Network Working Group G. Bernstein Internet Draft Grotto Networking Intended status: Informational Y. Lee Expires: December 2007 Huawei June 25, 2007 Applicability of GMPLS and PCE to Wavelength Switched Optical Networks draft-bernstein-ccamp-wavelength-switched-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. This document may not be modified, and derivative works of it may not be created, except to publish it as an RFC and to translate it into languages other than English. 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 December 25, 2007. Copyright Notice Copyright (C) The IETF Trust (2007). Abstract Bernstein and Lee Expires December 25, 2007 [Page 1] Internet-Draft Wavelength Switched Optical Networks June 2007 This memo examines the applicability of Generalized Multi-Protocol Label Switching (GMPLS) and the Path Computation Element (PCE) architecture to the control of wavelength switched optical networks. In particular we investigate how WDM based systems consisting of tunable laser transmitters and reconfigurable optical add/drop multiplexers (ROADM) or Wavelength Selective Switches (WSS) can be controlled with the current GMPLS/PCE protocols. Minor protocol extension requirements are identified where necessary. The three cases of full wavelength conversion, no wavelength conversion, and limited wavelength conversion and their impacts on GMPLS signaling, GMPLS routing, and PCE communications protocol are discussed. 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 [RFC2119]. Table of Contents 1. Introduction...................................................3 2. Terminology....................................................4 3. Routing and Wavelength Assignment..............................5 3.1. Implications for GMPLS signaling..........................6 3.1.1. No Wavelength Conversion.............................6 3.1.2. Limited Wavelength Conversion........................7 3.1.3. Full Wavelength Conversion...........................7 3.1.4. Future Issues for GMPLS Signaling....................7 3.2. Implications for GMPLS Routing............................8 3.2.1. Need for Wavelength-Specific Maximum Bandwidth Information.................................................8 3.2.2. Need for Wavelength-Specific Availability Information8 3.2.3. Describing Wavelength Conversion Capabilities........9 3.2.4. Relationship to Link Bundling and Layering..........10 3.3. Optical Path Computation and Implications for PCE........10 3.3.1. No or Limited Wavelength Conversion.................10 3.3.2. Full Wavelength Conversion..........................11 3.3.3. PCE Discovery.......................................11 4. Security Considerations.......................................11 5. IANA Considerations...........................................12 6. Conclusions...................................................12 7. Acknowledgments...............................................12 8. References....................................................13 8.1. Normative References.....................................13 Bernstein & Lee Expires December 25, 2007 [Page 2] Internet-Draft Wavelength Switched Optical Networks June 2007 8.2. Informative References...................................13 Author's Addresses...............................................15 Intellectual Property Statement..................................15 Disclaimer of Validity...........................................16 1. Introduction Two key optical components have emerged that are making wavelength switched optical networks more cost effective and dynamic. First introduced to reduce inventory costs, tunable optical laser transmitters are becoming widely deployed [Coldren04], [Buus06]. This allows flexibility in the wavelength used for optical transmission. Reconfigurable add/drop optical multiplexers (ROADM) have matured and are available in different forms and technologies [Basch06]. This allows wavelength based optical switching. However, another optical component, the wavelength converter, has not advanced as uniformly and different system designs may choose to utilize this component to varying degrees or not at all. Wavelength converters take an ingress optical signal at one wavelength and emit an equivalent content optical signal at another wavelength on egress. There are currently two approaches to building wavelength converters. One approach is based on optical to electrical to optical (OEO) conversion with tunable lasers on egress. This approach can be dependent upon the signal rate and format, i.e., this is basically an electrical regenerator combined with a tunable laser. The other approach performs the wavelength conversion, optically via non-linear optical effects, similar in spirit to the familiar