draft-ietf-ccamp-flexi-grid-fwk-07.txt   rfc7698.txt 
CCAMP Working Group O. Gonzalez de Dios, Ed. Internet Engineering Task Force (IETF) O. Gonzalez de Dios, Ed.
Internet-Draft Telefonica I+D Request for Comments: 7698 Telefonica I+D
Intended status: Informational R. Casellas, Ed. Category: Informational R. Casellas, Ed.
Expires: March 2, 2016 CTTC ISSN: 2070-1721 CTTC
August 30, 2015 F. Zhang
Huawei
X. Fu
Stairnote
D. Ceccarelli
Ericsson
I. Hussain
Infinera
November 2015
Framework and Requirements for GMPLS-based control of Flexi-grid DWDM Framework and Requirements for GMPLS-Based Control
networks of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM) Networks
draft-ietf-ccamp-flexi-grid-fwk-07
Abstract Abstract
To allow efficient allocation of optical spectral bandwidth for high To allow efficient allocation of optical spectral bandwidth for
bit-rate systems, the International Telecommunication Union systems that have high bit-rates, the International Telecommunication
Telecommunication Standardization Sector (ITU-T) has extended its Union Telecommunication Standardization Sector (ITU-T) has extended
Recommendations G.694.1 and G.872 to include a new dense wavelength its Recommendations G.694.1 and G.872 to include a new Dense
division multiplexing (DWDM) grid by defining a set of nominal Wavelength Division Multiplexing (DWDM) grid by defining a set of
central frequencies, channel spacings and the concept of "frequency nominal central frequencies, channel spacings, and the concept of the
slot". In such an environment, a data plane connection is switched "frequency slot". In such an environment, a data-plane connection is
based on allocated, variable-sized frequency ranges within the switched based on allocated, variable-sized frequency ranges within
optical spectrum creating what is known as a flexible grid (flexi- the optical spectrum, creating what is known as a flexible grid
grid). (flexi-grid).
Given the specific characteristics of flexi-grid optical networks and Given the specific characteristics of flexi-grid optical networks and
their associated technology, this document defines a framework and their associated technology, this document defines a framework and
the associated control plane requirements for the application of the the associated control-plane requirements for the application of the
existing GMPLS architecture and control plane protocols to the existing GMPLS architecture and control-plane protocols to the
control of flexi-grid DWDM networks. The actual extensions to the control of flexi-grid DWDM networks. The actual extensions to the
GMPLS protocols will be defined in companion documents. GMPLS protocols will be defined in companion documents.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This document is not an Internet Standards Track specification; it is
provisions of BCP 78 and BCP 79. published for informational purposes.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 2, 2016. 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/rfc7698.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction ....................................................4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Terminology .....................................................5
2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.1. Requirements Language ......................................5
2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 2.2. Abbreviations ..............................................5
3. Overview of Flexi-grid Networks . . . . . . . . . . . . . . . 5 3. Overview of Flexi-Grid Networks .................................6
3.1. Flexi-grid in the Context of OTN . . . . . . . . . . . . 5 3.1. Flexi-Grid in the Context of OTN ...........................6
3.2. Flexi-grid Terminology . . . . . . . . . . . . . . . . . 6 3.2. Flexi-Grid Terminology .....................................6
3.2.1. Frequency Slots . . . . . . . . . . . . . . . . . . . 6 3.2.1. Frequency Slots .....................................7
3.2.2. Media Layer Elements . . . . . . . . . . . . . . . . 8 3.2.2. Media-Layer Elements ................................9
3.2.3. Media Channels . . . . . . . . . . . . . . . . . . . 8 3.2.3. Media Channels .....................................10
3.2.4. Optical Tributary Signals . . . . . . . . . . . . . . 9 3.2.4. Optical Tributary Signals ..........................10
3.2.5. Composite Media Channels . . . . . . . . . . . . . . 9 3.2.5. Composite Media Channels ...........................11
3.3. Hierarchy in the Media Layer . . . . . . . . . . . . . . 10 3.3. Hierarchy in the Media Layer ..............................11
3.4. Flexi-grid Layered Network Model . . . . . . . . . . . . 10 3.4. Flexi-Grid Layered Network Model ..........................12
3.4.1. DWDM Flexi-grid Enabled Network Element Models . . . 12 3.4.1. DWDM Flexi-Grid Enabled Network Element Models .....13
4. GMPLS Applicability . . . . . . . . . . . . . . . . . . . . . 12 4. GMPLS Applicability ............................................14
4.1. General Considerations . . . . . . . . . . . . . . . . . 12 4.1. General Considerations ....................................14
4.2. Consideration of TE Links . . . . . . . . . . . . . . . . 13 4.2. Consideration of TE Links .................................14
4.3. Consideration of LSPs in Flexi-grid . . . . . . . . . . . 15 4.3. Consideration of LSPs in Flexi-Grid .......................17
4.4. Control Plane Modeling of Network Elements . . . . . . . 20 4.4. Control-Plane Modeling of Network Elements ................22
4.5. Media Layer Resource Allocation Considerations . . . . . 20 4.5. Media Layer Resource Allocation Considerations ............22
4.6. Neighbor Discovery and Link Property Correlation . . . . 24 4.6. Neighbor Discovery and Link Property Correlation ..........26
4.7. Path Computation / Routing and Spectrum Assignment (RSA) 25 4.7. Path Computation, Routing and Spectrum Assignment (RSA) ...27
4.7.1. Architectural Approaches to RSA . . . . . . . . . . . 25 4.7.1. Architectural Approaches to RSA ....................28
4.8. Routing and Topology Dissemination . . . . . . . . . . . 26 4.8. Routing and Topology Dissemination ........................29
4.8.1. Available Frequency Ranges/Slots of DWDM Links . . . 27 4.8.1. Available Frequency Ranges (Frequency
4.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 27 Slots) of DWDM Links ...............................29
4.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 27 4.8.2. Available Slot Width Ranges of DWDM Links ..........29
4.8.4. Information Model . . . . . . . . . . . . . . . . . . 28 4.8.3. Spectrum Management ................................29
5. Control Plane Requirements . . . . . . . . . . . . . . . . . 29 4.8.4. Information Model ..................................30
5.1. Support for Media Channels . . . . . . . . . . . . . . . 29 5. Control-Plane Requirements .....................................31
5.1.1. Signaling . . . . . . . . . . . . . . . . . . . . . . 30 5.1. Support for Media Channels ................................31
5.1.2. Routing . . . . . . . . . . . . . . . . . . . . . . . 30 5.1.1. Signaling ..........................................32
5.2. Support for Media Channel Resizing . . . . . . . . . . . 31 5.1.2. Routing ............................................32
5.3. Support for Logical Associations of Multiple Media 5.2. Support for Media Channel Resizing ........................33
Channels . . . . . . . . . . . . . . . . . . . . . . . . 31 5.3. Support for Logical Associations of Multiple Media
5.4. Support for Composite Media Channels . . . . . . . . . . 31 Channels ..................................................33
5.5. Support for Neighbor Discovery and Link Property 5.4. Support for Composite Media Channels ......................33
Correlation . . . . . . . . . . . . . . . . . . . . . . . 32 5.5. Support for Neighbor Discovery and Link Property
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 Correlation ...............................................34
7. Security Considerations . . . . . . . . . . . . . . . . . . . 32 6. Security Considerations ........................................34
8. Manageability Considerations . . . . . . . . . . . . . . . . 33 7. Manageability Considerations ...................................35
9. Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 8. References .....................................................36
10. Contributing Authors . . . . . . . . . . . . . . . . . . . . 34 8.1. Normative References ......................................36
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 37 8.2. Informative References ....................................37
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 37 Acknowledgments ...................................................39
12.1. Normative References . . . . . . . . . . . . . . . . . . 37 Contributors ......................................................39
12.2. Informative References . . . . . . . . . . . . . . . . . 38 Authors' Addresses ................................................41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction 1. Introduction
The term "Flexible grid" (flexi-grid for short) as defined by the The term "flexible grid" ("flexi-grid" for short), as defined by the
International Telecommunication Union Telecommunication International Telecommunication Union Telecommunication
Standardization Sector (ITU-T) Study Group 15 in the latest version Standardization Sector (ITU-T) Study Group 15 in the latest version
of [G.694.1], refers to the updated set of nominal central of [G.694.1], refers to the updated set of nominal central
frequencies (a frequency grid), channel spacing and optical spectrum frequencies (a frequency grid), channel spacing, and optical spectrum
management/allocation considerations that have been defined in order management and allocation considerations that have been defined in
to allow an efficient and flexible allocation and configuration of order to allow an efficient and flexible allocation and configuration
optical spectral bandwidth for high bit-rate systems. of optical spectral bandwidth for systems that have high bit-rates.
A key concept of flexi-grid is the "frequency slot"; a variable-sized A key concept of flexi-grid is the "frequency slot": a variable-sized
optical frequency range that can be allocated to a data connection. optical frequency range that can be allocated to a data connection.
As detailed later in the document, a frequency slot is characterized As detailed later in the document, a frequency slot is characterized
by its nominal central frequency and its slot width which, as per by its nominal central frequency and its slot width, which, as per
[G.694.1], is constrained to be a multiple of a given slot width [G.694.1], is constrained to be a multiple of a given slot width
granularity. granularity.
Compared to a traditional fixed grid network, which uses fixed size Compared to a traditional fixed-grid network, which uses fixed-size
optical spectrum frequency ranges or frequency slots with typical optical spectrum frequency ranges or frequency slots with typical
channel separations of 50 GHz, a flexible grid network can select its channel separations of 50 GHz, a flexible-grid network can select its
media channels with a more flexible choice of slot widths, allocating media channels with a more flexible choice of slot widths, allocating
as much optical spectrum as required. as much optical spectrum as required.
From a networking perspective, a flexible grid network is assumed to From a networking perspective, a flexible-grid network is assumed to
be a layered network [G.872][G.800] in which the media layer is the be a layered network [G.872] [G.800] in which the media layer is the
server layer and the optical signal layer is the client layer. In server layer and the optical signal layer is the client layer. In
the media layer, switching is based on a frequency slot, and the size the media layer, switching is based on a frequency slot, and the size
of a media channel is given by the properties of the associated of a media channel is given by the properties of the associated
frequency slot. In this layered network, a media channel can frequency slot. In this layered network, a media channel can
transport more than one Optical Tributary Signals (OTSi), as defined transport more than one Optical Tributary Signal (OTSi), as defined
later in this document. later in this document.
A Wavelength Switched Optical Network (WSON), addressed in [RFC6163], A Wavelength Switched Optical Network (WSON), addressed in [RFC6163],
is a term commonly used to refer to the application/deployment of a is a term commonly used to refer to the application/deployment of a
GMPLS-based control plane for the control (provisioning/recovery, GMPLS-based control plane for the control (e.g., provisioning and
etc.) of a fixed grid wavelength division multiplexing (WDM) network recovery) of a fixed-grid Wavelength Division Multiplexing (WDM)
in which media (spectrum) and signal are jointly considered. network in which media (spectrum) and signal are jointly considered.
This document defines the framework for a GMPLS-based control of This document defines the framework for a GMPLS-based control of
flexi-grid enabled dense wavelength division multiplexing (DWDM) flexi-grid enabled Dense Wavelength Division Multiplexing (DWDM)
networks (in the scope defined by ITU-T layered Optical Transport networks (in the scope defined by ITU-T layered Optical Transport
Networks [G.872]), as well as a set of associated control plane Networks [G.872]), as well as a set of associated control-plane
requirements. An important design consideration relates to the requirements. An important design consideration relates to the
decoupling of the management of the optical spectrum resource and the decoupling of the management of the optical spectrum resource and the
client signals to be transported. client signals to be transported.
2. Terminology 2. Terminology
Further terminology specific to flexi-grid networks can be found in Further terminology specific to flexi-grid networks can be found in
Section 3.2. Section 3.2.
2.1. Requirements Language 2.1. Requirements Language
skipping to change at page 4, line 47 skipping to change at page 5, line 38
2.2. Abbreviations 2.2. Abbreviations
FS: Frequency Slot FS: Frequency Slot
FSC: Fiber-Switch Capable FSC: Fiber-Switch Capable
LSR: Label Switching Router LSR: Label Switching Router
NCF: Nominal Central Frequency NCF: Nominal Central Frequency
OCC: Optical Channel Carrier
OCh: Optical Channel OCh: Optical Channel
OCh-P: Optical Channel Payload OCh-P: Optical Channel Payload
OTN: Optical Transport Network OTN: Optical Transport Network
OTSi: Optical Tributary Signal OTSi: Optical Tributary Signal
OTSiG: OTSi Group is a set of OTSi OTSiG: OTSi Group is a set of OTSi
OCC: Optical Channel Carrier
PCE: Path Computation Element PCE: Path Computation Element
ROADM: Reconfigurable Optical Add/Drop Multiplexer
ROADM: Reconfigurable Optical Add-Drop Multiplexer
SSON: Spectrum-Switched Optical Network SSON: Spectrum-Switched Optical Network
SWG: Slot Width Granularity SWG: Slot Width Granularity
3. Overview of Flexi-grid Networks 3. Overview of Flexi-Grid Networks
3.1. Flexi-grid in the Context of OTN 3.1. Flexi-Grid in the Context of OTN
[G.872] describes, from a network level, the functional architecture [G.872] describes, from a network level, the functional architecture
of an OTN. It is decomposed into independent layer networks with of an OTN. It is decomposed into independent-layer networks with
client/layer relationships among them. A simplified view of the OTN client/layer relationships among them. A simplified view of the OTN
layers is shown in Figure 1. layers is shown in Figure 1.
