From 4bfd864f10b68b71482b35c818559068ef8d5797 Mon Sep 17 00:00:00 2001 From: Thomas Voss Date: Wed, 27 Nov 2024 20:54:24 +0100 Subject: doc: Add RFC documents --- doc/rfc/rfc7446.txt | 1291 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 1291 insertions(+) create mode 100644 doc/rfc/rfc7446.txt (limited to 'doc/rfc/rfc7446.txt') diff --git a/doc/rfc/rfc7446.txt b/doc/rfc/rfc7446.txt new file mode 100644 index 0000000..ae90109 --- /dev/null +++ b/doc/rfc/rfc7446.txt @@ -0,0 +1,1291 @@ + + + + + + +Internet Engineering Task Force (IETF) Y. Lee, Ed. +Request for Comments: 7446 Huawei +Category: Informational G. Bernstein, Ed. +ISSN: 2070-1721 Grotto Networking + D. Li + Huawei + W. Imajuku + NTT + February 2015 + + + Routing and Wavelength Assignment Information Model + for Wavelength Switched Optical Networks + +Abstract + + This document provides a model of information needed by the Routing + and Wavelength Assignment (RWA) process in Wavelength Switched + Optical Networks (WSONs). The purpose of the information described + in this model is to facilitate constrained optical path computation + in WSONs. This model takes into account compatibility constraints + between WSON signal attributes and network elements but does not + include constraints due to optical impairments. Aspects of this + information that may be of use to other technologies utilizing a + GMPLS control plane are discussed. + +Status of This Memo + + This document is not an Internet Standards Track specification; it is + published for informational purposes. + + This document is a product of the Internet Engineering Task Force + (IETF). It represents the consensus of the IETF community. It has + received public review and has been approved for publication by the + Internet Engineering Steering Group (IESG). Not all documents + approved by the IESG are a candidate for any level of Internet + Standard; see Section 2 of RFC 5741. + + Information about the current status of this document, any errata, + and how to provide feedback on it may be obtained at + http://www.rfc-editor.org/info/rfc7446. + + + + + + + + + + +Lee, et al. Informational [Page 1] + +RFC 7446 WSON Information Model February 2015 + + +Copyright Notice + + Copyright (c) 2015 IETF Trust and the persons identified as the + document authors. All rights reserved. + + This document is subject to BCP 78 and the IETF Trust's Legal + Provisions Relating to IETF Documents + (http://trustee.ietf.org/license-info) in effect on the date of + publication of this document. Please review these documents + carefully, as they describe your rights and restrictions with respect + to this document. Code Components extracted from this document must + include Simplified BSD License text as described in Section 4.e of + the Trust Legal Provisions and are provided without warranty as + described in the Simplified BSD License. + +Table of Contents + + 1. Introduction ....................................................3 + 2. Terminology .....................................................3 + 3. Routing and Wavelength Assignment Information Model .............3 + 3.1. Dynamic and Relatively Static Information ..................4 + 4. Node Information (General) ......................................4 + 4.1. Connectivity Matrix ........................................5 + 5. Node Information (WSON Specific) ................................5 + 5.1. Resource Accessibility/Availability ........................7 + 5.2. Resource Signal Constraints and Processing Capabilities ...11 + 5.3. Compatibility and Capability Details ......................12 + 5.3.1. Shared Input or Output Indication ..................12 + 5.3.2. Optical Interface Class List .......................12 + 5.3.3. Acceptable Client Signal List ......................13 + 5.3.4. Processing Capability List .........................13 + 6. Link Information (General) .....................................13 + 6.1. Administrative Group ......................................14 + 6.2. Interface Switching Capability Descriptor .................14 + 6.3. Link Protection Type (for This Link) ......................14 + 6.4. Shared Risk Link Group Information ........................14 + 6.5. Traffic Engineering Metric ................................15 + 6.6. Port Label Restrictions ...................................15 + 6.6.1. Port-Wavelength Exclusivity Example ................17 + 7. Dynamic Components of the Information Model ....................18 + 7.1. Dynamic Link Information (General) ........................19 + 7.2. Dynamic