Path Computation Element (PCE) Protocol Extension for Stateful PCE Usage in GMPLS Networks
Author(s): Ramon Casellas, Oscar de Dios, Xian Zhang, Fatai Zhang, Young Lee
The Path Computation Element (PCE) facilitates Traffic Engineering (TE) based path calculation in large, multi-domain, multi-region, or multi-layer networks. [Stateful-PCE] provides the fundamental PCEP extensions needed to support stateful PCE functions, without specifying the technology-specific extensions. This memo...
Network Working Group Xian Zhang Internet-Draft Young Lee Intended status: Standards Track Fatai Zhang Huawei Ramon Casellas CTTC Oscar Gonzalez de Dios Telefonica I+D Expires: August 21, 2013 February 22, 2013 Path Computation Element (PCE) Protocol Extension for Stateful PCE Usage in GMPLS Networks draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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 August 21, 2013. Zhang Expires August 2013 [Page 1] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 Abstract The Path Computation Element (PCE) facilitates Traffic Engineering (TE) based path calculation in large, multi-domain, multi-region, or multi-layer networks. [Stateful-PCE] provides the fundamental PCEP extensions needed to support stateful PCE functions, without specifying the technology-specific extensions. This memo provides extensions required for PCE communication protocol (PCEP) so as to enable the usage of a stateful PCE capability in GMPLS networks. Conventions used in this document 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 [RFC2119]. Table of Contents Table of Contents .............................................. 2 1. Introduction ................................................ 3 2. PCEP Extensions ............................................. 3 2.1. Overview of Requirements................................ 3 2.2. Stateful PCE Capability Advertisement and Negotiation....4 2.2.1. PCE Capability Negotiation/Advertisement in Multi-layer Networks ................................................. 4 2.3. LSP Delegation in GMPLS Networks ........................5 2.4. LSP Synchronization in GMPLS networks ...................6 2.5. Modification of Existing PCEP Messages and Procedures....8 2.5.1. Use cases ......................................... 8 2.5.2. Modification for LSP Re-optimization ...............9 2.5.3. Modification for Route Exclusion ...................9 2.6. Additional Error Type and Error Values Defined..........10 3. IANA Considerations ........................................ 10 4. Manageability Considerations................................ 10 4.1. Requirements on Other Protocols and Functional Components11 5. Security Considerations..................................... 11 6. Acknowledgement ............................................ 11 7. References ................................................. 11 7.1. Normative References................................... 11 7.2. Informative References................................. 12 8. Contributors' Address....................................... 12 Authors' Addresses ............................................ 13 Zhang Expires August 2013 [Page 2] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 1. Introduction [RFC4655] presents the architecture of a Path Computation Element (PCE)-based model for computing Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic Engineering Label Switched Paths (TE LSPs). To perform such a constrained computation, a PCE stores the network topology (i.e., TE links and nodes) and resource information (i.e., TE attributes) in its TE Database (TED). To request path computation services to a PCE, [RFC5440] defines the PCE Communication Protocol (PCEP) for communications between a Path Computation Client (PCC) and a PCE, or between two PCEs. PCEP protocol specified in [RFC5440] mainly focuses on MPLS networks and the PCEP extensions needed for GMPLS-controlled networks are provided in [PCEP-GMPLS]. Stateful PCEs are shown to be helpful in many application scenarios, in both MPLS and GMPLS networks, as illustrated in [Stateful-APP]. In order for these applications to able to exploit the capability of stateful PCEs, extensions to the PCE communication protocol (i.e., PCEP) are required. [Stateful-PCE] provides the fundamental extensions needed for stateful PCE to support general functionality, but leaves out the specification for technology-specific objects/TLVs. Complementarily, this document focuses on the extensions that are necessary in order for its deployment in GMPLS-controlled networks. 