND)",RFC 3971,                  March 2005.8.2.  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 Std 802.16e, "IEEE standard for Local and                  metropolitan area networks, Part 16:Air Interface for                  fixed and Mobile broadband wireless access systems",                  October 2005.   [RFC4541]      Christensen, M., Kimball, K., and F. Solensky,                  "Considerations for Internet Group Management Protocol                  (IGMP) and Multicast Listener Discovery (MLD) Snooping                  Switches",RFC 4541, May 2006.   [RFC4903]      Thaler, D., "Multi-Link Subnet Issues",RFC 4903,                  June 2007.   [RFC4968]      Madanapalli, S., "Analysis of IPv6 Link Models for                  802.16 Based Networks",RFC 4968, August 2007.Jee, et al.                  Informational                     [Page 12]

RFC 5154              IP over 802.16 PS and Goals             April 2008Authors' Addresses   Junghoon Jee (editor)   ETRI   161 Gajeong-dong Yuseong-gu   Daejeon  305-700   Korea   Phone: +82 42 860 5126   EMail: jhjee@etri.re.kr   Syam Madanapalli   Ordyn Technologies   1st Floor, Creator Building, ITPL   Bangalore - 560066   India   EMail: smadanapalli@gmail.com   Jeff Mandin   Runcom   EMail: j_mandin@yahoo.comJee, et al.                  Informational                     [Page 13]

RFC 5154              IP over 802.16 PS and Goals             April 2008Full Copyright Statement   Copyright (C) The IETF Trust (2008).   This document is subject to the rights, licenses and restrictions   contained inBCP 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, THE IETF TRUST 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 inBCP 78 andBCP 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 athttp://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.Jee, et al.                  Informational                     [Page 14]