Internet Draft Dae-Gun Kim (KT) Document: draft-kim-ccamp-gmpls-mgoxc-0`.txt Gyu Myoung Lee (ICU) Expiration Date: August 2004 Jun Kyun Choi (ICU) Jin Woo Park (Korea University) Chul-Hee Kang (Korea University) February 2004 GMPLS Extensions to support Multi-Granularity Optical Cross-Connect with Heterogeneous Optical Interfaces draft-kim-ccamp-gmpls-mgoxc-01.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of [RFC2026]. 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. Abstract The concept of waveband has been recently introduced as a means to reduce OXC complexity and cost. The waveband is formed by grouping several wavelengths and is routed as a single channel. This document describes the major carrier’s requirements for Multi- Granularity Optical Cross-Connect (MG-OXC) when using the waveband technology in GMPLS networks. The requirements of multiple optical layers (wavelength, waveband, fiber) and protection for MG-OXC are described. Also, extensions of signaling and routing for MG-OXC are considered. Kim et al. Expires - August 2004 [Page 1] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 Conventions 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....................................................2 1.1. Terminology and Definitions...................................3 1.2. Network Hierarchy of MG-OXC in GMPLS Networks.................4 1.3. Node Architecture of MG-OXC in GMPLS Networks.................4 2. Requirements of MG-OXC in GMPLS networks........................6 2.1. Signaling Aspects for MG-OXC..................................7 2.2. Routing Aspects for MG-OXC....................................7 2.3. Requirements for lightpath selection..........................8 2.4. Requirements on Protection of MG-OXC..........................8 3. Security Considerations.........................................9 References.........................................................9 Author's Addresses................................................10 1. Introduction According to the recent rapid increasing of IP traffic, there is no doubt that in the near future data communications will be based on optical networking. Wavelength Division Multiplexing (WDM) technology is becoming a technology-of-choice to meet the tremendous bandwidth demand of IP traffic. WDM networks using wavelength routing by optical cross-connect (OXC) have emerged as the most feasible architecture solution for next generation optical networks. OXC facilitate the switching of individual wavelengths at the nodes of a WDM-based network. However, increase in the number of wavelength channels results in increased complexity of OXCs and increased difficulty in implementing and maintaining OXCs. The concept of multi-granularity OXC (MG-OXC) has been recently introduced as a means to reduce OXC complexity and cost [WAVEBAND][HCROSS]. MG-OXC can not only switch traffic at multiple granularities such as fiber, waveband, and wavelength, but also add and drop traffic at multiple granularities. Note that multi- granularity of MG-OXC means the waveband with multiple granularities of wavelength optical interfaces in MG-OXC and does not mean the granularity of traffic bandwidth in network resources. The waveband is formed by grouping several wavelengths and is routed as a single channel. Also the fiber channel is formed by grouping several wavebands and is routed as a single channel. Kim et al. Expires - August 2004 [Page 2] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 GMPLS (Generalized MPLS) extends the MPLS control plane to include packet, layer2, TDM, wavelength, waveband, and fiber switching. Furthermore GMPLS networks need to evolve so as to drastically reduce both deployment costs and operating expenses. In a multiple optical layer environment, carriers require that GMPLS technology will create tremendous convenience for the network operators and service providers to offer smooth interoperability with legacy system and easy operation, and in the long run to reduce the their operating cost (OpEx saving), and to improve their network utilization efficiency (CapEx saving). The MG-OXC system will provide the reduction of operating cost because of reduction of port count as increasing demand of traffic when compared with single-granularity OXC. This document describes the major carrier’s requirements for Multi- Granularity Optical Cross-Connect (MG-OXC) from operator’s perspectives. Also, the optical service-related function requirements for MG-OXC in GMPLS networks are described 1.1. Terminology and Definitions The reader is assumed to be familiar with the GMPLS terminology as defined in [GMPLS-ARCH]. The following abbreviations are used in this document: OXC (Optical Cross-Connect): is to switch only several wavelengths traffic and add or drop traffic at single granularity MG-OXC (Multi-Granularity OXC): several wavelengths are grouped together as a waveband and switched as a single port whenever possible. A waveband is demultiplexed into individual wavelengths if and only if necessary when the waveband carries at least one lightpath that needs to be dropped or added. Multi-granularity OXCs not only switch traffic at multiple layers such as wavelength, waveband, and fiber, but also add and drop traffic at multiple granularities. WXC (Wavelength Cross-Connect): is to switch lightpaths by wavelength unit. BXC (Waveband Cross-Connect): is to switch lightpaths by waveband unit. The waveband is formed by grouping several wavelengths and is routed as a single channel. FXC (Fiber Cross-Connect): is to switch lightpaths by fiber unit. The fiber channel is formed by grouping several wavebands and is routed as a single channel. Optical LSP (Label Switched Path): include the W-LSP, B-LSP, F-LSP Kim et al. Expires - August 2004 [Page 3] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 W-LSP (Wavelength Label Switched Path) WB-LSP (Waveband Label Switched Path) F-LSP (Fiber Label Switched Path) Network Hierarchy: is an abstraction of a part of a network’s topology, routing and signaling mechanisms. Abstraction may be used as a mechanism to build large networks or as a technique for enforcing administrative, topological, or geographic boundaries. For example, network hierarchy might be used to separate the regional and backbone sections of a network, or to interconnect service provider networks (with BGP which reduces a network to an Autonomous System). Vertical Hierarchy: is oriented between two network technology layers. Horizontal Hierarchy: is oriented between two areas or administrative subdivisions within the same network technology layer. Wavelength granularity: the number of wavelength in a waveband 1.2. Network Hierarchy of MG-OXC in GMPLS Networks In GMPLS networks, the network hierarchy is established by dividing wavelength layer, waveband layer, and fiber layer. Vertical hierarchical network is between each optical layer and Horizontal hierarchical network is between two areas within the same optical layer [RFC3386]. This hierarchical LSP is created to allow designated MG-OXCs to exchange information with one another and act as border MG-OXCs to a large area of GMPLS networks and other MG-OXCs. The aggregation of optical LSP is carried out by aggregating smaller optical LSPs. The larger optical LSP traverses through the GMPLS networks. For example, optical hierarchical LSP has following relations: F-LSP > B-LSP > W- LSP. At the end of the larger optical LSP, the smaller optical LSPs are separated. 1.3. Node Architecture of MG-OXC in GMPLS Networks In GMPLS networks, an Optical Cross-Connect (OXC) consists of three major parts: demultiplexer, optical switch matrix, and multiplexer. OXC complexity can be characterized by the size of optical switch matrix. Note that intermediate traffic dominates over end-to-end traffic in GMPLS networks. Since many lightpath conveying intermediate might have the same route, the size of the optical switch matrix would be largely reduced if they were dealt with as a single channel or port. In single-granularity OXCs, OXC switches traffic only at the wavelength layer, and wavelengths either terminate at or transparently pass through a node, each requiring a port. However, in multi-granularity OXCs several wavelengths are grouped together as a waveband and switched as a single port whenever Kim et al. Expires - August 2004 [Page 4] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 possible. A waveband is demultiplexed into individual wavelengths if and only if necessary when the waveband carries at least one lightpath that needs to be dropped or added. Multi-granularity OXCs not only switch traffic at multiple layers such as wavelength, waveband, and fiber, but also add and drop traffic at multiple granularities. Traffic can be transported from one layer to another via multiplexers and demultiplexers within the MG-OXC. The multilayer MG-OXC is shown in Fig.1, which includes the wavelength cross-connect (WXC) layer, waveband cross-connect (BXC) layer, and fiber cross-connect (FXC) layer. The WXC and BXC layers consist of cross-connects and multiplexers/demultiplexers. The WXC layer includes a WXC switch that is used to switch wavelength lightpaths. To add/drop wavelengths from the WXC layer, we need wavelength add/drop ports. In addition, waveband to wavelength demultiplxers are used to demultiplex wavebands to wavelengths, and wavelength to waveband multiplexers are used to multiplex wavelengths to wavebands. At the BXC layer, the waveband cross-connect, waveband add/drop ports are used for bypass and add/drop wavebands. Fiber to waveband demultiplexers are used to demultiplex fibers to wavebands. Waveband to fiber multiplexers are used to multiplex wavebands to form fibers. Similarly, fiber cross-connect and fiber add/drop ports are used to switch and add/drop fibers at FXC layer. In order to reduce the number of ports, the MG-OXC switches a fiber using one port at the fiber cross-connect if none of its wavelength is used to add and to drop a lightpath. Otherwise, it will demultiplex the fiber into wavebands, and switch an entire wavebands using one port at the waveband cross-connect if none of its wavelength is used to add and to drop a lightpath. In other words, only the wavebands whose wavelengths are needed to be added or dropped will be demultiplexed, and only the wavelengths in those wavebands that carry bypass traffic needed to be switched using the WXC. With this architecture, it is possible to dynamically select fibers for multiplexing/demultilexing from the FXC to the BXC layer, and wavebands