Network work group Dan Li Internet Draft Young Lee Jianhua Gao Huawei Intended Status: Informational Expires: May 2008 November 1, 2007 Evaluation of Possible Interior Gateway Protocol Extensions for Wavelength Switching Optical Networks draft-li-ccamp-wson-igp-eval-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of 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 May 1, 2008. Abstract Wavelength Division Multiplexing (WDM) is a technology for optical communications, in which the user traffic is carried by data channels of different optical wavelengths. In traditional WDM Networks, each wavelength path is statically configured. With the deployment of the Li, Lee, and Gao Expires May 1, 2008 [Page 1] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Reconfigurable Optical Add-Drop Multiplexer (ROADM) and the Wavelength Selective Switch (WSS), WDM networks have become more dynamic, and operators can flexibly set up wavelength paths to carry user traffic. This document discusses the set of Interior Gateway Protocol (IGP) requirements that would enable distributed light path computation in Wavelength Switched Optical Networks (WSON). An IGP impact analysis is also provided. According to the analysis, there is no significant impact on the IGP performance. 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 RFC-2119 [RFC 2119]. Table of Contents 1. Introduction..................................... ...........2 2. Typical WDM Node................................. ...........3 3. Wavelength Conversion Constraints............................4 4. Available Wavelength Information.............................5 5. Requirements for IGP Extensions..............................5 6. Assessment of the WDM Node Constraint Information............6 6.1. Potential Wavelength Connectivity Information...........6 6.2. Wavelength Status Information...........................8 6.3. IGP Extensions................................ .........8 7. Security Considerations.....................................11 8. IANA Considerations.............................. ..........11 9. Acknowledgments.................................. ..........11 10. References....................................... .........12 10.1. Normative References..................................12 11. Authors' Addresses............................... .........12 12. Full Copyright Statement...................................13 13. Intellectual Property Statement............................14 1. Introduction Wavelength Division Multiplexing (WDM) is a technology for optical communications, in which the user traffic is carried by different data channels of optical wavelengths. In traditional WDM Networks, each wavelength path is statically configured. With the deployment of the Reconfigurable Optical Add-Drop Multiplexer (ROADM) and the Li, Lee, and Gao Expires May 1, 2008 [Page 2] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Wavelength Selective Switch (WSS), WDM networks have become more dynamic, and operators can flexibly set up wavelength paths to carry user traffic. [WSON-FRAME] provides control plane models for key wavelength switched optical network subsystems and processes. Section 5.2 of [WSON-FRAME] describes the subsystem properties which may be conveyed via an Interior Gateway Protocol (IGP). This document discusses the set of IGP requirements that would enable distributed light path computation in Wavelength Switched Optical Networks (WSON). An IGP impact analysis is also provided. According to the analysis, there is no significant impact on the IGP performance. This document is currently limited to consideration of single component links per TE link. Link Bundles are for future consideration. 2. Typical WDM Node +-------------------------------+ | +---------------+ | | /|---| +-----------+ |---|\ | Fiber 1 | | |---| |\ /| |---| | | Fiber 3 Dir 1 =====|=| | . | | \ / | | . | |=|===== Dir 3 | | | . | |Wavelength | | . | | | | \|---| | Switch | |---|/ | | | | \ / | | | | /|---| | / | |---|\ | Fiber 2 | | |---| | / \ | |---| | | Fiber 4 Dir 2 =====|=| | . | | / \ | | . | |=|===== Dir 4 | | | . | | / \ | | . | | | | \|---| | / \ | |---|/ | | | |/ \| | | | +---| +-----------+ |---+ | | | +---------------+ | | | | +- - - - - - -+ | | | | | Wavelength | | | | +----| Converter |----+ | | | (Optional) | | | +- - - - - - -+ | +-------------------------------+ Figure 1: Typical WDM Node Figure 1 shows a typical WDM node, which consists of a Wavelength Switch module, a Multiplexer/DeMultiplexer module, and a Wavelength Li, Lee, and Gao Expires May 1, 2008 [Page 3] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Converter module. In this example, there are four directions on the line side. For the ROADM, there also should have some Add/Drop modules, but current we only focus on the line side. For example, in a 160-wavelength system, each fiber contains 160 wavelengths, and traffic can be carried by each wavelength. The wavelength can be switched to a different direction (or a different fiber) at the WDM node. Moreover, if the WDM node has the wavelength conversion capability, one wavelength can be switched to a different wavelength of a different direction. But there may be a limitation for wavelength conversion, so that not every wavelength can be switched to any other wavelength on any other fiber. 