draft-ietf-ccamp-flexi-grid-fwk-02.txt | draft-ietf-ccamp-flexi-grid-fwk-03.txt | |||
---|---|---|---|---|
Network Working Group O. Gonzalez de Dios, Ed. | Network Working Group O. Gonzalez de Dios, Ed. | |||
Internet-Draft Telefonica I+D | Internet-Draft Telefonica I+D | |||
Intended status: Standards Track R. Casellas, Ed. | Intended status: Standards Track R. Casellas, Ed. | |||
Expires: February 27, 2015 CTTC | Expires: August 27, 2015 CTTC | |||
F. Zhang | F. Zhang | |||
Huawei | Huawei | |||
X. Fu | X. Fu | |||
ZTE | ZTE | |||
D. Ceccarelli | D. Ceccarelli | |||
Ericsson | Ericsson | |||
I. Hussain | I. Hussain | |||
Infinera | Infinera | |||
August 26, 2014 | February 23, 2015 | |||
Framework and Requirements for GMPLS based control of Flexi-grid DWDM | Framework and Requirements for GMPLS-based control of Flexi-grid DWDM | |||
networks | networks | |||
draft-ietf-ccamp-flexi-grid-fwk-02 | draft-ietf-ccamp-flexi-grid-fwk-03 | |||
Abstract | Abstract | |||
This document defines a framework and the associated control plane | ||||
requirements for the GMPLS based control of flexi-grid DWDM networks. | ||||
To allow efficient allocation of optical spectral bandwidth for high | To allow efficient allocation of optical spectral bandwidth for high | |||
bit-rate systems, the International Telecommunication Union | bit-rate systems, the International Telecommunication Union | |||
Telecommunication Standardization Sector (ITU-T) has extended the | Telecommunication Standardization Sector (ITU-T) has extended its | |||
recommendations [G.694.1] and [G.872] to include the concept of | Recommendations G.694.1 and G.872 to include a new dense wavelength | |||
flexible grid. A new DWDM grid has been developed within the ITU-T | division multiplexing (DWDM) grid by defining a set of nominal | |||
Study Group 15 by defining a set of nominal central frequencies, | central frequencies, channel spacings and the concept of "frequency | |||
channel spacings and the concept of "frequency slot". In such | slot". In such an environment, a data plane connection is switched | |||
environment, a data plane connection is switched based on allocated, | based on allocated, variable-sized frequency ranges within the | |||
variable-sized frequency ranges within the optical spectrum. | optical spectrum creating what is known as a flexible grid (flexi- | |||
grid). | ||||
This document defines a framework and the associated control plane | ||||
requirements for the GMPLS-based control of flexi-grid DWDM networks. | ||||
Status of This Memo | Status of This Memo | |||
This Internet-Draft is submitted in full conformance with the | This Internet-Draft is submitted in full conformance with the | |||
provisions of BCP 78 and BCP 79. | provisions of BCP 78 and BCP 79. | |||
Internet-Drafts are working documents of the Internet Engineering | Internet-Drafts are working documents of the Internet Engineering | |||
Task Force (IETF). Note that other groups may also distribute | Task Force (IETF). Note that other groups may also distribute | |||
working documents as Internet-Drafts. The list of current Internet- | working documents as Internet-Drafts. The list of current Internet- | |||
Drafts is at http://datatracker.ietf.org/drafts/current/. | Drafts is at http://datatracker.ietf.org/drafts/current/. | |||
Internet-Drafts are draft documents valid for a maximum of six months | Internet-Drafts are draft documents valid for a maximum of six months | |||
and may be updated, replaced, or obsoleted by other documents at any | and may be updated, replaced, or obsoleted by other documents at any | |||
time. It is inappropriate to use Internet-Drafts as reference | time. It is inappropriate to use Internet-Drafts as reference | |||
material or to cite them other than as "work in progress." | material or to cite them other than as "work in progress." | |||
This Internet-Draft will expire on February 27, 2015. | ||||
This Internet-Draft will expire on August 27, 2015. | ||||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2014 IETF Trust and the persons identified as the | Copyright (c) 2015 IETF Trust and the persons identified as the | |||
document authors. All rights reserved. | document authors. All rights reserved. | |||
This document is subject to BCP 78 and the IETF Trust's Legal | This document is subject to BCP 78 and the IETF Trust's Legal | |||
Provisions Relating to IETF Documents | Provisions Relating to IETF Documents | |||
(http://trustee.ietf.org/license-info) in effect on the date of | (http://trustee.ietf.org/license-info) in effect on the date of | |||
publication of this document. Please review these documents | publication of this document. Please review these documents | |||
carefully, as they describe your rights and restrictions with respect | carefully, as they describe your rights and restrictions with respect | |||
to this document. Code Components extracted from this document must | to this document. Code Components extracted from this document must | |||
include Simplified BSD License text as described in Section 4.e of | include Simplified BSD License text as described in Section 4.e of | |||
the Trust Legal Provisions and are provided without warranty as | the Trust Legal Provisions and are provided without warranty as | |||
described in the Simplified BSD License. | described in the Simplified BSD License. | |||
Table of Contents | Table of Contents | |||
1. Requirements Language . . . . . . . . . . . . . . . . . . . . 3 | 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 | |||
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 | 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 | |||
3. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . 4 | 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 | |||
4. Flexi-grid Networks . . . . . . . . . . . . . . . . . . . . . 4 | 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 | |||
4.1. Flexi-grid in the context of OTN . . . . . . . . . . . . 4 | 3. Overview of Flexi-grid Networks . . . . . . . . . . . . . . . 5 | |||
4.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 | 3.1. Flexi-grid in the Context of OTN . . . . . . . . . . . . 5 | |||
4.2.1. Frequency Slots . . . . . . . . . . . . . . . . . . . 5 | 3.2. Flexi-grid Terminology . . . . . . . . . . . . . . . . . 6 | |||
4.2.2. Media Channels . . . . . . . . . . . . . . . . . . . 7 | 3.2.1. Frequency Slots . . . . . . . . . . . . . . . . . . . 6 | |||
4.2.3. Media Layer Elements . . . . . . . . . . . . . . . . 7 | 3.2.2. Media Channels . . . . . . . . . . . . . . . . . . . 8 | |||
4.2.4. Optical Tributary Signals . . . . . . . . . . . . . . 8 | 3.2.3. Media Layer Elements . . . . . . . . . . . . . . . . 8 | |||
4.3. Flexi-grid layered network model . . . . . . . . . . . . 8 | 3.2.4. Optical Tributary Signals . . . . . . . . . . . . . . 9 | |||
4.3.1. Hierarchy in the Media Layer . . . . . . . . . . . . 9 | 3.2.5. Composite Media Channels . . . . . . . . . . . . . . 9 | |||
4.3.2. DWDM flexi-grid enabled network element models . . . 10 | 3.3. Hierarchy in the Media Layer . . . . . . . . . . . . . . 10 | |||
5. GMPLS applicability . . . . . . . . . . . . . . . . . . . . . 11 | 3.4. Flexi-grid Layered Network Model . . . . . . . . . . . . 10 | |||
5.1. General considerations . . . . . . . . . . . . . . . . . 11 | 3.4.1. DWDM Flexi-grid Enabled Network Element Models . . . 12 | |||
5.2. Considerations on TE Links . . . . . . . . . . . . . . . 11 | 4. GMPLS Applicability . . . . . . . . . . . . . . . . . . . . . 12 | |||
