Internet DRAFT - draft-ietf-ccamp-wson-iv-info
draft-ietf-ccamp-wson-iv-info
CCAMP G. Martinelli, Ed.
Internet-Draft Cisco
Intended status: Informational H. Zheng, Ed.
Expires: March 12, 2021 Huawei Technologies
G. Galimberti
Cisco
Y. Lee
Samsung
F. Zhang
Huawei Technologies
September 08, 2020
Information Model for Wavelength Switched Optical Networks (WSONs) with
Impairments Validation
draft-ietf-ccamp-wson-iv-info-12
Abstract
This document defines an information model to support Impairment-
Aware (IA) Routing and Wavelength Assignment (RWA) functionality.
This information model extends the information model for impairment-
free RWA process in WSON to facilitate computation of paths where
optical impairment constraints need to considered.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on March 12, 2021.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions, Applicability and Properties . . . . . . . . . . 3
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Properties . . . . . . . . . . . . . . . . . . . . . . . 5
3. ITU-T List of Optical Parameters . . . . . . . . . . . . . . 6
4. Background from WSON-RWA Information Model . . . . . . . . . 8
5. Optical Impairment Information Model . . . . . . . . . . . . 9
5.1. The Optical Impairment Vector . . . . . . . . . . . . . . 10
5.2. Node Information . . . . . . . . . . . . . . . . . . . . 10
5.2.1. Impairment Matrix . . . . . . . . . . . . . . . . . . 10
5.2.2. Impairment Resource Block Information . . . . . . . . 12
5.3. Link Information . . . . . . . . . . . . . . . . . . . . 12
5.4. Path Information . . . . . . . . . . . . . . . . . . . . 12
6. Encoding Considerations . . . . . . . . . . . . . . . . . . . 13
7. Control Plane Architectures . . . . . . . . . . . . . . . . . 13
7.1. IV-Centralized . . . . . . . . . . . . . . . . . . . . . 14
7.2. IV-Distributed . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 14
9. Contributing Authors . . . . . . . . . . . . . . . . . . . . 14
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
11. Security Considerations . . . . . . . . . . . . . . . . . . . 15
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
12.1. Normative References . . . . . . . . . . . . . . . . . . 16
12.2. Informative References . . . . . . . . . . . . . . . . . 16
Appendix A. FAQ . . . . . . . . . . . . . . . . . . . . . . . . 17
A.1. Why the Application Code does not suffice for Optical
Impairment Validation? . . . . . . . . . . . . . . . . . 17
A.2. Are DWDM network multivendor? . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
1. Introduction
In the context of Wavelength Switched Optical Network (WSON),
[RFC6163] describes the basic framework for a GMPLS and PCE-based
Routing and Wavelength Assignment (RWA) control plane. The
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associated information model [RFC7446] defines information/parameters
required by an RWA process without optical impairment considerations.
There are cases of WSON where optical impairments play a significant
role and are considered as important constraints. The framework
document [RFC6566] defines the problem scope and related control
plane architectural options for the Impairment Aware RWA (IA-RWA)
operation. Options include different combinations of Impairment
Validation (IV) and RWA functions in term of different combination of
control plane functions (i.e., PCE, Routing, Signaling).
A Control Plane with RWA-IA will not be able to solve the optical
impairment problem in a detailed and exhaustive way, however, it may
take advantage of some data plane knowledge to make better decisions
during its path computing phase. The final outcome will be a path,
instantiated through a wavelength in the data plane, that has a
"better chance" to work than that path were calculated without IA
information. "Better chance" means that path setup may still fail
and the GMPLS control plane will follow its usual procedures upon
errors and failures. A control plane will not replace a the network
design phase that remains a fundamental step for DWDM Optical
Networks. As the non-linear impairments which need to be considered
in the calculation of an optical path will be vendor-dependent, the
parameters considered in this document is not an exhaustive list.
This document provides an information model for the impairment aware
case to allow the impairment validation function implemented in the
control plane or enabled by control plane available information.
This model goes in addition to [RFC7446] and shall support any
control plane architectural option described by the framework
document (see sections 4.2 and 4.3 of [RFC6566]) where a set of
combinations of control plane functions vs. IV function is provided.