+----------------+ +----------------+
| Digital Layer | | Digital Layer |
+----------------+ +----------------+
| Signal Layer | | Signal Layer |
+----------------+ +----------------+
| Media Layer | | Media Layer |
+----------------+ +----------------+
Figure 1: Generic OTN Overview Figure 1: Generic OTN Overview
In the OTN layering context, the media layer is the server layer of In the OTN layering context, the media layer is the server layer of
the optical signal layer. The optical signal is guided to its the optical signal layer. The optical signal is guided to its
destination by the media layer by means of a network media channel. destination by the media layer by means of a network media channel.
In the media layer, switching is based on a frequency slot. In the media layer, switching is based on a frequency slot.
In this scope, this document uses the term flexi-grid enabled DWDM In this scope, this document uses the term "flexi-grid enabled DWDM
network to refer to a network in which switching is based on network" to refer to a network in which switching is based on
frequency slots defined using the flexible grid, and covers mainly frequency slots defined using the flexible grid. This document
the Media Layer as well as the required adaptations from the Signal mainly covers the media layer, as well as the required adaptations
layer. The present document is thus focused on the control and from the signal layer. The present document is thus focused on the
management of the media layer. control and management of the media layer.
3.2. Flexi-grid Terminology 3.2. Flexi-Grid Terminology
This section presents the definition of the terms used in flexi-grid This section presents the definitions of the terms used in flexi-grid
networks. More detail about these terms can be found in the ITU-T networks. More details about these terms can be found in ITU-T
Recommendations [G.694.1], [G.872]), [G.870], [G.8080], and Recommendations [G.694.1], [G.872], [G.870], [G.8080], and
[G.959.1-2013]. [G.959.1-2013].
Where appropriate, this documents also uses terminology and Where appropriate, this document also uses terminology and
lexicography from [RFC4397]. lexicography from [RFC4397].
3.2.1. Frequency Slots 3.2.1. Frequency Slots
This subsection is focused on the frequency slot and related terms. This subsection is focused on the frequency slot and related terms.
o Frequency Slot [G.694.1]: The frequency range allocated to a slot o Frequency Slot [G.694.1]: The frequency range allocated to a slot
within the flexible grid and unavailable to other slots. A within the flexible grid and unavailable to other slots. A
frequency slot is defined by its nominal central frequency and its frequency slot is defined by its nominal central frequency and its
slot width. slot width.
o Nominal Central Frequency: Each of the allowed frequencies as per o Nominal Central Frequency: Each of the allowed frequencies as per
the definition of flexible DWDM grid in [G.694.1]. The set of the definition of the flexible DWDM grid in [G.694.1]. The set of
nominal central frequencies can be built using the following nominal central frequencies can be built using the following
expression expression:
f = 193.1 THz + n x 0.00625 THz f = 193.1 THz + n x 0.00625 THz
where 193.1 THz is ITU-T "anchor frequency" for transmission over where 193.1 THz is the ITU-T "anchor frequency" for transmission
the C band, and n is a positive or negative integer including 0. over the C-band and 'n' is a positive or negative integer
including 0.
-5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n -5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n
...+--+--+--+--+--+--+--+--+--+--+- ...+--+--+--+--+--+--+--+--+--+--+-
^ ^
193.1 THz <- anchor frequency 193.1 THz <- anchor frequency
Figure 2: Anchor Frequency and Set of Nominal Central Frequencies Figure 2: Anchor Frequency and Set of Nominal Central Frequencies
o Nominal Central Frequency Granularity: This is the spacing between o Nominal Central Frequency Granularity: The spacing between allowed
allowed nominal central frequencies and it is set to 6.25 GHz nominal central frequencies. It is set to 6.25 GHz [G.694.1].
[G.694.1].
o Slot Width Granularity (SWG): 12.5 GHz, as defined in [G.694.1]. o Slot Width Granularity (SWG): 12.5 GHz, as defined in [G.694.1].
o Slot Width: The slot width determines the "amount" of optical o Slot Width: Determines the "amount" of optical spectrum,
spectrum regardless of its actual "position" in the frequency regardless of its actual "position" in the frequency axis. A slot
axis. A slot width is constrained to be m x SWG (that is, m x width is constrained to be m x SWG (that is, m x 12.5 GHz),
12.5 GHz), where m is an integer greater than or equal to 1. where 'm' is an integer greater than or equal to 1.
Frequency Slot 1 Frequency Slot 2 Frequency Slot 1 Frequency Slot 2
------------- ------------------- ------------- -------------------
| | | | | | | |
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
...--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... ...--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--...
------------- ------------------- ------------- -------------------
^ ^ ^ ^
Slot NCF = 193.1THz Slot NCF = 193.14375 THz Slot NCF = 193.1 THz Slot NCF = 193.14375 THz
Slot width = 25 GHz Slot width = 37.5 GHz Slot width = 25 GHz Slot width = 37.5 GHz
n=0, m=2 n=7, m=3 n = 0, m = 2 n = 7, m = 3
Figure 3: Example Frequency Slots Figure 3: Example Frequency Slots
* The symbol '+' represents the allowed nominal central * The symbol '+' represents the allowed nominal central
frequencies frequencies.
* The '--' represents the nominal central frequency granularity * The '--' represents the nominal central frequency granularity
in units of 6.25 GHz in units of 6.25 GHz.
* The '^' represents the slot nominal central frequency * The '^' represents the slot nominal central frequency.
* The number on the top of the '+' symbol represents the 'n' in * The number on the top of the '+' symbol represents the 'n' in
the frequency calculation formula. the frequency calculation formula.
* The nominal central frequency is 193.1 THz when n equals to * The nominal central frequency is 193.1 THz when n equals zero.
zero.
o Effective Frequency Slot [G.870]: The effective frequency slot of o Effective Frequency Slot [G.870]: That part of the frequency slots
a media channel is that part of the frequency slots of the filters of the filters along the media channel that is common to all of
along the media channel that is common to all of the filters' the filters' frequency slots. Note that both the terms "frequency
frequency slots. Note that both the Frequency Slot and Effective slot" and "effective frequency slot" are applied locally.
Frequency Slot are local terms.
o Figure 4 shows the effect of combining two filters along a o Figure 4 shows the effect of combining two filters along a
channel. The combination of frequency slot 1 and frequency slot 2 channel. The combination of Frequency Slot 1 and Frequency Slot 2
applied to the media channel is effective frequency slot shown. applied to the media channel is the effective frequency slot
shown.
Frequency Slot 1 Frequency Slot 1
------------- -------------
| | | |
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--...
Frequency Slot 2 Frequency Slot 2
------------------- -------------------
| | | |
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--...
=============================================== ===============================================
Effective Frequency Slot Effective Frequency Slot
------------- -------------
| | | |
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11
..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--...
Figure 4: Effective Frequency Slot Figure 4: Effective Frequency Slot
3.2.2. Media Layer Elements 3.2.2. Media-Layer Elements
o Media Element: A media element directs an optical signal or o Media Element: A media element directs an optical signal or
affects the properties of an optical signal. It does not modify affects the properties of an optical signal. It does not modify
the properties of the information that has been modulated to the properties of the information that has been modulated to
produce the optical signal [G.870]. Examples of media elements produce the optical signal [G.870]. Examples of media elements
include fibers, amplifiers, filters, and switching matrices. include fibers, amplifiers, filters, and switching matrices.
o Media Channel Matrixes: The media channel matrix provides flexible o Media Channel Matrix: The media channel matrix provides flexible
connectivity for the media channels. That is, it represents a connectivity for the media channels. That is, it represents a
point of flexibility where relationships between the media ports point of flexibility where relationships between the media ports
at the edge of a media channel matrix may be created and broken. at the edge of a media channel matrix may be created and broken.
The relationship between these ports is called a matrix channel. The relationship between these ports is called a "matrix channel".
(Network) Media Channels are switched in a Media Channel Matrix. (Network) media channels are switched in a media channel matrix.
3.2.3. Media Channels 3.2.3. Media Channels
This section defines concepts such as (Network) Media Channel; the This section defines concepts such as the (network) media channel;
mapping to GMPLS constructs (i.e., LSP) is detailed in Section 4. the mapping to GMPLS constructs (i.e., LSP) is detailed in Section 4.
o Media Channel: A media association that represents both the o Media Channel: A media association that represents both the
topology (i.e., path through the media) and the resource topology (i.e., path through the media) and the resource
(frequency slot) that it occupies. As a topological construct, it (frequency slot) that it occupies. As a topological construct, it
represents a frequency slot (an effective frequency slot) represents a frequency slot (an effective frequency slot)
supported by a concatenation of media elements (fibers, supported by a concatenation of media elements (fibers,
amplifiers, filters, switching matrices...). This term is used to amplifiers, filters, switching matrices...). This term is used to
identify the end-to-end physical layer entity with its identify the end-to-end physical-layer entity with its
corresponding (one or more) frequency slots local at each link corresponding (one or more) frequency slots local at each link
filters. filter.
o Network Media Channel: [G.870] defines the Network Media Channel o Network Media Channel: Defined in [G.870] as a media channel that
as a media channel that transports a single OTSi, defined next. transports a single OTSi (defined in the next subsection).
3.2.4. Optical Tributary Signals 3.2.4. Optical Tributary Signals
o Optical Tributary Signal (OTSi) [G.959.1-2013]: The optical signal o Optical Tributary Signal (OTSi): The optical signal that is placed
that is placed within a network media channel for transport across within a network media channel for transport across the optical
the optical network. This may consist of a single modulated network. This may consist of a single modulated optical carrier
optical carrier or a group of modulated optical carriers or or a group of modulated optical carriers or subcarriers. To
subcarriers. To provide a connection between the OTSi source and provide a connection between the OTSi source and the OTSi sink,
the OTSi sink the optical signal must be assigned to a network the optical signal must be assigned to a network media channel
media channel. (see also [G.959.1-2013]).
o OTSi Group (OTSiG): The set of OTSi that are carried by a group of o OTSi Group (OTSiG): The set of OTSi that are carried by a group of
network media channels. Each OTSi is carried by one network media network media channels. Each OTSi is carried by one network media
channel. From a management perspective it SHOULD be possible to channel. From a management perspective, it SHOULD be possible to
manage both the OTSiG and a group of Network Media Channels as manage both the OTSiG and a group of network media channels as
single entities. single entities.
3.2.5. Composite Media Channels 3.2.5. Composite Media Channels
o It is possible to construct an end-to-end media channel as a o It is possible to construct an end-to-end media channel as a
composite of more than one network media channels. A composite composite of more than one network media channel. A composite
media channel carries a group of OTSi (i.e., OTSiG). Each OTSi is media channel carries a group of OTSi (i.e., OTSiG). Each OTSi is
carried by one network media channel. This group of OTSi are carried by one network media channel. This OTSiG is carried over
carried over a single fibre. a single fiber.
o In this case, the effective frequency slots may be contiguous o In this case, the effective frequency slots may be contiguous
(i.e., there is no spectrum between them that can be used for (i.e., there is no spectrum between them that can be used for
other media channels) or non-contiguous. other media channels) or non-contiguous.
o It is not currently envisaged that such composite media channels o It is not currently envisaged that such composite media channels
may be constructed from slots carried on different fibers whether may be constructed from slots carried on different fibers whether
those fibers traverse the same hop-by-hop path through the network those fibers traverse the same hop-by-hop path through the network
or not. or not.
o Furthermore, it is not considered likely that a media channel may o Furthermore, it is not considered likely that a media channel may
be constructed from a different variation of slot composition on be constructed from a different variation of slot composition on
each hop. That is, the slot composition (i.e., the group of OTSi each hop. That is, the slot composition (i.e., the group of OTSi
carried by the composite media channel) must be the same from one carried by the composite media channel) must be the same from one
end to the other of the media channel even if the specific slot end of the media channel to the other, even if the specific slot
for each OTSi and the spacing among slots may vary hop by hop. for each OTSi and the spacing among slots may vary hop by hop.
o How the signal is carried across such groups of network media o How the signal is carried across such groups of network media
channels is out of scope for this document. channels is out of scope for this document.
3.3. Hierarchy in the Media Layer 3.3. Hierarchy in the Media Layer
In summary, the concept of frequency slot is a logical abstraction In summary, the concept of the frequency slot is a logical
that represents a frequency range, while the media layer represents abstraction that represents a frequency range, while the media layer
the underlying media support. Media Channels are media associations, represents the underlying media support. Media channels are media
characterized by their (effective) frequency slot, respectively; and associations, characterized by their respective (effective) frequency
media channels are switched in media channel matrixes. From the slots, and media channels are switched in media channel matrices.
control and management perspective, a media channel can be logically From the control and management perspective, a media channel can be
split into network media channels. logically split into network media channels.
In Figure 5, a media channel has been configured and dimensioned to In Figure 5, a media channel has been configured and dimensioned to
support two network media channels, each of them carrying one OTSi. support two network media channels, each of them carrying one OTSi.
Media Channel Frequency Slot Media Channel Frequency Slot
+-------------------------------X------------------------------+ +-------------------------------X------------------------------+
| | | |
| Frequency Slot Frequency Slot | | Frequency Slot Frequency Slot |
| +-----------X-----------+ +----------X-----------+ | | +-----------X-----------+ +----------X-----------+ |
| | OTSi | | OTSi | | | | OTSi | | OTSi | |
| | o | | o | | | | o | | o | |
| | | | | | | | | | | | | | | |
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12
--+---+---+---+---+---+---+---+---+---+---+---+--+---+---+---+---+-- --+---+---+---+---+---+---+---+---+---+---+---+--+---+---+---+---+--
<- Network Media Channel-> <- Network Media Channel-> <- Network Media Channel -> <- Network Media Channel ->
<------------------------ Media Channel -----------------------> <------------------------ Media Channel ----------------------->
X - Frequency Slot Central Frequency X - Frequency Slot Central Frequency
o - Signal Central Frequency o - Signal Central Frequency
Figure 5: Example of Media Channel / Network Media Channels and Figure 5: Example of Media Channel, Network Media Channels, and
Associated Frequency Slots Associated Frequency Slots
3.4. Flexi-grid Layered Network Model 3.4. Flexi-Grid Layered Network Model
In the OTN layered network, the network media channel transports a In the OTN layered network, the network media channel transports a
single OTSi (see Figure 6) single OTSi (see Figure 6).
| OTSi | | OTSi |
O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O
| | | |
| Channel Port Network Media Channel Channel Port | | Channel Port Network Media Channel Channel Port |
O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O
| | | |
+--------+ +-----------+ +--------+ +--------+ +-----------+ +--------+
| \ (1) | | (1) | | (1) / | | \ (1) | | (1) | | (1) / |
| \----|-----------------|-----------|-------------------|-----/ | | \----|-----------------|-----------|-------------------|-----/ |
+--------+ Link Channel +-----------+ Link Channel +--------+ +--------+ Link Channel +-----------+ Link Channel +--------+
Media Channel Media Channel Media Channel Media Channel Media Channel Media Channel
Matrix Matrix Matrix Matrix Matrix Matrix
The symbol (1) indicates a Matrix Channel The symbol (1) indicates a matrix channel
Figure 6: Simplified Layered Network Model Figure 6: Simplified Layered Network Model
Note that a particular example of OTSi is the OCh-P. Figure 7 shows Note that a particular example of OTSi is the OCh-P. Figure 7 shows
this specific example as defined in G.805 [G.805]. this specific example as defined in G.805 [G.805].
