Network Working Group G. Bernstein Internet Draft Grotto Networking Y. Lee D. Li Huawei Intended status: Informational October 29, 2008 Expires: April 2009 A Framework for the Control and Measurement of Wavelength Switched Optical Networks (WSON) with Impairments draft-bernstein-ccamp-wson-impairments-01.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 April 29, 2009. Copyright Notice Copyright (C) The IETF Trust (2008). Bernstein Expires April 29, 2009 [Page 1] Internet-Draft Framework for Networks with Impairments October 2008 Abstract The operation of optical networks can require a level of detail in the characterization of network elements, subsystems, devices, and cabling not typically encountered with other networking technologies. In addition, these physical characteristics may be important to consider during typical day-to-day operations such as optical path establishment and connection monitoring, as well as during the network planning, installation, and turn-up phases. This document discusses how the definition and characterization of optical fiber, devices, subsystems, and network elements contained in various ITU-T recommendations can be combined with common control and measurement plane and path computation element technologies to support impairment aware Routing and Wavelength Assignment (RWA) in optical networks. Table of Contents 1. Introduction...................................................3 2. Impairment Aware Optical Path Computation......................4 2.1. IA-RWA Computing Architectures............................6 2.1.1. Combined Routing, WA, and IV.........................7 2.1.2. Separate Routing, WA, or IV..........................7 2.1.3. Distributed WA and/or IV.............................7 2.2. Information Model for Impairments.........................8 2.3. Protocol Extension Implications...........................8 2.3.1. Routing..............................................8 2.3.2. Signaling............................................9 2.3.3. PCE..................................................9 3. Security Considerations........................................9 4. IANA Considerations............................................9 5. Acknowledgments...............................................10 APPENDIX A: Overview of Optical Layer ITU-T Recommendations......11 A.1. Fiber and Cables.........................................11 A.2. Devices..................................................12 A.2.1. Optical Amplifiers..................................12 A.2.2. Dispersion Compensation.............................13 A.2.3. Optical Transmitters................................14 A.2.4. Optical Receivers...................................14 A.3. Components and Subsystems................................15 A.4. Network Elements.........................................16 6. References....................................................18 6.1. Normative References.....................................18 6.2. Informative References...................................20 Author's Addresses...............................................20 Bernstein & Lee Expires April 29, 2009 [Page 2] Internet-Draft Framework for Networks with Impairments October 2008 Intellectual Property Statement..................................21 Disclaimer of Validity...........................................22 1. Introduction As an optical signal progresses along its path it may be altered by the various physical processes in the optical fibers and devices it encounters. When such alterations result in signal degradation, we usually refer to these processes as "impairments". An overview of some critical optical impairments and their routing (path selection) implications can be found in [RFC4054]. Roughly speaking, optical impairments accumulate along the path (without 3R regeneration) traversed by the signal. They are influenced by the type of fiber used, the types and placement of various optical devices and the presence of other optical signals that may share a fiber segment along the signal's path. The degradation of the optical signals due to impairments can result in unacceptable bit error rates or even a complete failure to demodulate and/or detect the received signal. Therefore, path selection in any WSON requires consideration of optical impairments so that the signal will be propagated from the network ingress point to the egress point with acceptable amount of degradation. Some optical subnetworks are designed such that over any path the degradation to an optical signal due to impairments never exceeds prescribed bounds. This may be due to the limited geographic extent of the network, the network topology, and/or the quality of the fiber and devices employed. In such networks the path selection problem reduces to determining a continuous wavelength from source to destination (the Routing and Wavelength Assignment problem). These networks are discussed in [WSON-Frame]. In other optical networks, impairments are important and the path selection process must be impairment-aware. Although [RFC4054] describes a number of key optical impairments, a more complete description of optical impairments and the processes that spawn them can be found in textbooks or reference books on optical communications [Agrawal02], [Agrawal07]. To be useful to