draft-ietf-ccamp-wson-iv-info-04.txt   draft-ietf-ccamp-wson-iv-info-05.txt 
CCAMP G. Martinelli, Ed. CCAMP G. Martinelli, Ed.
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Informational X. Zhang, Ed. Intended status: Informational X. Zhang, Ed.
Expires: September 14, 2017 Huawei Technologies Expires: January 2, 2018 Huawei Technologies
G. Galimberti G. Galimberti
Cisco Cisco
A. Zanardi A. Zanardi
D. Siracusa D. Siracusa
F. Pederzolli F. Pederzolli
CREATE-NET CREATE-NET
Y. Lee Y. Lee
F. Zhang F. Zhang
Huawei Technologies Huawei Technologies
March 13, 2017 July 2017
Information Model for Wavelength Switched Optical Networks (WSONs) with Information Model for Wavelength Switched Optical Networks (WSONs) with
Impairments Validation Impairments Validation
draft-ietf-ccamp-wson-iv-info-04 draft-ietf-ccamp-wson-iv-info-05
Abstract Abstract
This document defines an information model to support Impairment- This document defines an information model to support Impairment-
Aware (IA) Routing and Wavelength Assignment (RWA) functionality. Aware (IA) Routing and Wavelength Assignment (RWA) functionality.
This information model extends the information model for impairment- This information model extends the information model for impairment-
free RWA process in WSON to facilitate computation of paths where free RWA process in WSON to facilitate computation of paths where
optical impairment constraints need to considered. optical impairment constraints need to considered.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 14, 2017. This Internet-Draft will expire on January 2, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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A Control Plane with RWA-IA will not be able to solve the optical 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 impairment problem in a detailed and exhaustive way, however, it may
take advantage of some data plane knowledge to make better decisions take advantage of some data plane knowledge to make better decisions
during its path computing phase. The final outcome will be a path, during its path computing phase. The final outcome will be a path,
instantiated through a wavelength in the data plane, that has a instantiated through a wavelength in the data plane, that has a
"better chance" to work than that path were calculated without IA "better chance" to work than that path were calculated without IA
information. "Better chance" means that path setup may still fail information. "Better chance" means that path setup may still fail
and the GMPLS control plane will follow its usual procedures upon and the GMPLS control plane will follow its usual procedures upon
errors and failures. A control plane will not replace a the network errors and failures. A control plane will not replace a the network
design phase that remains a foundamental step for DWDM Optical design phase that remains a fundamental step for DWDM Optical
Networks. As the non-linear impairments which need to be considered Networks. As the non-linear impairments which need to be considered
in the calculation of an optical path will be vendor-dependent, the in the calculation of an optical path will be vendor-dependent, the
parameters considered in this document is not an exhaustive list. parameters considered in this document is not an exhaustive list.
This document provides an information model for the impairment aware This document provides an information model for the impairment aware
case to allow the impairment validation function implemented in the case to allow the impairment validation function implemented in the
control plane or enabled by control plane available information. control plane or enabled by control plane available information.
This model goes in addition to [RFC7446] and shall support any This model goes in addition to [RFC7446] and shall support any
control plane architectural option described by the framework control plane architectural option described by the framework
document (see sections 4.2 and 4.3 of [RFC6566]) where a set of document (see sections 4.2 and 4.3 of [RFC6566]) where a set of
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not precluding future evolutions towards more detailed or different not precluding future evolutions towards more detailed or different
impairments estimation methods. impairments estimation methods.
On the same line, ITU SG15/Q6 provides (through [LS78]) a list of On the same line, ITU SG15/Q6 provides (through [LS78]) a list of
optical parameters with following observations: optical parameters with following observations:
(a) the problem of calculating the non-linear impairments in a (a) the problem of calculating the non-linear impairments in a
multi-vendor environment is not solved. The transfer functions multi-vendor environment is not solved. The transfer functions
works only for the so called [ITU.G680] "Situation 1". works only for the so called [ITU.G680] "Situation 1".
(b) The generated list of parameters is not definitive or exaustive. (b) The generated list of parameters is not exhaustive however
provide a guideline for control plane optical impairment
awareness.