Node Information (WSON Specific) ..................19 + 8. Security Considerations ........................................19 + 9. References .....................................................20 + 9.1. Normative References ......................................20 + 9.2. Informative References ....................................21 + Contributors ......................................................22 + Authors' Addresses ................................................23 + + + +Lee, et al. Informational [Page 2] + +RFC 7446 WSON Information Model February 2015 + + +1. Introduction + + The purpose of the WSON information model described in this document + is to facilitate constrained optical path computation, and as such it + is not a general-purpose network management information model. This + constraint is frequently referred to as the "wavelength continuity" + constraint, and the corresponding constrained optical path + computation is known as the Routing and Wavelength Assignment (RWA) + problem. Hence, the information model must provide sufficient + topology and wavelength restriction and availability information to + support this computation. More details on the RWA process and WSON + subsystems and their properties can be found in [RFC6163]. The model + defined here includes constraints between WSON signal attributes and + network elements but does not include optical impairments. + + In addition to presenting an information model suitable for path + computation in WSON, this document also highlights model aspects that + may have general applicability to other technologies utilizing a + GMPLS control plane. The portion of the information model applicable + to technologies beyond WSON is referred to as "general" to + distinguish it from the "WSON-specific" portion that is applicable + only to WSON technology. + +2. Terminology + + Refer to [RFC6163] for definitions of Reconfigurable Optical Add/Drop + Multiplexer (ROADM), RWA, Wavelength Conversion, Wavelength Division + Multiplexing (WDM), WSON, and other related terminology used in this + document. + +3. Routing and Wavelength Assignment Information Model + + The WSON RWA information model in this document comprises four + categories of information. The categories are independent of whether + the information comes from a switching subsystem or from a line + subsystem -- a switching subsystem refers to WSON nodes such as a + ROADM or an Optical Add/Drop Multiplexer (OADM), and a line subsystem + refers to devices such as WDM or Optical Amplifier. The categories + are these: + + o Node Information + + o Link Information + + o Dynamic Node Information + + o Dynamic Link Information + + + + +Lee, et al. Informational [Page 3] + +RFC 7446 WSON Information Model February 2015 + + + Note that this is roughly the categorization used in Section 7 of + [G.7715]. + + In the following, where applicable, the Reduced Backus-Naur Form + (RBNF) syntax of [RBNF] is used to aid in defining the RWA + information model. + +3.1. Dynamic and Relatively Static Information + + All the RWA information of concern in a WSON network is subject to + change over time. Equipment can be upgraded; links may be placed in + or out of service and the like. However, from the point of view of + RWA computations, there is a difference between information that can + change with each successive connection establishment in the network + and information that is relatively static and independent of + connection establishment. A key example of the former is link + wavelength usage since this can change with connection setup/teardown + and this information is a key input to the RWA process. Examples of + relatively static information are the potential port connectivity of + a WDM ROADM, and the channel spacing on a WDM link. + + This document separates, where possible, dynamic and static + information so that these can be kept separate in possible encodings. + This allows for separate updates of these two types of information, + thereby reducing processing and traffic load caused by the timely + distribution of the more dynamic RWA WSON information. + +4. Node Information (General) + + The node information described here contains the relatively static + information related to a WSON node. This includes connectivity + constraints amongst ports and wavelengths since WSON switches can + exhibit asymmetric switching properties. Additional information + could include properties of wavelength converters in the node, if any + are present. In [Switch] it was shown that the wavelength + connectivity constraints for a large class of practical WSON devices + can be modeled via switched and fixed connectivity matrices along + with corresponding switched and fixed port constraints. These + connectivity matrices are included with the node information, while + the switched and fixed port wavelength constraints are included with + the link information. + + Formally, + + ::= [...] + + Where the Node_ID would be an appropriate identifier for the node + within the WSON RWA context. + + + +Lee, et al. Informational [Page 4] + +RFC 7446 WSON Information Model February 2015 + + + Note that multiple connectivity matrices are allowed and hence can + fully support the most-general cases enumerated in [Switch]. + +4.1. Connectivity Matrix + + The connectivity matrix (ConnectivityMatrix) represents either the + potential connectivity matrix for asymmetric switches (e.g., ROADMs + and such) or fixed connectivity for an asymmetric device such as a + multiplexer. Note that this matrix does not represent any particular + internal blocking behavior but indicates which input ports and + wavelengths could possibly be connected to a particular output port. + For a switch or ROADM, representing blocking that is dependent on the + internal state is beyond the scope of this document. Due to its + highly implementation-dependent nature, it would most likely not be + subject to standardization in the future. The connectivity matrix is + a conceptual M by N matrix representing the potential switched or + fixed connectivity, where M represents the number of input ports and + N the number of output ports. This is a "conceptual" matrix since + the matrix tends to exhibit structure that allows for very compact + representations that are useful for both transmission and path + computation. + + Note that the connectivity matrix information element can be useful + in any technology context where asymmetric switches are utilized. + + ::= + + + + + + Where + + is a unique identifier for the matrix. + + can be either 0 or 1 depending upon whether the + connectivity is either fixed or switched. + + represents the fixed or switched connectivity in that + Matrix(i, j) = 0 or 1 depending on whether input port i can connect + to output port j for one or more wavelengths. + +5. Node Information (WSON Specific) + + As discussed in [RFC6163], a WSON node may contain electro-optical + subsystems such as regenerators, wavelength converters or entire + switching subsystems. The model present here can be used in + characterizing the accessibility and availability of limited + + + +Lee, et al. Informational [Page 5] + +RFC 7446 WSON Information Model February 2015 + + + resources such as regenerators or wavelength converters as well as + WSON signal attribute constraints of electro-optical subsystems. As + such, this information element is fairly specific to WSON + technologies. + + In this document, the term "resource" is used to refer to a physical + component of a WSON node such as a regenerator or a wavelength + converter. Multiple instances of such components are often present + within a single WSON node. This term is not to be confused with the + concept of forwarding or switching resources such as bandwidth or + lambdas. + + A WSON node may include regenerators or wavelength converters + arranged in a shared pool. As discussed in [RFC6163], a WSON node + can also include WDM switches that use optical-electronic-optical + (OEO) processing. There are a number of different approaches used in + the design of WDM switches containing regenerator or converter pools. + However, from the point of view of path computation, the following + need to be known: + + 1. The nodes that support regeneration or wavelength conversion. + + 2. The accessibility and availability of a wavelength converter to + convert from a given input wavelength on a particular input port + to a desired output wavelength on a particular output port. + + 3. Limitations on the types of signals that can be converted and the + conversions that can be performed. + + Since resources tend to be packaged together in blocks of similar + devices, e.g., on line cards or other types of modules, the + fundamental unit of identifiable resource in this document is the + "resource block". + + A resource block is a collection of resources from the same WSON node + that are grouped together for administrative reasons and for ease of + encoding in the protocols. All resources in the same resource block + behave in the same way and have similar characteristics relevant to + the optical