5.3. Considerations on Labeled Switched Path (LSP) in Flexi- | 4.1. General Considerations . . . . . . . . . . . . . . . . . 12 | |||
grid . . . . . . . . . . . . . . . . . . . . . . . . . . 14 | 4.2. Consideration of TE Links . . . . . . . . . . . . . . . . 13 | |||
5.4. Control Plane modeling of Network elements . . . . . . . 18 | 4.3. Consideration of LSPs in Flexi-grid . . . . . . . . . . . 16 | |||
5.5. Media Layer Resource Allocation considerations . . . . . 19 | 4.4. Control Plane Modeling of Network Elements . . . . . . . 21 | |||
5.6. Neighbor Discovery and Link Property Correlation . . . . 23 | 4.5. Media Layer Resource Allocation Considerations . . . . . 21 | |||
5.7. Path Computation / Routing and Spectrum Assignment (RSA) 23 | 4.6. Neighbor Discovery and Link Property Correlation . . . . 25 | |||
5.7.1. Architectural Approaches to RSA . . . . . . . . . . . 24 | 4.7. Path Computation / Routing and Spectrum Assignment (RSA) 26 | |||
5.8. Routing / Topology dissemination . . . . . . . . . . . . 24 | 4.7.1. Architectural Approaches to RSA . . . . . . . . . . . 26 | |||
5.8.1. Available Frequency Ranges/slots of DWDM Links . . . 25 | 4.8. Routing and Topology Dissemination . . . . . . . . . . . 27 | |||
5.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 25 | 4.8.1. Available Frequency Ranges/Slots of DWDM Links . . . 28 | |||
5.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 25 | 4.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 28 | |||
5.8.4. Information Model . . . . . . . . . . . . . . . . . . 26 | 4.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 28 | |||
6. Control Plane Requirements . . . . . . . . . . . . . . . . . 27 | 4.8.4. Information Model . . . . . . . . . . . . . . . . . . 28 | |||
6.1. Support for Media Channels . . . . . . . . . . . . . . . 27 | 5. Control Plane Requirements . . . . . . . . . . . . . . . . . 30 | |||
6.2. Support for Media Channel Resizing . . . . . . . . . . . 27 | 5.1. Support for Media Channels . . . . . . . . . . . . . . . 30 | |||
6.3. Support for Logical Associations of multiple media | 5.1.1. Signaling . . . . . . . . . . . . . . . . . . . . . . 31 | |||
channels . . . . . . . . . . . . . . . . . . . . . . . . 28 | 5.1.2. Routing . . . . . . . . . . . . . . . . . . . . . . . 31 | |||
7. Security Considerations . . . . . . . . . . . . . . . . . . . 28 | 5.2. Support for Media Channel Resizing . . . . . . . . . . . 32 | |||
8. Contributing Authors . . . . . . . . . . . . . . . . . . . . 28 | 5.3. Support for Logical Associations of Multiple Media | |||
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 30 | Channels . . . . . . . . . . . . . . . . . . . . . . . . 32 | |||
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30 | 5.4. Support for Composite Media Channels . . . . . . . . . . 32 | |||
10.1. Normative References . . . . . . . . . . . . . . . . . . 30 | 5.5. Support for Neighbor Discovery and Link Property | |||
10.2. Informative References . . . . . . . . . . . . . . . . . 32 | Correlation . . . . . . . . . . . . . . . . . . . . . . . 32 | |||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 32 | 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 | |||
7. Security Considerations . . . . . . . . . . . . . . . . . . . 33 | ||||
1. Requirements Language | 8. Manageability Considerations . . . . . . . . . . . . . . . . 33 | |||
9. Contributing Authors . . . . . . . . . . . . . . . . . . . . 34 | ||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", | 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 37 | |||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 37 | |||
document are to be interpreted as described in [RFC2119]. | 11.1. Normative References . . . . . . . . . . . . . . . . . . 37 | |||
11.2. Informative References . . . . . . . . . . . . . . . . . 38 | ||||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39 | ||||
2. 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/allocation considerations that have been defined in order | |||
to allow an efficient and flexible allocation and configuration of | to allow an efficient and flexible allocation and configuration of | |||
optical spectral bandwidth for high bit-rate systems. | optical spectral bandwidth for high bit-rate systems. | |||
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, allowing high bit rate signals | as much optical spectrum as required. | |||
(e.g., 400G, 1T or higher) that do not fit in the fixed grid. | ||||
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, the media channel | frequency slot. In this layered network, the media channel can | |||
transports an Optical Tributary Signal. | transport more than one Optical Tributary Signals. | |||
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 | |||
Generalized Multi-Protocol Label Switching (GMPLS)-based control | GMPLS-based control plane for the control (provisioning/recovery, | |||
plane for the control (provisioning/recovery, etc) of a fixed grid | etc.) of a fixed grid wavelength division multiplexing (WDM) network | |||
WDM network in which media (spectrum) and signal are jointly | in which media (spectrum) and signal are jointly considered. | |||
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 DWDM networks (in the scope defined by ITU-T | flexi-grid enabled dense wavelength division multiplexing (DWDM) | |||
layered Optical Transport Networks [G.872]), as well as a set of | networks (in the scope defined by ITU-T layered Optical Transport | |||
associated control plane requirements. An important design | Networks [G.872]), as well as a set of associated control plane | |||
consideration relates to the decoupling of the management of the | requirements. An important design consideration relates to the | |||
optical spectrum resource and the client signals to be transported. | decoupling of the management of the optical spectrum resource and the | |||
client signals to be transported. | ||||
3. Acronyms | 2. Terminology | |||
Further terminology specific to flexi-grid networks can be found in | ||||
Section 3.2. | ||||
2.1. Requirements Language | ||||
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", | ||||
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this | ||||
document are to be interpreted as described in [RFC2119]. | ||||
2.2. Abbreviations | ||||
EFS: Effective Frequency Slot | EFS: Effective Frequency Slot | |||
FS: Frequency Slot | FS: Frequency Slot | |||
FSC: Fiber-Switch Capable | ||||
LSR: Label Switching Router | ||||
NCF: Nominal Central Frequency | NCF: Nominal Central Frequency | |||
OCh: Optical Channel | OCh: Optical Channel | |||
OCh-P: Optical Channel Payload | OCh-P: Optical Channel Payload | |||
OTSi: Optical Tributary Signal | ||||
OTS: Optical Tributary Signal | OTSiG: OTSi Group is the set of OTSi signals | |||
OCC: Optical Channel Carrier | OCC: Optical Channel Carrier | |||
PCE: Path Computation Element | ||||
ROADM: Reconfigurable Optical Add-Drop Multiplexer | ||||
SSON: Spectrum-Switched Optical Network | ||||
SWG: Slot Width Granularity | SWG: Slot Width Granularity | |||
4. Flexi-grid Networks | 3. Overview of Flexi-grid Networks | |||
4.1. 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 of | [G.872] describes, from a network level, the functional architecture | |||
Optical Transport Networks (OTN). The OTN is decomposed into | of Optical Transport Networks (OTN). The OTN is decomposed into | |||
independent layer networks with client/layer relationships among | independent layer networks with client/layer relationships among | |||