In particular, [ITU.G680] contains many parameters that would be In particular, [ITU.G680] contains many parameters that would be
required to estimate linear impairments. Some of the Computational required to estimate linear impairments. Some of the Computational
Models defined within [ITU.G680] requires parameters defined in Models defined within [ITU.G680] requires parameters defined in
other documents like [ITU.G671]. The purpose of the list here below other documents like [ITU.G671]. The purpose of the list here below
makes this match between the two documents. makes this match between the two documents.
[ITU.G697] defines parameters can be monitored in an optical network. [ITU.G697] defines parameters can be monitored in an optical network.
This Information Model and associated encoding document will reuse This Information Model and associated encoding document will reuse
[ITU.G697] parameters identifiers and encoding for the purpose of [ITU.G697] parameters identifiers and encoding for the purpose of
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of reflected power Pr to incident power Pi at a given port of a of reflected power Pr to incident power Pi at a given port of a
passive component, for given conditions of spectral passive component, for given conditions of spectral
composition, polarization and geometrical distribution. composition, polarization and geometrical distribution.
Generally expressed in dB. Might be monitored in some critical Generally expressed in dB. Might be monitored in some critical
cases. We neglect this effect as first approximation. cases. We neglect this effect as first approximation.
L-12 "Channel Isolation". From [ITU.G671] Section 3.2.2.2 (Adjacent L-12 "Channel Isolation". From [ITU.G671] Section 3.2.2.2 (Adjacent
Channel Isolation) and Section 3.2.2.29 (Non Adjacent Channel Channel Isolation) and Section 3.2.2.29 (Non Adjacent Channel
Isolation). Document [ITU.GSUP39] provide the formula for Isolation). Document [ITU.GSUP39] provide the formula for
calculation as channel cross-talk and measure it in dB. This calculation as channel cross-talk and measure it in dB. This
paramterer shall be considered for path computation. parameterer shall be considered for path computation.
L-13 "Channel extinction". From [ITU.G671] Section 3.2.2.9 needed L-13 "Channel extinction". From [ITU.G671] Section 3.2.2.9 needed
for Interferometric Crosstalk. Document [ITU.GSUP39] has the for Interferometric Crosstalk. Document [ITU.GSUP39] has the
formula for penalty computation. Unit of measurement is dB. formula for penalty computation. Unit of measurement is dB.
L-14 "Attenuation coefficient (for a fibre segment)". Document L-14 "Attenuation coefficient (for a fibre segment)". Document
[ITU.G650.1] Section 3.6.2. The unit of measure is dB. This [ITU.G650.1] Section 3.6.2. The unit of measure is dB. This
is a typical link parameter (as associated to a fiber). is a typical link parameter (as associated to a fiber).
L-15 "Non-linear coefficient (for a fibre segment)", [ITU.G650.2]. L-15 "Non-linear coefficient (for a fibre segment)", [ITU.G650.2].
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L-8, L-12, L-13, L-14. L-8, L-12, L-13, L-14.
4. Background from WSON-RWA Information Model 4. Background from WSON-RWA Information Model
In this section we report terms already defined for the WSON-RWA In this section we report terms already defined for the WSON-RWA
(impairment free) as in [RFC7446] and [RFC7579]. The purpose is to (impairment free) as in [RFC7446] and [RFC7579]. The purpose is to
provide essential information that will be reused or extended for the provide essential information that will be reused or extended for the
impairment case. impairment case.
In particular [RFC7446] Section 4.1 defines the ConnectivityMatrix In particular [RFC7446] Section 4.1 defines the ConnectivityMatrix
explaing that it does not represent any particular internal blocking and states that such matrix does not represent any particular
behavior but indicates which input ports and wavelengths could internal blocking behaviour but indicates which input ports and
possibly be connected to a particular output port. wavelengths could possibly be connected to a particular output port.
<ConnectivityMatrix> ::= <MatrixID> <ConnType> <Matrix> <ConnectivityMatrix> ::= <MatrixID> <ConnType> <Matrix>
According to [RFC7579], this definition is further detailed as: According to [RFC7579], this definition is further detailed as:
<ConnectivityMatrix> ::= <ConnectivityMatrix> ::=
<MatrixID> <ConnType> ((<LinkSet> <LinkSet>) ...) <MatrixID> <ConnType> ((<LinkSet> <LinkSet>) ...)