OCh AP Trail (OCh) OCh AP OCh AP Trail (OCh) OCh AP
O- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O O- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O
| | | |
--- OCh-P OCh-P --- --- OCh-P OCh-P ---
skipping to change at page 11, line 43 skipping to change at page 13, line 27
|Channel Port Network Media Channel Channel Port | |Channel Port Network Media Channel Channel Port |
O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O
| | | |
+--------+ +-----------+ +---------+ +--------+ +-----------+ +---------+
| \ (1) | OCh-P LC | (1) | OCh-P LC | (1) / | | \ (1) | OCh-P LC | (1) | OCh-P LC | (1) / |
| \----|-----------------|-----------|-----------------|------/ | | \----|-----------------|-----------|-----------------|------/ |
+--------+ Link Channel +-----------+ Link Channel +---------+ +--------+ Link Channel +-----------+ Link Channel +---------+
Media Channel Media Channel Media Channel Media Channel Media Channel Media Channel
Matrix Matrix Matrix Matrix Matrix Matrix
The symbol (1) indicates a Matrix Channel The symbol (1) indicates a matrix channel
"LC" indicates a link connection
Figure 7: Layered Network Model According to G.805 Figure 7: Layered Network Model According to G.805
3.4.1. DWDM Flexi-grid Enabled Network Element Models 3.4.1. DWDM Flexi-Grid Enabled Network Element Models
A flexible grid network is constructed from subsystems that include A flexible-grid network is constructed from subsystems that include
WDM links, tunable transmitters, and receivers, (i.e, media elements WDM links, tunable transmitters, and receivers (i.e., media elements
including media layer switching elements that are media matrices) as including media-layer switching elements that are media matrices), as
well as electro-optical network elements. This is just the same as well as electro-optical network elements. This is just the same as
in a fixed grid network except that each element has flexible grid in a fixed-grid network, except that each element has flexible-grid
characteristics. characteristics.
As stated in Clause 7 of [G.694.1] the flexible DWDM grid has a As stated in Clause 7 of [G.694.1], the flexible DWDM grid has a
nominal central frequency granularity of 6.25 GHz and a slot width nominal central frequency granularity of 6.25 GHz and a slot width
granularity of 12.5 GHz. However, devices or applications that make granularity of 12.5 GHz. However, devices or applications that make
use of the flexible grid might not be capable of supporting every use of the flexible grid might not be capable of supporting every
possible slot width or position. In other words, applications may be possible slot width or position. In other words, applications may be
defined where only a subset of the possible slot widths and positions defined where only a subset of the possible slot widths and positions
are required to be supported. For example, an application could be is required to be supported. For example, an application could be
defined where the nominal central frequency granularity is 12.5 GHz defined where the nominal central frequency granularity is 12.5 GHz
(by only requiring values of n that are even) and that only requires (by only requiring values of n that are even) and where slot widths
slot widths as a multiple of 25 GHz (by only requiring values of m are a multiple of 25 GHz (by only requiring values of m that are
that are even). even).
4. GMPLS Applicability 4. GMPLS Applicability
The goal of this section is to provide an insight into the The goal of this section is to provide an insight into the
application of GMPLS as a control mechanism in flexi-grid networks. application of GMPLS as a control mechanism in flexi-grid networks.
Specific control plane requirements for the support of flexi-grid Specific control-plane requirements for the support of flexi-grid
networks are covered in Section 5. This framework is aimed at networks are covered in Section 5. This framework is aimed at
controlling the media layer within the OTN hierarchy, and controlling controlling the media layer within the OTN hierarchy and controlling
the required adaptations of the signal layer. This document also the required adaptations of the signal layer. This document also
defines the term Spectrum-Switched Optical Network (SSON) to refer to defines the term "Spectrum-Switched Optical Network" (SSON) to refer
a Flexi-grid enabled DWDM network that is controlled by a GMPLS/PCE to a flexi-grid enabled DWDM network that is controlled by a GMPLS or
control plane. PCE control plane.
This section provides a mapping of the ITU-T G.872 architectural This section provides a mapping of the ITU-T G.872 architectural
aspects to GMPLS/Control plane terms, and considers the relationship aspects to GMPLS and control-plane terms and also considers the
between the architectural concept/construct of media channel and its relationship between the architectural concept or construct of a
control plane representations (e.g., as a TE link, as defined in media channel and its control-plane representations (e.g., as a TE
[RFC3945]). link, as defined in [RFC3945]).
4.1. General Considerations 4.1. General Considerations
The GMPLS control of the media layer deals with the establishment of The GMPLS control of the media layer deals with the establishment of
media channels that are switched in media channel matrices. GMPLS media channels that are switched in media channel matrices. GMPLS
labels are used to locally represent the media channel and its labels are used to locally represent the media channel and its
associated frequency slot. Network media channels are considered a associated frequency slot. Network media channels are considered a
particular case of media channels when the end points are particular case of media channels when the endpoints are transceivers
transceivers (that is, source and destination of an OTSi). (that is, the source and destination of an OTSi).
4.2. Consideration of TE Links 4.2. Consideration of TE Links
From a theoretical / abstract point of view, a fiber can be modeled From a theoretical point of view, a fiber can be modeled as having a
as having a frequency slot that ranges from minus infinity to plus frequency slot that ranges from minus infinity to plus infinity.
infinity. This representation helps understand the relationship This representation helps us understand the relationship between
between frequency slots and ranges. frequency slots and ranges.
The frequency slot is a local concept that applies within a component The frequency slot is a local concept that applies within a component
or element. When applied to a media channel, we are referring to its or element. When applied to a media channel, we are referring to its
effective frequency slot as defined in [G.872]. effective frequency slot as defined in [G.872].
The association sequence of the three components (i.e., a filter, a The association sequence of the three components (i.e., a filter, a
fiber, and a filter), is a media channel in its most basic form. fiber, and a filter) is a media channel in its most basic form. From
From the control plane perspective this may modeled as a (physical) the control-plane perspective, this may be modeled as a (physical)
TE-link with a contiguous optical spectrum. This can be represented TE link with a contiguous optical spectrum. This can be represented
by saying that the portion of spectrum available at time t0 depends by saying that the portion of spectrum available at time t0 depends
on which filters are placed at the ends of the fiber and how they on which filters are placed at the ends of the fiber and how they
have been configured. Once filters are placed we have a one-hop have been configured. Once filters are placed, we have a one-hop
media channel. In practical terms, associating a fiber with the media channel. In practical terms, associating a fiber with the
terminating filters determines the usable optical spectrum. terminating filters determines the usable optical spectrum.
---------------+ +-----------------+ ---------------+ +-----------------
| | | |
+--------+ +--------+ +--------+ +--------+
| | | | +--------- | | | | +---------
---o| =============================== o--| ---o| =============================== o--|
| | Fiber | | | --\ /-- | | Fiber | | | --\ /--
---o| | | o--| \/ ---o| | | o--| \/
| | | | | /\ | | | | | /\
---o| =============================== o--| --/ \-- ---o| =============================== o--| --/ \--
| Filter | | Filter | | | Filter | | Filter | |
| | | | +--------- | | | | +---------
+--------+ +--------+ +--------+ +--------+
| | | |
|------- Basic Media Channel ---------| |------- Basic Media Channel ---------|
---------------+ +-----------------+ ---------------+ +-----------------
--------+ +-------- --------+ +--------
|--------------------------------------| |--------------------------------------|
LSR | TE link | LSR LSR | TE link | LSR
|--------------------------------------| |--------------------------------------|
+--------+ +-------- --------+ +--------
Figure 8: (Basic) Media Channel and TE Link Figure 8: (Basic) Media Channel and TE Link
Additionally, when a cross-connect for a specific frequency slot is Additionally, when a cross-connect for a specific frequency slot is
considered, the resulting media support of joining basic media considered, the resulting media support of joining basic media
channels is still a media channel, i.e., a longer association channels is still a media channel, i.e., a longer association
sequence of media elements and its effective frequency slot. In sequence of media elements and its effective frequency slot. In
other words, It is possible to "concatenate" several media channels other words, it is possible to "concatenate" several media channels
(e.g., patch on intermediate nodes) to create a single media channel. (e.g., patch on intermediate nodes) to create a single media channel.
The architectural construct resulting of the association sequence of The architectural construct resulting from the association sequence
basic media channels and media layer matrix cross-connects can be of basic media channels and media-layer matrix cross-connects can be
represented as (i.e., corresponds to) a Label Switched Path (LSP) represented as (i.e., corresponds to) a Label Switched Path (LSP)
from a control plane perspective. from a control-plane perspective.
----------+ +------------------------------+ +--------- ----------+ +------------------------------+ +---------
| | | | | | | |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | | | +----------+ | | | | | | | | +----------+ | | | |
--o| ========= o--| |--o ========= o-- --o| ========= o--| |--o ========= o--
| | Fiber | | | --\ /-- | | | Fiber | | | | Fiber | | | --\ /-- | | | Fiber | |
--o| | | o--| \/ |--o | | o-- --o| | | o--| \/ |--o | | o--
| | | | | /\ | | | | | | | | | | /\ | | | | |
--o| ========= o--***********|--o ========= o-- --o| ========= o--***********|--o ========= o--
|Filter| |Filter| | | |Filter| |Filter| |Filter| |Filter| | | |Filter| |Filter|
| | | | | | | | | | | | | | | |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | | | | | | |
<- Basic Media -> <- Matrix -> <- Basic Media-> <- Basic Media -> <- Matrix -> <- Basic Media ->
|Channel| Channel |Channel| |Channel| Channel |Channel|
----------+ +------------------------------+ +--------- ----------+ +------------------------------+ +---------
<-------------------- Media Channel ----------------> <-------------------- Media Channel ---------------->
------+ +---------------+ +------ ------+ +---------------+ +------
|------------------| |------------------| |------------------| |------------------|
LSR | TE link | LSR | TE link | LSR LSR | TE link | LSR | TE link | LSR
|------------------| |------------------| |------------------| |------------------|
------+ +---------------+ +------ ------+ +---------------+ +------
Figure 9: Extended Media Channel Figure 9: Extended Media Channel
Furthermore, if appropriate, the media channel can also be Furthermore, if appropriate, the media channel can also be
represented as a TE link or Forwarding Adjacency (FA) [RFC4206], represented as a TE link or Forwarding Adjacency (FA) [RFC4206],
augmenting the control plane network model. augmenting the control-plane network model.
----------+ +------------------------------+ +--------- ----------+ +------------------------------+ +---------
| | | | | | | |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | | | +----------+ | | | | | | | | +----------+ | | | |
--o| ========= o--| |--o ========= o-- --o| ========= o--| |--o ========= o--
| | Fiber | | | --\ /-- | | | Fiber | | | | Fiber | | | --\ /-- | | | Fiber | |
--o| | | o--| \/ |--o | | o-- --o| | | o--| \/ |--o | | o--
| | | | | /\ | | | | | | | | | | /\ | | | | |
--o| ========= o--***********|--o ========= o-- --o| ========= o--***********|--o ========= o--
skipping to change at page 15, line 28 skipping to change at page 17, line 32
----------+ +------------------------------+ +--------- ----------+ +------------------------------+ +---------
<------------------------ Media Channel -----------> <------------------------ Media Channel ----------->
------+ +----- ------+ +-----
|------------------------------------------------------| |------------------------------------------------------|
LSR | TE link | LSR LSR | TE link | LSR
|------------------------------------------------------| |------------------------------------------------------|
------+ +----- ------+ +-----
Figure 10: Extended Media Channel / TE Link / FA Figure 10: Extended Media Channel TE Link or FA
4.3. Consideration of LSPs in Flexi-grid 4.3. Consideration of LSPs in Flexi-Grid
The flexi-grid LSP is a control plane representation of a media The flexi-grid LSP is a control-plane representation of a media
channel. Since network media channels are media channels, an LSP may channel. Since network media channels are media channels, an LSP may
also be the control plane representation of a network media channel also be the control-plane representation of a network media channel
(without considering the adaptation functions). From a control plane (without considering the adaptation functions). From a control-plane
perspective, the main difference (regardless of the actual effective perspective, the main difference (regardless of the actual effective
frequency slot which may be dimensioned arbitrarily) is that the LSP frequency slot, which may be dimensioned arbitrarily) is that the LSP
that represents a network media channel also includes the endpoints that represents a network media channel also includes the endpoints
(transceivers), including the cross-connects at the ingress and (transceivers), including the cross-connects at the ingress and
egress nodes. The ports towards the client can still be represented egress nodes. The ports towards the client can still be represented
as interfaces from the control plane perspective. as interfaces from the control-plane perspective.