consumers and producers of optical fiber, components, and subsystems, optical characteristics need to be precisely defined along with methods for their measurement, estimation and approximation. The ITU- T and other SDOs have assumed this responsibility and as optical technology has advanced these documents have been updated. Appendix A of this document provides an overview of the extensive ITU-T documentation in this area. Bernstein & Lee Expires April 29, 2009 [Page 3] Internet-Draft Framework for Networks with Impairments October 2008 The benefits of operating networks of different technologies using an intelligent control plane have been described in many places, and the Generalized Multiprotocol Label Switching (GMPLS) control plane is described in [RFC3945]. The advantages of using a path computation element (PCE) to perform complex path computations are discussed in [RFC4655]. Given the existing standards covering optical characteristics (impairments) and the knowledge how the impact of impairments may be estimated along a path, this document provides a framework for impairment aware path computation and establishment utilizing GMPLS protocols and the PCE architecture. As in the impairment free case covered in [WSON-Frame] a number of different control plane architectural options are described. 2. Impairment Aware Optical Path Computation One of the most basic questions in communications is whether one can successfully transmit information from a transmitter to a receiver within a prescribed error tolerance, usually specified as a maximum permissible bit error ratio (BER). This generally depends on the nature of the signal transmitted between the sender and receiver and the nature of the communications channel between the sender and receiver. The optical path utilized (along with the wavelength) determines the communications channel. The optical impairments incurred by the signal along the fiber and at each optical network element along the path determine whether the BER performance or any other measure of signal quality can be met for this particular signal on this particular path. From a control plane perspective it is useful to classify optical networks into categories based on how one determines whether a particular optical signal on a particular optical path can meet desired signal quality objectives such as BER [WD24],[WD05]. In the following we say a path is "conformant" for a particular type of signal if the signal quality objectives are achieved at the receiver. The four classes of optical networks with regards to impairments are: 1. Networks designed such that every possible path is conformant for the signal types permitted on the network. In this case impairments are only taken into account during network design and after that, for example during optical path computation, they can be ignored. This is the case discussed in [WSON-Frame] where impairments could be ignored by the control plane. Bernstein & Lee Expires April 29, 2009 [Page 4] Internet-Draft Framework for Networks with Impairments October 2008 2. Networks in which a limited number of pre-calculated paths are conformant for each type of signal permitted in the network. In this case the control plane is not have any detailed information about optical impairments. Instead we are given a list of qualified paths for each permitted signal in the network. This might occur if proprietary impairment models are used to evaluate paths or a vendor chooses not to publish impairment information. For example if a single WDM line system vendor is used within an optical subnetwork and chooses not to publish optical impairment information, that vendor with knowledge of the characteristics of the ROADMS and PXCs used in the network could pre-calculate a list of valid paths. Note that the structure of such a qualified path/wavelength list could be useful to standardize as part of an impairment aware information model. 3. Networks in which impairment effects can be estimated via approximation techniques such as link budgets and dispersion (rise time) budgets [Agrawal02],[G.680],[G.sup39]. As networks grow larger listing all useable paths for each signal type can encounter scaling issues. Instead the viability of most optical paths for a particular class of signals is performed using well defined approximation techniques [G.680], [G.sup39]. Much work at ITU-T has gone into developing impairment models at this and more detailed levels. Impairment characterization of network elements could then made available via the control plane and then used to calculate which paths are conformant with a specified BER for a particular signal type. This case requires that all relevant impairment information is available from all optical subsystems. 