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Network Working Group                                            J. LangRequest for Comments: 4207                                   Sonos, Inc.Category: Standards Track                               D. Papadimitriou                                                                 Alcatel                                                            October 2005Synchronous Optical Network (SONET)/Synchronous Digital Hierarchy (SDH)       Encoding for Link Management Protocol (LMP) Test MessagesStatus of This Memo   This document specifies an Internet standards track protocol for the   Internet community, and requests discussion and suggestions for   improvements.  Please refer to the current edition of the "Internet   Official Protocol Standards" (STD 1) for the standardization state   and status of this protocol.  Distribution of this memo is unlimited.Copyright Notice   Copyright (C) The Internet Society (2005).Abstract   This document details the Synchronous Optical Network   (SONET)/Synchronous Digital Hierarchy (SDH) technology-specific   information needed when sending Link Management Protocol (LMP) test   messages.1.  Introduction   For scalability purposes, multiple physical resources that   interconnect Label Switching Routers (LSRs) can be combined to form a   single traffic engineering (TE) link for the purposes of path   computation and signaling.  These resources may represent one or more   physical links that connect the LSRs, or they may represent a Label   Switched Path (LSP) if LSP hierarchy [RFC4206] is used.  The   management of TE links is not restricted to in-band messaging, but   instead can be done using out-of-band techniques.   The Link Management Protocol (LMP) [RFC4204] has been developed as   part of the Generalized MPLS (GMPLS) protocol suite to manage TE   links.  LMP currently consists of four main procedures, of which the   first two are mandatory and the last two are optional:Lang & Papadimitriou        Standards Track                     [Page 1]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005      1.  Control channel management      2.  Link property correlation      3.  Link verification      4.  Fault management   Control channel management is used to establish and maintain control   channel connectivity between adjacent nodes.  This is done using a   Config message exchange followed by a lightweight keep-alive message   exchange.  Link property correlation is used to aggregate multiple   data links into a single TE Link and to synchronize the link   properties.  Link verification is used to verify the physical   connectivity of the data links and to exchange the Interface_Ids of   the data links.  Fault management is primarily used to suppress   alarms and to localize failures in both opaque and transparent   networks.  When LMP is used with SONET/SDH, however, the fault   management procedures may not be needed as existing SONET/SDH   mechanisms can be used.   In this document, the SONET/SDH technology-specific information for   LMP is defined.  Specifically, the SONET/SDH test procedures used for   link verification and link property correlation are detailed.  These   procedures include the trace correlation transport mechanism (defined   for J0, J1, J2) that supports a separation of the transport and   control plane identifiers.  The latter procedure requires a new trace   monitoring function that is discussed in this document.  Once the   data links have been verified, they can be grouped to form TE links.2.  Terminology   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].   The reader is assumed to be familiar with the terminology in   [RFC4204], [G.707], and [T1.105].  The following abbreviations are   used in this document:   CRC-N:   Cyclic Redundancy Check-N.   DCC:     Data communications channel.   LOVC:    Lower-order virtual container.   HOVC:    Higher-order virtual container.   MS:      Multiplex section.   MSOH:    Multiplex section overhead.   POH:     Path overhead.   RS:      Regenerator section.   RSOH:    Regenerator section overhead.   SDH:     Synchronous digital hierarchy.   SOH:     Section overhead.Lang & Papadimitriou        Standards Track                     [Page 2]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005   SONET:   Synchronous Optical Network.   STM(-N): Synchronous Transport Module (-N) (SDH).   STS(-N): Synchronous Transport Signal-Level N (SONET).   VC-n:    Virtual Container-n (SDH).   VTn:     Virtual Tributary-n (SONET).3.  Verifying Link Connectivity   In [RFC4204], a link verification procedure is defined whereby Test   messages are transmitted in-band over the data links.  This is used   for data plane discovery, Interface_Id exchange (Interface_Ids are   used in GMPLS signaling, either as port labels [RFC3471] or component   link identifiers [RFC4201], depending on the configuration), and   physical connectivity verification.  Multiple data links can be   verified using a single verification procedure; the correlation is   done using the Verify_Id that is assigned to the procedure.   As part of the link verification procedure, a BeginVerify message   exchange is used to agree upon parameters for the Test procedure.   