2. PCEP Extensions 2.1. Overview of Requirements This section notes the main functional requirements for PCEP extensions to support stateful PCE for use in GMPLS networks, based on the description in [Stateful-APP]. Many requirements are common across a variety of network types (e.g., MPLS-TE networks and GMPLS networks) and the protocol extensions to meet the requirements are already described in [Stateful-PCE]. This document does not repeat the description of those protocol extensions. Other requirements that are also common across a variety of network types do not currently have protocol extensions defined in [Stateful-PCE]. In these cases, this document presents protocol extensions for discussion by the PCE working group and potential inclusion in [Stateful-PCE]. In addition, this document presents protocol extensions for a set of requirements which are specific to the use of a stateful PCE in a GMPLS-controlled network. The basic requirements are as follows: Zhang Expires August 2013 [Page 3] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 o Advertisement and negotiation of the stateful PCE capability. This generic requirement is covered in Section 7.1.1 of [Stateful-PCE] Section 2.2 of this document discusses other potential extensions for this functionality. o LSP delegation is already covered in Section 5.5 of [Stateful- PCE]. Section 2.3 of this document provides extension for its application in GMPLS-controlled networks. Moreover, further discussion of some generic details that may need additional consideration is provided. o LSP synchronization (see [Stateful-APP] Section 2.2). This is a generic requirement already covered in Section 5.4 of [Stateful- PCE]. However, there are further extensions required specifically for GMPLS networks and discussed in Section 2.4.o Reference to LSPs by identifiers is discussed in Section 7.2 of [Stateful-PCE]. This feature can be applied to reduce the data carried in PCEP messages. Use cases and additional Error Codes are necessary, as described in Section 2.5 and 2.6. 2.2. Stateful PCE Capability Advertisement and Negotiation Whether a PCE has stateful capability or not can be negotiated during the PCEP session establishment process. It can also be advertised through routing protocols as described in [RFC5088]. In either case, the following additional aspects should also be considered. 2.2.1. PCE Capability Negotiation/Advertisement in Multi-layer Networks In multi-layer network scenarios, such as an IP-over-optical network, if there are dedicated PCEs responsible for each layer, then the PCCs should be informed of which PCEs they should synchronize their LSP states with, as well as send path computation requests to. The Layer-Cap TLV defined in [INTER-LAYER] can be used to indicate which layer a PCE is in charge of. This TLV is optional and MAY be carried in the OPEN object. It is RECOMMMENDED that a PCC synchronizes its LSP states with the same PCEs that it can use for path computation in a multi-layer network. In a single layer, this TLV MAY not be used. However, if the PCE capability discovery depends on IGP and if an IGP instance spans across multiple layers, this TLV is still needed. Alternatively, the extension to current OSPF PCED TLV is needed. A new domain-type denoting the layer information can be defined: domain-type: T.B.D. Zhang Expires August 2013 [Page 4] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 When it is carried in PCE-DOMAIN sub-TLV, it denotes the layer for which a PCE is responsible for path computation as well as LSP state synchronization. When carried in the PCE-NEIG-DOMAIN sub-TLV, it denotes its adjacent layers for which a PCE can compute paths and synchronize the LSP states. The DOMAIN-ID information can be represented using the following format, to denote the layer information: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP Enc. Type | Switching Type| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 2.3. LSP Delegation in GMPLS Networks To enable the PCE to control an LSP, the PCUpd message is defined in [Stateful-PCE]. However, technology-specific specification is not covered. The following defines the <path> descriptor that should be used in GMPLS networks: <path>::=<ERO><attribute-list> Where: <attribute-list> ::= [<LSPA>] [<BANDWIDTH>] [<GENERALIZED-BANDWIDTH>...] [<metric-list>] <metric-list>::= <METRIC>[<metric-list>] The O bit in the <GENERALIZED-BANDWIDTH> object has no meaning for LSP state synchronization and MUST be set to 0. Furthermore, this object MAY appear twice, one with R set to 1 and the other with R set to 0. This is to denote the asymmetric bandwidth property of the updated bi-directional LSP. As explained in [stateful-APP], LSP state synchronization and/or LSP parameter change controlled by a stateful PCE in a multi-domain network is complex and requires well-defined operational procedures as well as protocol design. Zhang Expires August 2013 [Page 5] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 [TBD: protocol extensions] 2.4. LSP Synchronization in GMPLS networks For LSP state synchronization of stateful PCEs in GMPLS networks, the LSP attributes, such as its bandwidth, associated route as well as protection information etc, should be updated by PCCs to PCE LSP database (LSP-DB). Note the LSP state synchronization described in this document denotes both the bulk LSP report at the initialization phase as well as the LSP state report afterwards described in [Stateful-PCE]. As per [Stateful-PCE], it does not cover technology-specific specification for state synchronization. Therefore, extensions of PCEP protocol for stateful PCE usage in GMPLS networks are required. For LSP state synchronization, the objects/TLVs that should be used for stateful PCE in GMPLS networks are defined in [PCEP-GMPLS] and are briefly summarized as below: o GENERALIZED BANDWIDTH o GENERALIZED ENDPOINTS o PROTECTION ATTRIBUTE o Use of IF_ID_ERROR_SPEC. [Stateful-PCE] section 7.2.2 only considers RSVP ERROR_SPEC TLVs. GMPLS extends this to also support IF_ID_ERROR_SPEC, for example, to report about failed unnumbered interfaces. o Extended Objects to support the inclusion of the label and unnumbered links. Per [Stateful-PCE], the PCRpt message is defined for LSP state synchronization purpose. PCRpt is used by a PCC to report one or more of its LSPs to a stateful PCE. However, the <path> descriptor is technology-specific and left undefined. For LSP state synchronization in GMPLS networks, the encoding of the <path> descriptor is defined as follows: <path>::=<ERO><attribute-list> Where: <attribute-list> ::= [<LSPA>] [<BANDWIDTH>] Zhang Expires August 2013 [Page 6] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 [<GENERALIZED-BANDWIDTH>...] [<RRO>] [<IRO>] [<XRO>] [<metric-list>] <metric-list>::= <METRIC>[<metric-list>] The objects included in the <path> descriptor can be found in [RFC5440], [PCE-GMPLS] and [RFC5521]. For all the objects presented in this section, the P and I bit MUST be set to 0 since they are only used by a PCC to report its LSP information. In GMPLS networks, the <ERO> object may include a list of the label sub-object for SDH/SONET, OTN and DWDM networks. It may also include a list of unnumbered interface IDs to denote the allocated resource. The <RRO>, <IRO> and <XRO> objects MAY include unnumbered interface IDs and labels for networks such as OTN and WDM networks. If the LSP being reported is a protecting LSP, the <PROTECTION- ATTRIBUTE> TLV MUST be included in the <LSPA> object to denote its attributes and restrictions. Moreover, if the status of the protecting LSP changes from non-operational to operational, this should be synchronized to the stateful PCE. For example, in 1:1 protection, the combination of S=0, P=1 and O=0 denotes the protecting path is set up already but not used for carrying traffic. Upon the working path failure, the operational status of the aforementioned protecting LSP changes to in-use (i.e., O=1). This information should be synchronized with a stateul PCE through a PCRpt message. The O bit in the <GENERALIZED-BANDWIDTH> object has no meaning for LSP state synchronization and MUST be set to 0. Furthermore, this object MAY appear twice, one with R set to 1 and the other with R set to 0. This is to denote the asymmetric bandwidth property of the updated bi-directional LSP. Zhang Expires August 2013 [Page 7] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 2.5. Modification of Existing PCEP Messages and Procedures One of the advantages mentioned in [Stateful-APP] is that the stateful nature of a PCE simplifies the information conveyed in PCEP messages, notably between PCC and PCE, since it is possible to refer to PCE managed state for active LSPs. To be more specific, with a stateful PCE, it is possible to refer to a LSP with an unique identifier in the scope of the PCC-PCEP session and thus use such identifier to refer to that LSP. 2.5.1. Use cases Use Case 1: Assuming a stateful PCE's LSP-DB is up-to-date, a PCC (e.g. NMS) requesting for a re-optimization of one or several LSPs can send the request with ''R'' bit set and only provides the relevant LSP unique identifiers. Upon receiving the PCReq message, PCE should be able to correlate with one or multiple LSPs with their detailed state information and carry out optimization accordingly. The handling of RP object specified in [RFC5440] is stated as following: ''The absence of an RRO in the PCReq message for a non-zero-bandwidth TE LSP (when the R bit of the RP object is set) MUST trigger the sending of a PCErr message with Error-Type="Required Object Missing" and Error-value="RRO Object missing for re-optimization." If a PCE has stateful capabilities, and such capabilities