4. Networks in which impairment effects must be more accurately estimated. This typically includes detailed dispersion, interference and/or nonlinear effect simulations. This includes evaluation of the impact to any existing paths prior to the addition of a new path. This is currently performed via methods that solve the partial differential equations describing signal propagation in fiber along with more detail models for the other network elements [Agrawal02],[Agrawal07]. The estimation/simulation time required can be very situation dependent. The implication is that a significant amount of time could be required to "qualify" a path and this would need to be taken into account in a PCE architecture that includes impaired path validation. ITU-T recommendations contain a good deal of more detailed optical characteristics (see Appendix A) for fibers and devices, however these are not currently assembled into a single modeling document as was done for the approximate analysis model in [G.680]. Bernstein & Lee Expires April 29, 2009 [Page 5] Internet-Draft Framework for Networks with Impairments October 2008 2.1. IA-RWA Computing Architectures As previously stated from the point of view of RWA we may take optical impairments into account by being given: 1. A list of valid paths with corresponding wavelength constraints; 2. Sufficient approximate impairment information to determine valid paths; 3. A validation decision from an estimation incorporating more complete impairment models; Hence to take into account optical impairments we add additional constraints to the impairment-free RWA process described in [WSON- Frame]. In IA-RWA, there are conceptually three functions to be considered in path computation. o Routing (R): finding a route for the given source-destination. o Wavelength Assignment (WA): assigning a wavelength for the route o Impairment Validation (IV): applying a set of impairment constraints to the route and selected wavelength to see whether they would provide signal quality satisfaction. The IA-RWA architecture options can be built from the non-IA RWA computation architectures defined in the WSON framework document [WSON Frame]. Recall that the following three RWA computation architecture options [WSON-Frame]. o Combined RWA --- Both routing and wavelength assignment are performed at a single computational entity. This choice assumes that computational entity has sufficient WSON network link/nodal and topology information to be able to compute RWA. o Separate Routing and WA --- Separate entities perform routing and wavelength assignment. The path obtained from the routing computational entity must be furnished to the entity performing wavelength assignment. o Routing with Distributed WA --- Routing is performed at a computational entity while wavelength assignment is performed in a distributed fashion across the nodes along the path. The following subsections consider three major classes of IA-RWA path computation architectures. Bernstein & Lee Expires April 29, 2009 [Page 6] Internet-Draft Framework for Networks with Impairments October 2008 2.1.1. Combined Routing, WA, and IV We can conceptually or algorithmically combine the processes of routing, wavelength assignment and impairment validation if we are given: (a) the impairment-free WSON network information as discussed in [WSON-Frame] and (b) either a list of validated paths/wavelengths or sufficient approximate impairment information to perform calculations to validate potential paths. In this case routing (R) and wavelength assignment (WA) and impairment validation (IV) are performed at a single computational entity. This situation could benefit from an information model that compactly describes a list of valid paths/wavelengths or characterizes impairments at a level similar to that in [G.680]. 2.1.2. Separate Routing, WA, or IV As was discussed in [WSON-Frame] there can be advantages to separating routing from WA. In addition, as previously described in the case of detailed impairment modeling we may want to logically separate IV from RWA. In addition for systems operating closer to physical limits the validation computations could be proprietary and hence by necessity may be logically separated. The following conceptual architectures belong in this general category: o R+WA+IV -- separate routing, wavelength assignment, and impairment validation o R + (WA & IV) -- routing separate from a combined wavelength assignment and impairment validation process. Note that impairment validation is typically wavelength dependent hence combining WA with IV can lead to efficiencies. o (RWA)+IV - combined routing and wavelength assignment with a separate impairment validation process. 2.1.3. Distributed WA and/or IV In the case where the effects of impairments can be calculated via approximate models such as those in [G.680] standard methods can be applied to calculate the combined potential impairment effects on a signal following a prescribed network path. This can allow for the distributed computation of impairment effects and avoid the need to distribute impairment characteristics of network elements and links via route protocols or by other means. An example of such an approach Bernstein & Lee Expires April 29, 2009 [Page 7] Internet-Draft Framework for Networks with Impairments October 2008 is given in [Martinelli] and utilizes enhancements to RSVP signaling to carry accumulated impairment related information. For such a system to be interoperable the various impairment measures to be accumulated would need to be agreed upon. Section 9 of [G.680] can be useful in deriving such cumulative measures but doesn't explicitly state how a distributed computation would take place. For example in the computation of the optical signal to noise ratio along a path (see equation 9-3 of [G.680]) one could accumulate the linear sum terms and convert to dBs at the destination or one could convert in and out of dBs at each intermediate point along the path. If distributed WA is being done at the same time as distribute IV then we may need to accumulate impairment related information for all wavelengths that could be used. This is somewhat winnowed down as potential wavelengths are discovered to be in use, but could be a significant burden for lightly loaded high channel count networks. 