This can be initiated by sending a BeginVerify message over the   control channel.  This message includes a BEGIN_VERIFY object that   contains a number of fields specifying, among other things, the   transmission (bit) rate, encoding type, and transport mechanisms for   the Test Messages.  If the remote node receives a BeginVerify message   and is ready to begin the procedure, it sends a BeginVerifyAck   message specifying the desired transport mechanism for the Test   messages.  The remote node also assigns a Verify_Id to the procedure   and includes it in the BeginVerifyAck message.   The transmission rate of the data link over which the Test Messages   will be transmitted is represented in IEEE floating-point format   using a 32-bit number field and expressed in bytes per second.  See   [RFC3471] for values defined for SONET/SDH.   The encoding type identifies the encoding supported by an interface.   The defined encoding is consistent with the LSP Encoding Type as   defined in [RFC3471].  For SONET/SDH, this value must equal the value   given for "SDH ITU-T G.707/SONET ANSI T1.105".   The transport mechanism is defined using the Verify Transport   Mechanism bit mask.  The scope of this bit mask is restricted to the   link encoding type.  Multiple bits may be set when this field is   included in the BeginVerify message; however, only one bit may be set   when it is included in the BeginVerifyAck message.Lang & Papadimitriou        Standards Track                     [Page 3]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005   In the following subsection, the various options for Verify Transport   Mechanism are defined when the encoding is SONET/SDH.  The trace   correlation transport mechanism (defined for J0, J1, J2) supports a   separation of the transport and control plane identifiers.3.1.  Verify Transport Mechanism   This field is 16 bits in length.   In this document, the flags for SONET/SDH encoding are defined.  Note   that all values are defined in network byte order (i.e., big-endian   byte order).        0x0001: Reserved        0x0002 DCCS: Test Message over the Section/RS DCC                Capable of transmitting Test Messages using the DCC                Section/RS Overhead bytes with bit-oriented High-Level                Data Link Control (HDLC) framing format [RFC1662].                The Test Message is sent as defined in [RFC4204].        0x0004 DCCL: Test Message over the Line/MS DCC                Capable of transmitting Test Messages using the DCC                Line/MS Overhead bytes with bit-oriented HDLC framing                format [RFC1662].                The Test Message is sent as defined in [RFC4204].        0x0008 J0-trace: J0 Section Trace Correlation                Capable of transmitting SONET/SDH Section/RS trace over                J0 Section/RS overhead byte as defined in [T1.105] and                [G.707].                The Test Message is not transmitted using the J0 bytes                (i.e., over the data link), but is sent over the control                channel and correlated for consistency to the received                J0 pattern.                In order to get the mapping between the Interface_Id                over which the J0 Test Message is sent and the J0                pattern sent in-band, the transmitting node must provide                the correlation between this pattern and the J0 Test                Message.  This correlation is done using the TRACE                object as defined inSection 4.Lang & Papadimitriou        Standards Track                     [Page 4]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005                The format of the Test Message is as follows:                <Test Message> ::=<Common Header> <LOCAL_INTERFACE_ID>                <VERIFY_ID> <TRACE>        0x0010:  Reserved        0x0020:  Reserved        0x0040 J1-trace: J1 Path Trace Correlation                Capable of transmitting SONET/SDH STS SPE/HOVC Path                trace over J1 Path overhead byte as defined in [T1.105]                and [G.707].                The Test Message is not transmitted using the J1 bytes                (i.e., over the data link), but is sent over the control                channel and correlated for consistency to the received                J1 pattern.                In order to get the mapping between the Interface_Id                over which the J1 Test Message is sent and the J1                pattern sent in-band, the transmitting node must provide                the correlation between this pattern and the J1 Test                Message.  This correlation is done using the TRACE                object as defined inSection 4.                The Test Message format is identical to that defined                above in J0-trace.        0x0080 J2-trace: J2 Path Trace Correlation                Capable of transmitting SONET/SDH VT SPE/LOVC Path trace                over J2 Path overhead byte as defined in [T1.105] and                [G.707].                The Test Message is not transmitted using the J2 bytes                (i.e., over the data link), but is sent over the control                channel and correlated for consistency to the received                J2 pattern.                