2. Definitions, Applicability and Properties
This section provides some concepts to help understand the model and
to make a clear separation from data plane definitions (ITU-T
recommendations). The first sub-section provides definitions while
the Applicability sections uses the defined definitions to scope this
document.
2.1. Definitions
o Computational Model / Optical Computational Model.
Defined by ITU standard documents (e.g. [ITU.G680]). In this
context we look for models able to compute optical impairments for
a given lightpath.
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o Information Model.
Defined by IETF (this document) and provides the set of
information required by control plane to apply the Computational
Model.
o Level of Approximation.
This concept refers to the Computational Model as it may compute
optical impairment with a certain level of uncertainty. This
level is generally not measured but [RFC6566] Section 4.1.1
provides a rough classification about it.
o Feasible Path.
It is the output of the C-SPF with RWA-IV capability. It's an
optical path that satisfies optical impairment constraints. The
path, instantiated through wavelength(s), may actually work or not
work depending of the level of approximation.
o Existing Service Disruption.
An effect known to optical network designers is the cross-
interaction among spectrally adjacent wavelengths: an existing
wavelength may experience increased BER due to the setup of an
adjacent wavelength. Solving this problem is a typical optical
network design activity. Just as an example, a simple solution is
adding optical margins (e.g., additional OSNR), although complex
and detailed methods exist.
o DWDM Line Segments.
[ITU.G680] provides definition and picture for the "Situation 1"
DWDM Line segments: " Situation 1 - The optical path between two
consecutive 3R regenerators is composed of DWDM line segments from
a single vendor and OADMs and PXCs from another vendor". Document
[RFC6566] Figure 1 shows an LSP composed by two DWDM line segments
according to [ITU.G680] definition.
2.2. Applicability
This document targets at Scenario C defined in [RFC6566] section
4.1.1. as approximate impairment estimation. The Approximate
concept refer to the fact that this Information Model covers
information mainly provided by [ITU.G680] Computational Model.
Computational models having no or little approximation, referred as
IV-Detailed in the [RFC6566], currently does not exist in term of
ITU-T recommendation. They generally deal with non-linear optical
impairment and are usually vendor specific.
The Information Model defined in this document does not speculate
about the mathematical formulas used to fill up information model
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parameters, hence it does not preclude changing the computational
model. At the same time, the authors do not believe this Information
Model is exhaustive and if necessary further documents will cover
additional models after they become available.
The result of RWA-IV process implementing this Information Model is a
path (and a wavelength in the data plane) that has better chance to
be feasible than if it was computed without any IV function. The
Existing Service Disruption, as per the definition above, would still
be a problem left to a network design phase.
2.3. Properties
An information model may have several attributes or properties that
need to be defined for each optical parameter made available to the
control plane. The properties will help to determine how the control
plane can deal with a specific impairment parameter, depending on
architectural options chosen within the overall impairment framework
[RFC6566]. In some case, properties value will help to identify the
level of approximation supported by the IV process.
o Time Dependency
This identifies how an impairment parameter may vary with time.
There could be cases where there is no time dependency, while in
other cases there may be need of re-evaluation after a certain
time. In this category, variations in impairments due to
environmental factors such as those discussed in [ITU.GSUP47] are
considered. In some cases, an impairment parameter that has time
dependency may be considered as a constant for approximation. In
this information model, we do neglect this property.
o Wavelength Dependency
This property identifies if an impairment parameter can be
considered as constant over all the wavelength spectrum of
interest or not. Also in this case a detailed impairment
evaluation might lead to consider the exact value while an
approximation IV might take a constant value for all wavelengths.
In this information model, we consider both case: dependency / no
dependency on a specific wavelength. This property appears
directly in the information model definitions and related
encoding.
o Linearity
As impairments are representation of physical effects, there are
some that have a linear behaviour while other are non-linear.
Linear approximation is in scope of Scenario C of [RFC6566].
During the impairment validation process, this property implies
that the optical effect (or quantity) satisfies the superposition
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principle, thus a final result can be calculated by the sum of
each component. The linearity implies the additivity of optical
quantities considered during an impairment validation process.