2.2. Information Model for Impairments As previously discussed we are either given a list of conformant optical paths through a network or we are given information concerning the impairments for each network element which we can use to validate a path for a particular signal type. GMPLS and other IETF protocols have included descriptions of paths in the past and methods for compact representations of available wavelengths have been discussed in [WSON-Info]. A number of ITU-T recommendations cover detailed as well as approximate impairment characteristics of fibers and a variety of devices and subsystems. A well integrated impairment model for optical network elements is given in [G.680] and is used to form the basis for an optical impairment model in a companion document [Imp-Info]. 2.3. Protocol Extension Implications Given the previous architectures and information models we have the following implications for routing, signaling and PCE related protocols. 2.3.1. Routing Different approaches to path/wavelength impairment validation gives rise to different demands placed on GMPLS routing protocols. Bernstein & Lee Expires April 29, 2009 [Page 8] Internet-Draft Framework for Networks with Impairments October 2008 In the case where a list of conformant paths/lambdas needs to be distributed to PCEs (or network elements with co-located PCEs) the routing protocol might be expected to help distribute this list. In the case where approximate impairment information is used to validate paths GMPLS routing may be used to distribute the impairment characteristics of the network elements and links. In the case where a separate path/wavelength validation server is used no additional demands may be require of GMPLS routing. 2.3.2. Signaling Although we see impacts on signaling in cases where distributed impairment validation is performed, we may also want to add information to a connection request such as desired egress signal quality (defined in some appropriate sense). In addition, since the characteristics of the signal itself, such as modulation type, can play a major role in the tolerance of impairments, this type of information will need to be implicitly or explicitly signaled. In the cases of distributed validation of path/wavelength and distributed wavelength assignment and validation we need to accumulate impairment information as discussed in section 2.1.3. 2.3.3. PCE For a PCE involved with impairment related computations we have two potential areas of impact: (a) impairment information model, (b) PCEP extensions for dealing with impairment related requests. 3. Security Considerations This document discusses a number of control plane architectures that incorporate knowledge of impairments in optical networks. If such architecture is put into use within a network it will by its nature contain details of the physical characteristics of an optical network. Such information would need to be protected from intentional or unintentional disclosure. 4. IANA Considerations This draft does not currently require any consideration from IANA. Bernstein & Lee Expires April 29, 2009 [Page 9] Internet-Draft Framework for Networks with Impairments October 2008 5. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. Bernstein & Lee Expires April 29, 2009 [Page 10] Internet-Draft Framework for Networks with Impairments October 2008 APPENDIX A: Overview of Optical Layer ITU-T Recommendations For optical fiber, devices, subsystems and network elements the ITU-T has a variety of recommendations that include definitions, characterization parameters and test methods. In the following we take a bottom up survey to emphasize the breadth and depth of the existing recommendations. We focus on digital communications over single mode optical fiber. A.1. Fiber and Cables Fibers and cables form a key component of what from the control plane perspective could be termed an optical link. Due to the wide range of uses of optical networks a fairly wide range of fiber types are used in practice. The ITU-T has three main recommendations covering the definition of attributes and test methods for single mode fiber: o Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable [G.650.1] o Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable [G.650.2] o Test methods for installed single-mode fibre cable sections [G.650.3] General Definitions[G.650.1]: Mechanical Characteristics (numerous), Mode field characteristics(mode field, mode field diameter, mode field centre, mode field concentricity error, mode field non- circularity), Glass geometry characteristics, Chromatic dispersion definitions (chromatic dispersion, group delay, chromatic dispersion coefficient, chromatic dispersion slope, zero-dispersion wavelength, zero-dispersion slope), cut-off wavelength, attenuation. Definition of equations and fitting coefficients for chromatic dispersion (Annex