Figure 11 shows an LSP routed between 3 nodes. The LSP is terminated Figure 11 shows an LSP routed between three nodes. The LSP is
before the optical matrix of the ingress and egress nodes and can terminated before the optical matrix of the ingress and egress nodes
represent a media channel. This case does not (and cannot) represent and can represent a media channel. This case does not (and cannot)
a network media channel because it does not include (and cannot represent a network media channel because it does not include (and
include) the transceivers. cannot include) the transceivers.
---------+ +--------------------------------+ +-------- ---------+ +--------------------------------+ +--------
| | | | | | | |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | | | +----------+ | | | | | | | | +----------+ | | | |
-o| ========= o---| |---o ========= o- -o| ========= o---| |---o ========= o-
| | Fiber | | | --\ /-- | | | Fiber | | | | Fiber | | | --\ /-- | | | Fiber | |
-o|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>o- -o|>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>o-
| | | | | /\ | | | | | | | | | | /\ | | | | |
-o| ========= o---***********|---o ========= o- -o| ========= o---***********|---o ========= o-
skipping to change at page 16, line 27 skipping to change at page 18, line 33
| | | | | | | |
---------+ +--------------------------------+ +-------- ---------+ +--------------------------------+ +--------
>>>>>>>>>>>>>>>>>>>>>>>>>>>> LSP >>>>>>>>>>>>>>>>>>>>>>>> >>>>>>>>>>>>>>>>>>>>>>>>>>>> LSP >>>>>>>>>>>>>>>>>>>>>>>>
-----+ +---------------+ +----- -----+ +---------------+ +-----
|------------------| |----------------| |------------------| |----------------|
LSR | TE link | LSR | TE link | LSR LSR | TE link | LSR | TE link | LSR
|------------------| |----------------| |------------------| |----------------|
-----+ +---------------+ +----- -----+ +---------------+ +-----
Figure 11: Flex-grid LSP Representing a Media Channel that Starts at Figure 11: Flexi-Grid LSP Representing a Media Channel That Starts at
the Filter of the Outgoing Interface of the Ingress LSR and ends at the Filter of the Outgoing Interface of the Ingress LSR and Ends at
the Filter of the Incoming Interface of the Egress LSR the Filter of the Incoming Interface of the Egress LSR
In Figure 12 a Network Media Channel is represented as terminated at In Figure 12, a network media channel is represented as terminated at
the network side of the transceivers. This is commonly named an the network side of the transceivers. This is commonly named an
OTSi-trail connection. OTSi-trail connection.
|--------------------- Network Media Channel ----------------------| |--------------------- Network Media Channel ----------------------|
+----------------------+ +----------------------+ +----------------------+ +----------------------+
| | | | | |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | +----+ | | | | +----+ | |OTSi | | +----+ | | | | +----+ | |OTSi
OTSi| o-| |-o | +-----+ | o-| |-o |sink OTSi| o-| |-o | +-----+ | o-| |-o |sink
skipping to change at page 17, line 35 skipping to change at page 20, line 5
LSP LSP
<------------------------------------------------------------------> <------------------------------------------------------------------>
+-----+ +--------+ +-----+ +-----+ +--------+ +-----+
o--- | |-------------------| |----------------| |---o o--- | |-------------------| |----------------| |---o
| LSR | TE link | LSR | TE link | LSR | | LSR | TE link | LSR | TE link | LSR |
| |-------------------| |----------------| | | |-------------------| |----------------| |
+-----+ +--------+ +-----+ +-----+ +--------+ +-----+
Figure 12: LSP Representing a Network Media Channel (OTSi Trail) Figure 12: LSP Representing a Network Media Channel (OTSi Trail)
In a third case, a Network Media Channel is terminated on the Filter In a third case, a network media channel is terminated on the filter
ports of the Ingress and Egress nodes. This is named in G.872 as ports of the ingress and egress nodes. This is defined in G.872 as
OTSi Network Connection. As can be seen from the figures, there is an OTSi Network Connection. As can be seen from the figures, from a
no difference from a GMPLS modelling perspective between these cases, GMPLS modeling perspective there is no difference between these
but they are shown as distinct examples to highlight the differences cases, but they are shown as distinct examples to highlight the
in the data plane. differences in the data plane.
|--------------------- Network Media Channel --------------------| |--------------------- Network Media Channel --------------------|
+------------------------+ +------------------------+ +------------------------+ +------------------------+
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| | +----+ | | | | +----+ | | | | +----+ | | | | +----+ | |
| o-| |-o | +------+ | o-| |-o | | o-| |-o | +------+ | o-| |-o |
| | | | | =====+-+ +-+=====| | | | | | | | | | | =====+-+ +-+=====| | | | | |
T-o******o********************************************************O-R T-o******o********************************************************O-R
| | |\ /| | | | | | | | |\ /| | | | | |\ /| | | | | | | | |\ /| | |
skipping to change at page 18, line 32 skipping to change at page 20, line 39
LSP LSP
LSP LSP
<--------------------------------------------------------------> <-------------------------------------------------------------->
+-----+ +--------+ +-----+ +-----+ +--------+ +-----+
o--| |--------------------| |-------------------| |--o o--| |--------------------| |-------------------| |--o
| LSR | TE link | LSR | TE link | LSR | | LSR | TE link | LSR | TE link | LSR |
| |--------------------| |-------------------| | | |--------------------| |-------------------| |
+-----+ +--------+ +-----+ +-----+ +--------+ +-----+
Figure 13: LSP Representing a Network Media Channel (OTSi Network Figure 13: LSP Representing a Network Media Channel
Connection) (OTSi Network Connection)
Applying the notion of hierarchy at the media layer, by using the LSP Applying the notion of hierarchy at the media layer, by using the LSP
as an FA (i.e., by using hierarchical LSPs), the media channel as an FA (i.e., by using hierarchical LSPs), the media channel
created can support multiple (sub-)media channels. created can support multiple (sub-)media channels.
+--------------+ +--------------+ +--------------+ +--------------+
| Media Channel| TE | Media Channel| Virtual TE | Media Channel| TE | Media Channel| Virtual TE
| | link | | link | | link | | link
| Matrix |o- - - - - - - - - - o| Matrix |o- - - - - - | Matrix |o- - - - - - - - - - o| Matrix |o- - - - - -
+--------------+ +--------------+ +--------------+ +--------------+
| +---------+ | | +---------+ |
| | Media | | | | Media | |
|o----| Channel |-----o| |o----| Channel |-----o|
| | | |
| Matrix | | Matrix |
+---------+ +---------+
Figure 14: Topology View with TE Link / FA Figure 14: Topology View with TE Link or FA
Note that there is only one media layer switch matrix (one Note that there is only one media-layer switch matrix (one
implementation is a FlexGrid ROADM) in SSON, while a signal layer LSP implementation is a flexi-grid ROADM) in SSON, while a signal-layer
(Network Media Channel) is established mainly for the purpose of LSP (network media channel) is established mainly for the purpose of
management and control of individual optical signals. Signal layer management and control of individual optical signals. Signal-layer
LSPs with the same attributes (such as source and destination) can be LSPs with the same attributes (such as source and destination) can be
grouped into one media-layer LSP (media channel): this has advantages grouped into one media-layer LSP (media channel); this has advantages
in spectral efficiency (reduce guard band between adjacent OChs in in spectral efficiency (reduced guard band between adjacent OChs in
one FSC channel) and LSP management. However, assuming some network one FSC channel) and LSP management. However, assuming that some
elements perform signal layer switching in an SSON, there must be network elements perform signal-layer switching in an SSON, there
enough guard band between adjacent OTSis in any media channel to must be enough guard band between adjacent OTSi in any media channel
compensate for the filter concatenation effects and other effects to compensate for the filter concatenation effects and other effects
caused by signal layer switching elements. In such a situation, the caused by signal-layer switching elements. In such a situation, the
separation of the signal layer from the media layer does not bring separation of the signal layer from the media layer does not bring
any benefit in spectral efficiency or in other aspects, but makes the any benefit in spectral efficiency or in other aspects, and it makes
network switch and control more complex. If two OTSis must be the network switching and control more complex. If two OTSi must be
switched to different ports, it is better to carry them by diferent switched to different ports, it is better to carry them via different
FSC channels, and the media layer switch is enough in this scenario. FSC channels, and the media-layer switch is enough in this scenario.
As discussed in Section 3.2.5, a media channel may be constructed As discussed in Section 3.2.5, a media channel may be constructed
from a compsite of network media channels. This may be achieved in from a composite of network media channels. This may be achieved in
two ways using LSPs. These mechanisms may be compared to the two ways using LSPs. These mechanisms may be compared to the
techniques used in GMPLS to support inverse multiplexing in Time techniques used in GMPLS to support inverse multiplexing in Time
Division Multiplexing (TDM) networks and in OTN [RFC4606], [RFC6344], Division Multiplexing (TDM) networks and in OTN [RFC4606] [RFC6344]
and [RFC7139]. [RFC7139].
o In the first case, a single LSP may be established in the control o In the first case, a single LSP may be established in the control
plane. The signaling messages include information for all of the plane. The signaling messages include information for all of the
component network media channels that make up the composite media component network media channels that make up the composite media
channel. channel.
o In the second case, each component network media channel is o In the second case, each component network media channel is
established using a separate control plane LSP, and these LSPs are established using a separate control-plane LSP, and these LSPs are
associated within the control plane so that the end points may see associated within the control plane so that the endpoints may see
them as a single media channel. them as a single media channel.
4.4. Control Plane Modeling of Network Elements 4.4. Control-Plane Modeling of Network Elements
Optical transmitters and receivers may have different tunability Optical transmitters and receivers may have different tunability
constraints, and media channel matrixes may have switching constraints, and media channel matrices may have switching
restrictions. Additionally, a key feature of their implementation is restrictions. Additionally, a key feature of their implementation is
their highly asymmetric switching capability which is described in their highly asymmetric switching capability, which is described in
detail in [RFC6163]. Media matrices include line side ports that are detail in [RFC6163]. Media matrices include line-side ports that are
connected to DWDM links, and tributary side input/output ports that connected to DWDM links and tributary-side input/output ports that
can be connected to transmitters/receivers. can be connected to transmitters/receivers.
A set of common constraints can be defined: A set of common constraints can be defined:
o Slot widths: The minimum and maximum slot width. o Slot widths: The minimum and maximum slot width.
o Granularity: The optical hardware may not be able to select o Granularity: The optical hardware may not be able to select
parameters with the lowest granularity (e.g., 6.25 GHz for nominal parameters with the lowest granularity (e.g., 6.25 GHz for nominal
central frequencies or 12.5 GHz for slot width granularity). central frequencies or 12.5 GHz for slot width granularity).
o Available frequency ranges: The set or union of frequency ranges o Available frequency ranges: The set or union of frequency ranges
that have not been allocated (i.e., are available). The relative that have not been allocated (i.e., are available). The relative
grouping and distribution of available frequency ranges in a fiber grouping and distribution of available frequency ranges in a fiber
is usually referred to as "fragmentation". are usually referred to as "fragmentation".
o Available slot width ranges: The set or union of slot width ranges o Available slot width ranges: The set or union of slot width ranges
supported by media matrices. It includes the following supported by media matrices. It includes the following
information. information:
* Slot width threshold: The minimum and maximum Slot Width * Slot width threshold: The minimum and maximum slot width
supported by the media matrix. For example, the slot width supported by the media matrix. For example, the slot width
could be from 50GHz to 200GHz. could be from 50 GHz to 200 GHz.
* Step granularity: The minimum step by which the optical filter * Step granularity: The minimum step by which the optical filter
bandwidth of the media matrix can be increased or decreased. bandwidth of the media matrix can be increased or decreased.
This parameter is typically equal to slot width granularity This parameter is typically equal to slot width granularity
(i.e., 12.5GHz) or integer multiples of 12.5GHz. (i.e., 12.5 GHz) or integer multiples of 12.5 GHz.
4.5. Media Layer Resource Allocation Considerations 4.5. Media Layer Resource Allocation Considerations
A media channel has an associated effective frequency slot. From the A media channel has an associated effective frequency slot. From the
perspective of network control and management, this effective slot is perspective of network control and management, this effective slot is
seen as the "usable" end-to-end frequency slot. The establishment of seen as the "usable" end-to-end frequency slot. The establishment of
an LSP is related to the establishment of the media channel and the an LSP is related to the establishment of the media channel and the
configuration of the effective frequency slot. configuration of the effective frequency slot.
A "service request" is characterized (at a minimum) by its required A "service request" is characterized (at a minimum) by its required
effective slot width. This does not preclude that the request may effective slot width. This does not preclude the request from adding
add additional constraints such as also imposing the nominal central additional constraints, such as also imposing the nominal central
frequency. A given effective frequency slot may be requested for the frequency. A given effective frequency slot may be requested for the
media channel in the control plane LSP setup messages, and a specific media channel in the control-plane LSP setup messages, and a specific
frequency slot can be requested on any specific hop of the LSP setup. frequency slot can be requested on any specific hop of the LSP setup.
Regardless of the actual encoding, the LSP setup message specifies a Regardless of the actual encoding, the LSP setup message specifies a
minimum effective frequency slot width that needs to be fulfilled in minimum effective frequency slot width that needs to be fulfilled in
order to successful establish the requsted LSP. order to successfully establish the requested LSP.
An effective frequency slot must equally be described in terms of a An effective frequency slot must equally be described in terms of a
central nominal frequency and its slot width (in terms of usable central nominal frequency and its slot width (in terms of usable
spectrum of the effective frequency slot). That is, it must be spectrum of the effective frequency slot). That is, it must be
possible to determine the end-to-end values of the n and m possible to determine the end-to-end values of the n and m
parameters. We refer to this by saying that the "effective frequency parameters. We refer to this by saying that the "effective frequency
slot of the media channel/LSP must be valid". slot of the media channel or LSP must be valid".