have been negotiated and advertised, specific rules given in [RFC5440] may need to be relaxed. In particular, the re-optimization case: if the re-optimization request refers to a given LSP state, and the RRO information is available, the PCE can proceed. Use Case 2: in order to set up a LSP which has a constraint that its route should not use resources used by one or more existing LSPs, a PCC can send a PCReq with the identifiers of these LSPs. A stateful PCE should be able to find the corresponding route and resource information so as to meet the constraints set by the requesting PCC. Hence, the LSP identifier TLV defined in [Stateful-PCE] can be used in XRO object for this purpose. Note that if the PCC is a node in the network, the constraint LSP ID information will be confined to the LSPs initiated by itself. Zhang Expires August 2013 [Page 8] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 2.5.2. Modification for LSP Re-optimization For re-optimization, upon receiving a path computation request and the ''R'' bit is set, the stateful PCE SHOULD still perform the re- optimization in the following two cases: Case 1: the existing bandwidth and route information of the to-be- optimized LSP is provided in the path computation request. This information should be provided via <BANDWIDTH>, <GENERARLIZED- BANDWIDTH>, <ERO> objects. Case 2: the existing bandwidth and route information can be found locally in its LSP-DB. In this case, the PCRep and PCReq messages need to be modified to carry LSP identifiers. The stateful PCE can find this information using the per-node LSP ID together with the PCC's address. If no LSP state information is available to carry out re- optimization, the stateful PCE should report the error ''LSP state information unavailable for the LSP re-optimization'' (Error Type = T.B.D., Error value= T.B.D.). 2.5.3. Modification for Route Exclusion A LSP identifier sub-object is defined and its format as follows: 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |L| Type (T.B.D.) | Length | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LSP ID | Flag | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | | // Optional TLVs // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ L bit: The L bit SHOULD NOT be set, so that the subobject represents a strict hop in the explicit route. Type: Subobject Type for a per-node LSP identifier. Length: The Length contains the total length of the subobject in bytes, including the Type and Length fields. Zhang Expires August 2013 [Page 9] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 LSP ID: This is the identifier given to a LSP and it is unique on a node basis. It is defined in [Stateful-PCE]. Flags: This field is defined in [Stateful-PCE]. It is not used in this sub-object and should be ignored upon receipt. Optional TLVs: Additional TLVs can be defined in the future to provide further information to identify a LSP. In this document, no TLVs are defined. One or multiple of these sub-objects can be present in the XRO object. When a stateful PCE receives a path computation request carrying this sub-object, it should find relevant information of these LSPs and preclude the resource during the path computation process. If a stateful PCE cannot recognize one or more of the received LSP identifiers, it should reply PCErr saying ''the LSP state information for route exclusion purpose cannot be found'' (Error-type = T.B.D., Error-value= T.B.D.). Optionally, it may provide with the unrecognized identifier information to the requesting PCC. 2.6. Additional Error Type and Error Values Defined Error Type Meaning 21(TBD) LSP state information missing Error-value 1: LSP state information unavailable for the LSP re-optimization 3. Error-value 2: the LSP state information for route exclusion purpose cannot be found IANA Considerations IANA is requested to allocate new Types for the TLV/Object defined in this document. T.B.D. 4. Manageability Considerations The description and functionality specifications presented related to stateful PCEs should also comply with the manageability specifications covered in Section 8 of [RFC4655]. Furthermore, a further list of manageability issues presented in [Stateful-PCE] should also be considered. Zhang Expires August 2013 [Page 10] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 Additional considerations are presented in the next sections. 4.1. Requirements on Other Protocols and Functional Components When the detailed route information is included for LSP state synchronization (either at the initial stage or during LSP state report process), this require the ingress node of an LSP carry the RRO object in order to enable the collection of such information. 