them. A simplified view of the OTN layers is shown in Figure 1. | them. A simplified view of the OTN 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, and the | In the media layer, switching is based on a frequency slot. | |||
size of a media channel is given by the properties of the associated | ||||
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, and covers mainly | |||
the Media Layer as well as the required adaptations from the Signal | the Media Layer as well as the required adaptations from the Signal | |||
layer. The present document is thus focused on the control and | layer. The present document is thus focused on the control and | |||
management of the media layer. | management of the media layer. | |||
4.2. Terminology | 3.2. Flexi-grid Terminology | |||
This section presents the definition of the terms used in flexi-grid | This section presents the definition of the terms used in flexi-grid | |||
networks. These terms are included in the ITU-T recommendations | networks. More detail about these terms can be found in the ITU-T | |||
[G.694.1], [G.872]), [G.870], [G.8080] and [G.959.1-2013]. | Recommendations [G.694.1], [G.872]), [G.870], [G.8080], and | |||
[G.959.1-2013]. | ||||
Where appropriate, this documents also uses terminology and | Where appropriate, this documents also uses terminology and | |||
lexicography from [RFC4397]. | lexicography from [RFC4397]. | |||
4.2.1. Frequency Slots | 3.2.1. Frequency Slots | |||
This subsection is focused on the frequency slot related terms. | This subsection is focused on the frequency slot 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. | |||
Nominal Central Frequency: each of the allowed frequencies as per the | o Effective Frequency Slot [G.870]: The effective frequency slot of | |||
definition of flexible DWDM grid in [G.694.1]. The set of nominal | a media channel is that part of the frequency slots of the filters | |||
central frequencies can be built using the following expression f = | along the media channel that is common to all of the filters' | |||
193.1 THz + n x 0.00625 THz, where 193.1 THz is ITU-T ''anchor | frequency slots. Note that both the Frequency Slot and Effective | |||
frequency'' for transmission over the C band, n is a positive or | Frequency Slot are both local terms. | |||
negative integer including 0. | ||||
-5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n | o Nominal Central Frequency: Each of the allowed frequencies as per | |||
...+--+--+--+--+--+--+--+--+--+--+- | the definition of flexible DWDM grid in [G.694.1]. The set of | |||
^ | nominal central frequencies can be built using the following | |||
193.1 THz <- anchor frequency | expression | |||
Figure 2: Anchor frequency and set of nominal central frequencies | f = 193.1 THz + n x 0.00625 THz | |||
Nominal Central Frequency Granularity: It is the spacing between | where 193.1 THz is ITU-T "anchor frequency" for transmission over | |||
allowed nominal central frequencies and it is set to 6.25 GHz (note: | the C band, and n is a positive or negative integer including 0. | |||
sometimes referred to as 0.00625 THz). | ||||
Slot Width Granularity: 12.5 GHz, as defined in [G.694.1]. | -5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n | |||
...+--+--+--+--+--+--+--+--+--+--+- | ||||
^ | ||||
193.1 THz <- anchor frequency | ||||
Slot Width: The slot width determines the "amount" of optical | Figure 2: Anchor Frequency and Set of Nominal Central Frequencies | |||
spectrum regardless of its actual "position" in the frequency axis. | ||||
A slot width is constrained to be m x SWG (that is, m x 12.5 GHz), | ||||
where m is an integer greater than or equal to 1. | ||||
Frequency Slot 1 Frequency Slot 2 | o Nominal Central Frequency Granularity: This is the spacing between | |||
------------- ------------------- | allowed nominal central frequencies and it is set to 6.25 GHz. | |||
| | | | | ||||
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 | ||||
..--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... | ||||
------------- ------------------- | ||||
^ ^ | ||||
Central F = 193.1THz Central F = 193.14375 THz | ||||
Slot width = 25 GHz Slot width = 37.5 GHz | ||||
Figure 3: Example Frequency slots | o Slot Width Granularity (SWG): 12.5 GHz, as defined in [G.694.1]. | |||
o The symbol '+' represents the allowed nominal central frequencies, | o Slot Width: The slot width determines the "amount" of optical | |||
the '--' represents the nominal central frequency granularity, and | spectrum regardless of its actual "position" in the frequency | |||
the '^' represents the slot nominal central frequency. The number | axis. A slot width is constrained to be m x SWG (that is, m x | |||
on the top of the '+' symbol represents the 'n' in the frequency | 12.5 GHz), where m is an integer greater than or equal to 1. | |||
calculation formula. The nominal central frequency is 193.1 THz | ||||
when n equals zero. | ||||
Effective Frequency Slot: the effective frequency slot of a media | Frequency Slot 1 Frequency Slot 2 | |||
channel is the common part of the frequency slots along the media | ------------- ------------------- | |||
channel through a particular path through the optical network. It is | | | | | | |||
a logical construct derived from the (intersection of) frequency | -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 | |||
slots allocated to each device in the path. The effective frequency | ...--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... | |||
slot is an attribute of a media channel and, being a frequency slot, | ------------- ------------------- | |||
it is described by its nominal central frequency and slot width, | ^ ^ | |||
according to the already described rules. | Central F = 193.1THz Central F = 193.14375 THz | |||
Slot width = 25 GHz Slot width = 37.5 GHz | ||||
Figure 3: Example Frequency Slots | ||||
* The symbol '+' represents the allowed nominal central | ||||
frequencies | ||||
* The '--' represents the nominal central frequency granularity | ||||
* The '^' represents the slot nominal central frequency | ||||
* The number on the top of the '+' symbol represents the 'n' in | ||||
the frequency calculation formula. | ||||
* The nominal central frequency is 193.1 THz when n equals zero. | ||||
o Effective Frequency Slot: The effective frequency slot of a media | ||||
channel is the common part of the frequency slots along the media | ||||
channel through a particular path through the optical network. It | ||||
is a logical construct derived from the (intersection of) | ||||
frequency slots allocated to each device in the path. The | ||||
effective frequency slot is an attribute of a media channel and, | ||||
being a frequency slot, it is described by its nominal central | ||||
frequency and slot width, according to the already described | ||||
rules. | ||||
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 | |||
------------------- | ------------------- | |||
| | | | | | |||
skipping to change at page 7, line 26 | skipping to change at page 8, line 26 | |||
=============================================== | =============================================== | |||
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 | |||
4.2.2. Media Channels | 3.2.2. Media Channels | |||
Media Channel: a media association that represents both the topology | This section defines concepts such as (Network) Media Channel; the | |||
(i.e., path through the media) and the resource (frequency slot) that | mapping to GMPLS constructs (i.e., LSP) is detailed in Section 4. | |||
it occupies. As a topological construct, it represents a (effective) | ||||