frequency mixing used in radio frequency systems, but significantly harder to implement. Such processes/effects may place limits on the range of achievable conversion. These may depend on the wavelength of the input signal and the properties of the converter as opposed to the only the properties of the converter in the OEO case. The presence and amount of wavelength conversion available at a wavelength switching interface has an impact on the information that needs to be transferred by the control plane (Generalized Multiprotocol Label Switching - GMPLS) and the Path Computation Element (PCE) architecture. Figure 1, below, summarizes the current capabilities of GMPLS signaling, GMPLS routing and the PCE architecture to support the control of switched optical networks consisting of (a) full wavelength conversion capabilities, (b) no wavelength conversion capabilities, and (c) limited wavelength conversion capabilities. Bernstein & Lee Expires December 25, 2007 [Page 3] Internet-Draft Wavelength Switched Optical Networks June 2007 Signaling Routing PCE ------------------------------------------------ Full | Yes | Yes | Yes | Conversion | | | | ------------------------------------------------ No | Yes | No | Partial | Conversion | | | | ------------------------------------------------ Limited | Yes | No | Partial | Conversion | | | | ------------------------------------------------ Figure 1 Current support for wavelength switching in GMPLS & PCE. The full wavelength conversion case occurs when all ROADMs or WSSs have wavelength converters available on every interface. This, for example, would occur in the case of OEO switches with WDM interfaces featuring tunable lasers. Limited wavelength conversion capabilities exist in a network when either wavelength conversion is either not present on every port or not present at every switching node. Finally, in the case of no conversion, none of the wavelength switching nodes has wavelength conversion capability. 2. Terminology ROADM: Reconfigurable optical add/drop multiplexer. A reduced port count wavelength selective switching element featuring ingress and egress line side ports as well as add/drop side ports. Wavelength Conversion/Converters: The process of converting an information bearing optical signal centered at a given wavelength to one with "equivalent" content centered at a different wavelength. Wavelength conversion can be implemented via an optical-electronic- optical (OEO) process or via a strictly optical process. Wavelength Switched Optical Networks: Wavelength Division Multiplex (WDM) based optical networks in which switching is performed selectively based on the center wavelength of an optical signal. Wavelength Selective Switch (WSS): A general, multi-port, switch used in wavelength switched optical networks. Switches data based on ingress port and ingress lambda. May or may not have wavelength conversion capabilities. Bernstein & Lee Expires December 25, 2007 [Page 4] Internet-Draft Wavelength Switched Optical Networks June 2007 3. Routing and Wavelength Assignment In wavelength switched optical networks consisting of tunable lasers and wavelength selective switches with wavelength converters on every interface, path selection is similar to the MPLS and TDM circuit switched cases in that the labels, in this case wavelengths (lambdas), have only local significance. That is, a wavelength- convertible network with full wavelength-conversion capability at each node is equivalent to a circuit-switched TDM network with full time slot interchange capability; thus, the routing problem needs to be addressed only at the level of the TE link choice, and wavelength assignment can be resolved by the switches on a hop-by-hop basis. However, in the limiting case of an optical network with no wavelength converters, a light path (optical channel - OCh -) needs a route from source to destination and must pick a single wavelength that can be used along that path without "colliding" with the wavelength used by any other light path that may share an optical span. This is sometimes referred to as a "wavelength continuity constraint". To ease up on this constraint while keeping network costs in check a limited number of wavelength converters maybe introduce at key points in the network [Chu03]. In the general case of limited or no wavelength converters this computation is known as the Routing and Wavelength Assignment (RWA) problem [HZang00]. The "hardness" of this problem is well documented, however, there exists a number of reasonable approximate methods for its solution [HZang00]. The inputs to the basic RWA problem are the requested light paths source and destination, the networks topology, the locations and capabilities of any wavelength converters, and the