In GMPLS the requested effective frequency slot is represented to the In GMPLS, the requested effective frequency slot is represented to
TSpec present in the RSVP-TE Path message, and the effective the TSpec present in the RSVP-TE Path message, and the effective
frequency slot is mapped to the FlowSpec carried in the RSVP-TE Resv frequency slot is mapped to the FlowSpec carried in the RSVP-TE Resv
message. message.
In GMPLS-controlled systems, the switched element corresponds to the In GMPLS-controlled systems, the switched element corresponds to the
'label'. In flexi-grid where the switched element is a frequency 'label'. In flexi-grid, the switched element is a frequency slot,
slot, the label represents a frequency slot. In consequence, the and the label represents a frequency slot. Consequently, the label
label in flexi-grid conveys the necessary information to obtain the in flexi-grid conveys the necessary information to obtain the
frequency slot characteristics (i.e, central frequency and slot frequency slot characteristics (i.e., central frequency and slot
width: the n and m parameters). The frequency slot is locally width: the n and m parameters). The frequency slot is locally
identified by the label. identified by the label.
The local frequency slot may change at each hop, given hardware The local frequency slot may change at each hop, given hardware
constraints and capabilities (e.g., a given node might not support constraints and capabilities (e.g., a given node might not support
the finest granularity). This means that the values of n and m may the finest granularity). This means that the values of n and m may
change at each hop. As long as a given downstream node allocates change at each hop. As long as a given downstream node allocates
enough optical spectrum, m can be different along the path. This enough optical spectrum, m can be different along the path. This
covers the issue where media matrices can have different slot width covers the issue where media matrices can have different slot width
granularities. Such variations in the local value of m will appear granularities. Such variations in the local value of m will appear
in the allocated label that encodes the frequency slot as well as the in the allocated label that encodes the frequency slot as well as in
in the FlowSpec that describes the flow. the FlowSpec that describes the flow.
Different operational modes can be considered. For Routing and Different operational modes can be considered. For Routing and
Spectrum Assignment (RSA) with explicit label control, and for Spectrum Assignment (RSA) with explicit label control, and for
Routing and Distributed Spectrum Assignment (R+DSA), the GMPLS Routing and Distributed Spectrum Assignment (R+DSA), the GMPLS
signaling procedures are similar to those described in section 4.1.3 signaling procedures are similar to those described in Section 4.1.3
of [RFC6163] for Routing and Wavelength Assignment (RWA) and for of [RFC6163] for Routing and Wavelength Assignment (RWA) and for
Routing and Distributed Wavelength Assignment (R+DWA). The main Routing and Distributed Wavelength Assignment (R+DWA). The main
difference is that the label set specifies the available nominal difference is that the label set specifies the available nominal
central frequencies that meet the slot width requirements of the LSP. central frequencies that meet the slot width requirements of the LSP.
The intermediate nodes use the control plane to collect the The intermediate nodes use the control plane to collect the
acceptable central frequencies that meet the slot width requirement acceptable central frequencies that meet the slot width requirement
hop by hop. The tail-end node also needs to know the slot width of hop by hop. The tail-end node also needs to know the slot width of
an LSP to assign the proper frequency resource. Except for an LSP to assign the proper frequency resource. Except for
identifying the resource (i.e., fixed wavelength for WSON, and identifying the resource (i.e., fixed wavelength for WSON, and
frequency resource for flexible grids), the other signaling frequency resource for flexible grids), the other signaling
requirements (e.g., unidirectional or bidirectional, with or without requirements (e.g., unidirectional or bidirectional, with or without
converters) are the same as for WSON as described in section 6.1 of converters) are the same as for WSON as described in Section 6.1 of
[RFC6163]. [RFC6163].
Regarding how a GMPLS control plane can assign n and m hop-by-hop Regarding how a GMPLS control plane can assign n and m hop by hop
along the path of an LSP, different cases can apply: along the path of an LSP, different cases can apply:
a. n and m can both change. It is the effective frequency slot that a. n and m can both change. It is the effective frequency slot that
matters, it needs to remain valid along the path. matters; it needs to remain valid along the path.
b. m can change, but n needs to remain the same along the path. b. m can change, but n needs to remain the same along the path.
This ensures that the nominal central frequency stays the same, This ensures that the nominal central frequency stays the same,
but the width of the slot can vary along the path. Again, the but the width of the slot can vary along the path. Again, the
important thing is that the effective frequency slot remains important thing is that the effective frequency slot remains
valid and satisfies the requested parameters along the whole path valid and satisfies the requested parameters along the whole path
of the LSP. of the LSP.
c. n and m need to be unchanging along the path. This ensures that c. n and m need to be unchanging along the path. This ensures that
the frequency slot is well-known end-to-end, and is a simple way the frequency slot is well known from end to end and is a simple
to ensure that the effective frequency slot remains valid for the way to ensure that the effective frequency slot remains valid for
whole LSP. the whole LSP.
d. n can change, but m needs to remain the same along the path. d. n can change, but m needs to remain the same along the path.
This ensures that the effective frequency slot remains valid, but This ensures that the effective frequency slot remains valid but
allows the frequency slot to be moved within the spectrum from also allows the frequency slot to be moved within the spectrum
hop to hop. from hop to hop.
The selection of a path that ensures n and m continuity can be The selection of a path that ensures n and m continuity can be
delegated to a dedicated entity such as a Path Computation Element delegated to a dedicated entity such as a Path Computation Element
(PCE). Any constraint (including frequency slot and width (PCE). Any constraint (including frequency slot and width
granularities) can be taken into account during path computation. granularities) can be taken into account during path computation.
Alternatively, A PCE can compute a path leaving the actual frequency Alternatively, A PCE can compute a path, leaving the actual frequency
slot assignment to be done, for example, with a distributed slot assignment to be done, for example, with a distributed
(signaling) procedure: (signaling) procedure:
o Each downstream node ensures that m is >= requested_m. o Each downstream node ensures that m is >= requested_m.
o A downstream node cannot foresee what an upstream node will o A downstream node cannot foresee what an upstream node will
allocate. A way to ensure that the effective frequency slot is allocate. A way to ensure that the effective frequency slot is
valid along the length of the LSP is to ensure that the same value valid along the length of the LSP is to ensure that the same value
of n is allocated at each hop. By forcing the same value of n we of n is allocated at each hop. By forcing the same value of n, we
avoid cases where the effective frequency slot of the media avoid cases where the effective frequency slot of the media
channel is invalid (that is, the resulting frequency slot cannot channel is invalid (that is, the resulting frequency slot cannot
be described by its n and m parameters). be described by its n and m parameters).
o This may be too restrictive, since a node (or even a centralized/ o This may be too restrictive, since a node (or even a centralized/
combined RSA entity) may be able to ensure that the resulting end- combined RSA entity) may be able to ensure that the resulting
to-end effective frequency slot is valid even if n varies locally. end-to-end effective frequency slot is valid, even if n varies
That means, the effective frequency slot that characterizes the locally. That means that the effective frequency slot that
media channel from end to end is consistent and is determined by characterizes the media channel from end to end is consistent and
its n and m values, but that the effective frequency slot and is determined by its n and m values but that the effective
those values are logical (i.e., do not map direct to the frequency slot and those values are logical (i.e., do not map
physically assigned spectrum) in the sense that they are the "direct" to the physically assigned spectrum) in the sense that
result of the intersection of locally-assigned frequency slots they are the result of the intersection of locally assigned
applicable at local components (such as filters) each of which may frequency slots applicable at local components (such as filters),
have assigned different frequency slots. each of which may have different frequency slots assigned to them.
For Figure 15 the effective slot is made valid by ensuring that the
minimum m is greater than the requested m. The effective slot
(intersection) is the lowest m (bottleneck).
For Figure 16 the effective slot is made valid by ensuring that it is As shown in Figure 15, the effective slot is made valid by ensuring
valid at each hop in the upstream direction. The intersection needs that the minimum m is greater than the requested m. The effective
to be computed because invalid slots could result otherwise. slot (intersection) is the lowest m (bottleneck).
C B A C B A
|Path(m_req) | ^ | |Path(m_req) | ^ |
|---------> | # | |---------> | # |
| | # ^ | | # ^
-^--------------^----------------#----------------#-- -^--------------^----------------#----------------#--
Effective # # # # Effective # # # #
FS n, m # . . . . . . .#. . . . . . . . # . . . . . . . .# <-fixed FS n, m # . . . . . . .#. . . . . . . . # . . . . . . . .# <-fixed
# # # # n # # # # n
-v--------------v----------------#----------------#--- -v--------------v----------------#----------------#---
| | # v | | # v
| | # Resv | | | # Resv |
| | v <------ | | | v <------ |
| | |FlowSpec(n, m_a)| | | |FlowSpec(n, m_a)|
| | <--------| | | | <--------| |
| | FlowSpec (n, | | | FlowSpec(n, |
<--------| min(m_a, m_b)) <--------| min(m_a, m_b))
FlowSpec (n, | FlowSpec(n, |
min(m_a, m_b, m_c)) min(m_a, m_b, m_c))
m_a, m_b, m_c: Selected frequency slot widths m_a, m_b, m_c: Selected frequency slot widths
Figure 15: Distributed Allocation with Different m and Same n Figure 15: Distributed Allocation with Different m and Same n
In Figure 16, the effective slot is made valid by ensuring that it is
valid at each hop in the upstream direction. The intersection needs
to be computed; otherwise, invalid slots could result.
C B A C B A
|Path(m_req) ^ | | |Path(m_req) ^ | |
|---------> # | | |---------> # | |
| # ^ ^ | # ^ ^
-^-------------#----------------#-----------------#-------- -^-------------#----------------#-----------------#--------
Effective # # # # Effective # # # #
FS n, m # # # # FS n, m # # # #
# # # # # # # #
-v-------------v----------------#-----------------#-------- -v-------------v----------------#-----------------#--------
| | # v | | # v
| | # Resv | | | # Resv |
| | v <------ | | | v <------ |
| | |FlowSpec(n_a, m_a) | | |FlowSpec(n_a, m_a)
| | <--------| | | | <--------| |
| | FlowSpec (FSb [intersect] FSa) | | FlowSpec(FSb [intersect] FSa)
<--------| <--------|
FlowSpec ([intersect] FSa,FSb,FSc) FlowSpec([intersect] FSa,FSb,FSc)
n_a: Selected nominal central frequencyfr by node A n_a: Selected nominal central frequency by node A
m_a: Selected frequency slot widths by node A m_a: Selected frequency slot widths by node A
FSa, FSb, FSc: Frequency slot at each hop A, B, C FSa, FSb, FSc: Frequency slot at each hop A, B, C
Figure 16: Distributed Allocation with Different m and Different n Figure 16: Distributed Allocation with Different m and Different n
Note, when a media channel is bound to one OTSi (i.e., is a network Note that when a media channel is bound to one OTSi (i.e., is a
media channel), the effective FS must be the one of the OTSi. The network media channel), the effective FS must be the frequency slot
media channel setup by the LSP may contain the effective FS of the of the OTSi. The media channel set up by the LSP may contain the
network media channel effective FS. This is an endpoint property: effective FS of the network media channel effective FS. This is an
the egress and ingress have to constrain the Effective FS to be the endpoint property; the egress and ingress have to constrain the
OTSi Effective FS. effective FS to be the OTSi effective FS.
4.6. Neighbor Discovery and Link Property Correlation 4.6. Neighbor Discovery and Link Property Correlation
There are potential interworking problems between fixed-grid DWDM and There are potential interworking problems between fixed-grid DWDM
flexi-grid DWDM nodes. Additionally, even two flexi-grid nodes may nodes and flexi-grid DWDM nodes. Additionally, even two flexi-grid
have different grid properties, leading to link property conflict nodes may have different grid properties, leading to link property
with resulting limited interworking. conflict and resulting in limited interworking.
Devices or applications that make use of the flexi-grid might not be Devices or applications that make use of flexi-grid might not be able
able to support every possible slot width. In other words, different to support every possible slot width. In other words, different
applications may be defined where each supports a different grid applications may be defined where each supports a different grid
granularity. In this case the link between two optical nodes with granularity. In this case, the link between two optical nodes with
different grid granularities must be configured to align with the different grid granularities must be configured to align with the
larger of both granularities. Furthermore, different nodes may have larger of both granularities. Furthermore, different nodes may have
different slot-width tuning ranges. different slot width tuning ranges.
In summary, in a DWDM Link between two nodes, at least the following In summary, in a DWDM link between two nodes, at a minimum, the
properties need to be negotiated: following properties need to be negotiated:
o Grid capability (channel spacing) - Between fixed-grid and flexi- o Grid capability (channel spacing) - Between fixed-grid and
grid nodes. flexi-grid nodes.
o Grid granularity - Between two flexi-grid nodes. o Grid granularity - Between two flexi-grid nodes.
o Slot width tuning range - Between two flexi-grid nodes. o Slot width tuning range - Between two flexi-grid nodes.
4.7. Path Computation / Routing and Spectrum Assignment (RSA) 4.7. Path Computation, Routing and Spectrum Assignment (RSA)
In WSON, if there is no (available) wavelength converter in an In WSON, if there is no (available) wavelength converter in an
optical network, an LSP is subject to the "wavelength continuity optical network, an LSP is subject to the "wavelength continuity
constraint" (see section 4 of [RFC6163]). Similarly in flexi-grid, constraint" (see Section 4 of [RFC6163]). Similarly, in flexi-grid,
if the capability to shift or convert an allocated frequency slot is if the capability to shift or convert an allocated frequency slot is
absent, the LSP is subject to the "Spectrum Continuity Constraint". absent, the LSP is subject to the "spectrum continuity constraint".
Because of the limited availability of wavelength/spectrum converters Because of the limited availability of spectrum converters (in what
(in what is called a "sparse translucent optical network") the is called a "sparse translucent optical network"), the spectrum
wavelength/spectrum continuity constraint always has to be continuity constraint always has to be considered. When available,
considered. When available, information regarding spectrum information regarding spectrum conversion capabilities at the optical
conversion capabilities at the optical nodes may be used by RSA nodes may be used by RSA mechanisms.
mechanisms.
