Network Working Group Fatai Zhang Internet Draft Dan Li Category: Standards Track Huawei D. Ceccarelli D. Caviglia Ericsson Guoying Zhang CATR P.Grandi S.Belotti Alcatel-Lucent Expires: March 2010 September 25, 2009 Link Management Protocol (LMP) extensions for G.709 Optical Transport Networks draft-zhang-ccamp-gmpls-g709-lmp-discovery-01.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 24, 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). Zhang Expires March 2010 [Page 1] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 Since equipments deployed prior to recently defined ITU-T recommendations only support 2.5 Gbps Tributary Slot granularity and 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...............................4 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.......................................8 5.1.1. LinkSummary Message................................8 5.1.2. LinkSummaryAck Message.............................8 5.1.3. LinkSummaryNack Message............................8 5.2. Object Definitions......................................9 5.3. Procedures.............................................10 6. Security Considerations.....................................12 7. IANA Considerations.........................................12 8. Acknowledgments.............................................12 9. References..................................................12 9.1. Normative References...................................12 9.2. Informative References.................................12 10. Authors' Addresses.........................................13 11. Contributors...............................................14 Zhang Expires March 2010 [Page 2] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.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. After discovering, the consistent link capability information can be flooded by routing protocol for routing functionality. This document extends the LMP and describes the solution of discovering HO ODU or OTU 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]. Zhang Expires March 2010 [Page 3] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 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 Tributary Slots (with a granularity of 2.5Gbps) of OPUk where j 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) Zhang Expires March 2010 [Page 4] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 - 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) - 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: - ODU1 into ODU2 multiplexing - 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) - 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. - 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 Zhang Expires March 2010 [Page 5] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 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. - 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 | | | 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 Zhang Expires March 2010 [Page 6] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 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 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. Zhang Expires March 2010 [Page 7] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 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 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. Zhang Expires March 2010 [Page 8] draft-zhang-ccamp-gmpls-g.709-lmp-discovery-01.txt September 2009 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: 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): This 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