wavelengths available on each optical link. The output from an algorithm solving the RWA problem is an explicit route through ROADMs or WSSs, a wavelength for the optical transmitter, and a set of locations (generally associated with switches) where wavelength conversion is to occur and the new wavelength to be used on each component link after that point in the route. It is to be noted that the RWA algorithm is out of the scope for this document. This document discusses GMPLS signaling and routing requirements and PCE requirements that enable RWA aware light path computation and the establishment of the LSPs in wavelength switched optical networks. Bernstein & Lee Expires December 25, 2007 [Page 5] Internet-Draft Wavelength Switched Optical Networks June 2007 3.1. Implications for GMPLS signaling In [RFC3471] a wavelength label is just a 32 bit integer that at a minimum must have significance to the two neighbors, i.e., maps to a specific wavelength or frequency. To set up a transparent network it makes more sense to map labels to wavelengths at the network (domain) level so we have an easy and consistent way to describe them in GMPLS signaling. ITU-T recommendation [G.694.1] describes a WDM grid defined in terms of frequency spacing of 12.5GHz, 25GHz, 50GHz, 100GHz, and other multiples of 100GHz. To see that the 32 bit GMPLS label currently allocated is sufficient, consider a wideband fiber such as that specified in [G.656] which is capable of operating over a wavelength range of 1460-1625nm. This would correspond to a frequency range of approximately 53.44THz, and with the currently finest grid spacing of 12.5GHz would require approximately 4276 < 2^13 labels. This is far less than the possible 2^32 lambda labels available via GMPLS hence a simplistic network wide map of wavelengths to labels is feasible. An alternative to a global network map of labels to wavelengths would be to use LMP to assign the map for each link then convey that information to any path computation entities, e.g., label switch routers or stand alone PCEs. For use in GMPLS RSVP-TE path messages GMPLS already has the lambda (value 9) LSP encoding type [RFC3471], or for G.709 compatible optical channels, the LSP encoding type (value = 13) "G.709 Optical Channel" from [RFC4328]. 3.1.1. No Wavelength Conversion Given a system-wide mapping between labels and lambdas and assuming that the RWA problem has been solved to yield a path as a series of links traversed by a single wavelength(explicit route). We can then use the GMPLS signaling procedures [RFC3471] to set up the light path with an appropriate interpretation of the parameters made at each ROADM. In particular, the source of the light path would originate a path message containing a label set consisting of a single label (that corresponds to the assigned lambda). Upon reception at the first ROADM or WSS this wavelength is confirmed to not be used on the selected outgoing interface (fiber). Per [RFC3471] procedures for the non-wavelength converter case the incoming label set (consisting of a single label) forms the basis for the out-going label set and in this way a path can be set up for the assigned wavelength and any potential lambda collisions can be caught by GMPLS signaling processing. Hence current GMPLS signaling can support the case with no wavelength conversion. Bernstein & Lee Expires December 25, 2007 [Page 6] Internet-Draft Wavelength Switched Optical Networks June 2007 3.1.2. Limited Wavelength Conversion When the optical network contains a limited number of wavelength converters, the solution to the RWA problem will consist of a route from the source to destination along with the wavelengths (generalized labels) to be used along portions of the path. Current GMPLS signaling supports an explicit route object (ERO) and within an ERO an ERO Label subobject can be use to indicate the wavelength to be used at a particular node. Hence current GMPLS signaling supports the case of limited wavelength conversion. 3.1.3. Full Wavelength Conversion When the optical network consists of full wavelength converters, label assignment is strictly a link local matter and wavelength assignment is not an issue beyond the local link, i.e., one doesn't have to solve the wavelength assignment portion of the RWA problem. Hence current GMPLS signaling (local) label assignment techniques can be used and the current GMPLS signaling supports the case of full wavelength conversion. 