A). [G.650.2] polarization mode dispersion (PMD) - phenomenon of PMD, principal states of polarization (PSP), differential group delay (DGD), PMD value, PMD coefficient, random mode coupling, negligible mode coupling, mathematical definitions in terms of Stokes or Jones vectors. Nonlinear attributes: Effective area, correction factor k, non-linear coefficient (refractive index dependent on intensity), Stimulated Billouin scattering. Tests defined [G.650.1]: Mode field diameter, cladding diameter, core concentricity error, cut-off wavelength, attenuation, chromatic dispersion. [G.650.2]: test methods for polarization mode dispersion. [G.650.3] Test methods for characteristics of fibre cable sections following installation: attenuation, splice loss, splice location, Bernstein & Lee Expires April 29, 2009 [Page 11] Internet-Draft Framework for Networks with Impairments October 2008 fibre uniformity and length of cable sections (these are OTDR based), PMD, Chromatic dispersion. With these definitions a variety of single mode fiber types are defined as shown in the table below: ITU-T Standard | Common Name ------------------------------------------------------------ G.652 [G.652] | Standard SMF | G.653 [G.653] | Dispersion shifted SMF | G.654 [G.654] | Cut-off shifted SMF | G.655 [G.655] | Non-zero dispersion shifted SMF | G.656 [G.656] | Wideband non-zero dispersion shifted SMF | ------------------------------------------------------------ A.2. Devices A.2.1. Optical Amplifiers Optical amplifiers greatly extend the transmission distance of optical signals in both single channel and multi channel (WDM) subsystems. The ITU-T has the following recommendations: o Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems [G.661] o Generic characteristics of optical amplifier devices and subsystems [G.662] o Application related aspects of optical amplifier devices and subsystems [G.663] o Generic characteristics of Raman amplifiers and Raman amplified subsystems [G.665] Reference [G.661] starts with general classifications of optical amplifiers based on technology and usage, and include a near exhaustive list of over 60 definitions for optical amplifier device attributes and parameters. In references [G.662] and [G.665] we have characterization of specific devices, e.g., semiconductor optical amplifier, used in a particular setting, e.g., line amplifier. For example reference[G.662] gives the following minimum list of relevant parameters for the specification of an optical amplifier device used as line amplifier in a multichannel application: Bernstein & Lee Expires April 29, 2009 [Page 12] Internet-Draft Framework for Networks with Impairments October 2008 a) Channel allocation. b) Total input power range. c) Channel input power range. d) Channel output power range. e) Channel signal-spontaneous noise figure. f) Input reflectance. g) Output reflectance. h) Maximum reflectance tolerable at input. i) Maximum reflectance tolerable at output. j) Maximum total output power. k) Channel addition/removal (steady-state) gain response. l) Channel addition/removal (transient) gain response. m) Channel gain. n) Multichannel gain variation (inter-channel gain difference). o) Multichannel gain-change difference (inter-channel gain-change difference). p) Multichannel gain tilt (inter-channel gain-change ratio). q) Polarization Mode Dispersion (PMD). A.2.2. Dispersion Compensation In optical systems two forms of dispersion are commonly encountered [RFC4054] chromatic dispersion and polarization mode dispersion (PMD). There are a number of techniques and devices used for compensating for these effects. The following ITU-T recommendations characterize such devices: o Characteristics of PMD compensators and PMD compensating receivers [G.666] Bernstein & Lee Expires April 29, 2009 [Page 13] Internet-Draft Framework for Networks with Impairments October 2008 o Characteristics of Adaptive Chromatic Dispersion Compensators [G.667] The above furnish definitions as well as parameters and characteristics. For example in [G.667] adaptive chromatic dispersion compensators are classified as being receiver, transmitter or line based, while in [G.666] PMD compensators are only defined for line and receiver configurations. Parameters that are common to both PMD and chromatic dispersion compensators include: line fiber type, maximum and minimum input power, maximum and minimum bit rate, and modulation type. In addition there are a great many parameters that apply to each type of device and configuration. A.2.3. Optical Transmitters The definitions of the characteristics of optical transmitters can be found in references [G.957], [G.691], [G.692] and [G.959.1]. In addition references [G.957], [G.691], and [G.959.1] define specific parameter values or parameter ranges for these characteristics for interfaces for use in particular situations. We generally have the following types of parameters Wavelength related: Central frequency, Channel spacing, Central frequency deviation[G.692]. Spectral characteristics of the transmitter: Nominal source type (LED, MLM lasers, SLM lasers) [G.957], Maximum spectral width, Chirp parameter, Side mode suppression ratio, Maximum spectral power density [G.691]. Power related: Mean launched power, Extinction ration, Eye pattern mask [G.691], Maximum and minimum mean