CCAMP Working Group S. Belotti Internet-Draft P. Grandi Intended status: Informational Alcatel-Lucent Expires: December 16, 2010 D. Ceccarelli D. Caviglia Ericsson F. Zhang D. Li Huawei Technologies June 14, 2010 Information model for G.709 Optical Transport Networks (OTN) draft-bccg-ccamp-otn-g709-info-model-00 Abstract The recent revision of ITU-T recommendation G.709 [G.709-v3] has introduced new fixed and flexible ODU containers in Optical Transport Networks (OTNs), enabling optimized support for an increasingly abundant service mix. This document provides a model of information needed by the routing process in OTNs to support Generalized Multiprotocol Label Switching (GMPLS) control of all currently defined ODU containers both at sub- lambdas and lambda level granularity. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on December 16, 2010. Copyright Notice Copyright (c) 2010 IETF Trust and the persons identified as the document authors. All rights reserved. Belotti, et al. Expires December 16, 2010 [Page 1] Internet-Draft Information model for G.709 OTN June 2010 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. OSPF requirements overview . . . . . . . . . . . . . . . . . . 3 3. G.709 Digital Layer TE Information and Requirement Analysis . 5 3.1. Tributary Slot type . . . . . . . . . . . . . . . . . . . 7 3.2. Sygnal type . . . . . . . . . . . . . . . . . . . . . . . 7 3.3. Unreserved Resources . . . . . . . . . . . . . . . . . . . 8 3.4. Maximum LSP Bandwidth . . . . . . . . . . . . . . . . . . 9 3.5. Distinction between multiplexing and line rate capacity . 9 3.6. Priority Support . . . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Belotti, et al. Expires December 16, 2010 [Page 2] Internet-Draft Information model for G.709 OTN June 2010 1. Introduction An Opaque OSPF (Open Shortest Path First) LSA (Link State Advertisements) carrying application-specific information can be generated and advertised to other nodes following the flooding procedures defined in [RFC5250]. Three types of opaque LSA are defined, i.e. type 9 - link-local flooding scope, type 10 - area- local flooding scope, type 11 - AS flooding scope. Traffic Engineering(TE) LSA using type 10 opaque LSA is defined in [RFC3630] for TE purpose. This type of LSA is composed of a standard LSA header and a payload including one top-level TLV and possible several nested sub-TLVs. [RFC3630]defines two top-level TLVs: Router Address TLV and Link TLV; and nine possible sub-TLVs for the Link TLV, used to carry link related TE information. The Link type sub- TLVs are enhanced by [RFC4203] in order to support GMPLS networks and related specific link information. In GMPLS networks each node generates TE LSAs to advertise its TE information and capabilities (link-specific or node-specific)through the network. The TE information carried in the LSAs are collected by the other nodes of the network and stored into their local Traffic Engineering Databases (TED). In a GMPLS enabled G.709 Optical Transport Networks (OTN), routing is fundamental in order to allow automatic calculation of routes for ODUk LSPs signaled via RSVP-TE protocol. The recent revision of ITU-T Recommendation G.709 [G709-V3] has introduced new fixed and flexible ODU containers that augment those specified in foundation OTN. As a result, it is necessary to provide OSPF routing protocol extensions to allow Generalized MPLS (GMPLS) control of all currently defined ODU containers, in support of sub-lambda and lambda level routing granularity. This document provides a model of information needed by the routing process in OTNs to support Generalized Multiprotocol Label Switching (GMPLS) control of all currently defined ODU containers both at sub- lambdas and lambda level granularity. OSPF requirements are defined in [OTN-FWK], while protocol extensions are defined in [OTN-OSPF]. 