The non-linear effects in general do not satisfy this property.
The information model presented in this document however, easily
allow introduction of non-linear optical effects with a linear
approximated contribution to the linear ones.
o Multi-Channel
There are cases where a channel's impairments take different
values depending on the aside wavelengths already in place, this
is mostly due to non-linear impairments. The result would be a
dependency among different LSPs sharing the same path. This
information model do not consider this kind of property.
The following table summarise the above considerations where in the
first column reports the list of properties to be considered for each
optical parameter, while the second column states if this property is
taken into account or not by this information model.
+-----------------------+----------------------+
| Property | Info Model Awareness |
+-----------------------+----------------------+
| Time Dependency | no |
| Wavelength Dependency | yes |
| Linearity | yes |
| Multi-channel | no |
+-----------------------+----------------------+
Table 1: Optical Impairment Properties
3. ITU-T List of Optical Parameters
As stated by Section 2.2 this Information Model does not intend to be
exhaustive and targets an approximate computational model although
not precluding future evolutions towards more detailed or different
impairments estimation methods.
On the same line, ITU SG15/Q6 provides (through [LS78]) a list of
optical parameters with following observations:
(a) the problem of calculating the non-linear impairments in a
multi-vendor environment is not solved. The transfer functions
works only for the so called [ITU.G680] "Situation 1".
(b) The generated list of parameters is not exhaustive however
provide a guideline for control plane optical impairment
awareness.
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In particular, [ITU.G680] contains many parameters that would be
required to estimate linear impairments. Some of the Computational
Models defined within [ITU.G680] requires parameters defined in other
documents like [ITU.G671]. The purpose of the list here below makes
this match between the two documents.
[ITU.G697] defines parameters can be monitored in an optical network.
This Information Model and associated encoding document will reuse
[ITU.G697] parameters identifiers and encoding for the purpose of
path computation.
The list of optical parameters starts from [ITU.G680] Section 9 which
provides the optical computational models for the following p:
G-1 OSNR. Section 9.1
G-2 Chromatic Dispersion (CD). Section 9.2
G-3 Polarization Mode Dispersion (PMD). Section 9.3
G-4 Polarization Dependent Loss (PDL). Section 9.3
In addition to the above, the following list of parameters has been
mentioned by [LS78]:
L-1 "Channel frequency range", [ITU.G671]. This parameter is part
of the application code and encoded through Optical Interface
Class as defined in [RFC7446].
L-2 "Modulation format and rate". This parameter is part of the
application code and encoded through Optical Interface Class as
defined in [RFC7446].
L-3 "Channel power". Required by G-1.
L-4 "Ripple". According to [ITU.G680], this parameter can be taken
into account as additional OSNR penalty.
L-5 "Channel signal-spontaneous noise figure", [ITU.G680].
Required by OSNR calculation (see G-1) above.
L-6 "Channel chromatic dispersion (for fibre segment or network
element)". Already in G-2 above.
L-7 "Channel local chromatic dispersion (for a fibre segment)".
Already in G-2 above (since consider both local and fiber
dispersions).
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L-8 "Differential group delay (for a network element)", [ITU.G671].
Required by G-3.
L-9 "Polarisation mode dispersion (for a fibre segment)",
[ITU.G650.2], [ITU.G680]. Defined above as G-3.
L-10 "Polarization dependent loss (for a network element)",
[ITU.G671] and [ITU.G680]. Defined above as G-4.
L-11 "Reflectance". From [ITU.G671] Section 3.2.2.37 is the ratio
of reflected power Pr to incident power Pi at a given port of a
passive component, for given conditions of spectral
composition, polarization and geometrical distribution.
Generally expressed in dB. Might be monitored in some critical
cases. We neglect this effect as first approximation.
L-12 "Channel Isolation". From [ITU.G671] Section 3.2.2.2 (Adjacent
Channel Isolation) and Section 3.2.2.29 (Non Adjacent Channel
Isolation). Document [ITU.GSUP39] provide the formula for
calculation as channel cross-talk and measure it in dB. This
parameterer shall be considered for path computation.