This second formula highlights how the ConnectivityMatrix is built by This second formula highlights how the ConnectivityMatrix is built by
pairs of LinkSet objects identifying the internal connectivity pairs of LinkSet objects identifying the internal connectivity
capability due to internal optical node constraint(s). It's capability due to internal optical node constraint(s). It's
essentially binary information and tell if a wavelength or a set of essentially binary information and tell if a wavelength or a set of
wavelengths can go from an input port to an output port. wavelengths can go from an input port to an output port.
As an additional note, ConnectivityMatrix belongs to node As an additional note, ConnectivityMatrix belongs to node
information, is uniquely identified by adverstising node and is a information, is uniquely identified by advertising node and is a
static information. Dynamic information related to the actual state static information. Dynamic information related to the actual state
of connections is available through specific extension to link of connections is available through specific extension to link
information. information.
The [RFC7446] introduces the concept of ResourceBlockInfo and The [RFC7446] introduces the concept of ResourceBlockInfo and
ResourcePool for the WSON nodes. The resource block is a collection ResourcePool for the WSON nodes. The resource block is a collection
of resources behaving in the same way and having similar of resources behaving in the same way and having similar
characteristics. The ResourceBlockInfo is defined as follow: characteristics. The ResourceBlockInfo is defined as follow:
<ResourceBlockInfo> ::= <ResourceBlockSet> [<InputConstraints>] <ResourceBlockInfo> ::= <ResourceBlockSet> [<InputConstraints>]
[<ProcessingCapabilities>] [<OutputConstraints>] [<ProcessingCapabilities>] [<OutputConstraints>]
The usage of resorurce block and resource pool is an efficient way to The usage of resource block and resource pool is an efficient way to
model constrains within a WSON node. model constrains within a WSON node.
5. Optical Impairment Information Model 5. Optical Impairment Information Model
The idea behind this information model is to categorize the The idea behind this document is to put optical impairment parameters
impairment parameters into three types and extend the information into categories and extend the information model already defined for
model already defined for impairment-free WSONs. The three impairment-free WSONs. The three categories are:
categories are:
o Node Information. The concept of connectivity matrix is reused o Node Information. The concept of connectivity matrix is reused
and extended to introduce an impairment matrix, which represents and extended to introduce an impairment matrix, which represents
the impairments suffered on the internal path between two ports. the impairments suffered on the internal path between two ports.
In addition, the concept of Resource Block is also reused and In addition, the concept of Resource Block is also reused and
extended to provide an efficient modelization of per-port extended to provide an efficient modelization of per-port
impairment. impairment.
o Link Information representing impairment information related to a o Link Information representing impairment information related to a
specific link or hop. specific link or hop.
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(since defined elsewhere, e.g. ITU-T), however it does not preclude (since defined elsewhere, e.g. ITU-T), however it does not preclude
extentions by adding new parameters. extentions by adding new parameters.
5.2. Node Information 5.2. Node Information
5.2.1. Impairment Matrix 5.2.1. Impairment Matrix
Impairment matrix describes a list of the optical parameters that Impairment matrix describes a list of the optical parameters that
applies to a network element as a whole or ingress/egress port pairs applies to a network element as a whole or ingress/egress port pairs
of a network element. Wavelength dependency property of optical of a network element. Wavelength dependency property of optical
paramters is also considered. parameters is also considered.
ImpairmentMatrix ::= <MatrixID> <ConnType> ImpairmentMatrix ::= <MatrixID> <ConnType>
((<LinkSet> <LinkSet> <OIV>) ...) ((<LinkSet> <LinkSet> <OIV>) ...)
Where: Where:
MatrixID. This ID is a unique identifier for the matrix. It MatrixID. This ID is a unique identifier for the matrix. It
shall be unique in scope among connectivity matrices defined in shall be unique in scope among connectivity matrices defined in
[RFC7446] and impairment matrices defined here. [RFC7446] and impairment matrices defined here.