channel output power [G.959.1]. A.2.4. Optical Receivers References [G.959.1], [G.691], [G.692] and [G.957], define optical receiver characteristics and [G.959.1], [G.691] and [G.957]give specific values of these parameters for particular interface types and network contexts. The receiver parameters include: Receiver sensitivity: minimum value of average received power to achieve a 1x10-10 BER [G.957] or 1x10-12 BER [G.691]. See [G.957] and [G.691] for assumptions on signal condition. Bernstein & Lee Expires April 29, 2009 [Page 14] Internet-Draft Framework for Networks with Impairments October 2008 Receiver overload: Receiver overload is the maximum acceptable value of the received average power for a 1x10.10 BER [G.957] or a 1x10-12 BER [G.691]. Receiver reflectance: "Reflections from the receiver back to the cable plant are specified by the maximum permissible reflectance of the receiver measured at reference point R." Optical path power penalty: "The receiver is required to tolerate an optical path penalty not exceeding X dB to account for total degradations due to reflections, intersymbol interference, mode partition noise, and laser chirp." When dealing with multi-channel systems or systems with optical amplifiers we may also need: Optical signal-to-noise ratio: "The minimum value of optical SNR required to obtain a 1x10-12 BER."[G.692] Receiver wavelength range: "The receiver wavelength range is defined as the acceptable range of wavelengths at point Rn. This range must be wide enough to cover the entire range of central frequencies over the OA passband." [G.692] Minimum equivalent sensitivity: "This is the minimum sensitivity that would be required of a receiver placed at MPI-RM in multichannel applications to achieve the specified maximum BER of the application code if all except one of the channels were to be removed (with an ideal loss-less filter) at point MPI-RM." [G.959.1] A.3. Components and Subsystems Reference [G.671] "Transmission characteristics of optical components and subsystems" covers the following components: o optical add drop multiplexer (OADM) subsystem; o asymmetric branching component; o optical attenuator; o optical branching component (wavelength non-selective); o optical connector; o dynamic channel equalizer (DCE); Bernstein & Lee Expires April 29, 2009 [Page 15] Internet-Draft Framework for Networks with Impairments October 2008 o optical filter; o optical isolator; o passive dispersion compensator; o optical splice; o optical switch; o optical termination; o tuneable filter; o optical wavelength multiplexer (MUX)/demultiplexer (DMUX); - coarse WDM device; - dense WDM device; - wide WDM device. Reference [G.671] then specifies applicable parameters for these components. For example an OADM subsystem will have parameters such as: insertion loss (input to output, input to drop, add to output), number of add, drop and through channels, polarization dependent loss, adjacent channel isolation, allowable input power, polarization mode dispersion, etc... A.4. Network Elements The previously cited ITU-T recommendations provide a plethora of definitions and characterizations of optical fiber, devices, components and subsystems. Reference [G.Sup39] "Optical system design and engineering considerations" provides useful guidance on the use of such parameters. In many situations the previous models while good don't encompass the higher level network structures that one typically deals with in the control plane, i.e, "links" and "nodes". In addition such models include the full range of network applications from planning, installation, and possibly day to day network operations, while with the control plane we are generally concerned with a subset of the later. In particular for many control plane applications we are interested in formulating the total degradation to an optical signal as it travels through multiple optical subsystems, devices and fiber segments. Bernstein & Lee Expires April 29, 2009 [Page 16] Internet-Draft Framework for Networks with Impairments October 2008 In reference [G.680] "Physical transfer functions of optical networks elements", a degradation function is currently defined for the following optical network elements: (a) DWDM Line segment, (b) Optical Add/Drop Multiplexers (OADM), and (c) Photonic cross-connect (PXC). The scope of [G.680] is currently for optical networks consisting of one vendors DWDM line systems along with another vendors OADMs or PXCs. The DWDM line system of [G.680] consists of the optical fiber, line amplifiers and any embedded dispersion compensators. Similarly the OADM/PXC network element may consist of the basic OADM component and optionally included optical amplifiers. The parameters for these optical network elements (ONE) are given under the following circumstances: o General ONE without optical amplifiers o General ONE with optical amplifiers o OADM without optical amplifiers o OADM with optical amplifiers o Reconfigurable OADM (ROADM) without optical amplifiers o ROADM with optical amplifiers o PXC without optical amplifiers o PXC with optical amplifiers Bernstein & Lee Expires April 29, 2009 [Page 17] Internet-Draft Framework for Networks with Impairments October 2008 6. References 6.1. Normative References [G.650.1] ITU-T Recommendation