2. OSPF requirements overview OTN serves as the convergence layer for transporting a wide range of services, including those whose bit rates do not allow efficient usage of the entire bandwidth associated with a single lambda. In such a case OTN allows aggregation (and recovery) of traffic to Belotti, et al. Expires December 16, 2010 [Page 3] Internet-Draft Information model for G.709 OTN June 2010 support optimization of overall network bandwidth allocation; i.e., OTN allows the aggregate service rate to be decoupled from the OTN line system capacity. Thus, it is necessary to define a scalable control plane solution that is able to fully exploit OTN flexibility (both in terms of aggregation and survivability). [Ed note] (could be part of Framework but for the moment can provide introduction to the overview) In this scope, Section 5.3 of the [draft-fwk] provides a set of functional routing requirements. These requirements are summarized below : - Support for link multiplexing capability advertisement: The routing protocol has to be able to carry information regarding the capability of an OTU link to support different type of ODUs - Support for TS granularity advertisement: Each ODUj can be multiplexed into an OTUk using different TS granularities. For example, ODU1 can be multiplexed into ODU2 with either 2.5Gbps TS granularity or 1.25G TS granularity. The routing protocol should be capable of carrying the TS granularity supported by the ODU interface. - Support of any ODUk and ODUflex: The routing protocol must be capable of carrying the required link bandwidth information for performing accurate route computation for any of the fixed rate ODUs as well as ODUflex. - Support for differentiation between link multiplexing capacity and link rate capacity - Support different priorities for resource reservation. How many priorities levels should be supported depends on operator policies. Therefore, the routing protocol should be capable of supporting either no priorities or up to 8 priority levels as defined in [RFC4202]. - Support link bundling either at the same line rate or different line rates (e.g. 40G and 10G). Bundling links at different rates makes the control plane more scalable and permits better networking flexibility. Belotti, et al. Expires December 16, 2010 [Page 4] Internet-Draft Information model for G.709 OTN June 2010 3. G.709 Digital Layer TE Information and Requirement Analysis Some types of ODUs (i.e., ODU1, ODU2, ODU3, ODU4) may assume either a client or server role within the context of a particular networking domain. ITU-T G.872 amendment 2 provides two tables definig mapping and multiplexing capabilities of OTNs. Such tables are shown hereinafter. +--------------------+--------------------+ | ODU client | OTU server | +--------------------+--------------------+ | ODU 0 | - | +--------------------+--------------------+ | ODU 1 | OTU 1 | +--------------------+--------------------+ | ODU 2 | OTU 2 | +--------------------+--------------------+ | ODU 2e | - | +--------------------+--------------------+ | ODU 3 | OTU 3 | +--------------------+--------------------+ | ODU 4 | OTU 4 | +--------------------+--------------------+ | ODU flex | - | +--------------------+--------------------+ Figure 1: OTN mapping capability Belotti, et al. Expires December 16, 2010 [Page 5] Internet-Draft Information model for G.709 OTN June 2010 +=================================+=========================+ | ODU client | ODU server | +---------------------------------+-------------------------+ | 1,25 Gbps client | | +---------------------------------+ ODU 0 | | - | | +=================================+=========================+ | 2,5 Gbps client | | +---------------------------------+ ODU 1 | | ODU 0 | | +=================================+=========================+ | 10 Gbps client | | +---------------------------------+ ODU 2 | | ODU0,ODU1,ODUflex | | +=================================+=========================+ | 10,3125 Gbps client | | +---------------------------------+ ODU 2e | | - | | +=================================+=========================+ | 40 Gbps client | | +---------------------------------+ ODU 3 | | ODU0,ODU1,ODU2,ODU2e,ODUflex | | +=================================+=========================+ | 100 Gbps client | | +---------------------------------+ ODU 4 | |ODU0,ODU1,ODU2,ODU2e,ODU3,ODUflex| | +=================================+=========================+ Figure 2: OTN multiplexing capability An ODUk mapped directly into an OTUk server in a particular networking domain, only uses the line rate capacity (OTUk capacity) and cannot be further electrically multiplexed. Within this draft, the term "line rate LSP" refers to the role of an ODU that has been mapped directly into an OTU server (e.g., a line rate 10Gbit/s can only traverse OTU2 links). A line rate LSP always has a capacity equivalent to a single lambda and may be carried over one or more wavelength sub-networks connected by