L-13 "Channel extinction". From [ITU.G671] Section 3.2.2.9 needed
for Interferometric Crosstalk. Document [ITU.GSUP39] has the
formula for penalty computation. Unit of measurement is dB.
L-14 "Attenuation coefficient (for a fibre segment)". Document
[ITU.G650.1] Section 3.6.2. The unit of measure is dB. This
is a typical link parameter (as associated to a fiber).
L-15 "Non-linear coefficient (for a fibre segment)", [ITU.G650.2].
Required for Non-Linear Optical Impairment Computational
Models. Neglected by this document.
The final list of parameters is G-1, G-2, G-3, G-4, L-3, L-4, L-5,
L-8, L-12, L-13, L-14.
4. Background from WSON-RWA Information Model
In this section we report terms already defined for the WSON-RWA
(impairment free) as in [RFC7446] and [RFC7579]. The purpose is to
provide essential information that will be reused or extended for the
impairment case.
In particular [RFC7446] Section 4.1 defines the ConnectivityMatrix
and states that such matrix does not represent any particular
internal blocking behaviour but indicates which input ports and
wavelengths could possibly be connected to a particular output port.
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<ConnectivityMatrix> ::= <MatrixID> <ConnType> <Matrix>
According to [RFC7579], this definition is further detailed as:
<ConnectivityMatrix> ::=
<MatrixID> <ConnType> ((<LinkSet> <LinkSet>) ...)
This second formula highlights how the ConnectivityMatrix is built by
pairs of LinkSet objects identifying the internal connectivity
capability due to internal optical node constraint(s). It's
essentially binary information and tell if a wavelength or a set of
wavelengths can go from an input port to an output port.
As an additional note, ConnectivityMatrix belongs to node
information, is uniquely identified by advertising node and is a
static information. Dynamic information related to the actual state
of connections is available through specific extension to link
information.
The [RFC7446] introduces the concept of ResourceBlockInfo and
ResourcePool for the WSON nodes. The resource block is a collection
of resources behaving in the same way and having similar
characteristics. The ResourceBlockInfo is defined as follow:
<ResourceBlockInfo> ::= <ResourceBlockSet> [<InputConstraints>]
[<ProcessingCapabilities>] [<OutputConstraints>]
The usage of resource block and resource pool is an efficient way to
model constrains within a WSON node.
5. Optical Impairment Information Model
The idea behind this document is to put optical impairment parameters
into categories and extend the information model already defined for
impairment-free WSONs. The three categories are:
o Node Information. The concept of connectivity matrix is reused
and extended to introduce an impairment matrix, which represents
the impairments suffered on the internal path between two ports.
In addition, the concept of Resource Block is also reused and
extended to provide an efficient representation of per-port
impairment.
o Link Information representing impairment information related to a
specific link or hop.
o Path Information representing the impairment information related
to the whole path.
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All the above three categories will make use of a generic container,
the Impairment Vector, to transport optical impairment information.
This information model however will allow however to add additional
parameters beyond the one defined by [ITU.G680] in order to support
additional computational models. This mechanism could eventually
applicable to both linear and non-linear parameters.
This information model makes the assumption that the each optical
node in the network is able to provide the control plane protocols
with its own parameter values. However, no assumption is made on how
the optical nodes get those value information (e.g., internally
computed, provisioned by a network management system, etc.). To this
extent, the information model intentionally ignores all internal
detailed parameters that are used by the formulas of the Optical
Computational Model (i.e., "transfer function") and simply provides
the object containers to carry results of the formulas.
5.1. The Optical Impairment Vector
Optical Impairment Vector (OIV) is defined as a list of optical
parameters to be associated to a WSON node or a WSON link. It is
defined as:
<OIV> ::= ([<LabelSet>] <OPTICAL_PARAM>) ...
The optional LabelSet object enables wavelength dependency property
as per Table 1. LabelSet has its definition in [RFC7579].
OPTICAL_PARAM. This object represents an optical parameter. The
Impairment vector can contain a set of parameters as identified by
[ITU.G697] since those parameters match the terms of the linear
impairments computational models provided by [ITU.G680]. This
information model does not speculate about the set of parameters
(since defined elsewhere, e.g. ITU-T), however it does not preclude
extensions by adding new parameters.