frequency slot supported by a concatenation of media elements | ||||
(fibers, amplifiers, filters, switching matrices...). This term is | ||||
used to identify the end-to-end physical layer entity with its | ||||
corresponding (one or more) frequency slots local at each link | ||||
filters. | ||||
Network Media Channel: It is a media channel that transports an | o Media Channel: A media association that represents both the | |||
Optical Tributary Signal [Editor's note: this definition goes beyond | topology (i.e., path through the media) and the resource | |||
current G.870 definition, which is still tightened to a particular | (frequency slot) that it occupies. As a topological construct, it | |||
case of OTS, the OCh-P] | represents a frequency slot (an effective frequency slot) | |||
supported by a concatenation of media elements (fibers, | ||||
amplifiers, filters, switching matrices...). This term is used to | ||||
identify the end-to-end physical layer entity with its | ||||
corresponding (one or more) frequency slots local at each link | ||||
filters. | ||||
4.2.3. Media Layer Elements | o Network Media Channel: [G.870] defines the Network Media Channel | |||
in terms of the media channel that transports the OTSi. This | ||||
document broadens the definition to cover any OTSi so that a | ||||
Network Media Channel is a media channel that transports an OTSi. | ||||
Media Element: a media element only directs the optical signal or | 3.2.3. Media Layer Elements | |||
affects the properties of an optical signal, it does not modify the | ||||
properties of the information that has been modulated to produce the | ||||
optical signal [G.870]. Examples of media elements include fibers, | ||||
amplifiers, filters and switching matrices. | ||||
Media Channel Matrixes: the media channel matrix provides flexible | o Media Element: A media element directs an optical signal or | |||
connectivity for the media channels. That is, it represents a point | affects the properties of an optical signal. It does not modify | |||
of flexibility where relationships between the media ports at the | the properties of the information that has been modulated to | |||
edge of a media channel matrix may be created and broken. The | produce the optical signal [G.870]. Examples of media elements | |||
relationship between these ports is called a matrix channel. | include fibers, amplifiers, filters, and switching matrices. | |||
(Network) Media Channels are switched in a Media Channel Matrix. | ||||
4.2.4. Optical Tributary Signals | o Media Channel Matrixes: The media channel matrix provides flexible | |||
connectivity for the media channels. That is, it represents a | ||||
point of flexibility where relationships between the media ports | ||||
at the edge of a media channel matrix may be created and broken. | ||||
The relationship between these ports is called a matrix channel. | ||||
(Network) Media Channels are switched in a Media Channel Matrix. | ||||
Optical Tributary Signal [G.959.1-2013]: The optical signal that is | 3.2.4. Optical Tributary Signals | |||
placed within a network media channel for transport across the | ||||
optical network. This may consist of a single modulated optical | ||||
carrier or a group of modulated optical carriers or subcarriers. One | ||||
particular example of Optical Tributary Signal is an Optical Channel | ||||
Payload (OCh-P) [G.872]. | ||||
4.3. Flexi-grid layered network model | o Optical Tributary Signal (OTSi) [G.959.1-2013]: The optical signal | |||
that is placed within a network media channel for transport across | ||||
the optical network. This may consist of a single modulated | ||||
optical carrier or a group of modulated optical carriers or | ||||
subcarriers. To provide a connection between the OTSi source and | ||||
the OTSi sink the optical signal must be assigned to a network | ||||
media channel. | ||||
In the OTN layered network, the network media channel transports a | o OTSi Group (OTSiG): The set of OTSi signals that are carried by a | |||
single Optical Tributary Signal (see Figure 5) | group of network media channels. Each OTSi is carried by one | |||
network media channel. From a management perspective it should be | ||||
possible to manage both the OTSiG and a group of Network Media | ||||
Channels as single entities. | ||||
3.2.5. Composite Media Channels | ||||
o It is possible to construct an end-to-end media channel as a | ||||
composite of more than one network media channels. A composite | ||||
media channel carries a group of OTSi (i.e., OTSiG). Each OTSi is | ||||
carried by one network media channel. This group of OTSi should | ||||
be carried over a single fibre. | ||||
o In this case, the effective frequency slots may be contiguous | ||||
(i.e., there is no spectrum between them that can be used for | ||||
other media channels) or non-contiguous. | ||||
o It is not currently envisaged that such composite media channels | ||||
may be constructed from slots carried on different fibers whether | ||||
those fibers traverse the same hop-by-hop path through the network | ||||
or not. | ||||
o Furthermore, it is not considered likely that a media channel may | ||||
be constructed from a different variation of slot composition on | ||||
each hop. That is, the slot composition must be the same from one | ||||
end to the other of the media channel even if the specific slots | ||||
and their spacing may vary hop by hop. | ||||
o How the signal is carried across such groups of network media | ||||
channels is out of scope for this document. | ||||
3.3. Hierarchy in the Media Layer | ||||
In summary, the concept of frequency slot is a logical abstraction | ||||
that represents a frequency range, while the media layer represents | ||||
the underlying media support. Media Channels are media associations, | ||||
characterized by their (effective) frequency slot, respectively; and | ||||
media channels are switched in media channel matrixes. From the | ||||
control and management perspective, a media channel can be logically | ||||
split into network media channels. | ||||
In Figure 5, a media channel has been configured and dimensioned to | ||||
support two network media channels, each of them carrying one optical | ||||
tributary signal. | ||||
Media Channel Frequency Slot | ||||
+-------------------------------X------------------------------+ | ||||
| | | ||||
| Frequency Slot Frequency Slot | | ||||
| +------------X-----------+ +----------X-----------+ | | ||||
| | Opt Tributary Signal | | Opt Tributary Signal | | | ||||
| | o | | o | | | ||||
| | | | | | | | | ||||
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 | ||||
--+---+---+---+---+---+---+---+---+---+---+---+--+---+---+---+---+-- | ||||
<- Network Media Channel-> <- Network Media Channel-> | ||||
<------------------------ Media Channel -----------------------> | ||||
X - Frequency Slot Central Frequency | ||||
o - signal central frequency | ||||
Figure 5: Example of Media Channel / Network Media Channels and | ||||
Associated Frequency Slots | ||||
3.4. Flexi-grid Layered Network Model | ||||
In the OTN layered network, the network media channel transports a | ||||
single Optical Tributary Signal (see Figure 6) | ||||
| Optical Tributary Signal | | | Optical Tributary Signal | | |||
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 | |||
(1) - Matrix Channel | The symbol (1) indicates a Matrix Channel | |||
Figure 5: Simplified Layered Network Model | Figure 6: Simplified Layered Network Model | |||
A particular example of Optical Tributary Signal is the OCh-P. | A particular example of Optical Tributary Signal is the OCh-P. | |||