The RSA process determines a route and frequency slot for an LSP. The RSA process determines a route and frequency slot for an LSP.
Hence, when a route is computed the spectrum assignment process (SA) Hence, when a route is computed, the spectrum assignment process
determines the central frequency and slot width based on the slot determines the central frequency and slot width based on the
width and available central frequencies information of the following:
transmitter and receiver, and utilizing the available frequency
ranges information and available slot width ranges of the links that o the requested slot width
the route traverses.
o the information regarding the transmitter and receiver
capabilities, including the availability of central frequencies
and their slot width granularity
o the information regarding available frequency slots (frequency
ranges) and available slot widths of the links traversed along
the route
4.7.1. Architectural Approaches to RSA 4.7.1. Architectural Approaches to RSA
Similar to RWA for fixed grids [RFC6163], different ways of Similar to RWA for fixed grids [RFC6163], different ways of
performing RSA in conjunction with the control plane can be performing RSA in conjunction with the control plane can be
considered. The approaches included in this document are provided considered. The approaches included in this document are provided
for reference purposes only: other possible options could also be for reference purposes only; other possible options could also be
deployed. deployed.
Note that all of these models allow the concept of a composite media Note that all of these models allow the concept of a composite media
channel supported by a single control plane LSP or by a set of channel supported by a single control-plane LSP or by a set of
associated LSPs. associated LSPs.
4.7.1.1. Combined RSA (R&SA) 4.7.1.1. Combined RSA (R&SA)
In this case, a computation entity performs both routing and In this case, a computation entity performs both routing and
frequency slot assignment. The computation entity needs access to frequency slot assignment. The computation entity needs access to
detailed network information, e.g., the connectivity topology of the detailed network information, e.g., the connectivity topology of the
nodes and links, the available frequency ranges on each link, the nodes and links, available frequency ranges on each link, and node
node capabilities, etc. capabilities.
The computation entity could reside on a dedicated PCE server, in the The computation entity could reside on a dedicated PCE server, in
provisioning application that requests the service, or on the ingress the provisioning application that requests the service, or on the
node. ingress node.
4.7.1.2. Separated RSA (R+SA) 4.7.1.2. Separated RSA (R+SA)
In this case, routing computation and frequency slot assignment are In this case, routing computation and frequency slot assignment are
performed by different entities. The first entity computes the performed by different entities. The first entity computes the
routes and provides them to the second entity. The second entity routes and provides them to the second entity. The second entity
assigns the frequency slot. assigns the frequency slot.
The first entity needs the connectivity topology to compute the The first entity needs the connectivity topology to compute the
proper routes. The second entity needs information about the proper routes. The second entity needs information about the
available frequency ranges of the links and the capabilities of the available frequency ranges of the links and the capabilities of the
nodes in order to assign the spectrum. nodes in order to assign the spectrum.
4.7.1.3. Routing and Distributed SA (R+DSA) 4.7.1.3. Routing and Distributed SA (R+DSA)
In this case an entity computes the route, but the frequency slot In this case, an entity computes the route, but the frequency slot
assignment is performed hop-by-hop in a distributed way along the assignment is performed hop by hop in a distributed way along the
route. The available central frequencies which meet the spectrum route. The available central frequencies that meet the spectrum
continuity constraint need to be collected hop-by-hop along the continuity constraint need to be collected hop by hop along the
route. This procedure can be implemented by the GMPLS signaling route. This procedure can be implemented by the GMPLS signaling
protocol. protocol.
4.8. Routing and Topology Dissemination 4.8. Routing and Topology Dissemination
In the case of the combined RSA architecture, the computation entity In the case of the combined RSA architecture, the computation entity
needs the detailed network information, i.e., connectivity topology, needs the detailed network information, i.e., connectivity topology,
node capabilities, and available frequency ranges of the links. node capabilities, and available frequency ranges of the links.
Route computation is performed based on the connectivity topology and Route computation is performed based on the connectivity topology and
node capabilities, while spectrum assignment is performed based on node capabilities, while spectrum assignment is performed based on
the available frequency ranges of the links. The computation entity the available frequency ranges of the links. The computation entity
may get the detailed network information via the GMPLS routing may get the detailed network information via the GMPLS routing
protocol. protocol.
For WSON, the connectivity topology and node capabilities can be For WSON, the connectivity topology and node capabilities can be
advertised by the GMPLS routing protocol (refer to section 6.2 of advertised by the GMPLS routing protocol (refer to Section 6.2 of
[RFC6163]. Except for wavelength-specific availability information, [RFC6163]). Except for wavelength-specific availability information,
the information for flexi-grid is the same as for WSON and can the information for flexi-grid is the same as for WSON and can
equally be distributed by the GMPLS routing protocol. equally be distributed by the GMPLS routing protocol.
This section analyses the necessary changes on link information This section analyzes the necessary changes to link information
brought by flexible grids. required by flexible grids.
4.8.1. Available Frequency Ranges/Slots of DWDM Links 4.8.1. Available Frequency Ranges (Frequency Slots) of DWDM Links
In the case of flexible grids, channel central frequencies span from In the case of flexible grids, channel central frequencies span from
193.1 THz towards both ends of the C band spectrum with 6.25 GHz 193.1 THz towards both ends of the C-band spectrum with a granularity
granularity. Different LSPs could make use of different slot widths of 6.25 GHz. Different LSPs could make use of different slot widths
on the same link. Hence, the available frequency ranges need to be on the same link. Hence, the available frequency ranges need to be
advertised. advertised.
4.8.2. Available Slot Width Ranges of DWDM Links 4.8.2. Available Slot Width Ranges of DWDM Links
The available slot width ranges need to be advertised in combination The available slot width ranges need to be advertised in combination
with the available frequency ranges, in order that the computing with the available frequency ranges, so that the computing entity can
entity can verify whether an LSP with a given slot width can be set verify whether an LSP with a given slot width can be set up or not.
up or not. This is constrained by the available slot width ranges of This is constrained by the available slot width ranges of the media
the media matrix. Depending on the availability of the slot width matrix. Depending on the availability of the slot width ranges, it
ranges, it is possible to allocate more spectrum than strictly needed is possible to allocate more spectrum than what is strictly needed by
by the LSP. the LSP.
4.8.3. Spectrum Management 4.8.3. Spectrum Management
The total available spectrum on a fiber can be described as a The total available spectrum on a fiber can be described as a
resource that can be partitioned. For example, a part of the resource that can be partitioned. For example, a part of the
spectrum could be assigned to a third party to manage, or parts of spectrum could be assigned to a third party to manage, or parts of
the spectrum could be assigned by the operator for different classes the spectrum could be assigned by the operator for different classes
of traffic. This partitioning creates the impression that spectrum of traffic. This partitioning creates the impression that the
is a hierarchy in view of Management and Control Plane: each spectrum is a hierarchy in view of the management plane and the
partition could be itself be partitioned. However, the hierarchy is control plane: each partition could itself be partitioned. However,
created purely within a management system: it defines a hierarchy of the hierarchy is created purely within a management system; it
access or management rights, but there is no corresponding resource defines a hierarchy of access or management rights, but there is no
hierarchy within the fiber. corresponding resource hierarchy within the fiber.
The end of fiber is a link end and presents a fiber port which The end of the fiber is a link end and presents a fiber port that
represents all of spectrum available on the fiber. Each spectrum represents all of the spectrum available on the fiber. Each spectrum
allocation appears as Link Channel Port (i.e., frequency slot port) allocation appears as a Link Channel Port (i.e., frequency slot port)
within fiber. Thus, while there is a hierarchy of ownership (the within the fiber. Thus, while there is a hierarchy of ownership (the
Link Channel Port and corresponding LSP are located on a fiber and so Link Channel Port and corresponding LSP are located on a fiber and
associated with a fiber port) there is no continued nesting hierarchy therefore are associated with a fiber port), there is no continued
of frequency slots within larger frequency slots. In its way, this nesting hierarchy of frequency slots within larger frequency slots.
mirrors the fixed grid behavior where a wavelength is associated with In its way, this mirrors the fixed-grid behavior where a wavelength
a port/fiber, but cannot be subdivided even though it is a partition is associated with a fiber port but cannot be subdivided even though
of the total spectrum available on the fiber. it is a partition of the total spectrum available on the fiber.
4.8.4. Information Model 4.8.4. Information Model
This section defines an information model to describe the data that This section defines an information model to describe the data that
represents the capabilities and resources available in an flexi-grid represents the capabilities and resources available in a flexi-grid
network. It is not a data model and is not intended to limit any network. It is not a data model and is not intended to limit any
protocol solution such as an encoding for an IGP. For example, protocol solution such as an encoding for an IGP. For example,
information required for routing/path selection may be the set of information required for routing and path selection may be the set of
available nominal central frequencies from which a frequency slot of available nominal central frequencies from which a frequency slot of
the required width can be allocated. A convenient encoding for this the required width can be allocated. A convenient encoding for this
information is for further study in an IGP encoding document. information is left for further study in an IGP encoding document.
Fixed DWDM grids can also be described via suitable choices of slots Fixed DWDM grids can also be described via suitable choices of slots
in a flexible DWDM grid. However, devices or applications that make in a flexible DWDM grid. However, devices or applications that make
use of the flexible grid may not be capable of supporting every use of the flexible grid may not be capable of supporting every
possible slot width or central frequency position. Thus, the possible slot width or central frequency position. Thus, the
information model needs to enable: information model needs to enable:
exchange of information to enable RSA in a flexi-grid network o the exchange of information to enable RSA in a flexi-grid network
representation of a fixed grid device participating in a flexi-
grid network
full interworking of fixed and flexible grid devices within the o the representation of a fixed-grid device participating in a
same network flexi-grid network
interworking of flexgrid devices with different capabilities. o full interworking of fixed-grid and flexible-grid devices within
the same network
The information model is represented using Routing Backus-Naur Format o interworking of flexible-grid devices with different capabilities
(RBNF) as defined in [RFC5511]. The information model is represented using the Routing Backus-Naur
Format (RBNF) as defined in [RFC5511].
<Available Spectrum> ::= <Available Spectrum> ::=
<Available Frequency Range-List> <Available Frequency Range-List>
<Available NCFs> <Available NCFs>
<Available Slot Widths> <Available Slot Widths>
where where
<Available Frequency Range-List> ::= <Available Frequency Range-List> ::=
<Available Frequency Range> [<Available Frequency Range-List>] <Available Frequency Range> [<Available Frequency Range-List>]
<Available Frequency Range> ::= <Available Frequency Range> ::=
( <Start NCF> <End NCF> ) | ( <Start NCF> <End NCF> ) |
<FS defined by (n, m) containing contiguous available NCFs> <FS defined by (n, m) containing contiguous available NCFs>
and and
<Available NCFs> ::= <Available NCFs> ::=
<Available NCF Granularity> [<Offset>] <Available NCF Granularity> [<Offset>]
-- Subset of supported n values given by p x n + q -- Subset of supported n values given by p x n + q
-- where p is a positive integer -- where p is a positive integer
-- and q (offset) belongs to 0,..,p-1. -- and q (offset) belongs to 0,..,p-1.
and and
<Available Slot Widths> ::= <Available Slot Widths> ::=
<Available Slot Width Granularity> <Available Slot Width Granularity>
<Min Slot Width> <Min Slot Width>
-- given by j x 12.5GHz, with j a positive integer -- given by j x 12.5 GHz, with j a positive integer
<Max Slot Width> <Max Slot Width>
-- given by k x 12.5GHz, with k a positive integer (k >= j) -- given by k x 12.5 GHz, with k a positive integer (k >= j)
Figure 17: Routing Information Model Figure 17: Routing Information Model
5. Control Plane Requirements 5. Control-Plane Requirements
The control of a flexi-grid networks places additional requirements The control of flexi-grid networks places additional requirements on
on the GMPLS protocols. This section summarizes those requirements the GMPLS protocols. This section summarizes those requirements for
for signaling and routing. signaling and routing.
5.1. Support for Media Channels 5.1. Support for Media Channels
The control plane SHALL be able to support Media Channels, The control plane SHALL be able to support media channels,
characterized by a single frequency slot. The representation of the characterized by a single frequency slot. The representation of the
Media Channel in the GMPLS control plane is the so-called flexi-grid media channel in the GMPLS control plane is the so-called "flexi-grid
LSP. Since network media channels are media channels, an LSP may LSP". Since network media channels are media channels, an LSP may
also be the control plane representation of a network media channel. also be the control-plane representation of a network media channel.
Consequently, the control plane will also be able to support network
Consequently, the control plane will also be able to support Network media channels.
Media Channels.
5.1.1. Signaling 5.1.1. Signaling
The signaling procedure SHALL be able to configure the nominal The signaling procedure SHALL be able to configure the nominal
central frequency (n) of a flexi-grid LSP. central frequency (n) of a flexi-grid LSP.
The signaling procedure SHALL allow a flexible range of values for The signaling procedure SHALL allow a flexible range of values for
the frequency slot width (m) parameter. Specifically, the control the frequency slot width (m) parameter. Specifically, the control
plane SHALL allow setting up a media channel with frequency slot plane SHALL allow setting up a media channel with frequency slot
width (m) ranging from a minimum of m=1 (12.5GHz) to a maximum of the width (m) ranging from a minimum of m = 1 (12.5 GHz) to a maximum of
entire C-band (the wavelength range 1530 nm to 1565 nm, which the entire C-band (the wavelength range 1530 nm to 1565 nm, which
corresponds to the amplification range of erbium doped fiber corresponds to the amplification range of erbium-doped fiber
amplifiers) with a slot width granularity of 12.5GHz. amplifiers) with a slot width granularity of 12.5 GHz.
