Network Working Group Fatai Zhang Internet Draft Dan Li Category: Standards Track Huawei D. Ceccarelli D. Caviglia Ericsson Guoying Zhang CATR Expires: July 2010 September 19, 2009 Link Management Protocol (LMP) extensions for G.709 Optical Transport Networks draft-zhang-ccamp-gmpls-g709-lmp-discovery-00.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 March 18, 2010. Abstract Recent progress of the Optical Transport Network (OTN) has introduced new signal types (i.e., ODU0, ODU4, ODU2e, ODU3e1, ODU3e2 and ODUflex) and new Tributary Slot granularity (1.25Gbps). Since equipments deployed prior to recently defined ITU-T recommendations only support 2.5 Gbps Tributary Slot granularity and Zhang Expires March 2010 [Page 1]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 ODU1, ODU2 and ODU3 containers, the compatibility problem should be considered. In addition, a Higher Order ODU (HO ODU) link may not support all the types of Lower Order ODU (LO ODU) signals defined by the new OTN standards because of the limitation of the devices at the two ends of a link. In these cases, the control plane is required to run the capability discovering functions for the evolving OTN. This document describes the extensions to the Link Management Protocol (LMP) needed to discover the capability of HO ODU link, including the granularity of Tributary Slot to be used and the LO ODU signal types that the link can support. 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]. Table of Contents 1. Introduction.................................................3 2. Terminology..................................................3 3. Overview of the Evolving G.709...............................3 3.1. Data Plane Backward Compatibility.......................5 4. Link Capability Discovery Requirements.......................6 4.1. Discovering the Granularity of the TS...................6 4.2. Discovering the Supported LO ODU Signal Types...........6 5. Extensions: LMP Link Summary Message.........................7 5.1. Message Extension.......................................7 5.1.1. LinkSummary Message................................8 5.1.2. LinkSummaryAck Message.............................8 5.1.3. LinkSummaryNack Message............................8 5.2. Object Definitions......................................8 5.3. Procedures.............................................10 6. Security Considerations.....................................11 7. IANA Considerations.........................................12 8. Acknowledgments.............................................12 9. References..................................................12 9.1. Normative References...................................12 9.2. Informative References.................................12 10. Authors' Addresses.........................................12 11. Contributors...............................................14 Zhang Expires March 2010 [Page 2]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 1. Introduction The Link Management Protocol (LMP) defined in [RFC4204] is being developed as part of the Generalized MPLS (GMPLS) protocol suite to manage Traffic Engineering (TE) links. Recently, great progress has been made for the Optical Transport Networking (OTN) technologies in ITU-T. New ODU containers (i.e., ODU0, ODU4, ODU2e, ODU3e1, ODU3e2 and ODUflex) and a new Tributary Slot (TS) granularity (1.25Gbps) have been introduced by the [G709- Amd3], [Gsup43] and [G709draft-v3], enhancing the flexibility of OTNs. With the evolution and deployment of G.709 technology, the backward compatibility problem requires to be considered. In data plane, the equipment supporting 1.25Gbps TS can combine the specific Tributary Slots together (e.g., combination of TS#i and TS#i+4 on an HO ODU2 link) so that it can interwork with other equipments which support 2.5Gbps TS. From the control plane point of view, it is necessary to discover which type of TS is supported at both ends of a link, so that it can choose and reserve the TS resources correctly in this link for the connection. Additionally, the requirement of discovering the signal types of Lower Order ODU (LO ODU) that can be supported by a Higher Order ODU (HO ODU) should be taken into account. Equipment at one end of an HO ODU link may not support to transport some types of LO ODU signals (e.g., may not support the ODUflex). In this case, this HO ODU link should not be selected for those types of LO ODU connections. From the perspective of control plane, it is necessary to discover the capability of an HO ODUk or OTUk link including the granularity of TS to be used and the LO ODU signal types that the link can support. This document extends the LMP and describes the solution of discovering HO ODU link capability. 