5.2. Node Information
5.2.1. Impairment Matrix
Impairment matrix describes a list of the optical parameters that
applies to a network element as a whole or ingress/egress port pairs
of a network element. Wavelength dependency property of optical
parameters is also considered.
ImpairmentMatrix ::= <MatrixID> <ConnType>
((<LinkSet> <LinkSet> <OIV>) ...)
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Where:
MatrixID. This ID is a unique identifier for the matrix. It
shall be unique in scope among connectivity matrices defined in
[RFC7446] and impairment matrices defined here.
ConnType. This number identifies the type of matrix and it shall
be unique in scope with other values defined by impairment-free
WSON documents.
LinkSet. Same object definition and usage as [RFC7579]. The
pairs of LinkSet identify one or more internal node constrain.
OIV. The Optical Impairment Vector defined above.
The model can be represented as a multidimensional matrix shown in
the following picture
_________________________________________
/ / / / / /|
/ / / / / / |
/________/_______/_______/_______/_______/ |
/ / / / / /| /|
/ / / / / / | |
/________/_______/_______/_______/_______/ | /|
/ / / / / /| /| |
/ / / / / / | | /|
/________/_______/_______/_______/_______/ | /| |
/ / / / / /| /| | /|
/ / / / / / | | /| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | /| | / PDL
<LinkSet#1> | - | | | | | /| | /|/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | /| /
<linkSet#2> | | - | | | | /| | / PND
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | /|/
<linkSet#3> | | | - | | | /| /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | / Chr.Disp.
<linkSet#4> | | | | - | | /|/
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
<linkSet#5> | | | | | - | / OSNR
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<LS#1> <LS#2> <LS#3> <LS#4> <LS#5>
The connectivity matrix from [RFC7579] is only a two dimensional
matrix, containing only binary information, through the LinkSet
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pairs. In this model, a third dimension is added by generalizing the
binary information through the Optical Impairment Vector associated
with each LinkSet pair. Optical parameters in the picture are
reported just as an example: proper list and encoding shall be
defined by other documents.
This representation shows the most general case however, the total
amount of information transported by control plane protocols can be
greatly reduced by proper encoding when the same set of values apply
to all LinkSet pairs.
5.2.2. Impairment Resource Block Information
This information model reuses the definition of Resource Block
Information adding the associated impairment vector.
ResourceBlockInfo ::= <ResourceBlockSet> [<InputConstraints>]
[<ProcessingCapabilities>] [<OutputConstraints>] [<OIV>]
The object ResourceBlockInfo is than used as specified within
[RFC7446].
5.3. Link Information
For the list of optical parameters associated to the link, the same
approach used for the node-specific impairment information can be
applied. The link-specific impairment information is extended from
[RFC7446] as the following:
<DynamicLinkInfo> ::= <LinkID> <AvailableLabels>
[<SharedBackupLabels>] [<OIV>]
DynamicLinkInfo is already defined in [RFC7446] while OIV is the
Optical Impairment Vector is defined in the previous section.
5.4. Path Information
There are cases where the optical impairments can only be described
as a constrains on the overall end to end path. In such case, the
optical impairment and/or parameter, cannot be derived (using a
simple function) from the set of node / link contributions.
An equivalent case is the option reported by [RFC6566] on IV-
Candidate paths where, the control plane knows a list of optically
feasible paths so a new path setup can be selected among that list.
Independent from the protocols and functions combination (i.e. RWA
vs. Routing vs. PCE), the IV-Candidates imply a path property stating
that a path is optically feasible.
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The concept of Optical Impairment Vector (OIV) might be used or
extended to report optical impairment information at path level
however this is case is letf for future studies.
6. Encoding Considerations
Details about encoding will be defined in a separate document
[I-D.ietf-ccamp-wson-iv-encode] however worth remembering that,
within [ITU.G697] Appending V, ITU already provides a guideline for
encoding some optical parameters.
In particular [ITU.G697] indicates that each parameter shall be
represented by a 32 bit floating point number.