system, e.g., processing properties, accessibility, etc. + + A resource pool is a collection of resource blocks for the purpose of + representing throughput or cross-connect capabilities in a WSON node. + A resource pool associates input ports or links on the node with + output ports or links and is used to indicate how signals may be + passed from an input port or link to an output port or link by way of + a resource block (in other words, by way of a resource). A resource + pool may, therefore, be modeled as a matrix. + + + + +Lee, et al. Informational [Page 6] + +RFC 7446 WSON Information Model February 2015 + + + A resource block may be present in multiple resource pools. + + This leads to the following formal high-level model: + + ::= + + [...] + + [] + + Where + + ::= ... + + [...] + + [...] + + [] + + First, the accessibility of resource blocks is addressed; then, their + properties are discussed. + +5.1. Resource Accessibility/Availability + + A similar technique as used to model ROADMs, and optical switches can + be used to model regenerator/converter accessibility. This technique + was generally discussed in [RFC6163] and consisted of a matrix to + indicate possible connectivity along with wavelength constraints for + links/ports. Since regenerators or wavelength converters may be + considered a scarce resource, it is desirable that the model include, + if desired, the usage state (availability) of individual regenerators + or converters in the pool. Models that incorporate more state to + further reveal blocking conditions on input or output to particular + converters are for further study and not included here. + + The three-stage model is shown schematically in Figures 1 and 2. The + difference between the two figures is that in Figure 1 it's assumed + that each signal that can get to a resource block may do so, while in + Figure 2 the access to sets of resource blocks is via a shared fiber + that imposes its own wavelength collision constraint. Figure 1 shows + that there can be more than one input to each resource block since + each input represents a single wavelength signal, while Figure 2 + shows a single WDM input or output, e.g., a fiber, to/from each set + of blocks. + + + + + + +Lee, et al. Informational [Page 7] + +RFC 7446 WSON Information Model February 2015 + + + This model assumes N input ports (fibers), P resource blocks + containing one or more identical resources (e.g., wavelength + converters), and M output ports (fibers). Since not all input ports + can necessarily reach each resource block, the model starts with a + resource pool input matrix RI(i,p) = {0,1} depending on whether input + port i can potentially reach resource block p. + + Since not all wavelengths can necessarily reach all the resources or + the resources may have limited input wavelength range, the model has + a set of relatively static input port constraints for each resource. + In addition, if the access to a set of resource blocks is via a + shared fiber (Figure 2), this would impose a dynamic wavelength + availability constraint on that shared fiber. The resource block + input port constraint is modeled via a static wavelength set + mechanism, and the case of shared access to a set of blocks is + modeled via a dynamic wavelength set mechanism. + + Next, a state vector RA(j) = {0,...,k} is used to track the number of + resources in resource block j in use. This is the only state kept in + the resource pool model. This state is not necessary for modeling + "fixed" transponder system or full OEO switches with WDM interfaces, + i.e., systems where there is no sharing. + + After that, a set of static resource output wavelength constraints + and possibly dynamic shared output fiber constraints maybe used. The + static constraints indicate what wavelengths a particular resource + block can generate or is restricted to generating, e.g., a fixed + regenerator would be limited to a single lambda. The dynamic + constraints would be used in the case where a single shared fiber is + used to output the resource block (Figure 2). + + Finally, to complete the model, a resource pool output matrix RE(p,k) + = {0,1} depending on whether the output from resource block p can + reach output port k, may be used. + + + + + + + + + + + + + + + + + +Lee, et al. Informational [Page 8] + +RFC 7446 WSON Information Model February 2015 + + + I1 +-------------+ +-------------+ O1 + ----->| | +--------+ | |-----> + I2 | +------+ Rb #1 +-------+ | O2 + ----->| | +--------+ | |-----> + | | | | + | Resource | +--------+ | Resource | + | Pool +------+ +-------+ Pool | + | | + Rb #2 + | | + | Input +------+ +-------| Output | + | Connection | +--------+ | Connection | + | Matrix | . | Matrix | + | | . | | + | | . | | + IN | | +--------+ | | OM + ----->| +------+ Rb #P +-------+ |-----> + | | +--------+ | | + +-------------+ ^ ^ +-------------+ + | | + | | + | | + | | + + Input wavelength Output wavelength + constraints for constraints for + each resource each resource + + Note: Rb is a resource block. + + Figure 1: Schematic Diagram of the Resource Pool Model + + + + + + + + + + + + + + + + + + + + + + +Lee, et al. Informational [Page 9] + +RFC 7446 WSON Information Model February 2015 + + + I1 +-------------+ +-------------+ O1 + ----->| | +--------+ | |-----> + I2 | +======+ Rb #1 +-+ | | O2 + ----->| | +--------+ | | |-----> + | | |=====| | + | Resource | +--------+ | | Resource | + | Pool | +-+ Rb #2 +-+ | Pool | + | | | +--------+ | | + | Input |====| | Output | + | Connection | | +--------+ | Connection | + | Matrix | +-| Rb #3 |=======| Matrix | + | | +--------+ | | + | | . | | + | | . | | + | | . | | + IN | | +--------+ | | OM + ----->| +======+ Rb #P +=======+ |-----> + | | +--------+ | | + +-------------+ ^ ^ +-------------+ + | | + | | + | | + Single (shared) fibers for block input and output + + Input wavelength Output wavelength + availability for availability for + each block input fiber each block output fiber + + Note: Rb is a resource block. + + Figure 2: Schematic Diagram of the Resource Pool Model with + Shared Block Accessibility + + Formally, the model can be specified as: + + ::= + + + + + ::= + + + + + ::= [] + + [] + + + +Lee, et al. Informational [Page 10] + +RFC 7446 WSON Information Model February 2015 + + + ::= + + + + [] + + [] + + Note that, except for , all the components of + are relatively static. Also, the + and are only used + in the cases of shared input or output access to the particular + block. See the resource block information in the next section for + how this is specified. + +5.2. Resource Signal Constraints and Processing Capabilities + + The wavelength conversion abilities of a resource (e.g., regenerator, + wavelength converter) were modeled in the + previously discussed. As discussed in [RFC6163], the constraints on + an electro-optical resource can be modeled in terms of input + constraints, processing capabilities, and output constraints: + + ::= + + [] + + [] + + [] + + Where is a list of resource block identifiers + with the same characteristics. If this set is missing, the + constraints are applied to the entire network element. + + The are constraints are based on signal + compatibility and/or shared access constraint indication. The + details of these constraints are defined in Section 5.3. + + ::= + + [] + + [] + + The are important operations that the + resource (or network element) can perform on the signal. The details + of these capabilities are defined in Section 5.3. + + + +Lee, et al. Informational [Page 11] + +RFC 7446 WSON Information Model February 2015 + + + ::= [] + + [] + + [] + + [] + + The are either restrictions on the properties of + the signal leaving the block, options concerning the signal + properties when leaving the resource, or shared fiber output + constraint indication. + + := + + [] + + [] + +5.3. Compatibility and Capability Details + +5.3.1. Shared Input or Output Indication + + As discussed in Section 5.2 and shown in Figure 2, the input or + output access to a resource block may be via a shared fiber. The + and elements are indicators for this + condition with respect to the block being described. + +5.3.2. Optical Interface Class List + + ::= ... + + The Optical Interface Class is a unique number that identifies all + information related to optical characteristics of a physical + interface. The class may include other optical parameters related to + other interface properties. A class always includes signal + compatibility information. + + The content of each class is out of the scope of this document and + can be defined by other entities (e.g., the ITU, optical equipment + vendors, etc.). + + Since even current implementation of physical interfaces may support + different optical characteristics, a single interface may support + multiple interface classes. Which optical interface class is used + among all the ones available for an interface is out of the scope of + this document but is an output of the RWA process. + + + + +Lee, et al. Informational [Page 12] + +RFC 7446 WSON Information Model February 2015 + + +5.3.3. Acceptable