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]. 3. Overview of the Evolving G.709 The traditional OTN standard [G709-Amd1] describes the optical transport hierarchy (OTH) and introduces three ODU signal types (i.e., ODU1, ODU2 and ODU3). The ODUj can be mapped into one or more Zhang Expires March 2010 [Page 3]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 Tributary Slots (with a granularity of 2.5Gbps) of OPUk where j<k. The ODUj can also be mapped into OTUj (j=1, 2 or 3) directly. Recent revisions of ITU-T Recommendation G.709 have introduced new features for Optical Transport Networks (OTN) ODU0, ODU4, ODU2e, ODU3e1, ODU3e2 and ODUflex. The new features for the evolutive OTN are described in the separate ITU-T documents. ODU0, ODU2e and ODU4 are described in [G709-Amd3]. ODU3e1 and ODU3e2 are described in [Gsup43]. And ODUflex is being developed in [G709draft-v3]. The ITU-T documents also define the new multiplexing hierarchy for the evolving OTN. In this multiplexing hierarchy, LO ODUj can be mapped into an OTUj, or multiplexed into an HO ODUk (where j<k) by occupying several tributary slots. In case of LO ODUj mapping into OTUj, the following mappings are defined: o ODU1 into OTU1 mapping o ODU2 into OTU2 mapping o ODU3 into OTU3 mapping o ODU4 into OTU4 mapping o ODU2e into OTU2e mapping In case of LO ODUj multiplexing into HO ODUk, a new Tributary Slot granularity (i.e., 1.25Gbps) is introduced in [G709-Amd3]. For the evolving OTN, the multiplexing of ODUj (j = 0, 1, 2, 2e, 3, flex) into an ODUk (k > j) signal can be depicted as follows: - ODU0 into ODU1 multiplexing (with 1,25Gbps TS granularity) - ODU0, ODU1, ODUflex into ODU2 multiplexing (with 1.25Gbps TS granularity) - ODU1 into ODU2 multiplexing (with 2.5Gbps TS granularity) - ODU0, ODU1, ODU2, ODU2e and ODUflex into ODU3 multiplexing (with 1.25Gbps TS granularity) - ODU1, ODU2 into ODU3 multiplexing (with 2.5Gbps TS granularity) - ODU0, ODU1, ODU2, ODU2e, ODU3 and ODUflex into ODU4 multiplexing (with 1.25Gbps TS granularity) Zhang Expires March 2010 [Page 4]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 - ODU2e into ODU3e1 multiplexing (with 2.5Gbps TS granularity) - ODU2e into ODU3e2 multiplexing (with 1.25Gbps TS granularity) In order to be backward compatible with the 2.5Gbps TS defined in [G709-Amd1], both the 2.5Gbps TS and the 1.25Gbps TS can be used in the two cases listed below: o ODU1 into ODU2 multiplexing o ODU1 and ODU2 into ODU3 multiplexing 3.1. Data Plane Backward Compatibility Equipment supporting a 1.25Gbps TS structure for OPU2 or OPU3 must be backward compatible with equipment which supports only the 2.5G TS structure. Specific Tributary Slots must be combined together (e.g., combination of TS#i and TS#i+4 on an HO ODU2 link) for the LO ODU at one end of the HO ODU link which supports the 1.25Gbps TS structure, so that the LO ODU can be carried on the HO ODU link correctly. In the following example, suppose that the two ends of an ODU2 or ODU3 link support different TS structure, where node A supports the 1.25Gbps TS structure, while node B supports the 2.5Gbps TS, as shown in the figure below: +-----+ +-----+ | | | | | A +-------ODU2/ODU3 link-------+ B | | | | | +-----+ +-----+ (Support 1.25G TS) (Support 2.5G TS) o In case of ODU1 multiplexing into ODU2, node A maps the ODU1 into the TS#i and TS#i+4 (where i<=4) (with the granularity of 1.25Gbps) of OPU2, so that node B can retrieve the ODU1 from the TS#i (with the granularity of 2.5Gbps) of the OPU2, and vice versa. o In case of ODU1 multiplexing into ODU3, node A maps the ODU1 into the TS#i and TS#i+16 (where i<=16) (with the granularity of 1.25Gbps) of OPU3, so that node B can retrieve the ODU1 from the TS#i (with the granularity of 2.5Gbps) of the OPU3, and vice versa. o In case of ODU2 multiplexing into ODU3, node A maps the ODU2 into the TS#a/TS#a+16, TS#b/TS#b+16, TS#c/TS#c+16 and TS#d/TS#d+16 (where a<b<c<d<=16) (with the granularity of 1.25Gbps) of OPU3, so Zhang Expires March 2010 [Page 5]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 that node B can retrieve the ODU2 from the TS#a, TS#b, TS#c and TS#d (with the granularity of 2.5Gbps) of the OPU3, and vice versa. 