for multiplexing/demultiplexing from the BXC to the WXC layer. GMPLS networks in conjunction with MG-OXCs can be bring about tremendous benefits in terms of reducing the number of ports of OXCs, which in turn reduces the size of the OEO (optical-electrical- optical) grooming switch, as well as the cost and difficulty associated with controlling them. In addition to reducing the port count, the use of wavebands reduces the number of entities that have to be managed in the system, and enables hierarchical and independent management of the information relevant to fibers, wavebands and wavelengths. Moreover, relatively small-scale modular switching matrices are now sufficient to construct large-capacity optical cross-connects, making the system more scalable. Finally all of these also result in reduced complexity of controlling the switch matrix, provisioning, and providing recovery. Note that wavelength conversion is allowed only at the wavelength crossconnect because of significant technical difficulty waveband conversion. Kim et al. Expires - August 2004 [Page 5] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 +-------------+ ------> | WXC |------> W-LSP +-------------+ | | +----+ +-----+ |mux | |demux| +----+ +-----+ | | +-------------+ ------> | BXC |------> B-LSP +-------------+ | | +----+ +-----+ |mux | |demux| +----+ +-----+ | | +-------------+ ------> | FXC |------> F-LSP +-------------+ [FIGURE 1] The Architecture of three layer Multi-Granularity Optical Cross-connect (MG-OXC) 2. Requirements of MG-OXC in GMPLS networks This section discusses the requirements of MG-OXC for network operation. For the interoperability with these legacy systems, wavelength- switching layer of MG-OXC is required to coexist with these legacy systems for the major interface services. - SONET/SDH, with different degree of transparency - DWDM, optical wavelength services, transparent or opaque - Ethernet In waveband switching layer, the wavelength granularity has a large effect on the performance of MG-OXC in GMPLS networks because optimal wavelength granularity leads to a maximum reduction gain of MG-OXC size. Also, optimal wavelength granularity may depend on network topology, traffic demand, and traffic pattern. Waveband switching schemes are classified into two variations depending on whether the number of wavelengths in a waveband is fixed or variable. The followings are required for the various waveband-switching techniques in waveband layer. - Programmable waveband switching, that is, the number of wavelengths in a waveband can be controlled by GMPLS control plane - The ratio of wavebands that can be demultiplexed to wavelengths should be controlled by GMPLS control plane Kim et al. Expires - August 2004 [Page 6] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 The following grouping strategies are required optionally to group lightpaths into wavebands - End-to-end grouping: grouping the lightpath with same source- destination only - One-end grouping: grouping the lightpath between the same source (or destination) nodes and different destination (or source) nodes - Intermediate-path grouping: grouping lightpath with common intermediate-path from any source to any destination Fiber level of MG-OXC has the ability of space switching for the lightpath by fiber unit. The followings are required for the fiber-switching layer. - The number of wavebands in a fiber can be controlled by GMPLS control plane - The ratio of fibers that can be demultiplexed to wavebands should be controlled by GMPLS control plane 2.1. Signaling Aspects for MG-OXC In order to perform the signaling of multi-granularity optical LSP, a generalized label can make the waveband label [RFC3471]. Signaling messages are used for the establishment, modification, status query and release of an end-to-end optical MG-OXC connection. - The association between local and remote optical LSP can be configured either manually or dynamically using [LMP]. - The association between the local/remote waveband and wavelength can be configured either manually or dynamically using [LMP]. 2.2. Routing Aspects for MG-OXC The following routing requirements of each layer should be considered respectively. - Information about physical topology (set of fiber connected between MG-OXCs) - Information about virtual topology (set of light path connected between MG-OXCs) of each layer - Information about link state of each layer Kim et al. Expires - August 2004 [Page 7] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 - Lightpath grouping strategy depending on whether the number of wavebands in a fiber is fixed or variable - Information about the continuity of wavelength or waveband allocated to each link, e.g. wavelength or waveband converter is equipped or not - Information about switching capability and port usage, that is, information of capability of wavelength, waveband, and fiber switching for each port - Information about the optical LSP (for example, link ID, link type, ingress and egress interface IP address, maximum bandwidth, maximum reservable bandwidth, unreserved bandwidth, explicit route object (ERO)) 2.3. Requirements for lightpath selection The following are functional requirements for path selection: - Path selection shall support shortest path routing. - Path