3.1.4. Future Issues for GMPLS Signaling Although Non-Return to Zero (NRZ) is currently the dominant form of optical modulation, new modulation formats are being researched [Winzer06] and deployed. With a choice in modulation formats we no longer have a one to one relationship between digital bandwidth in bytes or bits per second and the amount of optical spectrum (optical bandwidth) consumed. To simplify the specification of optical signals the ITU-T, in recommendation G.959.1, combined a rate bound and modulation format designator [G.959.1]. For example, two of the signal classes defined in [G.959.1] are: Optical tributary signal class NRZ 1.25G: "Applies to continuous digital signals with non-return to zero line coding, from nominally 622 Mbit/s to nominally 1.25 Gbit/s. Optical tributary signal class NRZ 1.25G includes a signal with STM-4 bit rate according to ITU-T Rec. G.707/Y.1322." Optical tributary signal class RZ 40G: "Applies to continuous digital signals with return to zero line coding, from nominally 9.9 Gbit/s to nominally 43.02 Gbit/s. Optical tributary signal class RZ 40G includes a signal with STM- 256 bit rate according to ITU-T Rec. G.707/Y.1322 and OTU3 bit rate according to ITU-T Rec. G.709/Y.1331." Bernstein & Lee Expires December 25, 2007 [Page 7] Internet-Draft Wavelength Switched Optical Networks June 2007 Hence, as was done in reference [RFC4606] for SONET/SDH, in the future it maybe worthwhile to define traffic parameters for lambda LSPs that include a signal type field that includes modulation format information. 3.2. Implications for GMPLS Routing GMPLS routing [RFC4202] currently defines an interface capability descriptor for "lambda switch capable" which we can use to describe the interfaces on a ROADM or other type of wavelength selective switch. 3.2.1. Need for Wavelength-Specific Maximum Bandwidth Information Difficulties are encountered when trying to use the bandwidth accounting methods of [RFC4202] and [RFC3630] to describe the availability of wavelengths on a WDM link. The current RFCs give three link resource measures: Maximum Bandwidth, Maximum Reservable Bandwidth, and Unreserved Bandwidth. Although these can be used to describe a WDM span they do not provide the fundamental information needed for RWA. We are not given the maximum bandwidth per wavelength for the span. If we did then we could use the aforementioned measures to tell us the maximum wavelength count and the number of available wavelengths. For example, suppose we have a 32 channel WDM span, and that the system in general supports ITU-T NRZ signals up to NRZ 10Gbps. Further suppose that the first 20 channels are carrying 1Gbps Ethernet, then the maximum bandwidth would be 320Gbps and the maximum reservable bandwidth would be 120Gbps (12 wavelengths). Alternatively, consider the case where the first 8 channels are carrying 2.5Gbps SDH STM-16 channels, then the maximum bandwidth would still be 320Gbps and the maximum reservable bandwidth would be 240Gbps (24 wavelengths). 3.2.2. Need for Wavelength-Specific Availability Information Even if we know the number of available wavelengths on a link, we actually need to know which specific wavelengths are available and which are occupied so we can assign a wavelength that can be used across the entire path from source to destination. This is currently not possible with GMPLS routing extensions. In the routing extensions for GMPLS [RFC4202], requirements for layer-specific TE attributes are discussed. The RWA problem for Bernstein & Lee Expires December 25, 2007 [Page 8] Internet-Draft Wavelength Switched Optical Networks June 2007 optical networks without wavelength converters imposes an additional requirement for the lambda (or optical channel) layer: that of knowing which specific wavelengths are in use. Note that current dense WDM (DWDM) systems range from 16 channels to 128 channels with advanced laboratory systems with as many as 300 channels. Given these channel limitations and if we take the approach of a global wavelength to label mapping or furnishing the local mappings to the PCEs then representing the use of wavelengths via a simple bit-map is feasible. In the GMPLS extensions for OSPF [RFC4203] the interface capability descriptor sub-TLV contains a subfield that contains switching capability specific information and is one possible place for a bit map of available lambdas. However, current GMPLS routing extensions do not provide enough information for the solution of the RWA problem. 3.2.3. Describing Wavelength Conversion Capabilities Topology, switching capabilities and resource status information are typically disseminated via GMPLS extensions to routing. From the point of view of an algorithm for RWA we are interested in the following features associated with an interface to a wavelength converter: 1. The number of wavelengths that can be converted, i.e., out of the N channels supported by the WDM link how many can be converted to a new lambda. 