The signaling procedure SHALL be able to configure the minimum width The signaling procedure SHALL be able to configure the minimum width
(m) of a flexi-grid LSP. In addition, the signaling procedure SHALL (m) of a flexi-grid LSP. In addition, the signaling procedure SHALL
be able to configure local frequency slots. be able to configure local frequency slots.
The control plane architecture SHOULD allow for the support of L-band The control-plane architecture SHOULD allow for the support of the
(the wavelength range 1565 nm to 1625 nm) and S-band (the wavelength L-band (the wavelength range 1565 nm to 1625 nm) and the S-band (the
range 1460 nm to 1530 nm). wavelength range 1460 nm to 1530 nm).
The signalling process SHALL be able to collect the local frequency The signaling process SHALL be able to collect the local frequency
slot assigned at each link along the path. slot assigned at each link along the path.
The signaling procedures SHALL support all of the RSA architectural The signaling procedures SHALL support all of the RSA architectural
models (R&SA, R+SA, and R+DSA) within a single set of protocol models (R&SA, R+SA, and R+DSA) within a single set of protocol
objects although some objects may only be applicable within one of objects, although some objects may only be applicable within one of
the models. the models.
5.1.2. Routing 5.1.2. Routing
The routing protocol will support all functions as described in The routing protocol will support all functions described in
[RFC4202] and extend them to a flexi-grid data plane. [RFC4202] and extend them to a flexi-grid data plane.
The routing protocol SHALL distribute sufficient information to The routing protocol SHALL distribute sufficient information to
compute paths to enable the signaling procedure to establish LSPs as compute paths to enable the signaling procedure to establish LSPs as
described in the previous sections. This includes, at a minimum the described in the previous sections. This includes, at a minimum, the
data described by the Information Model in Figure 17. data described by the information model in Figure 17.
The routing protocol SHALL update its advertisements of available The routing protocol SHALL update its advertisements of available
resources and capabilities as the usage of resources in the network resources and capabilities as the usage of resources in the network
varies with the establishment or tear-down of LSPs. These updates varies with the establishment or teardown of LSPs. These updates
SHOULD be amenable to damping and thresholds as in other traffic SHOULD be amenable to damping and thresholds as in other traffic
engineering routing advertisements. engineering routing advertisements.
The routing protocol SHALL support all of the RSA architectural The routing protocol SHALL support all of the RSA architectural
models (R&SA, R+SA, and R+DSA) without any configuration or change of models (R&SA, R+SA, and R+DSA) without any configuration or change of
behavior. Thus, the routing protocols SHALL be agnostic to the behavior. Thus, the routing protocols SHALL be agnostic to the
computation and signaling model that is in use. computation and signaling model that is in use.
5.2. Support for Media Channel Resizing 5.2. Support for Media Channel Resizing
The signaling procedures SHALL allow resizing (grow or shrink) the The signaling procedures SHALL allow the resizing (growing or
frequency slot width of a media channel/network media channel. The shrinking) of the frequency slot width of a media channel or network
resizing MAY imply resizing the local frequency slots along the path media channel. The resizing MAY imply resizing the local frequency
of the flexi-grid LSP. slots along the path of the flexi-grid LSP.
The routing protocol SHALL update its advertisements of available The routing protocol SHALL update its advertisements of available
resources and capabilities as the usage of resources in the network resources and capabilities as the usage of resources in the network
varies with the resizing of LSP. These updates SHOULD be amenable to varies with the resizing of LSPs. These updates SHOULD be amenable
damping and thresholds as in other traffic engineering routing to damping and thresholds as in other traffic engineering routing
advertisements. advertisements.
5.3. Support for Logical Associations of Multiple Media Channels 5.3. Support for Logical Associations of Multiple Media Channels
A set of media channels can be used to transport signals that have a A set of media channels can be used to transport signals that have a
logical association between them. The control plane architecture logical association between them. The control-plane architecture
SHOULD allow multiple media channels to be logically associated. The SHOULD allow multiple media channels to be logically associated. The
control plane SHOULD allow the co-routing of a set of media channels control plane SHOULD allow the co-routing of a set of media channels
that are logically associated. that are logically associated.
5.4. Support for Composite Media Channels 5.4. Support for Composite Media Channels
As described in Section 3.2.5 and Section 4.3, a media channel may be As described in Sections 3.2.5 and 4.3, a media channel may be
composed of multiple network media channels. composed of multiple network media channels.
The signaling procedures SHOULD include support for signaling a The signaling procedures SHOULD include support for signaling a
single control plane LSP that includes information about multiple single control-plane LSP that includes information about multiple
network media channels that will comprise the single compound media network media channels that will comprise the single compound media
channel. channel.
The signaling procedures SHOULD include a mechanism to associate The signaling procedures SHOULD include a mechanism to associate
separately signaled control plane LSPs so that the end points may separately signaled control-plane LSPs so that the endpoints may
correlate them into a single compound media channel. correlate them into a single compound media channel.
The signaling procedures MAY include a mechanism to dynamically vary The signaling procedures MAY include a mechanism to dynamically vary
the composition of a composite media channel by allowing network the composition of a composite media channel by allowing network
media channels to be added to or removed from the whole. media channels to be added to or removed from the whole.
The routing protocols MUST provide sufficient information for the The routing protocols MUST provide sufficient information for the
computation of paths and slots for composite media channels using any computation of paths and slots for composite media channels using any
of the three RSA architectural models (R&SA, R+SA, and R+DSA). of the three RSA architectural models (R&SA, R+SA, and R+DSA).
5.5. Support for Neighbor Discovery and Link Property Correlation 5.5. Support for Neighbor Discovery and Link Property Correlation
The control plane MAY include support for neighbor discovery such The control plane MAY include support for neighbor discovery such
that an flexi-grid network can be constructed in a "plug-and-play" that a flexi-grid network can be constructed in a "plug-and-play"
manner. Note, however, that in common operational practice manner. Note, however, that in common operational practice,
validation processes are used rather than automatic discovery. validation processes are used rather than automatic discovery.
The control plane SHOULD allow the nodes at opposite ends of a link The control plane SHOULD allow the nodes at opposite ends of a link
to correlate the properties that they will apply to the link. Such to correlate the properties that they will apply to the link. Such a
correlation SHOULD include at least the identities of the node and correlation SHOULD include at least the identities of the nodes and
the identities they apply to the link. Other properties such as the the identities that they apply to the link. Other properties, such
link characteristics described for the routing information model in as the link characteristics described for the routing information
Figure 17 SHOULD also be correlated. model in Figure 17, SHOULD also be correlated.
Such neighbor discovery and link property correlation, if provided, Such neighbor discovery and link property correlation, if provided,
MUST be able to operate in both an out-of-band and an out-of-fiber MUST be able to operate in both an out-of-band and an out-of-fiber
control channel. control channel.
6. IANA Considerations 6. Security Considerations
This framework document makes no requests for IANA action.
7. Security Considerations
The control plane and data plane aspects of a flexi-grid system are The control-plane and data-plane aspects of a flexi-grid system are
fundamentally the same as a fixed grid system and there is no fundamentally the same as a fixed-grid system, and there is no
substantial reason to expect the security considerations to be any substantial reason to expect the security considerations to be any
different. different.
A good overview of the security considerations for a GMPLS-based A good overview of the security considerations for a GMPLS-based
control plane can be found in [RFC5920]. control plane can be found in [RFC5920].
[RFC6163] includes a section describing security considerations for [RFC6163] includes a section describing security considerations for
WSON, and it is reasonable to infer that these considerations apply WSON, and it is reasonable to infer that these considerations apply
and may be exacerbated in a flexi-grid SSON system. In particular, and may be exacerbated in a flexi-grid SSON system. In particular,
the detailed and granular information describing a flexi- grid the detailed and granular information describing a flexi-grid network
network and the capabilities of nodes in that network could put and the capabilities of nodes in that network could put stress on the
stress on the routing protocol or the out-of-band control channel routing protocol or the out-of-band control channel used by the
used by the protocol. An attacker might be able to cause small protocol. An attacker might be able to cause small variations in the
variations in the use of the network or the available resources use of the network or the available resources (perhaps by modifying
(perhaps by modifying the environment of a fiber) and so trigger the the environment of a fiber) and so trigger the routing protocol to
routing protocol to make new flooding announcements. This situation make new flooding announcements. This situation is explicitly
is explicitly mitigated in the requirements for the routing protocol mitigated in the requirements for the routing protocol extensions
extensions where it is noted that the protocol must include damping where it is noted that the protocol must include damping and
and configurable thresholds as already exist in the core GMPLS configurable thresholds as already exist in the core GMPLS routing
routing protocols. protocols.
8. Manageability Considerations 7. Manageability Considerations
GMPLS systems already contain a number of management tools. GMPLS systems already contain a number of management tools:
o MIB modules exist to model the control plane protocols and the o MIB modules exist to model the control-plane protocols and the
network elements [RFC4802], [RFC4803], and there is early work to network elements [RFC4802] [RFC4803], and there is early work to
provide similar access through YANG. The features described in provide similar access through YANG. The features described in
these models are currently designed to represent fixed-label these models are currently designed to represent fixed-label
technologies such as optical networks using the fixed grid: technologies such as optical networks using the fixed grid;
extensions may be needed in order to represent bandwidth, extensions may be needed in order to represent bandwidth,
frequency slots, and effective frequency slots in flexi- grid frequency slots, and effective frequency slots in flexi-grid
networks. networks.
o There are protocol extensions within GMPLS signaling to allow o There are protocol extensions within GMPLS signaling to allow
control plane systems to report the presence of faults that affect control-plane systems to report the presence of faults that affect
LSPs [RFC4783], although it must be carefully noted that these LSPs [RFC4783], although it must be carefully noted that these
mechanisms do not constitute an alarm mechanism that could be used mechanisms do not constitute an alarm mechanism that could be used
to rapidly propagate information about faults in a way that would to rapidly propagate information about faults in a way that would
allow the data plane to perform protection switching. These allow the data plane to perform protection switching. These
mechanisms could easily be enhanced with the addition of mechanisms could easily be enhanced with the addition of
technology-specific reasons codes if any are needed. technology-specific reason codes if any are needed.
o The GMPLS protocols, themselves, already include fault detection o The GMPLS protocols, themselves, already include fault detection
and recovery mechanisms (such as the PathErr and Notify messages and recovery mechanisms (such as the PathErr and Notify messages
in RSVP-TE signaling as used by GMPLS [RFC3473]. It is not in RSVP-TE signaling as used by GMPLS [RFC3473]). It is not
anticipated that these mechanisms will need enhancement to support anticipated that these mechanisms will need enhancement to support
flexi-grid although additional reason codes may be needed to flexi-grid, although additional reason codes may be needed to
describe technology-specific error cases. describe technology-specific error cases.
o [RFC7260] describes a framework for the control and configuration o [RFC7260] describes a framework for the control and configuration
of data plane Operations, Administration, and Management (OAM). of data-plane Operations, Administration, and Maintenance (OAM).
It would not be appropriate for the IETF to define or describe It would not be appropriate for the IETF to define or describe
data plane OAM for optical systems, but the framework described in data-plane OAM for optical systems, but the framework described in
RFC 7260 could be used (with minor protocol extensions) to enable RFC 7260 could be used (with minor protocol extensions) to enable
data plane OAM that has been defined by the originators of the data-plane OAM that has been defined by the originators of the
flexi-grid data plane technology (the ITU-T). flexi-grid data-plane technology (the ITU-T).
o The Link Management Protocol [RFC4204] is designed to allow the o The Link Management Protocol (LMP) [RFC4204] is designed to allow
two ends of a network link to coordinate and confirm the the two ends of a network link to coordinate and confirm the
configuration and capabilities that they will apply to the link. configuration and capabilities that they will apply to the link.
This protocol is particularly applicable to optical links where LMP is particularly applicable to optical links, where the
the characteristics of the network devices may considerably affect characteristics of the network devices may considerably affect how
how the link is used and where misconfiguration of mis-fibering the link is used and where misconfiguration or mis-fibering could
could make physical interoperability impossible. LMP could easily make physical interoperability impossible. LMP could easily be
be extended to collect and report information between the end extended to collect and report information between the endpoints
points of links in a flexi-grid network. of links in a flexi-grid network.
9. Authors
Fatai Zhang
Huawei
Huawei Base, Longgang District, Chine
zhangfatai@huawei.com
Xihua Fu
ZTE
ZTE Plaza,No.10,Tangyan South Road, Gaoxin District, China
fu.xihua@zte.com.cn
Daniele Ceccarelli
Ericsson
Via Calda 5, Genova, Italy
daniele.ceccarelli@ericsson.com
Iftekhar Hussain
Infinera
140 Caspian Ct, Sunnyvale, 94089, USA
ihussain@infinera.com
10. Contributing Authors
Adrian Farrel
Old Dog Consulting
adrian@olddog.co.uk
Daniel King
Old Dog Consulting
daniel@olddog.co.uk
Xian Zhang
Huawei
zhang.xian@huawei.com
Cyril Margaria
Juniper Networks
cmargaria@juniper.net
Qilei Wang
ZTE
Ruanjian Avenue, Nanjing, China
wang.qilei@zte.com.cn
Malcolm Betts
ZTE
malcolm.betts@zte.com.cn
Sergio Belotti
Alcatel Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
+39 039 6863033
sergio.belotti@alcatel-lucent.com
Yao Li
Nanjing University
wsliguotou@hotmail.com
Fei Zhang
Huawei
zhangfei7@huawei.com
Lei Wang
wang.lei@bupt.edu.cn
Guoying Zhang
China Academy of Telecom Research
No.52 Huayuan Bei Road, Beijing, China
zhangguoying@ritt.cn
Takehiro Tsuritani
KDDI R&D Laboratories Inc.