In order to get the mapping between the Interface_Id                over which the J2 Test Message is sent and the J2                pattern sent in-band, the transmitting node must provide                the correlation between this pattern and the J2 Test                Message.  This correlation is done using the TRACE                object as defined inSection 4.Lang & Papadimitriou        Standards Track                     [Page 5]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005                The Test Message format is identical to that defined                above in J0-trace.4.  Trace Monitoring   The trace monitoring features described in this section allow a node   to do trace monitoring by using the SONET/SDH capabilities.     o   A node may request its neighbor (the remote node) to monitor a         link for a specific pattern in the overhead using the         TraceMonitor Message.  An example of this overhead is the SONET         Section Trace message transmitted in the J0 byte.  If the         actual trace message does not match the expected trace message,         the remote node MUST report the mismatch condition.     o   A node may request the value of the current trace message on a         given data link using the TraceReq Message.     o   A node may request a remote node to send a specific trace         message over a data link using the InsertTrace Message.4.1.1.  TraceMonitor Message   The TraceMonitor message (Message Type 21) is sent over the   control channel and is used to request the remote node to monitor a   data link for a specific trace value.  This value is inserted in the   <TRACE> object.  The format of the TraceMonitor message is as   follows:   <TraceMonitor Message> ::= <Common Header> <MESSAGE_ID>                              <LOCAL_INTERFACE_ID> <TRACE>   The above transmission order SHOULD be followed.   The remote node MUST respond to a TraceMonitor message with either a   TraceMonitorAck or TraceMonitorNack Message.Lang & Papadimitriou        Standards Track                     [Page 6]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20054.1.1.1.  TRACE Object Class   Class = 21   o    C-Type = 1, Trace    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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |N|   C-Type    |     Class     |            Length             |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |           Trace Type          |          Trace Length         |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |                                                               |   //                         Trace Message                       //   |                                                               |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   Trace Type: 16 bits       The type of the trace message.  The following values are defined.       All other values are reserved.       1 = SONET Section Trace (J0 Byte)       2 = SONET Path Trace (J1 Byte)       3 = SONET Path Trace (J2 Byte)       4 = SDH Section Trace (J0 Byte)       5 = SDH Path Trace (J1 Byte)       6 = SDH Path Trace (J2 Byte)   Trace Length:  16 bits       This is the length in bytes of the trace message (as specified by       the Trace Type).   Trace Message:       This is the value of the expected message to be received in-band.       The valid length and value combinations are determined by the       specific technology: for SONET see [T1.105] and for SDH see       [G.707].  The message MUST be padded with zeros to a 32-bit       boundary, if necessary.  Trace Length does not include padding       zeroes.   This object is nonnegotiable.Lang & Papadimitriou        Standards Track                     [Page 7]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20054.1.2.  TraceMonitorAck Message   The TraceMonitorAck message (Message Type 22) is used to acknowledge   receipt of the TraceMonitor message and indicate that all of the   TRACE Objects in the TraceMonitor message have been received and   processed correctly (i.e., no Trace Mismatch).   The format is as follows:   <TraceMonitorAck Message> ::= <Common Header> <MESSAGE_ID_ACK>   The above transmission order SHOULD be followed.   The MESSAGE_ID_ACK object is defined in [RFC4204].  The contents of   the MESSAGE_ID_ACK object MUST be obtained from the TraceMonitor   message being acknowledged.4.1.3.  TraceMonitorNack Message   The TraceMonitorNack message (Message Type 23) is used to acknowledge   receipt of the TraceMonitor message and indicate that the TRACE   Object in the TraceMonitor message was not processed correctly.  This   could be because the trace monitoring requested is not supported or   there was an error in the TRACE object value(s).   The format is as follows:   <TraceMonitorNack Message> ::= <Common Header> <MESSAGE_ID_ACK>                                  <ERROR_CODE>   The above transmission order SHOULD be followed.   The MESSAGE_ID_ACK and ERROR_CODE objects are defined in [RFC4204].   The contents of the MESSAGE_ID_ACK object MUST be obtained from the   TraceMonitor message being acknowledged.   