optical links. Within a particular networking domain, ODUs that are further electrically multiplexed into higher order ODUs may be carried over various types of links. The term "service rate LSP" may be used for describing the role of an ODU that will be further multiplexed within the networking domain. In other words, ODUs serving various roles may change in traversing a Belotti, et al. Expires December 16, 2010 [Page 6] Internet-Draft Information model for G.709 OTN June 2010 network; i.e., "service rate" LSP roles (used to carry client traffic) and "line rate" LSP roles (used to build infrastructure). These roles must be considered and distinguished from a path computation perspective. As detailed in [OTN-FWK], client ODUs can be carried over: o Case A) one or more wavelength sub-networks connected by optical links or o Case B) a line rate LSP or o Case C) a mix of line rate LSPs and wavelength sub-networks. This document only considers the TE information needed for ODU path computation, considering both service and line rate LSP roles. The following sections list and analyze each type of data that needs to be advertised in order to support path computation. 3.1. Tributary Slot type ITU-T recommendations define two types of TS but, each link can only work under one of them. The rules to be followed when selecting the TS to be used are: - if both ends of a link can support both 2.5Gbps TS and 1.25Gbps TS, then the link will work under 1.25Gbps TS. - If one end can support the 1.25Gbps TS, and another end the 2.5Gbps TS, the link will work under 2.5Gbps TS In addition, the bandwidth accounting depends on the type of TS. Therefore, the type of the TS should be known during LO ODU path computation. Currently such information is not provided by the routing protocol. 3.2. Sygnal type [RFC 4328] allows advertising G.709 foundation (single TS) without the capability of providing precise information about bandwidth special allocation. For example, in case of link bundling, dividing the unreserved bandwidth by the max LSP bandwidth it is not possible to know the exact number of LSPs at max LSP bandwidth size that can be set up. The lack of spatial allocation heavily impacts the restoration process, because the lack of information of free resources highly increases the number of crank-backs affecting network convergence Belotti, et al. Expires December 16, 2010 [Page 7] Internet-Draft Information model for G.709 OTN June 2010 time. Moreover actual tools provided by OSPF-TE only allow advertising signal types with fixed bandwidth and implicit hierarchy (e.g. SDH/ SONET networks) or variable bandwidth with no hierarchy (e.g. packet switching networks) but do not provide the means for advertising networks with mixed approach (e.g. ODUflex CBR and ODUflex packet). For example, advertising ODU0 as MIN LSP bandwith and ODU4 as MAX LSP bandwidth it is not possible to state whether the advertised link supports ODU4 and ODUFlex or ODU4, ODU3, ODU2, ODU1, ODU0 and ODUFlex. Such ambiguity is not present in SDH networks where the hierarchy is implicit and flexible containers like ODUFlex do not exist. Moreover with the current IETF solutions, ([RFC4202], [RFC4203]) as soon as no bandwidth is available for a certain signal type it is not advertised into the related ISCD, losing also the related capability until bandwidth is freed. Supposing for example to have an equivalent ODU-2 unreserved bandwidth in a TE-link (with bundling capability) distributed on 4 ODU-1, it would be advertised via the ISCD in this way: Max LSP Bw: ODU1 Min LSP Bw: ODU1 - Maximum Reservable Bandwidth (of the bundle) set to ODU2 - Unreserved Bandwidth (of the bundle) set to ODU2 In conclusion, the OSPF-TE extensions defined in [RFC4203] require a different ISCD per signal type in order to advertise each supported container. With respect to link bundling, the utilization of the ISCD as it is, would not allow precise advertising of spatial bandwidth allocation information unless using only one component link per TE link. 3.3. Unreserved Resources Unreserved resources need to be advertised per priority and per signal type in order to allow the correct functioning of the restoration process. [RFC4203] only allows advertising unreserved resources per priority, this leads not to know how many LSPs of a specific signal type can be restored. As example it is possible to consider the scenario depicted in the