Figure Figure 6 shows the example of the layered network model | Figure 7 shows this specific example as defined in G.805 [G.805]. | |||
particularized for the OCH-P case, as defined in 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 --- | |||
\ / source sink \ / | \ / source sink \ / | |||
+ + | + + | |||
| OCh-P OCh-P Network Connection OCh-P | | | OCh-P OCh-P Network Connection OCh-P | | |||
O TCP - - - - - - - - - - - - - - - - - - - - - - - - - - -TCP O | O TCP - - - - - - - - - - - - - - - - - - - - - - - - - - -TCP O | |||
| | | | | | |||
|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 | |||
(1) - Matrix Channel | The symbol (1) indicates a Matrix Channel | |||
Figure 6: Layered Network Model according to G.805 | ||||
By definition a network media channel only supports a single Optical | ||||
Tributary signal. How several Optical Tributary signals are bound | ||||
together is out of the scope of the present document and is a matter | ||||
of the signal layer. | ||||
4.3.1. Hierarchy in the Media Layer | ||||
In summary, the concept of frequency slot is a logical abstraction | ||||
that represents a frequency range while the media layer represents | ||||
the underlying media support. Media Channels are media associations, | ||||
characterized by their (effective) frequency slot, respectively; and | ||||
media channels are switched in media channel matrixes. From the | ||||
control and management perspective, a media channel can be logically | ||||
splited in other media channels. | ||||
In Figure 7 , a Media Channel has been configured and dimensioned to | ||||
support two network media channels, each of them carrying one optical | ||||
tributary signal. | ||||
Media Channel Frequency Slot | ||||
+-------------------------------X------------------------------+ | ||||
| | | ||||
| Frequency Slot Frequency Slot | | ||||
| +------------X-----------+ +----------X-----------+ | | ||||
| | Opt Tributary Signal | | Opt Tributary Signal | | | ||||
| | o | | o | | | ||||
| | | | | | | | | ||||
-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 | ||||
+---+---+---+---+---+---+---+---+---+---+---+--+---+---+---+---+--- | ||||
<- Network Media Channel-> <- Network Media Channel-> | ||||
<------------------------ Media Channel -----------------------> | ||||
X - Frequency Slot Central Frequency | ||||
o - signal central frequency | Figure 7: Layered Network Model According to G.805 | |||
Figure 7: Example of Media Channel / Network Media Channels and | By definition, a network media channel supports only a single Optical | |||
associated frequency slots | Tributary Signal. | |||
4.3.2. DWDM flexi-grid enabled network element models | 3.4.1. DWDM Flexi-grid Enabled Network Element Models | |||
Similar to fixed grid networks, a flexible grid network is also | A flexible grid network is constructed from subsystems that include | |||
constructed from subsystems that include Wavelength Division | WDM links, tunable transmitters, and receivers, (i.e, media elements | |||
Multiplexing (WDM) links, tunable transmitters and receivers, i.e, | including media layer switching elements that are media matrices) as | |||
media elements including media layer switching elements (media | well as electro-optical network elements. This is just the same as | |||
matrices), as well as electro-optical network elements, all of them | in a fixed grid network except that each element has flexible grid | |||
with flexible grid characteristics. | characteristics. | |||
As stated in [G.694.1] the flexible DWDM grid defined in Clause 7 has | As stated in Clause 7 of [G.694.1] the flexible DWDM grid has a | |||
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 may 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 | are 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 that only requires | |||
slot widths as a multiple of 25 GHz (by only requiring values of m | slot widths as a multiple of 25 GHz (by only requiring values of m | |||
that are even). | that are even). | |||
5. GMPLS applicability | 4. GMPLS Applicability | |||
The goal of this section is to provide an insight of the application | The goal of this section is to provide an insight into the | |||
of GMPLS to control flexi-grid networks, while specific requirements | application of GMPLS as a control mechanism in flexi-grid networks. | |||
are covered in the next section. The present framework is aimed at | Specific control plane requirements for the support of flexi-grid | |||
controlling the media layer within the Optical Transport Network | networks are covered in Section 5. This framework is aimed at | |||
(OTN) hierarchy and the required adaptations of the signal layer. | controlling the media layer within the OTN hierarchy, and controlling | |||
This document also defines the term SSON (Spectrum-Switched Optical | the required adaptations of the signal layer. This document also | |||
Network) to refer to a Flexi-grid enabled DWDM network that is | defines the term Spectrum-Switched Optical Network (SSON) to refer to | |||
controlled by a GMPLS/PCE control plane. | a Flexi-grid enabled DWDM network that is controlled by a GMPLS/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/Control plane terms, and considers the relationship | |||
between the architectural concept/construct of media channel and its | between the architectural concept/construct of media channel and its | |||
control plane representations (e.g. as a TE link). | control plane representations (e.g., as a TE link). | |||
5.1. 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, which are switched in media channel matrixes. GMPLS | media channels that are switched in media channel matrices. GMPLS | |||
labels locally represent the media channel and its associated | labels are used to locally represent the media channel and its | |||
frequency slot. Network media channels are considered a particular | associated frequency slot. Network media channels are considered a | |||
case of media channels when the end points are transceivers (that is, | particular case of media channels when the end points are | |||
source and destination of an Optical Tributary Signal) | transceivers (that is, source and destination of an Optical Tributary | |||
Signal) | ||||
5.2. Considerations on TE Links | 4.2. Consideration of TE Links | |||
From a theoretical / abstract point of view, a fiber can be modeled | From a theoretical / abstract point of view, a fiber can be modeled | |||
has having a frequency slot that ranges from (-inf, +inf). This | as having a frequency slot that ranges from minus infinity to plus | |||
representation helps understand the relationship between frequency | infinity. This representation helps understand the relationship | |||
slots / ranges. | between frequency slots and ranges. | |||
The frequency slot is a local concept that applies locally to a | The frequency slot is a local concept that applies within a component | |||
component / element. When applied to a media channel, we are | or element. When applied to a media channel, we are referring to its | |||
referring to its effective frequency slot as defined in [G.872]. | effective frequency slot as defined in [G.872]. | |||
The association of a filter, a fiber and a filter is a media channel | The association of the three components a filter, a fiber, and a | |||
in its most basic form, which from the control plane perspective may | filter, is a media channel in its most basic form. From the control | |||