Values for optical parameters are provided by optical node and it
could provide by direct measurement or from some internal computation
starting from indirect measurement. In such cases, it could be
useful to understand the variance associated with the value of the
optical parameter hence, the encoding shall provide the possibility
to include a variance as well.
This kind of information will enable IA-RWA process to make some
additional considerations on wavelength feasibility. [RFC6566]
Section 4.1.3 reports some considerations regarding this degree of
confidence during the impairment validation process.
7. Control Plane Architectures
This section briefly describes how the definitions contained in this
information model will match the architectural options described by
[RFC6566]. This section does not suggest suggested any specific
protocol option.
The assumption is that WSON GMPLS extensions are available and
operational. To such extent, the WSON-RWA will provide the following
information through its path computation (and RWA process):
o The wavelengths connectivity, considering also the connectivity
constraints limited by reconfigurable optics, and wavelengths
availability.
o The interface compatibility at the physical level.
o The Optical-Elettro-Optical (OEO) availability within the network
(and related physical interface compatibility). As already stated
by the framework this information it's very important for
impairment validation:
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A. If the IV functions fail (path optically infeasible), the path
computation function may use an available OEO point to find a
feasible path. In normally operated networks OEO are mainly
uses to support optically unfeasible path than mere wavelength
conversion.
B. The OEO points reset the optical impairment information since
a new light is generated.
7.1. IV-Centralized
Centralized IV process is performed by a single entity (e.g. a PCE or
other external entities). Given sufficient impairment information,
it can either be used to provide a list of paths between two nodes,
which are valid in terms of optical impairments. Alternatively, it
can help validate whether a particular selected path and wavelength
is feasible or not.
Centralized IV functions requires exchange of impairment information
to the entity performing the IV process from network nodes. This
information exchange may requires implementation of this information
model within an exsting protocol (i.e. routing procol vs PCEP vs BGP-
LS vs others).
7.2. IV-Distributed
Assuming the information model is implemented through a routing
protocol, every node in the WSON network shall be able to perform an
RWA-IV function.
The signalling phase may provide additional checking as others
traffic engineering parameters.
8. Acknowledgements
Authors would like to acknoledge Greg Bernstein and Moustafa Kattan
as authors of a previous similar draft whose content partially
converged here.
Authors would like to thank ITU SG15/Q6 and in particular Peter
Stassar and Pete Anslow for providing useful information and text to
CCAMP through join meetings and liaisons.
9. Contributing Authors
This document was the collective work of several authors. The text
and content of this document was contributed by the editors and the
co-authors listed below:
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Xian Zhang
Huawei Technologies
F3-5-B R&D Center, Huawei Base
Bantian, Longgang District
Shenzen 518129
P.R. China
Phone: +86 755 28972913
Email: zhang.xian@huawei.com
Domenico Siracusa
CREATE-NET
via alla Cascata 56/D, Povo
Trento 38123
Italy
Email: domenico.siracusa@create-net.org
Andrea Zanardi
CREATE-NET
via alla Cascata 56/D, Povo
Trento 38123
Italy
Email: andrea.zanardi@create-net.org
Federico Pederzolli
CREATE-NET
via alla Cascata 56/D, Povo
Trento 38123
Italy
Email: federico.perderzolli@create-net.org
10. IANA Considerations
This document does not contain any IANA requirement.
11. Security Considerations
This document defines an information model for impairments in optical
networks. If such a model is put into use within a network it will
by its nature contain details of the physical characteristics of an
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optical network. Such information would need to be protected from
intentional or unintentional disclosure.
12. References
12.1. Normative References
[ITU.G650.1]
International Telecommunications Union, "Transmission
media and optical systems characteristics - Optical fibre
cable", ITU-T Recommendation G.650.1, July 2010.
[ITU.G650.2]
International Telecommunications Union, "Definitions and
test methods for statistical and non-linear related
attributes of single-mode fibre and cable",
ITU-T Recommendation G.650.2, August 2015.
[ITU.G671]
International Telecommunications Union, "Transmission
characteristics of optical components and subsystems",
ITU-T Recommendation G.671, February 2012.
[ITU.G680]
International Telecommunications Union, "Physical transfer
functions of optical network elements",
ITU-T Recommendation G.680, July 2007.