4. Link Capability Discovery Requirements 4.1. Discovering the Granularity of the TS As described in section 3.1, if the two ends of a link use different granularities of TS, The LO ODU must be mapped into specific combined Tributary Slots in the end of link with TS of 1.25Gbps. From the perspective of control plane, when creating a LO ODU connection, the node MUST select and reserve specific TS for the connection if the two ends of a link use different granularities of TS. For example, for an ODU2 link, we suppose that node A only supports the 2.5Gbps TS while node B supports the 1.25Gbps TS. When node B receives a Path message from node A requesting an ODU1 connection, node B MUST reserve the TS#i and TS#i+4 (where i<=4) (with the granularity of 1.25Gbps) and tell node A via the label carried in the Resv message that the TS#i (with the granularity of 2.5Gbps) among the 4 slots has been reserved for the ODU1 connection. Otherwise, the reservation procedure will fail. +-----+ Path +-----+ | | ------------> | | | A +-------ODU2 link-------+ B | | | <------------- | | +-----+ Resv +-----+ (Support 2.5G TS) (Support 1.25G TS) Therefore, for an ODU2 or ODU3 link, in order to reserve TS resources correctly for a LO ODU connection, the control plane of the two ends MUST know which granularity the other end can support before creating the LO ODU connection. 4.2. Discovering the Supported LO ODU Signal Types Many new ODU signal types are introduced by [G709-Amd3], [Gsup43] and [G709draft-v3], such as ODU0, ODU4, ODU2e, ODU3e1, ODU3e2 and ODUflex. It is possible that equipment does not always support all the LO ODU signal types introduced by those new standards or drafts. If one end of an HO ODU link can not support a certain LO ODU signal type, the HO ODU link can not be selected to carry such type of LO ODU connection. For example, in the following figure, if the interfaces IF1, IF2, IF8, IF7, IF5 and IF6 can support ODUflex signals, while the interfaces IF Zhang Expires March 2010 [Page 6]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 3 and IF4 can not support ODUflex signals. In this case, if one ODUflex connection from A to C is requested, link #1 and #2 should be excluded, link #3 and link #4 are the candidates (the possible path could be A-D-C through link #3 and link #4). +-----+ link #3 | | link #4 +-----------------+ D +-----------------+ | IF8| |IF7 | | +-----+ | | | |IF1 IF6| +--+--+ +-----+ +--+--+ | | link #1 | | link #2 | | | A +--------------+ B +--------------+ C | | |IF2 IF3| |IF4 IF5| | +-----+ +-----+ +-----+ Therefore, it is necessary for the two ends of an HO ODU link to discover which types of LO ODU can be supported by the HO ODU link. After discovering, the capability information can be flooded by IGP, so that the correct path for an ODU connection can be calculated. 5. Extensions: LMP Link Summary Message [RFC4204] defines the Link Management Protocol (LMP) which consists of four main procedures: control channel management, link property correlation, link connectivity verificataion, and fault management. As part of LMP, the link property correlation is used to verify the consistency of the TE and data link information on both sides of a link. This document extends the link property correlation procedure to discover the capability of both sides of an HO ODU link. The designated HO ODU overhead bytes (e.g., the GCC1 and GCC2 overhead bytes) can be used as the control channel to carry the LMP message after the HO ODU link is created. The out-band Data Communication Network (DCN) can also be used. 5.1. Message Extension Three messages are used for link property correlation: LinkSummary, LinkSummaryAck and LinkSummaryNack Message. This document does not change the basic procedure of LMP but just add a new subobject (HO Zhang Expires March 2010 [Page 7]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 ODU Link Capability Subobject) in the DATA_LINK object to carry the capability of one end of an HO ODU link. The formats of LinkSummary, LinkSummaryAck and LinkSummaryNack messages are defined in [RFC4204]. 