2-1-15 Ohara, Fujimino, Saitama, Japan
tsuri@kddilabs.jp
Lei Liu
U.C. Davis, USA
leiliu@ucdavis.edu
Eve Varma
Alcatel-Lucent
+1 732 239 7656
eve.varma@alcatel-lucent.com
Young Lee
Huawei
Jianrui Han
Huawei
Sharfuddin Syed
Infinera
Rajan Rao
Infinera
Marco Sosa
Infinera
Biao Lu
Infinera
Abinder Dhillon
Infinera
Felipe Jimenez Arribas
Telefonica I+D
Andrew G. Malis
Huawei
agmalis@gmail.com
Huub van Helvoort
Hai Gaoming BV
The Neterlands
huubatwork@gmail.com
11. Acknowledgments
The authors would like to thank Pete Anslow for his insights and
clarifications, and to Matt Hartley and Jonas Maertensson for their
reviews.
This work was supported in part by the FP-7 IDEALIST project under
grant agreement number 317999.
12. References
12.1. Normative References 8. References
[G.694.1] International Telecomunications Union, "ITU-T 8.1. Normative References
Recommendation G.694.1, Spectral grids for WDM
applications: DWDM frequency grid", November 2012.
[G.800] International Telecomunications Union, "ITU-T [G.694.1] International Telecommunication Union, "Spectral grids for
Recommendation G.800, Unified functional architecture of WDM applications: DWDM frequency grid", ITU-T
transport networks.", February 2012. Recommendation G.694.1, February 2012,
<https://www.itu.int/rec/T-REC-G.694.1/en>.
[G.805] International Telecomunications Union, "ITU-T [G.800] International Telecommunication Union, "Unified functional
Recommendation G.805, Generic functional architecture of architecture of transport networks", ITU-T
transport networks.", March 2000. Recommendation G.800, February 2012,
<http://www.itu.int/rec/T-REC-G.800/>.
[G.8080] International Telecomunications Union, "ITU-T [G.805] International Telecommunication Union, "Generic functional
Recommendation G.8080/Y.1304, Architecture for the architecture of transport networks", ITU-T
automatically switched optical network", 2012. Recommendation G.805, March 2000,
<https://www.itu.int/rec/T-REC-G.805-200003-I/en>.
[G.870] International Telecomunications Union, "ITU-T [G.8080] International Telecommunication Union, "Architecture for
Recommendation G.870/Y.1352, Terms and definitions for the automatically switched optical network", ITU-T
optical transport networks", November 2012. Recommendation G.8080/Y.1304, February 2012,
<https://www.itu.int/rec/T-REC-G.8080-201202-I/en>.
[G.872] International Telecomunications Union, "ITU-T [G.870] International Telecommunication Union, "Terms and
Recommendation G.872, Architecture of optical transport definitions for optical transport networks", ITU-T
networks, draft v0.16 2012/09 (for discussion)", 2012. Recommendation G.870/Y.1352, October 2012,
<https://www.itu.int/rec/T-REC-G.870/en>.
[G.959.1-2013] [G.872] International Telecommunication Union, "Architecture of
International Telecomunications Union, "Update of ITU-T optical transport networks", ITU-T Recommendation G.872,
Recommendation G.959.1, Optical transport network physical October 2012,
layer interfaces", 2013. <http://www.itu.int/rec/T-REC-G.872-201210-I>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <http://www.rfc-editor.org/info/rfc2119>.
[RFC3945] Mannie, E., Ed., "Generalized Multi-Protocol Label [RFC3945] Mannie, E., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Architecture", RFC 3945, Switching (GMPLS) Architecture", RFC 3945,
DOI 10.17487/RFC3945, October 2004, DOI 10.17487/RFC3945, October 2004,
<http://www.rfc-editor.org/info/rfc3945>. <http://www.rfc-editor.org/info/rfc3945>.
[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions [RFC4202] Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
in Support of Generalized Multi-Protocol Label Switching Extensions in Support of Generalized Multi-Protocol Label
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, Switching (GMPLS)", RFC 4202, DOI 10.17487/RFC4202,
<http://www.rfc-editor.org/info/rfc4202>. October 2005, <http://www.rfc-editor.org/info/rfc4202>.
[RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP) [RFC4206] Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
Hierarchy with Generalized Multi-Protocol Label Switching Hierarchy with Generalized Multi-Protocol Label Switching
(GMPLS) Traffic Engineering (TE)", RFC 4206, (GMPLS) Traffic Engineering (TE)", RFC 4206,
DOI 10.17487/RFC4206, October 2005, DOI 10.17487/RFC4206, October 2005,
<http://www.rfc-editor.org/info/rfc4206>. <http://www.rfc-editor.org/info/rfc4206>.
[RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax
Used to Form Encoding Rules in Various Routing Protocol Used to Form Encoding Rules in Various Routing Protocol
Specifications", RFC 5511, DOI 10.17487/RFC5511, April Specifications", RFC 5511, DOI 10.17487/RFC5511,
2009, <http://www.rfc-editor.org/info/rfc5511>. April 2009, <http://www.rfc-editor.org/info/rfc5511>.
12.2. Informative References 8.2. Informative References
[G.959.1-2013]
International Telecommunication Union, "Optical transport
network physical layer interfaces", Update to ITU-T
Recommendation G.959.1, 2013.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label [RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol- Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473, Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003, DOI 10.17487/RFC3473, January 2003,
<http://www.rfc-editor.org/info/rfc3473>. <http://www.rfc-editor.org/info/rfc3473>.
[RFC4204] Lang, J., Ed., "Link Management Protocol (LMP)", RFC 4204, [RFC4204] Lang, J., Ed., "Link Management Protocol (LMP)", RFC 4204,
DOI 10.17487/RFC4204, October 2005, DOI 10.17487/RFC4204, October 2005,
<http://www.rfc-editor.org/info/rfc4204>. <http://www.rfc-editor.org/info/rfc4204>.
[RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the [RFC4397] Bryskin, I. and A. Farrel, "A Lexicography for the
Interpretation of Generalized Multiprotocol Label Interpretation of Generalized Multiprotocol Label
Switching (GMPLS) Terminology within the Context of the Switching (GMPLS) Terminology within the Context of the
ITU-T's Automatically Switched Optical Network (ASON) ITU-T's Automatically Switched Optical Network (ASON)
Architecture", RFC 4397, DOI 10.17487/RFC4397, February Architecture", RFC 4397, DOI 10.17487/RFC4397,
2006, <http://www.rfc-editor.org/info/rfc4397>. February 2006, <http://www.rfc-editor.org/info/rfc4397>.
[RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- [RFC4606] Mannie, E. and D. Papadimitriou, "Generalized
Protocol Label Switching (GMPLS) Extensions for Multi-Protocol Label Switching (GMPLS) Extensions for
Synchronous Optical Network (SONET) and Synchronous Synchronous Optical Network (SONET) and Synchronous
Digital Hierarchy (SDH) Control", RFC 4606, Digital Hierarchy (SDH) Control", RFC 4606,
DOI 10.17487/RFC4606, August 2006, DOI 10.17487/RFC4606, August 2006,
<http://www.rfc-editor.org/info/rfc4606>. <http://www.rfc-editor.org/info/rfc4606>.
[RFC4783] Berger, L., Ed., "GMPLS - Communication of Alarm [RFC4783] Berger, L., Ed., "GMPLS - Communication of Alarm
Information", RFC 4783, DOI 10.17487/RFC4783, December Information", RFC 4783, DOI 10.17487/RFC4783,
2006, <http://www.rfc-editor.org/info/rfc4783>. December 2006, <http://www.rfc-editor.org/info/rfc4783>.
[RFC4802] Nadeau, T., Ed., Farrel, A., and , "Generalized [RFC4802] Nadeau, T., Ed., Farrel, A., and , "Generalized
Multiprotocol Label Switching (GMPLS) Traffic Engineering Multiprotocol Label Switching (GMPLS) Traffic Engineering
Management Information Base", RFC 4802, Management Information Base", RFC 4802,
DOI 10.17487/RFC4802, February 2007, DOI 10.17487/RFC4802, February 2007,
<http://www.rfc-editor.org/info/rfc4802>. <http://www.rfc-editor.org/info/rfc4802>.
[RFC4803] Nadeau, T., Ed. and A. Farrel, Ed., "Generalized [RFC4803] Nadeau, T., Ed., and A. Farrel, Ed., "Generalized
Multiprotocol Label Switching (GMPLS) Label Switching Multiprotocol Label Switching (GMPLS) Label Switching
Router (LSR) Management Information Base", RFC 4803, Router (LSR) Management Information Base", RFC 4803,
DOI 10.17487/RFC4803, February 2007, DOI 10.17487/RFC4803, February 2007,
<http://www.rfc-editor.org/info/rfc4803>. <http://www.rfc-editor.org/info/rfc4803>.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<http://www.rfc-editor.org/info/rfc5920>. <http://www.rfc-editor.org/info/rfc5920>.
[RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku, [RFC6163] Lee, Y., Ed., Bernstein, G., Ed., and W. Imajuku,
skipping to change at page 39, line 46 skipping to change at page 38, line 42
<http://www.rfc-editor.org/info/rfc6344>. <http://www.rfc-editor.org/info/rfc6344>.
[RFC7139] Zhang, F., Ed., Zhang, G., Belotti, S., Ceccarelli, D., [RFC7139] Zhang, F., Ed., Zhang, G., Belotti, S., Ceccarelli, D.,
and K. Pithewan, "GMPLS Signaling Extensions for Control and K. Pithewan, "GMPLS Signaling Extensions for Control
of Evolving G.709 Optical Transport Networks", RFC 7139, of Evolving G.709 Optical Transport Networks", RFC 7139,
DOI 10.17487/RFC7139, March 2014, DOI 10.17487/RFC7139, March 2014,
<http://www.rfc-editor.org/info/rfc7139>. <http://www.rfc-editor.org/info/rfc7139>.
[RFC7260] Takacs, A., Fedyk, D., and J. He, "GMPLS RSVP-TE [RFC7260] Takacs, A., Fedyk, D., and J. He, "GMPLS RSVP-TE
Extensions for Operations, Administration, and Maintenance Extensions for Operations, Administration, and Maintenance
(OAM) Configuration", RFC 7260, DOI 10.17487/RFC7260, June (OAM) Configuration", RFC 7260, DOI 10.17487/RFC7260,
2014, <http://www.rfc-editor.org/info/rfc7260>. June 2014, <http://www.rfc-editor.org/info/rfc7260>.
Acknowledgments
The authors would like to thank Pete Anslow for his insights and
clarifications, and Matt Hartley and Jonas Maertensson for their
reviews.
This work was supported in part by the FP-7 IDEALIST project under
grant agreement number 317999.
Contributors
Adrian Farrel
Old Dog Consulting
Email: adrian@olddog.co.uk
Daniel King
Old Dog Consulting
Email: daniel@olddog.co.uk
Xian Zhang
Huawei
Email: zhang.xian@huawei.com
Cyril Margaria
Juniper Networks
Email: cmargaria@juniper.net
Qilei Wang
ZTE
Ruanjian Avenue, Nanjing, China
Email: wang.qilei@zte.com.cn
Malcolm Betts
ZTE
Email: malcolm.betts@zte.com.cn
Sergio Belotti
Alcatel-Lucent
Optics CTO
Via Trento 30 20059 Vimercate (Milano) Italy
Phone: +39 039 686 3033
Email: sergio.belotti@alcatel-lucent.com
Yao Li
Nanjing University
Email: wsliguotou@hotmail.com
Fei Zhang
Huawei
Email: zhangfei7@huawei.com
Lei Wang
Email: wang.lei@bupt.edu.cn
Guoying Zhang
China Academy of Telecom Research
No.52 Huayuan Bei Road, Beijing, China
Email: zhangguoying@ritt.cn
Takehiro Tsuritani
KDDI R&D Laboratories Inc.
2-1-15 Ohara, Fujimino, Saitama, Japan
Email: tsuri@kddilabs.jp
Lei Liu
UC Davis, United States
Email: leiliu@ucdavis.edu
Eve Varma
Alcatel-Lucent
Phone: +1 732 239 7656
Email: eve.varma@alcatel-lucent.com
Young Lee
Huawei
Jianrui Han
Huawei
Sharfuddin Syed
Infinera
Rajan Rao
Infinera
Marco Sosa
Infinera
Biao Lu
Infinera
Abinder Dhillon
Infinera
Felipe Jimenez Arribas
Telefonica I+D
Andrew G. Malis
Huawei
Email: agmalis@gmail.com
Huub van Helvoort
Hai Gaoming BV
The Netherlands
Email: huubatwork@gmail.com
Authors' Addresses Authors' Addresses
Oscar Gonzalez de Dios (editor) Oscar Gonzalez de Dios (editor)
Telefonica I+D Telefonica I+D
Don Ramon de la Cruz 82-84 Ronda de la Comunicacion s/n
Madrid 28045 Madrid 28050
Spain Spain
Phone: +34913128832 Phone: +34 91 312 96 47
Email: oscar.gonzalezdedios@telefonica.com Email: oscar.gonzalezdedios@telefonica.com
Ramon Casellas (editor) Ramon Casellas (editor)
CTTC CTTC
Av. Carl Friedrich Gauss n.7 Av. Carl Friedrich Gauss n.7
Castelldefels Barcelona Castelldefels Barcelona
Spain Spain
Phone: +34 93 645 29 00 Phone: +34 93 645 29 00
Email: ramon.casellas@cttc.es Email: ramon.casellas@cttc.es
Fatai Zhang
Huawei
Huawei Base, Bantian, Longgang District
Shenzhen 518129
China
Phone: +86 755 28972912
Email: zhangfatai@huawei.com
Xihua Fu
Stairnote
No.118, Taibai Road, Yanta District
Xi'An
China
Email: fu.xihua@stairnote.com
Daniele Ceccarelli
Ericsson
Via Calda 5
Genova
Italy
Phone: +39 010 600 2512
Email: daniele.ceccarelli@ericsson.com
Iftekhar Hussain
Infinera
140 Caspian Ct.
Sunnyvale, CA 94089
United States
Phone: 408 572 5233
Email: ihussain@infinera.com
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