G.650.1, Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable, June 2004. [650.2] ITU-T Recommendation G.650.2, Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable, July 2007. [650.3] ITU-T Recommendation G.650.3 [G.652] ITU-T Recommendation G.652, Characteristics of a single-mode optical fibre and cable, June 2005. [G.653] ITU-T Recommendation G.653, Characteristics of a dispersion- shifted single-mode optical fibre and cable, December 2006. [G.654] ITU-T Recommendation G.654, Characteristics of a cut-off shifted single-mode optical fibre and cable, December 2006. [G.655] ITU-T Recommendation G.655, Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable, March 2006. [G.656] ITU-T Recommendation G.656, Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport, December 2006. [G.661] ITU-T Recommendation G.661, Definition and test methods for the relevant generic parameters of optical amplifier devices and subsystems, March 2006. [G.662] ITU-T Recommendation G.662, Generic characteristics of optical amplifier devices and subsystems, July 2005. [G.671] ITU-T Recommendation G.671, Transmission characteristics of optical components and subsystems, January 2005. [G.680] ITU-T Recommendation G.680, Physical transfer functions of optical network elements, July 2007. [G.691] ITU-T Recommendation G.691, Optical interfaces for multichannel systems with optical amplifiers, November 1998. Bernstein & Lee Expires April 29, 2009 [Page 18] Internet-Draft Framework for Networks with Impairments October 2008 [G.692] ITU-T Recommendation G.692, Optical interfaces for single channel STM-64 and other SDH systems with optical amplifiers, March 2006. [G.872] ITU-T Recommendation G.872, Architecture of optical transport networks, November 2001. [G.957] ITU-T Recommendation G.957, Optical interfaces for equipments and systems relating to the synchronous digital hierarchy, March 2006. [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network Physical Layer Interfaces, March 2006. [G.694.1] ITU-T Recommendation G.694.1, Spectral grids for WDM applications: DWDM frequency grid, June 2002. [G.694.2] ITU-T Recommendation G.694.2, Spectral grids for WDM applications: CWDM wavelength grid, December 2003. [G.Sup39] ITU-T Series G Supplement 39, Optical system design and engineering considerations, February 2006. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3945] Mannie, E., Ed., "Generalized Multi-Protocol Label Switching (GMPLS) Architecture", RFC 3945, October 2004. [RFC4054] Strand, J., Ed., and A. Chiu, Ed., "Impairments and Other Constraints on Optical Layer Routing", RFC 4054, May 2005. [RFC4655] Farrel, A., Vasseur, J.-P., and J. Ash, "A Path Computation Element (PCE)-Based Architecture", RFC 4655, August 2006. [WSON-Frame] G. Bernstein, Y. Lee, W. Imajuku, "Framework for GMPLS and PCE Control of Wavelength Switched Optical Networks", work in progress: draft-ietf-ccamp-wavelength-switched- framework-00.txt, July 2008. [WSON-Info] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks", work in progress: draft-ietf- ccamp-rwa-info-00.txt, August 2008. Bernstein & Lee Expires April 29, 2009 [Page 19] Internet-Draft Framework for Networks with Impairments October 2008 6.2. Informative References [Agrawal02] Govind P. Agrawal, Fiber-Optic Communications Systems - Third Edition, Wiley-Interscience, 2002. [Agrawal07] Govind P. Agrawal, Nonlinear Fiber Optics - Fourth Edition, Academic Press, 2007. [Imp-Info] G. Bernstein, Y. Lee, D. Li, "A Framework for the Control and Measurement of Wavelength Switched Optical Networks (WSON) with Impairments", work in progress: draft- bernstein-wson-impairment-info-00.txt, October 2008. [Martinelli] G. Martinelli (ed.) and A. Zanardi (ed.), "GMPLS Signaling Extensions for Optical Impairment Aware Lightpath Setup", Work in Progress: draft-martinelli-ccamp-optical- imp-signaling-01.txt, February 2008. [WD05] Malcolm Betts, Hing-Kam Lam, " Report of Q12/15 and Q14/15 Joint Interregnum Meeting in Beijing, 22 - 26 September 2008", Study Group 15, Question 12 & 14, WD 05r2, September 2008. [WD24] Malcolm Betts, "Considerations on the model of media layer networks", Study Group 15, Question 12, WD 24, September 2008. Author's Addresses Greg M. Bernstein (ed.) Grotto Networking Fremont California, USA Phone: (510) 573-2237 Email: gregb@grotto-networking.com Bernstein & Lee Expires April 29, 2009 [Page 20] Internet-Draft Framework for Networks with Impairments October 2008 Young Lee (ed.) Huawei Technologies 1700 Alma Drive, Suite 100 Plano, TX 75075 USA Phone: (972) 509-5599 (x2240) Email: ylee@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 Contributor's Addresses Ming Chen 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: mchen@huawei.com Rebecca Han 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: hanjianrui@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 Bernstein & Lee Expires April 29, 2009 [Page 21] Internet-Draft Framework for Networks with Impairments October 2008 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. 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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 (2008). 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 We thank Chen Ming of DICONNET Project who provided valuable information relevant to this document. Bernstein & Lee Expires April 29, 2009 [Page 22]