selection shall also support constraint-based routing. At least the following constraints shall be supported: - Cost - Link utilization - Diversity - Service Class - Path selection shall be able to include/exclude some specific network resources, based on policy. - Path selection shall be able to support different levels of diversity, including node, link, SRLG and SRG. - Path selection algorithms shall provide carriers the ability to support a wide range of services and multiple levels of service classes. Parameters such as service type, transparency, bandwidth, latency, bit error rate, etc. may be relevant. Constraint-based routing in the MG-OXC network is significantly complex compared to the IP network. There are many optical layer constraints to consider such as wavelength, waveband, fiber, diversity, optical layer impairments, etc. 2.4. Requirements on Protection of MG-OXC When the failure of waveband lightpath occurs, it is very difficult how to recover several wavelength lightpaths in a failed waveband lighpath that have each different end-to-end path. The GMPLS networks Kim et al. Expires - August 2004 [Page 8] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 can be segmented into several areas, such as, wavelength, waveband, fiber areas in order to optimize the resilience and scalability of networks. Each area of optical LSP has the independent local protection from other areas that the node adjacent to the failure reroutes the lightpath around the failure. This can occur a lot faster because no failure notification across the networks is necessary. In doing this, one must distinguish between inter- and intra-area protection because the GMPLS hierarchical networks are separated into several areas. The MG-OXC interconnecting two or more areas is called by border MG-OXC. This is done by local area protection by the node adjacent to the failure or by the border MG- OXC on the path to the destination. 3. Security Considerations This document does not introduce new security issues beyond those inherent in GMPLS. It is, however, possible that using the suggested network management attributes provisioning can be done as administrative usage. References [WAVEBAND] R.Douville et al.,"Extensions to Generalized MPLS in support of Waveband Switching,’’ Internet Draft, Work in progress, draft-douville-ccamp-waveband-extensions- 04.txt, June 2003. [HCROSS] M. Lee et al.,"Design of Hierarchical Crossconnect WDM Networks Employing A Two-Stage Multiplexing Scheme of Waveband and Wavelength," IEEE JSAC, vol. 20, no. 1 January 2002, pp 166-71. [GMPLS-ARCH] Mannie, E.,’’Generalized Multi-Protocol Label Switching Architecture", Internet Draft, Work in progress, draft- ietf-ccamp-gmpls-architecture-07.txt, May 2003. [LMP] Lang, J., "Link Management Protocol (LMP)", Internet Draft, Work in progress, draft-ietf-ccamp-lmp-10.txt, October 2003. [RFC2026] S. Bradner, "The Internet Standards Process -- Revision 3", RFC 2026, October 1996. [RFC2119] Brander, s., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2205] Braden, R., et al., "Resource ReSerVation Protocol (RSVP) -- Version 1 Functional Specification", RFC 2205, September 1997. [RFC3212] Jamoussi, B., et al., "Constraint-Based LSP Setup using LDP", RFC 3212, January 2002. [RFC3386] W. Lai, D. McDysan, "Network Hierarchy and Multilayer Survivability," IETF RFC 3386, November 2002. [RFC3471] L. Berger (Editor),’’ Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", IETF RFC 3471, January 2003. Kim et al. Expires - August 2004 [Page 9] draft-kim-ccamp-gmpls-mgoxc-01.txt February 2004 Author's Addresses Dae-Gun Kim KT 206 Jungja-dong, Bundang-gu, Sungnam-City, Kyonggi-do,463-711, Korea Phone : 82-31-707-8766 e-mail : dkim@kt.co.kr Gyu Myoung Lee Information and Communication University (ICU) 103-6 Munji-dong, Yuseong-gu, Daejeon, 305-732, Korea Phone: 042-866-6122 e-mail : gmlee@icu.ac.kr Jun Kyun Choi Information and Communication University (ICU) 103-6 Munji-dong, Yuseong-gu, Daejeon, 305-732, Korea Phone: 042-866-6122 e-mail : jkchoi@icu.ac.kr Jin Woo Park Korea University 1,5-ka, Anam-dong, Sungbuk-ku, Seoul, 136-701, Korea Phone: 82-2-3290-3225 e-mail: jwpark@korea.ac.kr Chul-Hee Kang Korea University 1,5-ka, Anam-dong, Sungbuk-ku, Seoul, 136-701, Korea Phone: 82-2-927-6116 e-mail: chkang@widecomm.korea.ac.kr Full Copyright Statement "Copyright (C) The Internet Society 2003. All Rights Reserved". This document and translations of it may be copied and furnished to others, and derivative works that comment on or otherwise explain it or assist in its implementation may be prepared, copied, published and distributed, in whole or in part, without restriction of any kind, provided that the above copyright notice and this paragraph are included on all such copies and derivative works. However, this document itself may not be modified in any way, such as by removing the copyright notice or references to the Internet Society or other Internet organizations, except as needed for the purpose of developing Internet standards in which case the procedures for copyrights defined in the Internet Standards process must be followed, or as required to translate it into Document: draft-kim-gmpls-mgoxc-01.txt Expiration Date: August 2004 Kim et al. Expires - August 2004 [Page 10]