2. The range of conversion for a given lambda. In all optical wavelength conversion this is typically a function of the input lambda. In electro-optic wavelength conversion it is just a property of the egress tunable laser. A switching node may share a pool of wavelength converters amongst many ports hence it would be appropriate to feed this overall node constraint to a RWA algorithm particularly in the case of batch processing of multiple light paths. See [TE-NODE] for examples of currently shared TE node capabilities. Currently the wavelength conversion capabilities/properties of a lambda switch capable interface are not defined in GMPLS routing extensions [RFC4202]. In reference [RFC4202] an interface can be denoted as lambda switching capable (LSC), but the default assumption seems to be that no constraints on wavelength conversion exist. A simple way to indicate that a wavelength selective switch has no wavelength conversion capabilities would be desirable. Note that OSPF Bernstein & Lee Expires December 25, 2007 [Page 9] Internet-Draft Wavelength Switched Optical Networks June 2007 extensions for GMPLS [RFC4203] does provide a placeholder for "switching capability" specific information that could be used for this purpose. 3.2.4. Relationship to Link Bundling and Layering When dealing with static DWDM systems, particularly from a SONET/SDH or G.709 digital wrapper layer, each lambda looks like a separate link. Typically a bunch of unnumbered links, as supported in GMPLS routing extensions [RFC4202], would be used to describe a static DWDM system. In addition these links can be bundled into a TE link ([RFC4202], [RFC4201]) for more efficient dissemination of resource information. However, in the case discussed here we want to control a dynamic WDM layer and must deal with wavelengths as labels and not just as links or component links from the perspective of an upper (client) layer. In addition, a typical point to point optical cable contains many optical fibers and hence it may be desirable to bundle these separate fibers into a TE link. Note that in the no wavelength conversion or limited wavelength conversion situations that we will need information on wavelength usage on the individual component links. 3.3. Optical Path Computation and Implications for PCE As previously noted the RWA problem can be computationally intensive [HZang00]. Such computationally intensive path computations and optimizations were part of the impetus for the PCE (path computation element) architecture. 3.3.1. No or Limited Wavelength Conversion A network that consists of switches with no wavelength conversion is referred to as a transparent optical network. From the perspective of path computation, this type of network imposes an additional constraint; that is, a wavelength continuity constraint. It is not sufficient for a path that has available lambda channels on every link to be considered as a candidate path. At least one channel of the same wavelength must be available on every link of the path within a transparency domain. When the optical network contains a limited number of wavelength converters, the complexity of path computation increases. That is, the PCE needs to compute a route for a given source-destination pair along with the wavelengths to be used over some segments of the route. Bernstein & Lee Expires December 25, 2007 [Page 10] Internet-Draft Wavelength Switched Optical Networks June 2007 At a minimum to solve the RWA problem one needs the following information: (a) tuning range of the source laser, (b) network topology, (c) network resource availability (wavelengths in use/available on particular spans), and (d) location and capabilities of any wavelength converters. These attributes must be made available to the path computation engine via configuration or advertising. Tuning ranges of lasers can vary with product model and more specifically are usually associated with specific optical bands such as C band (1530-1562nm) and L band (1570-1605nm). Note that if we set up a mapping between the system frequency grid and labels then we can represent the tuning range of a laser by a range of labels. With respect to the PCE architecture the tuning range of the source laser could be configured via management or as a constraint furnished to the PCE in a PCEP request message. After the PCE has performed the RWA computation and wants to return the result to the PCC, it needs an object/TLV in which to send back the assigned wavelength (label)in the case of no conversion or a set of wavelengths corresponding to the egress wavelengths at the wavelength converters. This can be done with the ERO object in conjunction with the ERO label subobject given that there is either a global mapping of labels to lambdas known to the PCE or the PCE has a collection of local label to lambda mappings for each interface. 