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ / +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ /
<linkSet#5> | | | | | - | / OSNR <linkSet#5> | | | | | - | / OSNR
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
<LS#1> <LS#2> <LS#3> <LS#4> <LS#5> <LS#1> <LS#2> <LS#3> <LS#4> <LS#5>
The connectivity matrix from [RFC7579] is only a two dimensional The connectivity matrix from [RFC7579] is only a two dimensional
matrix, containing only binary information, through the LinkSet matrix, containing only binary information, through the LinkSet
pairs. In this model, a third dimension is added by generalizing the pairs. In this model, a third dimension is added by generalizing the
binary information through the Optical Impairment Vector associated binary information through the Optical Impairment Vector associated
with each LinkSet pair. Optical parameters in the picture are with each LinkSet pair. Optical parameters in the picture are
reported just as examples while details go into specific encoding reported just as an example: proper list and encoding shall be
draft [I-D.martinelli-ccamp-wson-iv-encode]. defined by other documents.
This representation shows the most general case however, the total This representation shows the most general case however, the total
amount of information transported by control plane protocols can be amount of information transported by control plane protocols can be
greatly reduced by proper encoding when the same set of values apply greatly reduced by proper encoding when the same set of values apply
to all LinkSet pairs. to all LinkSet pairs.
5.2.2. Impairment Resource Block Information 5.2.2. Impairment Resource Block Information
This information model reuses the definition of Resource Block This information model reuses the definition of Resource Block
Information adding the associated impairment vector. Information adding the associated impairment vector.
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[RFC7446] as the following: [RFC7446] as the following:
<DynamicLinkInfo> ::= <LinkID> <AvailableLabels> <DynamicLinkInfo> ::= <LinkID> <AvailableLabels>
[<SharedBackupLabels>] [<OIV>] [<SharedBackupLabels>] [<OIV>]
DynamicLinkInfo is already defined in [RFC7446] while OIV is the DynamicLinkInfo is already defined in [RFC7446] while OIV is the
Optical Impairment Vector is defined in the previous section. Optical Impairment Vector is defined in the previous section.
5.4. Path Information 5.4. Path Information
There are cases where the optical impariments can only be described There are cases where the optical impairments can only be described
as a contrains on the overall end to end path. In such case, the as a constrains on the overall end to end path. In such case, the
optical impariment and/or parameter, cannot be derived (using a optical impairment and/or parameter, cannot be derived (using a
simple function) from the set of node / link contributions. simple function) from the set of node / link contributions.
An equivalent case is the option reported by [RFC6566] on IV- An equivalent case is the option reported by [RFC6566] on IV-
Candidate paths where, the control plane knows a list of optically Candidate paths where, the control plane knows a list of optically
feasible paths so a new path setup can be selected among that list. feasible paths so a new path setup can be selected among that list.
Independent from the protocols and functions combination (i.e. RWA Independent from the protocols and functions combination (i.e. RWA
vs. Routing vs. PCE), the IV-Candidates imply a path property stating vs. Routing vs. PCE), the IV-Candidates imply a path property stating
that a path is optically feasible. that a path is optically feasible.
<PathInfo> ::= <OIV> <PathInfo> ::= <OIV>
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within [ITU.G697] Appending V, ITU already provides a guideline for within [ITU.G697] Appending V, ITU already provides a guideline for
encoding some optical parameters. encoding some optical parameters.
In particular [ITU.G697] indicates that each parameter shall be In particular [ITU.G697] indicates that each parameter shall be
represented by a 32 bit floating point number. represented by a 32 bit floating point number.
Values for optical parameters are provided by optical node and it Values for optical parameters are provided by optical node and it
could provide by direct measurement or from some internal computation could provide by direct measurement or from some internal computation
starting from indirect measurement. In such cases, it could be starting from indirect measurement. In such cases, it could be
useful to understand the variance associated with the value of the useful to understand the variance associated with the value of the
optical parmater hence, the encoding shall provide the possibility to optical parameter hence, the encoding shall provide the possibility
include a variance as well. to include a variance as well.
This kind of information will enable IA-RWA process to make some This kind of information will enable IA-RWA process to make some
additional considerations on wavelength feasibility. [RFC6566] additional considerations on wavelength feasibility. [RFC6566]
Section 4.1.3 reports some considerations regarding this degree of Section 4.1.3 reports some considerations regarding this degree of
confidence during the impairment validation process. confidence during the impairment validation process.
7. Control Plane Architectures 7. Control Plane Architectures
This section briefly describes how the defintions contained in this This section briefly describes how the definitions contained in this
information model will match the architectural options described by information model will match the architectural options described by
[RFC6566]. [RFC6566].