modeled as a (physical) TE-link with a contiguous optical spectrum at | plane perspective this may modeled as a (physical) TE-link with a | |||
start of day. A means to represent this is that the portion of | contiguous optical spectrum. This can be represented by saying that | |||
spectrum available at time t0 depends on which filters are placed at | the portion of spectrum available at time t0 depends on which filters | |||
the ends of the fiber and how they have been configured. Once | are placed at the ends of the fiber and how they have been | |||
filters are placed we have the one hop media channel. In practical | configured. Once filters are placed we have a one-hop media channel. | |||
terms, associating a fiber with the terminating filters determines | In practical terms, associating a fiber with the terminating filters | |||
the usable optical spectrum. | 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 underlying media support is still a media channel, | considered, the underlying media support is still a media channel, | |||
augmented, so to speak, with a bigger association of media elements | augmented, so to speak, with a bigger association of media elements | |||
and a resulting effective slot. When this media channel is the | and a resulting effective slot. When this media channel is the | |||
result of the association of basic media channels and media layer | result of the association of basic media channels and media layer | |||
matrix cross-connects, this architectural construct can be | matrix cross-connects, this architectural construct can be | |||
represented as / corresponds to a Label Switched Path (LSP) from a | represented as (i.e., corresponds to) a Label Switched Path (LSP) | |||
control plane perspective. In other words, It is possible to | from a control plane perspective. In other words, It is possible to | |||
"concatenate" several media channels (e.g. Patch on intermediate | "concatenate" several media channels (e.g., Patch on intermediate | |||
nodes) to create a single media channel. | nodes) to create a single media channel. | |||
-----------+ +------------------------------+ +---------- | ----------+ +------------------------------+ +--------- | |||
| | | | | | | | | | |||
+------+ +------+ +------+ +------+ | +------+ +------+ +------+ +------+ | |||
| | | | +----------+ | | | | | | | | | +----------+ | | | | | |||
--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 | |||
Additionally, if appropriate, it can also be represented as a TE link | Furthermore, if appropriate, the media channel can also be | |||
or Forwarding Adjacency (FA), augmenting the control plane network | represented as a TE link or Forwarding Adjacency (FA) [RFC4206], | |||
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-- | |||
|Filter| |Filter| | | |Filter| |Filter| | |Filter| |Filter| | | |Filter| |Filter| | |||
| | | | | | | | | | | | | | | | | | |||
+------+ +------+ +------+ +------+ | +------+ +------+ +------+ +------+ | |||
| | | | | | | | | | |||
-----------+ +------------------------------+ +---------- | ----------+ +------------------------------+ +--------- | |||
<------------------------ 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 / FA | |||
5.3. Considerations on Labeled Switched Path (LSP) in Flexi-grid | 4.3. Consideration of LSPs in Flexi-grid | |||
The flexi-grid LSP is seen as a control plane representation of a | The flexi-grid LSP is a control plane representation of a media | |||
media channel. Since network media channels are media channels, an | channel. Since network media channels are media channels, an LSP may | |||
LSP may also be the control plane representation of a network media | also be the control plane representation of a network media channel | |||
channel, in a particular context. From a control plane perspective, | (without considering the adaptation functions). From a control plane | |||
the main difference (regardless of the actual effective frequency | perspective, the main difference (regardless of the actual effective | |||
slot which may be dimensioned arbitrarily) is that the LSP that | frequency slot which may be dimensioned arbitrarily) is that the LSP | |||
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 / egress | (transceivers), including the cross-connects at the ingress and | |||
nodes. The ports towards the client can still be represented as | egress nodes. The ports towards the client can still be represented | |||
interfaces from the control plane perspective. | as interfaces from the control plane perspective. | |||
Figure 11 describes an LSP routed along 3 nodes. The LSP is | Figure 11 shows an LSP routed between 3 nodes. The LSP is terminated | |||
terminated before the optical matrix of the ingress and egress nodes | before the optical matrix of the ingress and egress nodes and can | |||
and can represent a Media Channel. This case does NOT (and cannot) | represent a media channel. This case does not (and cannot) represent | |||
represent a network media channel as it does not include (and cannot | a network media channel because it does not include (and cannot | |||
include) the transceivers. | 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- | |||
|Filter| |Filter| | | |Filter| |Filter| | |Filter| |Filter| | | |Filter| |Filter| | |||
| | | | | | | | | | | | | | | | | | |||
+------+ +------+ +------+ +------+ | +------+ +------+ +------+ +------+ | |||
| | | | | | | | | | |||
----------+ +--------------------------------+ +--------- | ---------+ +--------------------------------+ +-------- | |||
>>>>>>>>>>>>>>>>>>>>>>>>>>>> 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: Flex-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 DWDM side of the transponder, this is commonly named as OCh-trail | the DWDM side of the transponder. This is commonly named as OCh- | |||
connection. | trail connection. | |||
|--------------------- Network Media Channel ----------------------| | |--------------------- Network Media Channel ----------------------| | |||
+----------------------+ +----------------------+ | +----------------------+ +----------------------+ | |||
| | | | | | | | |||
+------+ +------+ +------+ +------+ | +------+ +------+ +------+ +------+ | |||
| | +----+ | | | | +----+ | |OCh-P | | | +----+ | | | | +----+ | |OTSi | |||
OCh-P| o-| |-o | +-----+ | o-| |-o |sink | OTSi| o-| |-o | +-----+ | o-| |-o |sink | |||
src | | | | | ===+-+ +-+==| | | | | O---|R | src | | | | | ===+-+ +-+==| | | | | O---|R | |||
T|***o******o******************************************************** | T|***o******o******************************************************** | |||
| | |\ /| | | | | | | | |\ /| | | | | | |\ /| | | | | | | | |\ /| | | | |||
| o-| \/ |-o ===| | | |==| o-| \/ |-o | | | o-| \/ |-o ===| | | |==| o-| \/ |-o | | |||
| | | /\ | | | +-+ +-+ | | | /\ | | | | | | | /\ | | | +-+ +-+ | | | /\ | | | | |||
| o-|/ \|-o | | \/ | | o-|/ \|-o | | | o-|/ \|-o | | \/ | | o-|/ \|-o | | |||
|Filter| | | |Filter| | /\ | |Filter| | | |Filter| | |Filter| | | |Filter| | /\ | |Filter| | | |Filter| | |||
+------+ | | +------+ +-----+ +------+ | | +------+ | +------+ | | +------+ +-----+ +------+ | | +------+ | |||
| | | | | | | | | | | | | | | | | | |||
+----------------------+ +----------------------+ | +----------------------+ +----------------------+ | |||
skipping to change at page 16, line 33 | skipping to change at page 18, line 33 | |||
<-------------------------------------------------------------------> | <-------------------------------------------------------------------> | |||