following figure. Belotti, et al. Expires December 16, 2010 [Page 8] Internet-Draft Information model for G.709 OTN June 2010 +------+ component link 1 +------+ | +------------------+ | | | component link 2 | | | N1 +------------------+ N2 | | | component link 3 | | | +------------------+ | +------+ +---+--+ Figure 3: Concurrent path computation Suppose to have a TE link comprising 3 ODU3 component links with 32TSs available on the first one, 24TSs on the second, 24TSs on the third and supporting ODU2 and ODU3 signal types. The node would advertise a TE link unreserved bandwidth equal to 80 TSs and a MAX LSP bandwidth equal to 32 TSs. In case of restoration the network could try to restore 2 ODU3 (64TSs) in such TE-link while only a single ODU3 can be set up and a crank-back would be originated. In more complex network scenarios the number of crank-backs can be much higher. 3.4. Maximum LSP Bandwidth Maximum LSP bandwidth is currently advertised in the common part of the ISCD and advertised per priority, while in OTN networks it is only required for ODUflex advertising. This leads to a significant waste of bits inside each LSA. 3.5. Distinction between multiplexing and line rate capacity The distinction between line rate and multiplexing capacity is a requirement as per [OTN-FWK]. [RFC4203] could achieve this distinction advertising different bandwidths for OTUk and ODUk signal types. This approach implies the usage of multiple ISCDs and therefore it is not efficient. For example a link with line rate capacity OTU3 and multiplexing capacity ODU1, ODU2 and ODU3, [RFC4203] would require the utilization of four different ISCDs, one for each capability. 3.6. Priority Support The IETF foresees that up to eight priorities must be supported and that all of them have to be advertised independently on the number of priorities supported by the implementation. Considering that the advertisement of all the different supported signal types will originate large LSAs, it is advised to advertise only the information related to the really supported priorities. Belotti, et al. Expires December 16, 2010 [Page 9] Internet-Draft Information model for G.709 OTN June 2010 4. Security Considerations TBD 5. IANA Considerations TBD 6. Acknowledgements TBD 7. References 7.1. Normative References [OTN-OSPF] D.Ceccarelli,D.Caviglia,F.Zhang,D.Li,Y.Xu,P.Grandi,S.Belot ti, "Traffic Engineering Extensions to OSPF for Generalized MPLS (GMPLS) Control of Evolutive G.709 OTN Networks", consented by ITU-T on Oct 2009. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4202, October 2005. [RFC4203] Kompella, K. and Y. Rekhter, "OSPF Extensions in Support of Generalized Multi-Protocol Label Switching (GMPLS)", RFC 4203, October 2005. [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Extensions for G.709 Optical Transport Networks Control", RFC 4328, January 2006. [RFC5250] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The OSPF Opaque LSA Option", RFC 5250, July 2008. Belotti, et al. Expires December 16, 2010 [Page 10] Internet-Draft Information model for G.709 OTN June 2010 7.2. Informative References [G.709] ITU-T, "Interface for the Optical Transport Network (OTN)", G.709 Recommendation (and Amendment 1), February 2001. [G.709-v3] ITU-T, "Draft revised G.709, version 3", consented by ITU-T on Oct 2009. [G.872-am2] ITU-T, "Amendment 2 of G.872 Architecture of optical transport networks for consent", consented by ITU-T on Oct 2009. [OTN-FWK] F.Zhang, D.Li, H.Li, S.Belotti, "Framework for GMPLS and PCE Control of G.709 Optical Transport Networks", work in progress draft-ietf-ccamp-gmpls-g709-framework-00, April 2010. Authors' Addresses Sergio Belotti Alcatel-Lucent Via Trento, 30 Vimercate Italy Email: sergio.belotti@alcatel-lucent.com Pietro Vittorio Grandi Alcatel-Lucent Via Trento, 30 Vimercate Italy Email: pietro_vittorio.grandi@alcatel-lucent.com Belotti, et al. Expires December 16, 2010 [Page 11] Internet-Draft Information model for G.709 OTN June 2010 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 Fatai Zhang Huawei Technologies F3-5-B R&D Center, Huawei Base Shenzhen 518129 P.R.China Bantian, Longgang District Phone: +86-755-28972912 Email: zhangfatai@huawei.com Dan Li Huawei Technologies F3-5-B R&D Center, Huawei Base Shenzhen 518129 P.R.China Bantian, Longgang District Phone: +86-755-28973237 Email: danli@huawei.com Belotti, et al. Expires December 16, 2010 [Page 12]