The first assumption is that the WSON GMPLS extentions are available The first assumption is that the WSON GMPLS extensions are available
and operational. To such extent, the WSON-RWA will provide the and operational. To such extent, the WSON-RWA will provide the
following information through its path computation (and RWA process): following information through its path computation (and RWA process):
o The wavelengths connectivity, considering also the connectivity o The wavelengths connectivity, considering also the connectivity
constraints limited by reconfigurable optics, and wavelengths constraints limited by reconfigurable optics, and wavelengths
availability. availability.
o The interface compatibility at the physical level. o The interface compatibility at the physical level.
o The Optical-Elettro-Optical (OEO) availability within the network o The Optical-Elettro-Optical (OEO) availability within the network
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B. The OEO points reset the optical impairment information since B. The OEO points reset the optical impairment information since
a new light is generated. a new light is generated.
7.1. IV-Centralized 7.1. IV-Centralized
Centralized IV process is performed by a single entity (e.g., a PCE). Centralized IV process is performed by a single entity (e.g., a PCE).
Given sufficient impairment information, it can either be used to Given sufficient impairment information, it can either be used to
provide a list of paths between two nodes, which are valid in terms provide a list of paths between two nodes, which are valid in terms
of optical impairments. Alternatively, it can help validate whether of optical impairments. Alternatively, it can help validate whether
a particular selected path and wavelength is feasiable or not. This a particular selected path and wavelength is feasible or not. This
requires distribution of impairment information to the entity requires distribution of impairment information to the entity
performing the IV process. performing the IV process.
This Informaton Model doesn't make any hypotesys on distribution This Information Model doesn't make any hypothesis on distribution
method for optical parameters but only defines the essential build method for optical parameters but only defines the essential build
blocks. A centralized entity may get knowledge of required blocks. A centralized entity may get knowledge of required
informaton through routing protocools or other mechanism such as BGP- information through routing protocols or other mechanism such as BGP-
LS. LS.
7.2. IV-Distributed 7.2. IV-Distributed
Assuming the information model is implemented through a routing Assuming the information model is implemented through a routing
protocol, every node in the WSON network shall be able to perform an protocol, every node in the WSON network shall be able to perform an
RWA-IV function. RWA-IV function.
The signalling phase may provide additional checking as others The signalling phase may provide additional checking as others
traffic engineering parameters. traffic engineering parameters.
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planes entities from different vendors. For example: DWDM interfaces planes entities from different vendors. For example: DWDM interfaces
(represented in the control plane through the Optical Interface (represented in the control plane through the Optical Interface
Class) from a vendor and network elements described by Stutation 1 Class) from a vendor and network elements described by Stutation 1
from another vendor. from another vendor.
Authors' Addresses Authors' Addresses
Giovanni Martinelli (editor) Giovanni Martinelli (editor)
Cisco Cisco
via Santa Maria Molgora, 48/C via Santa Maria Molgora, 48/C
Vimercate 20871 Vimercate, MB 20871
Italy Italy
Phone: +39 039 2092044 Phone: +39 039 2092044
Email: giomarti@cisco.com Email: giomarti@cisco.com
Xian Zhang (editor) Xian Zhang (editor)
Huawei Technologies Huawei Technologies
F3-5-B R&D Center, Huawei Base F3-5-B R&D Center, Huawei Base
Bantian, Longgang District Bantian, Longgang District
Shenzen 518129 Shenzen 518129
P.R. China P.R. China
Phone: +86 755 28972465 Phone: +86 755 28972465
Email: zhang.xian@huawei.com Email: zhang.xian@huawei.com
Gabriele M. Galimberti Gabriele M. Galimberti
Cisco Cisco
Via Santa Maria Molgora, 48/C Via Santa Maria Molgora, 48/C
Vimercate 20871 Vimercate, MB 20871
Italy Italy
Phone: +39 039 2091462 Phone: +39 039 2091462
Email: ggalimbe@cisco.com Email: ggalimbe@cisco.com
Andrea Zanardi Andrea Zanardi
CREATE-NET CREATE-NET
via alla Cascata 56/D, Povo via alla Cascata 56/D, Povo
Trento 38123 Trento 38123
Italy Italy
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