5.1.1. LinkSummary Message The local end of a TE link can send a LinkSummary message to the remote end to start the negotiation about the capability that the TE link can support. One new Subobject named HO ODU Link Capability Subobject in the DATA_LINK object is introduced by this document. This new subobect is used to tell the remote end of the HO ODU link which are the TS granularity and the LO ODU signal types that the local end can support. When the DATA_LINK object carries the new HO ODU Link Capability Subobject, the N flag SHOULD be set to 1 which means that the subobject is negotiable. 5.1.2. LinkSummaryAck Message The LinkSummaryAck message is used to tell the remote end that it has the same capability as the remote end after the LinkSummary message is received by the local end. 5.1.3. LinkSummaryNack Message The LinkSummaryNack message is used to tell the remote end that it has different capability from the remote end after the LinkSummary message is received by the local end. The LinkSummaryNack message also carries the HO ODU Link Capability Subobject in the DATA_LINK object to tell the remote end the exact capability of the HO ODU link after negotiation, i.e., the granularity of TS and the types of LO ODU that both side of the HO ODU link can support. 5.2. Object Definitions A new HO ODU Link Capability subobject type is introduced to the DATA LINK object to carry the HO ODU link capability information. The format of the new subobject is defined as follow: Zhang Expires March 2010 [Page 8]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length |OD(T)Uk| T | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A|B|C|D|E|F|G| LO ODU Flags | Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type (8 bits): The value of this subobject type is TBD. Length (8 bits): The Length field contains the total length of the subobject in bytes, including the Type and Length fields. As for RFC 4204, the Length MUST be at least 4, and MUST be a multiple of 4. Value of this field is 8. OD(T)Uk (4 bits): This field is used to indicate the HO ODU link type (in case of LO ODUj multiplexing into HO ODUk, wherein j<k) or the OTU link type (in case of LO ODUk mapping into OTUk). OD(T)Uk field Signal type of HO ODUk or OTUk ------------- ------------------------------ 0 Reserved (for future use) 1 HO ODU1 or OTU1 2 HO ODU2 or OTU2 3 HO ODU3 or OTU3 4 HO ODU4 or OTU4 5 OTU2e 6 OTU3e1 7 OTU3e2 8-15 Reserved (for future use) T (2 bits): The T bits are used to indicate the granularity of the TS of the HO ODU link. Zhang Expires March 2010 [Page 9]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 T field TS type ------- ------- 0 1.25Gbps TS granularity 1 2.5Gbps TS granularity 2-3 Reserved (for future use) LO ODU flags (A|B|C|D|E|F|G) (16 bits): These flags are used to indicate which LO ODU signal types that one end or the both end can support. The flags will be set to 1 if the corresponding LO ODU signal types are supported. Flag A: indicates whether LO ODU0 is supported. Flag B: indicates whether LO ODU1 is supported. Flag C: indicates whether LO ODU2 is supported. Flag D: indicates whether LO ODU3 is supported. Flag E: indicates whether LO ODU4 is supported. Flag F: indicates whether LO ODU2e is supported. Flag G: indicates whether LO ODUflex is supported. The remaining flags are reserved for future use and MUST be set to 0. 5.3. Procedures The Link Summary messages used for capability discovery for HO ODUk or OTUk link are sent between adjacent nodes after the HO ODU link is created or driven by some events (e.g., an operator command). The procedure is described below: o The local end of the HO ODU link sends a LinkSummary message including one or more DATA_LINK objects, each of which contains the Local_Interface_Id, the Remote_Interface_Id, and the HO ODU link capability subobject. This subobject carries the capability that the local end can support, i.e., the granularity of TS and the set of LO ODU signal types that the local end can support. The LinkSummary message is sent to the remote end. o On receipt of the LinkSummary message, the remote end of the HO ODU