If the Trace type is not supported, the ERROR_CODE MUST indicate   "Unsupported Trace Type" defined inSection 4.1.3.1.   If the TRACE object was not equal to the value seen in the trace, the   TraceMonitorNack message MUST include the ERROR_CODE indicating   "Invalid Trace Message".  The TraceMismatch message (seeSection4.1.4) SHOULD NOT be sent as a result of the mismatch.   The TraceMonitorNack message uses a new ERROR_CODE C-Type defined inSection 4.1.3.1.Lang & Papadimitriou        Standards Track                     [Page 8]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20054.1.3.1.  ERROR_CODE Class   C-Type = 3, TRACE_ERROR   The following new error code bit-values are defined:   0x01 = Unsupported Trace Type   0x02 = Invalid Trace Message   All other values are Reserved.   Multiple bits may be set to indicate multiple errors.   This Object is nonnegotiable.4.1.4.  TraceMismatch Message   The TraceMismatch message (Message Type 24) is sent over the control   channel and is used to report a trace mismatch on a data link for   which trace monitoring was requested.  The format is as follows:   <TraceMismatch message> ::= <Common Header> <MESSAGE_ID>                               <LOCAL_INTERFACE_ID>                               [<LOCAL_INTERFACE_ID> ...]   The above transmission order SHOULD be followed.   A neighboring node that receives a TraceMismatch message MUST respond   with a TraceMismatchAck message.   The LOCAL_INTERFACE_ID object is defined in [RFC4204].  The   LOCAL_INTERFACE_ID in this message is the local Interface Id of the   data link that has a trace mismatch.  A trace mismatch for multiple   LOCAL_INTERFACE_IDs may be reported in the same message.4.1.5.  TraceMismatchAck Message   The TraceMismatchAck message (Message Type 25) is used to acknowledge   receipt of a TraceMismatch message.  The format is as follows:   <TraceMismatchAck Message> ::= <Common Header> <MESSAGE_ID_ACK>   The MESSAGE_ID_ACK object is defined in [RFC4204].  The contents of   the MESSAGE_ID_ACK object MUST be obtained from the TraceMismatch   message being acknowledged.Lang & Papadimitriou        Standards Track                     [Page 9]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20054.1.6.  TraceReq Message   The TraceReq message (Message Type 26) is sent over the control   channel and is used to request the current trace value of a data   link.   <TraceReq Message> ::= <Common Header> <MESSAGE_ID>                          <LOCAL_INTERFACE_ID> <TRACE_REQ>   The above transmission order SHOULD be followed.   The format of the TRACE_REQ object is as follows:   Class = 22   O    C-Type = 1, TraceReq     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   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |N|   C-Type    |     Class     |            Length             |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   |           Trace Type          |           (Reserved)          |   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+   Trace Type: 16 bits         Defined inSection 4.1.1.1.   Reserved: 16 bits         This field MUST be set to zero when sent and ignored when         received4.1.7.  TraceReport Message   The TraceReport message (Message Type 27) is sent over the control   channel after receiving a TraceReq message.   <TraceReport Message> ::= <Common Header> <MESSAGE_ID_ACK> <TRACE>   The TraceReport message MUST include a TRACE Object (as described inSection 4.1.1.1) for the requested data link.   The MESSAGE_ID_ACK object is defined in [RFC4204].  The contents of   the MESSAGE_ID_ACK object MUST be obtained from the TraceReq message   being acknowledged.Lang & Papadimitriou        Standards Track                    [Page 10]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20054.1.8.  TraceReqNack Message   The TraceReqNack message (Message Type 28) is sent over the control   channel after receiving a TraceReq message.   <TraceReqNack Message> ::= <Common Header> <MESSAGE_ID_ACK>                            <ERROR_CODE>   The above transmission order SHOULD be followed.   The MESSAGE_ID_ACK object is defined in [RFC4204].  The contents of   the MESSAGE_ID_ACK object MUST be obtained from the TraceReq message   being acknowledged.   The TraceReqNack message MUST include an ERROR_CODE Object (as   defined inSection 4.1.3.1) for the requested data link.4.1.9.  InsertTrace Message   The InsertTrace message (Message Type 29) is sent over the control   channel and is used to request a remote node to send a specific trace   message over a data link (this assumes that the remote knows the   mapping between the local and remote interface_Ids before fulfilling   such request).   The format is as follows:   <InsertTrace Message> ::=   <Common Header> <MESSAGE_ID>                               <LOCAL_INTERFACE_ID> <TRACE>   The above transmission order SHOULD be followed.   A node that receives an InsertTrace message MUST respond with either   an InsertTraceAck or an InsertTraceNack Message.   Once the InsertTraceAck message is received, the TraceMismatch   message (seeSection 4.1.4) is used to indicate a trace mismatch has   occurred.   The MESSAGE_ID_object is defined in [RFC4204].4.1.10.  