[ITU.G697]
International Telecommunications Union, "Optical
monitoring for dense wavelength division multiplexing
systems", ITU-T Recommendation G.697, February 2012.
[ITU.GSUP39]
International Telecommunications Union, "Optical System
Design and Engineering Considerations",
ITU-T Recommendation G. Supplement 39, September 2012.
[ITU.GSUP47]
International Telecommunications Union, "General aspects
of optical fibres and cables", ITU-T Recommendation G.
Supplement 47, September 2012.
12.2. Informative References
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[I-D.ietf-ccamp-wson-iv-encode]
Martinelli, G., Lee, Y., Galimberti, G., and F. Zhang,
"Information Encoding for WSON with Impairments
Validation", draft-ietf-ccamp-wson-iv-encode-02 (work in
progress), January 2019.
[LS78] International Telecommunications Union SG15/Q6, "LS/s on
CCAMP Liaison to ITU-T SG15 Q6 and Q12 on WSON",
LS https://datatracker.ietf.org/liaison/1288/, October
2013.
[RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
"Framework for GMPLS and Path Computation Element (PCE)
Control of Wavelength Switched Optical Networks (WSONs)",
RFC 6163, DOI 10.17487/RFC6163, April 2011,
<https://www.rfc-editor.org/info/rfc6163>.
[RFC6566] Lee, Y., Ed., Bernstein, G., Ed., Li, D., and G.
Martinelli, "A Framework for the Control of Wavelength
Switched Optical Networks (WSONs) with Impairments",
RFC 6566, DOI 10.17487/RFC6566, March 2012,
<https://www.rfc-editor.org/info/rfc6566>.
[RFC7446] Lee, Y., Ed., Bernstein, G., Ed., Li, D., and W. Imajuku,
"Routing and Wavelength Assignment Information Model for
Wavelength Switched Optical Networks", RFC 7446,
DOI 10.17487/RFC7446, February 2015,
<https://www.rfc-editor.org/info/rfc7446>.
[RFC7579] Bernstein, G., Ed., Lee, Y., Ed., Li, D., Imajuku, W., and
J. Han, "General Network Element Constraint Encoding for
GMPLS-Controlled Networks", RFC 7579,
DOI 10.17487/RFC7579, June 2015,
<https://www.rfc-editor.org/info/rfc7579>.
Appendix A. FAQ
A.1. Why the Application Code does not suffice for Optical Impairment
Validation?
Application Codes are encoded within GMPLS WSON protocol through the
Optical Interface Class as defined in [RFC7446].
The purpose of the Application Code in RWA is simply to assess the
interface compatibility: same Application Code means that two
interfaces can have an LSP connecting the two.
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Application Codes contain other information useful for IV process
(e.g., see the list of parameters) so they are required however
Computational Models requires more parameteres to assess the path
feasibility.
A.2. Are DWDM network multivendor?
According to [ITU.G680] "Situation 1" the DWDM line segments are
single are single vendor but an LSP can make use of different data
planes entities from different vendors. For example: DWDM interfaces
(represented in the control plane through the Optical Interface
Class) from a vendor and network elements described by Stutation 1
from another vendor.
Authors' Addresses
Giovanni Martinelli (editor)
Cisco
via Santa Maria Molgora, 48/C
Vimercate, MB 20871
Italy
Phone: +39 039 2092044
Email: giomarti@cisco.com
Haomian Zheng (editor)
Huawei Technologies
H1, Huawei Xiliu Beipo Village, Songshan Lake
Dongguan, Guangdong 523808
China
Phone: +8613066975206
Email: zhenghaomian@huawei.com
Gabriele M. Galimberti
Cisco
Via Santa Maria Molgora, 48/C
Vimercate, MB 20871
Italy
Phone: +39 039 2091462
Email: ggalimbe@cisco.com
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Young Lee
Samsung
Seoul
South Korea
Email: younglee.tx@gmail.com
Fatai Zhang
Huawei Technologies
H1, Huawei Xiliu Beipo Village, Songshan Lake
Dongguan, Guangdong 523808
China
Email: zhangfatai@huawei.com
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