5. Security Considerations The security issues presented in [RFC5440] and [Stateful-PCE] apply to this document. 6. Acknowledgement We would like to thank Adrian Farrel and Cyril Margaria for the useful comments and discussions. 7. References 7.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to indicate requirements levels", RFC2119, March 1997. [RFC4655] Farrel, A., Vasseur, J.-P., and Ash, J., "A Path Computation Element (PCE)-Based Architecture", RFC4655, August 2006. [RFC5440] Vasseur, J.-P., and Le Roux, JL., "Path Computation Element (PCE) Communication Protocol (PCEP)", RFC5440, March 2009. [RFC5088] Le Roux, JL., Vasseur, J.-P., Ikejiri, Y., Zhang, R., ''OSPF Protocol Extensions for Path Computation Element (PCE) Discovery'', RFC5088, January 2008. [INTER-LAYER] Oki, E., Takeda, Tomonori, Le Roux, JL., Farrel, A., Zhang, F., ''Extensions to the Path Computation Element communication Protocol(PCEP) for Inter-Layer MPLS and GMPLS Traffic Engineering'', draft-ietf-pce-inter-layer- ext-08.txt, XX 2013. Zhang Expires August 2013 [Page 11] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 7.2. Informative References [Stateful-APP] Zhang, F., Zhang, X., Lee, Y., Casellas, R., Gonzalez de Dios, O., "Applicability of Stateful Path Computation Element (PCE) ", draft-zhang-pce-stateful-pce-app-03, work in progress. [Stateful-PCE]Crabbe, E., Medved, J., Varga, R., Minei, I., ''PCEP Extensions for Stateful PCE'', draft-ietf-pce-stateful-pce, work in progress. [PCE-IA-WSON] Lee, Y., Bernstein G., Takeda, T., Tsuritani, T., ''PCEP Extensions for WSON Impairments'', draft-lee-pce- wson-impairments, work in progress. [PCEP-GMPLS] Margaria, C., Gonzalez de Dios, O., Zhang, F., ''PCEP extensions for GMPLS'', draft-ietf-pce-gmpls-pcep- extensions, work in progress. 8. Contributors' Address Dhruv Dhody Huawei Technology Leela Palace Bangalore, Karnataka 560008 INDIA EMail: firstname.lastname@example.org Yi Lin Huawei Technologies F3-5-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28972914 Email: email@example.com Zhang Expires August 2013 [Page 12] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 Authors' Addresses Xian Zhang Huawei Technologies F3-5-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28972913 Email: firstname.lastname@example.org Young Lee Huawei 1700 Alma Drive, Suite 100 Plano, TX 75075 US Phone: +1 972 509 5599 x2240 Fax: +1 469 229 5397 EMail: email@example.com Fatai Zhang Huawei F3-5-B R&D Center, Huawei Base Bantian, Longgang District P.R. China Phone: +86-755-28972912 Email: firstname.lastname@example.org Ramon Casellas CTTC Av. Carl Friedrich Gauss n7 Castelldefels, Barcelona 08860 Spain Phone: Email: email@example.com Oscar Gonzalez de Dios Telefonica Investigacion y Desarrollo Emilio Vargas 6 Madrid, 28045 Spain Zhang Expires August 2013 [Page 13] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 Phone: +34 913374013 Email: firstname.lastname@example.org Intellectual Property The IETF Trust 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 any IETF 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. Copies of Intellectual Property 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 any standard or specification contained in an IETF Document. Please address the information to the IETF at email@example.com. The definitive version of an IETF Document is that published by, or under the auspices of, the IETF. Versions of IETF Documents that are published by third parties, including those that are translated into other languages, should not be considered to be definitive versions of IETF Documents. The definitive version of these Legal Provisions is that published by, or under the auspices of, the IETF. Versions of these Legal Provisions that are published by third parties, including those that are translated into other languages, should not be considered to be definitive versions of these Legal Provisions. For the avoidance of doubt, each Contributor to the IETF Standards Process licenses each Contribution that he or she makes as part of the IETF Standards Process to the IETF Trust pursuant to the provisions of RFC 5378. No language to the contrary, or terms, conditions or rights that differ from or are inconsistent with the rights and licenses granted under RFC 5378, shall have any effect and shall be null and void, whether published or posted by such Contributor, or included with or in such Contribution. Zhang Expires August 2013 [Page 14] draft-zhang-pce-pcep-stateful-pce-gmpls-02.txt February 2013 Disclaimer of Validity All IETF Documents and the information contained therein 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 THEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Full Copyright Statement Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Zhang Expires August 2013 [Page 15]