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 (OCh-Trail) | Figure 12: LSP Representing a Network Media Channel (OTSi Trail) | |||
In a third case, a Network Media Channel 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 named in G.872 as | |||
OCh-NC (we need to discuss the implications, if any, once modeled at | OTSi Network Connection. As can be seen from the figures, there is | |||
the control plane level of models B and C). | no difference from a GMPLS modelling perspective between these cases, | |||
but they are shown as distinct examples to highlight the 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 17, line 32 | skipping to change at page 19, line 32 | |||
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 (OCh-P NC) | Figure 13: LSP Representing a Network Media Channel (OTSi Network | |||
Connection) | ||||
[Note: not clear the difference, from a control plane perspective, of | ||||
figs Figure 12 and Figure 13.] | ||||
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 a FA, the media channel created can support multiple (sub) media | as an FA (i.e., by using hierarchical LSPs), the media channel | |||
channels. [Editot note : a specific behavior related to Hierarchies | created can support multiple (sub-)media channels. | |||
will be verified at a later point in time]. | ||||
+--------------+ +--------------+ | +--------------+ +--------------+ | |||
| OCh-P | TE | OCh-P | 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: MRN/MLN topology view with TE link / FA | Figure 14: MRN/MLN Topology View with TE Link / 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 FlexGrid ROADM) in SSON, while "signal layer LSP is | implementation is a FlexGrid ROADM) in SSON, while a signal layer LSP | |||
mainly for the purpose of management and control of individual | (Network Media Channel) is established mainly for the purpose of | |||
optical signal". Signal layer LSPs (OChs) with the same attributions | management and control of individual optical signals. Signal layer | |||
(such as source and destination) could be grouped into one media- | LSPs with the same attributes (such as source and destination) can be | |||
layer LSP (media channel), which has advantages in spectral | grouped into one media-layer LSP (media channel): this has advantages | |||
efficiency (reduce guard band between adjacent OChs in one FSC) and | in spectral efficiency (reduce guard band between adjacent OChs in | |||
LSP management. However, assuming some network elements indeed | one FSC channel) and LSP management. However, assuming some network | |||
perform signal layer switch in SSON, there must be enough guard band | elements perform signal layer switching in an SSON, there must be | |||
between adjacent OChs in one media channel, in order to compensate | enough guard band between adjacent OTSis in any media channel to | |||
filter concatenation effect and other effects caused by signal layer | compensate filter concatenation effect and other effects caused by | |||
switching elements. In such condition, the separation of signal | signal layer switching elements. In such a situation, the separation | |||
layer from media layer cannot bring any benefit in spectral | of the signal layer from the media layer does not bring any benefit | |||
efficiency and in other aspects, but make the network switch and | in spectral efficiency or in other aspects, but makes the network | |||
control more complex. If two OChs must switch to different ports, it | switch and control more complex. If two OTSis must be switched to | |||
is better to carry them by diferent FSCs and the media layer switch | different ports, it is better to carry them by diferent FSC channels, | |||
is enough in this scenario. | and the media layer switch is enough in this scenario. | |||
5.4. Control Plane modeling of Network elements | 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 | ||||
two ways using LSPs. These mechanisms may be compared to the | ||||
techniques used in GMPLS to support inverse multiplexing in Time | ||||
Division Multiplexing (TDM) networks and in OTN [RFC4606], [RFC6344], | ||||
and [RFC7139]. | ||||
Optical transmitters/receivers may have different tunability | o In the first case, a single LSP may be established in the control | |||
plane. The signaling messages include information for all of the | ||||
component network media channels that make up the composite media | ||||
channel. | ||||
o In the second case, each component network media channel is | ||||
established using a separate control plane LSP, and these LSPs are | ||||
associated within the control plane so that the end points may see | ||||
them as a single media channel. | ||||
4.4. Control Plane Modeling of Network Elements | ||||
Optical transmitters and receivers may have different tunability | ||||
constraints, and media channel matrixes may have switching | constraints, and media channel matrixes 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 | |||
[RFC6163] in detail. Media matrices include line side ports which | detail in [RFC6163]. Media matrices include line side ports that are | |||
are connected to DWDM links and tributary side input/output ports | connected to DWDM links, and tributary side input/output ports that | |||
which 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 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 are not allocated (i.e. available). The relative grouping | that have not been allocated (i.e., are available). The relative | |||
and distribution of available frequency ranges in a fiber is | grouping and distribution of available frequency ranges in a fiber | |||
usually referred to as ''fragmentation''. | is 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 can | supported by the media matrix. For example, the slot width | |||
be from 50GHz to 200GHz. | could be from 50GHz to 200GHz. | |||
* 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., 12.5GHz) or integer multiples of 12.5GHz. | |||
[Editor's note: different configurations such as C/CD/CDC will be | ||||
added later. This section should state specifics to media channel | ||||
matrices, ROADM models need to be moved to an appendix]. | ||||
5.5. 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" frequency slot end to end. The establishment of | seen as the "usable" end-to-end frequency slot. The establishment of | |||
an LSP related the establishment of the media channel and effective | an LSP is related to the establishment of the media channel and the | |||
frequency slot. | configuration of the effective frequency slot. | |||
In this context, when used unqualified, the frequency slot is a local | ||||
term, which applies at each hop. An effective frequency slot applies | ||||
at the media chall (LSP) level | ||||
A "service" request is characterized as a minimum, by its required | ||||
effective slot width. This does not preclude that the request may | ||||
add additional constraints such as imposing also the nominal central | ||||
frequency. A given frequency slot is requested for the media channel | ||||
say, with the Path message. Regardless of the actual encoding, the | ||||
Path message sender descriptor sender_tspec shall specify a minimum | ||||
frequency slot width that needs to be fulfilled. | ||||
In order to allocate a proper effective frequency slot for a LSP, the | A "service request" is characterized (at a minimum) by its required | |||
signaling should specify its required slot width. | effective frequency slot width. This does not preclude that the | |||
request may add additional constraints such as also imposing the | ||||