Client Signal List + + The list is simply: + + ::=[]... + + Where the Generalized Protocol Identifiers (G-PID) object represents + one of the IETF-standardized G-PID values as defined in [RFC3471] and + [RFC4328]. + +5.3.4. Processing Capability List + + The ProcessingCapabilities are defined in Section 5.2. + + The processing capability list sub-TLV is a list of processing + functions that the WSON network element (NE) can perform on the + signal including: + + 1. number of resources within the block + + 2. regeneration capability + + 3. fault and performance monitoring + + 4. vendor-specific capability + + Note that the code points for fault and performance monitoring and + vendor-specific capability are subject to further study. + +6. Link Information (General) + + MPLS-TE routing protocol extensions for OSPF [RFC3630] and IS-IS + [RFC5305], along with GMPLS routing protocol extensions for OSPF + [RFC4203] and IS-IS [RFC5307] provide the bulk of the relatively + static link information needed by the RWA process. However, WSONs + bring in additional link-related constraints. These stem from + characterizing WDM line systems, restricting laser transmitter + tuning, and switching subsystem port wavelength constraints, e.g., + "colored" ROADM drop ports. + + The following syntax summarizes both information from existing GMPLS + routing protocols and new information that may be needed by the RWA + process. + + + + + + + + +Lee, et al. Informational [Page 13] + +RFC 7446 WSON Information Model February 2015 + + + ::= + + [] + + [] + + [] + + [...] + + [] + + [...] + + Note that these additional link characteristics only apply to line- + side ports of a WDM system or add/drop ports pertaining to the + resource pool (e.g., regenerator or wavelength converter pool). The + advertisement of input/output tributary ports is not intended here. + +6.1. Administrative Group + + Administrative Group: Defined in [RFC3630] and extended for MPLS-TE + [RFC7308]. Each set bit corresponds to one administrative group + assigned to the interface. A link may belong to multiple groups. + This is a configured quantity and can be used to influence routing + decisions. + +6.2. Interface Switching Capability Descriptor + + InterfaceSwCapDesc: Defined in [RFC4202]; lets us know the different + switching capabilities on this GMPLS interface. In both [RFC4203] + and [RFC5307], this information gets combined with the maximum Link + State Protocol Data Unit (LSP) bandwidth that can be used on this + link at eight different priority levels. + +6.3. Link Protection Type (for This Link) + + Protection: Defined in [RFC4202] and implemented in [RFC4203] and + [RFC5307]. Used to indicate what protection, if any, is guarding + this link. + +6.4. Shared Risk Link Group Information + + SRLG: Defined in [RFC4202] and implemented in [RFC4203] and + [RFC5307]. This allows for the grouping of links into shared risk + groups, i.e., those links that are likely, for some reason, to fail + at the same time. + + + + +Lee, et al. Informational [Page 14] + +RFC 7446 WSON Information Model February 2015 + + +6.5. Traffic Engineering Metric + + TrafficEngineeringMetric: Defined in [RFC3630] and [RFC5305]. This + allows for the identification of a data-channel link metric value for + traffic engineering that is separate from the metric used for path + cost computation of the control plane. + + Note that multiple "link metric values" could find use in optical + networks; however, it would be more useful to the RWA process to + assign these specific meanings such as "link mile" metric, + "probability of failure" metric, etc. + +6.6. Port Label Restrictions + + Port label restrictions could be applied generally to any label types + in GMPLS by adding new kinds of restrictions. Wavelength is a type + of label. + + Port label (wavelength) restrictions (PortLabelRestriction) model the + label (wavelength) restrictions that the link and various optical + devices, such as Optical Cross-Connects (OXCs), ROADMs, and waveband + multiplexers, may impose on a port. These restrictions tell us what + wavelength may or may not be used on a link and are relatively + static. This plays an important role in fully characterizing a WSON + switching device [Switch]. Port wavelength restrictions are + specified relative to the port in general or to a specific + connectivity matrix (Section 4.1). [Switch] gives an example where + both switch and fixed connectivity matrices are used and both types + of constraints occur on the same port. + + ::= + + + + + + + ::= + + | + + | + +