3.3.2. Full Wavelength Conversion When the optical network consists of full wavelength converters, only the routing problem needs to be addressed, and wavelength assignment can be handled locally. In this case the PCE would not necessarily need to be involved with lambda/label assignments. 3.3.3. PCE Discovery The algorithms and network information needed for solving the RWA are somewhat specialized and computationally intensive hence not all PCEs within a domain would necessarily need or want this capability. Hence, it would be useful via the mechanisms being established for PCE discovery [DISCO] to indicate that a PCE has the ability to deal with the RWA problem. Reference [DISCO] indicates that a sub-TLV could be allocated for this purpose. 4. Security Considerations TBD Bernstein & Lee Expires December 25, 2007 [Page 11] Internet-Draft Wavelength Switched Optical Networks June 2007 5. IANA Considerations TBD 6. Conclusions TBD 7. Acknowledgments The authors would like to thank Adrian Farrel for many helpful comments that greatly improved the contents of this draft. This document was prepared using 2-Word-v2.0.template.dot. Bernstein & Lee Expires December 25, 2007 [Page 12] Internet-Draft Wavelength Switched Optical Networks June 2007 8. References 8.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003. [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, September 2003. [RFC4201] Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling in MPLS Traffic Engineering (TE)", RFC 4201, October 2005. [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. [G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM applications: DWDM frequency grid", June, 2002. [DISCO] J.L. Le Roux, J.P. Vasseur, Yuichi Ikejiri, and Raymond Zhang, "OSPF protocol extensions for Path Computation Element (PCE) Discovery", work in progress, draft-ietf-pce- disco-proto-ospf-05.txt, May 2007. 8.2. Informative References [TE-NODE] J.P. Vasseur and J.L. Le Roux (eds), "IGP Routing Protocol Extensions for Discovery of Traffic Engineering Node Capabilities", work in progress, draft-ietf-ccamp-te-node- cap-05.txt, April 2007. Bernstein & Lee Expires December 25, 2007 [Page 13] Internet-Draft Wavelength Switched Optical Networks June 2007 [HZang00] H. Zang, J. Jue and B. Mukherjeee, "A review of routing and wavelength assignment approaches for wavelength-routed optical WDM networks", Optical Networks Magazine, January 2000. [Coldren04] Larry A. Coldren, G. A. Fish, Y. Akulova, J. S. Barton, L. Johansson and C. W. Coldren, "Tunable Seiconductor Lasers: A Tutorial", Journal of Lightwave Technology, vol. 22, no. 1, pp. 193-202, January 2004. [Chu03] Xiaowen Chu, Bo Li and Chlamtac I, "Wavelength converter placement under different RWA algorithms in wavelength- routed all-optical networks", IEEE Transactions on Communications, vol. 51, no. 4, pp. 607-617, April 2003. [Buus06] Jens Buus EJM, "Tunable Lasers in Optical Networks", Journal of Lightware Technology, vol. 24, no. 1, pp. 5-11, January 2006. [Basch06] E. Bert Bash, Roman Egorov, Steven Gringeri and Stuart Elby, "Architectural Tradeoffs for Reconfigurable Dense Wavelength-Division Multiplexing Systems", IEEE Journal of Selected Topics in Quantum Electronics, vol. 12, no. 4, pp. 615-626, July/August 2006. [Winzer06] Peter J. Winzer and Rene-Jean Essiambre, "Advanced Optical Modulation Formats", Proceedings of the IEEE, vol. 94, no. 5, pp. 952-985, May 2006. [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network Physical Layer Interfaces, March 2006. [RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- Protocol Label Switching (GMPLS) Extensions for Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) Control", RFC 4606, August 2006. Bernstein & Lee Expires December 25, 2007 [Page 14] Internet-Draft Wavelength Switched Optical Networks June 2007 Author's Addresses Greg Bernstein Grotto Networking Fremont, CA, USA Phone: (510) 573-2237 Email: gregb@grotto-networking.com Young Lee Huawei Technologies 1700 Alma Drive, Suite 100 Plano, TX 75075 USA Phone: (972) 509-5599 (x2240) Email: ylee@huawei.com Intellectual Property Statement The IETF 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 this 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. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR 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 this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Bernstein & Lee Expires December 25, 2007 [Page 15] Internet-Draft Wavelength Switched Optical Networks June 2007 Disclaimer of Validity 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. 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. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society. Bernstein & Lee Expires December 25, 2007 [Page 16]