link firstly determines whether the local/remote Interface_Id Zhang Expires March 2010 [Page 10]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 mappings match those that are stored locally as described in [RFC4204], and then obtains the HO ODU link capability subobject and determines the capability of the HO ODU link that both ends can support. The detail procedures are as follow: - Only if both ends support the 1.25Gbps TS, the remote end would choose the 1.25Gbps as the negotiated granularity for the HO ODU link. In other cases, the 2.5Gbps TS MUST be used (i.e., if the local end can support 1.25Gbps, and the remote end can support 2.5Gbps, and then the local end should imitate 2.5Gbps). - The remote end compares the two sets of LO ODU signal types that the local end and the remote end can support, and calculates the intersection of them, i.e., extracts all the LO ODU signal types that both two ends can support. This intersection is the set of LO ODU signal types that the HO ODU link can support. o If both the two ends support the same capability, i.e., they support the same granularity of TS and the same LO ODU signal types, the remote end replies a LinkSummaryAck message to the local end. So the both ends know what capability the HO ODU link can support. o If the two ends support different capabilities, i.e., they support different granularities of TS or different LO ODU signal types, the remote end replies a LinkSummaryNack message to the local end. The LinkSummaryNack message carries an ERROR_CODE object and one or more DATA_LINK objects. The ERROR_CODE object indicates that the two ends of the HO ODU link support different capabilities, and the DATA_LINK object carries the HO ODU link capability subobject which contains the negotiated granularity of TS and the set of LO ODU signal types that both ends can support. The local end can learn the HO ODU link capability after receiving the LinkSummaryNack message. o If the remote end does not support the HO ODU link capability negotiation procedure, the LinkSummaryNack message MUST be responded with an ERROR_CODE indicating the reason of rejection. 6. Security Considerations TBD. Zhang Expires March 2010 [Page 11]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 7. IANA Considerations TBD. 8. Acknowledgments TBD. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC4204] J. Lang, Ed., "Link Management Protocol (LMP)", RFC 4204, October 2005 [G709-Amd1] ITU-T, "Interface for the Optical Transport Network (OTN)", G.709 Recommendation (and Amendment 1), February 2001 (October 2001). [G709-Amd3] ITU-T, "Interface for the Optical Transport Network (OTN)", G.709 Recommendation (Amendment3), December 2008. [Gsup43] ITU-T, "Proposed revision of G.sup43 (for agreement)", December 2008. [G709draft-v3] ITU-T, "Draft revised G.709, version 3", May 2009. 9.2. Informative References [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4328] D. Papadimitriou, Ed. "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control", RFC 4328, Jan 2006. 10. Authors' Addresses Fatai Zhang Huawei Technologies F3-5-B R&D Center, Huawei Base Bantian, Longgang District Shenzhen 518129 P.R.China Zhang Expires March 2010 [Page 12]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 Phone: +86-755-28972912 Email: zhangfatai@huawei.com Dan Li Huawei Technologies Co., Ltd. F3-5-B R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28972910 Email: danli@huawei.com Daniele Ceccarelli Ericsson Via A. Negrone 1/A Genova - Sestri Ponente Italy Email: daniele.ceccarelli@ericsson.com Diego Caviglia Ericsson Via A. Negrone 1/A Genova - Sestri Ponente Italy Email: diego.caviglia@ericsson.com Guoying Zhang China Academy of Telecommunication Research of MII 11 Yue Tan Nan Jie Beijing, P.R.China Phone: +86-10-68094272 Email: zhangguoying@mail.ritt.com.cn Zhang Expires March 2010 [Page 13]
draft-zhang-ccamp-gmpls-g.709-lmp-discovery-00.txt September 2009 11. Contributors Yi Lin Huawei Technologies Co., Ltd. F3-5-B R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28972914 Email: linyi_hw@huawei.com 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 ietf-ipr@ietf.org. 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. Zhang Expires March 2010 [Page 14]
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