InsertTraceAck Message   The InsertTraceAck message (Message Type 30) is used to acknowledge   receipt of the InsertTrace message and indicate that the TRACE Object   in the InsertTrace message has been received and processed correctly   (i.e., no Trace Mismatch).  The format is as follows:Lang & Papadimitriou        Standards Track                    [Page 11]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005   <InsertTraceAck Message> ::= <Common Header> <MESSAGE_ID_ACK>   The MESSAGE_ID_ACK object is defined in [RFC4204].  The contents of   the MESSAGE_ID_ACK object MUST be obtained from the InsertTrace   message being acknowledged.4.1.11.  InsertTraceNack Message   The InsertTraceNack message (Message Type 31) is used to acknowledge   receipt of the InsertTrace message and to indicate that the TRACE   Object in the InsertTrace message was not processed correctly.  This   could be because the trace monitoring requested is not supported or   there was an error in the value.   The format is as follows:   <InsertTraceNack Message> ::= <Common Header> <MESSAGE_ID_ACK>                                 <ERROR_CODE>   The above transmission order SHOULD be followed.   The MESSAGE_ID_ACK object is defined in [RFC4204].   The InsertTraceNack message MUST include an ERROR_CODE Object (as   defined inSection 4.1.3.1) for the requested data link.5.  Security Considerations   LMP message security uses IPsec as described in [RFC4204].  This   document introduces no other new security considerations not covered   in [RFC4204].6.  IANA Considerations   LMP [RFC4204] defines the following name spaces and how IANA can make   assignments in those namespaces:   - LMP Message Type.   - LMP Object Class.   - LMP Object Class type (C-Type) unique within the Object Class.   - LMP Sub-object Class type (Type) unique within the Object Class.   This memo introduces the following new assignments:   LMP Message Type:      o TraceMonitor message      (Message type = 21)      o TraceMonitorAck message   (Message type = 22)Lang & Papadimitriou        Standards Track                    [Page 12]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005      o TraceMonitorNack message  (Message type = 23)      o TraceMismatch message     (Message type = 24)      o TraceMismatchAck message  (Message type = 25)      o TraceReq message          (Message type = 26)      o TraceReport message       (Message type = 27)      o TraceReqNack message      (Message type = 28)      o InsertTrace message       (Message type = 29)      o InsertTraceAck message    (Message type = 30)      o InsertTraceNack message   (Message type = 31)   LMP Object Class name space and Class type (C-Type):      o TRACE              Class name (21)        - Type 1           (C-Type = 1)      o TRACE REQ          Class name (22)        - Type 1           (C-Type = 1)7.  References7.1.  Normative References   [RFC4201]   Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling               in MPLS Traffic Engineering (TE)",RFC 4201, October               2005.   [G.707]     ITU-T Recommendation G.707, "Network node interface for               the synchronous digital hierarchy (SDH)," October 2000.   [RFC4204]   Lang, J., Ed., "Link Management Protocol (LMP)",RFC4204, October 2005.   [RFC1662]   Simpson, W., "PPP in HDLC-like Framing", STD 51,RFC1662, July 1994.   [RFC2119]   Bradner, S., "Key words for use in RFCs to Indicate               Requirement Levels",BCP 14,RFC 2119, March 1997.   [RFC3471]   Berger, L., "Generalized Multi-Protocol Label Switching               (GMPLS) Signaling Functional Description",RFC 3471,               January 2003.   [T1.105]    T1.105, "Revised Draft T105 SONET Base Standard," January               2001.Lang & Papadimitriou        Standards Track                    [Page 13]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 20057.2.  Informative References   [RFC4206]   Kompella, K., and Y. Rekhter, "Label Switched Paths (LSP)               Hierarchy with Generalized Multi-Protocol Label Switching               (GMPLS) Traffic Engineering (TE)",RFC 4206, October               2005.8.  Acknowledgements   The authors would like to thank Bernard Sales, Emmanuel Desmet, Gert   Grammel, Jim Jones, Stefan Ansorge, John Drake, and James Scott for   their many contributions to this document.   We would also like to thank Greg Bernstein and Michiel van Everdingen   for their insightful comments and for acting with a strong   combination of toughness, professionalism, and courtesy.Authors' Addresses   Jonathan P. Lang   Sonos, Inc.   223 E. De La Guerra St.   Santa Barbara, CA 93101   EMail: jplang@ieee.org   Dimitri Papadimitriou   Alcatel   Francis Wellesplein 1   B-2018 Antwerpen, Belgium   EMail: dimitri.papadimitriou@alcatel.beLang & Papadimitriou        Standards Track                    [Page 14]

RFC 4207        SONET/SDH Encoding for LMP Test Messages    October 2005Full Copyright Statement   Copyright (C) The Internet Society (2005).   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 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.Acknowledgement   Funding for the RFC Editor function is currently provided by the   Internet Society.Lang & Papadimitriou        Standards Track                    [Page 15]