3. Wavelength Conversion Constraints For each WDM node, not all the wavelengths on a fiber can necessarily be converted to any other wavelength on any other fiber. For example, lambda 1 on an incoming fiber might only be convertable to lambda 2, lambda 3, or lambda 4 on a particular outgoing fiber, and cannot be converted to lambda 5 or other wavelengths on that outgoing fiber. The wavelength conversion constraints directly affect the potential connectivity of wavelengths in WSON. There are three kinds of wavelength conversion capabilities: o No wavelength conversion. o Partial wavelength conversion. Some of the wavelengths can be converted to different wavelengths. o Full wavelength conversion. All of the wavelengths can be converted to any wavelengths. If no wavelength conversion is possible, there may be three more cases: o Each of the wavelengths on one fiber can only be connected to the same wavelength on some other fibers. o Some subset of wavelengths on one fiber can be connected only as a set to the same wavelengths on some other fibers. o A particular wavelength on one fiber can be connected only to the same wavelength on another specific fiber. Li, Lee, and Gao Expires May 1, 2008 [Page 4] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 4. Available Wavelength Information In order to perform end-to-end wavelength computation, the wavelength label is certainly convenient to have global semantics, but it is not necessary. For example, an NMS could know the details of each NE and perform its own mappings between the local significance wavelength labels. So the collection of potential wavelength connectivity information, wavelength path computation, and signaling the wavelength path, all could be solved by local wavelength label mappings performed by NMS. In order to avoid such complicated and potentially error-prone operations, it is desirable to use the same semantics for the wavelength label on every hop. For example, the wavelength label range [lambda 1, lambda 5] of fiber 1 can be connected to the same wavelength label range of fiber 2. But only lambda 3 is available to carry the traffic, other wavelength labels are occupied. In order to compute a wavelength path, available wavelength information needs to be known by the node performing the computation. If the wavelength availability information is not known by the node performing the path computation, then the computation can only be performed at the level of TE links, and wavelength assignment must be resolved locally by the switches on a hop-by-hop basis enhanced by signaling protocol mechanisms used to negotiate label selection. However, this case may be very inefficient in the signaling protocol, and can easily lead to blocking problems where a path is selected for which there is no suitable wavelength availability, unless some or all of the switches along the path are capable of full wavelength conversion. In the general case of limited or no wavelength conversion, information on wavelength availability is essential to perform efficient and accurate path computation. 5. Requirements for IGP Extensions In WSON, wavelength path computations based on the data link topology and the TE link states alone cannot guarantee that computed wavelength paths can actually be successfully established. The following three factors should also be considered in wavelength path computation: o Wavelength conversion constraints o Wavelength connectivity o Per-fiber wavelength availability information. Li, Lee, and Gao Expires May 1, 2008 [Page 5] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Each WDM node has this information about its own fibers, but the information needs to be distributed to the points of computation. The IGP that is already used to advertise TE information within the WSON is a candidate solution to distribute this constraint information. If the IGP were to be used in this way then the following requirements would need to be applied: o The constraint information should be small, so that it must not affect the performance of IGP; o IGP extension should support all kinds of wavelength conversion capabilities; o IGP extension should support the scalability of different wavelength multiplexer systems, such as 40-wavelength WDM, 80- wavelength WDM, and 160-wavelength WDM; 6. Assessment of the WDM Node Constraint Information When computing an available wavelength from source to destination, two types of information are needed along with potential paths. One is available wavelength information in all the fibers, the other is the potential wavelength connectivity in all the nodes. In a deployed WDM network, the information which is required to compute a wavelength path consists of: - Potential wavelength connectivity information - Wavelength status information. 6.1. Potential Wavelength Connectivity Information The wavelength that an optical fiber can support is pre-configured, static information. This information needs to be advertised only once in the general case, because it is not expected to change frequently when the network is running. This information should be advertised again, only if: o The link is updated to support more or fewer wavelengths; o The link is changed to use a new wavelength band; Li, Lee, and Gao Expires May 1, 2008 [Page 6] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 o The switch at the end of the link runs out of shared wavelength conversion capability (for example, uses up all capacity on a switch fabric) which will affect the potential wavelength connectivity. For a fiber which can support 160 wavelengths, the size of wavelength information supported by the fiber reaches about 160*4 = 640 bytes, where each wavelength is identified by the wavelength label format defined in [Lambda-Label]. For a fiber that can support 160 wavelengths, and considering a node that has wavelength conversion capability, the size of potential wavelength connectivity information of each fiber pair may be as much as 3200 bytes: Input fiber = lambda 1, lambda 2, ..., lambda 160 Output fiber = lambda 1, lambda 2, ..., lambda 160 So the 160x160 matrix (M[160,160]) can be represented by a bitmap. For example, if lambda 1 of Input fiber can be connected or converted to lambda 4 of Output fiber, then M[1,4] is set to 1. Otherwise, M[1,4] is set to 0. The bit-matrix is correlated to the static list of wavelengths available on the fiber as described earlier in this section. Total size = 160 * 160 / 8 = 3200 bytes. This information is not expected to change frequently. It can be advertised just once. Further more, by applying some encoding or compression algorithm, the size of this information may be reduced a lot. The wavelength conversion capability is not supported at all nodes in a WSON. It may be the case that only a few WDM nodes support wavelength conversion. In this case, for most of the WDM nodes, the potential wavelength connectivity information may be simplified to the following information: o Input fiber and Output fiber with full wavelength range; or, o Input fiber and Output fiber with a specific wavelength range (from lambda m to lambda n); Li, Lee, and Gao Expires May 1, 2008 [Page 7] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 6.2. Wavelength Status Information In WSON, the status information of a certain wavelength in a fiber should be refreshed following any change. When a wavelength is assigned to set up a wavelength LSP or released when a wavelength LSP is torn down, the status information of this wavelength on each link along the path should be updated. This information is dynamic information and needs to be distributed to all computation points. To minimize the size of information, we can use a bitmap to indicate the wavelength status information of a fiber, i.e. only one bit is used to indicate the status of a certain wavelength (the wavelength is either available or not available). The bitmap is correlated to the static wavelength list described in Section 6.1. For a fiber which can support 160 wavelengths, the size of the wavelength status information of a fiber is only 20 bytes. So it should not impact the IGP performance to advertise this information. 6.3. IGP Extensions A new Opaque LSA can be introduced to carry wavelength information of a fiber and potential wavelength connectivity information of node. The format of wavelength information is proposed 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Lambda_num | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lambda 1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lambda 2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ ...... ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Lambda n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Reserved: 16 bits This field is reserved. It MUST be set to 0 on transmission and MUST be ignored on receipt. Lambda_num: 16 bits Li, Lee, and Gao Expires May 1, 2008 [Page 8] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 The number of wavelengths that the fiber supports; Lambda n: 32 bits The wavelength label information. The label format is defined in Section 5 of [Lambda-Label]. The format of potential wavelength connectivity information is proposed 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |U| Reserved | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Row | Column | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Row link ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Column link ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Bitmap list | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ...... | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ...... | Padded bit | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ U: 1 bit Bidirection indicated bit. 1 = Unidirection; 0 = Bidirection; If U is set to 1 (unidirection), it only indicates the wavelength potential connectivity from row link identified by Row link ID to column link identified by column link ID. If U is set to 0 (bidirection), it indicates that the wavelength potential connectivity from row link identified by Row link ID to column link identified by column link ID is the same as that of from column link to row link. Li, Lee, and Gao Expires May 1, 2008 [Page 9] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Reserved: 31 bits This field is reserved. It MUST be set to 0 on transmission and MUST be ignored on receipt. Row: 16 bits Indicates the number of rows in the matrix. This has the same value as the count of wavelengths supported by this fiber (Lambda_num in the wavelength information sub-TLV). Column: 16 bits Indicates the number of columns in the matrix. This has the same value as the number of wavelengths of the TE link identified by Reachable_link ID. Row link ID: 32 bits Indicates the Row TE link to which this matrix applies. It is a 32 bit Unnumbered Interface ID. Column link ID: 32 bits Indicates the Column TE link to which this matrix applies. It is an 32 bit Unnumbered Interface ID. Bitmap list: Variable Length The matrix indicates the potential connectivity from lambdas on Row link ID, to Column link ID. Each bit indicates the potential connectivity of a certain wavelength pair indicated by M[m n]. If there has a potential connectivity, the corresponding bit is set to 1; otherwise it is set to 0. Indexes start at 1 and run to the count of wavelength on each fiber. The bit indicated by M[m n] is located at offset (m-1)*32+n from the first bit. Padded bit: Variable Length It is used to pad the bit to make the whole number of bits in the bitmap to be a multiple of 32. Padded bits MUST be set to 0. The bit-matrix compression techniques will be discussed in a future version of this document Li, Lee, and Gao Expires May 1, 2008 [Page 10] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 A new TE link sub-TLV of an Opaque LSA can be introduced to carry the wavelength status 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Reserved | Assigned Status Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Assigned_status | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ...... | Padded bits | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Assigned Status Length : 16 bits It is a bitmap that indicates the bit length of assigned_status bit, It has the same value with the number of wavelengths that the fiber supports. Assigned status: Variable Length Each bit indicates the availability status of one wavelength. 1 = available; 0 = not available (in use, or failed, or administratively down, or under test); Padded bit: Variable Length It is used to pad the bit to make the whole number of bits in bitmap be the time of 32. Padded bit MUST be set to 0. 7. Security Considerations TBD. 8. IANA Considerations This requirement document makes no requests for IANA action. 9. Acknowledgments We would like to thank Adrian Farrel for his useful comments. Li, Lee, and Gao Expires May 1, 2008 [Page 11] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 10. References 10.1. Normative References [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 [WSON-FRAME] G. Bernstein, Y. Lee, "Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks", Internet Draft, work in progress, draft-bernstein-ccamp-wavelength- switched-02.txt, October 2007 [Lambda-Label] T. Otani, H. Guo, "Generalized Labels of Lambda- Switching Capable Label Switching Routers (LSR)", Internet Draft, work in progress, draft-otani-ccamp-gmpls-lambda- labels-00.txt, June 2007 11. Authors' Addresses Jianhua Gao Huawei Technologies Co., Ltd. F3-5-B R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28973237 Email: gjhhit@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: +86-755-28973237 Email: danli@huawei.com Li, Lee, and Gao Expires May 1, 2008 [Page 12] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 Young Lee Huawei Technologies 1700 Alma Drive, Suite 100 Plano, TX 75075 USA Phone: (972) 509-5599 (x2240) Email: ylee@huawei.com Jianrui Han Huawei Technologies Co., Ltd. F3-5-B R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28973234 Email: hanjianrui@huawei.com Baoquan Rao Huawei Technologies Co., Ltd. F3-4-A R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28973239 Email: raobaoquan@huawei.com Xinghua Shi Huawei Technologies Co., Ltd. F3-4-A R&D Center, Huawei Base, Bantian, Longgang District Shenzhen 518129 P.R.China Phone: +86-755-28973238 Email: sxh@huawei.com 12. Full Copyright Statement Copyright (C) The IETF Trust (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Li, Lee, and Gao Expires May 1, 2008 [Page 13] Internet-Draft draft-li-ccamp-wson-igp-eval-00.txt November 2007 This document and the information contained herein 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 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 13. 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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 this standard. Please address the information to the IETF at ietf-ipr@ietf.org. 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". Li, Lee, and Gao Expires May 1, 2008 [Page 14]