nominal central frequency. A given effective frequency slot may be | ||||
requested for the media channel in the control plane LSP setup | ||||
messages, and a specific frequency slot can be requeste on any | ||||
specific hop of the LSP setup. Regardless of the actual encoding, | ||||
the LSP setup message specifies a minimum frequency slot width that | ||||
needs to be fulfilled in order to successful establish the requsted | ||||
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, one must be able | spectrum of the effective frequency slot). That is, it must be | |||
to obtain an end-to-end equivalent n and m parameters. We refer to | possible to determine the end-to-end values of the n and m | |||
this as the "effective frequency slot of the media channel/LSP must | parameters. We refer to this by saying that the "effective frequency | |||
be valid". | slot of the media channel/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 the | |||
TSpec and the effective frequency slot is mapped to the FlowSpec. | TSpec present in the Path message, and the effective frequency slot | |||
is mapped to the FlowSpec carried in the Resv message. | ||||
The switched element corresponds in GMPLS to the 'label'. As in | In GMPLS-controlled systems, the switched element corresponds to the | |||
flexi-grid the switched element is a frequency slot, the label | 'label'. In flexi-grid where the switched element is a frequency | |||
represents a frequency slot. Consequently, the label in flexi-grid | slot, the label represents a frequency slot. In consequence, the | |||
must convey the necessary information to obtain the frequency slot | label in flexi-grid conveys the necessary information to obtain the | |||
characteristics (i.e, center and width, the n and m parameters). The | frequency slot characteristics (i.e, central frequency and slot | |||
frequency slot is locally identified by the label | width: the n and m parameters). The frequency slot is locally | |||
identified by the label. | ||||
The local frequency slot may change at each hop, typically given | The local frequency slot may change at each hop, given hardware | |||
hardware constraints (e.g. a given node cannot support the finest | constraints and capabilities (e.g., a given node might not support | |||
granularity). Locally n and m may change. As long as a given | the finest granularity). This means that the values of n and m may | |||
downstream node allocates enough optical spectrum, m can be different | change at each hop. As long as a given downstream node allocates | |||
along the path. This covers the issue where concrete media matrices | enough optical spectrum, m can be different along the path. This | |||
can have different slot width granularities. Such "local" m will | covers the issue where media matrices can have different slot width | |||
appear in the allocated label that encodes the frequency slot as well | granularities. Such variations in the local value of m will appear | |||
as the flow descriptor flowspec. | in the allocated label that encodes the frequency slot as well as the | |||
in the FlowSpec that describes the flow. | ||||
Different modes are considered: RSA with explicit label control, and | Different operational modes can be considered. For Routing and | |||
for R+DSA, the GMPLS signaling procedure is similar to the one | Spectrum Assignment (RSA) with explicit label control, and for | |||
described in section 4.1.3 of [RFC6163] except that the label set | Routing and Distributed Spectrum Assignment (R+DSA), the GMPLS | |||
should specify the available nominal central frequencies that meet | signaling procedures are similar to those described in section 4.1.3 | |||
the slot width requirement of the LSP. The intermediate nodes can | of [RFC6163] for Routing and Wavelength Assignment (RWA) and for | |||
collect the acceptable central frequencies that meet the slot width | Routing and Distributed Wavelength Assignment (R+DWA). The main | |||
requirement hop by hop. The tail-end node also needs to know the | difference is that the label set specifies the available nominal | |||
slot width of a LSP to assign the proper frequency resource. | central frequencies that meet the slot width requirements of the LSP. | |||
Compared with [RFC6163], except identifying the resource (i.e., fixed | ||||
wavelength for WSON and frequency resource for flexible grids), the | ||||
other signaling requirements (e.g., unidirectional or bidirectional, | ||||
with or without converters) are the same as WSON described in the | ||||
section 6.1 of [RFC6163]. | ||||
Regarding how a GMPLS control plane can assign n and m, different | The intermediate nodes use the control plane to collect the | |||
cases can apply: | acceptable central frequencies that meet the slot width requirement | |||
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 | ||||
identifying the resource (i.e., fixed wavelength for WSON, and | ||||
frequency resource for flexible grids), the other signaling | ||||
requirements (e.g., unidirectional or bidirectional, with or without | ||||
converters) are the same as for WSON as described in section 6.1 of | ||||
[RFC6163]. | ||||
a) n and m can both change. It is the effective slot what | Regarding how a GMPLS control plane can assign n and m hop-by-hop | |||
matters. Some entity needs to make sure the effective frequency | along the path of an LSP, different cases can apply: | |||
slot remains valid. | ||||
b) m can change; n needs to be the same along the path. This | a. n and m can both change. It is the effective frequency slot that | |||
ensures that the nominal central frequency stays the same. | matters, it needs to remain valid along the path. | |||
c) n and m need to be the same. | b. m can change, but n needs to remain the same along the path. | |||
This ensures that the nominal central frequency stays the same, | ||||
but the width of the slot can vary along the path. Again, the | ||||
important thing is that the effective frequency slot remains | ||||
valid and satisfies the requested parameters along the whole path | ||||
of the LSP. | ||||
d)n can change, m needs to be the same. | 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 | ||||
to ensure that the effective frequency slot remains valid for the | ||||
whole LSP. | ||||
In consequence, an entity such as a PCE can make sure that the n and | d. n can change, but m needs to remain the same along the path. | |||
m stay the same along the path. Any constraint (including frequency | This ensures that the effective frequency slot remains valid, but | |||
slot and width granularities) is taken into account during path | allows the frequency slot to be moved within the spectrum from | |||
computation. alternatively, A PCE (or a source node) can compute a | hop to hop. | |||
path and the actual frequency slot assignment is done, for example, | ||||
with a distributed (signaling) procedure: | ||||
Each downstream node ensures that m is >= requested_m. | The selection of a path that ensures n and m continuity can be | |||
delegated to a dedicated entity such as a Path Computation Element | ||||
(PCE). Any constraint (including frequency slot and width | ||||
granularities) can be taken into account during path computation. | ||||
Alternatively, A PCE can compute a path leaving the actual frequency | ||||
slot assignment to be done, for example, with a distributed | ||||
(signaling) procedure: | ||||
Since a downstream node cannot foresee what an upstream node will | o Each downstream node ensures that m is >= requested_m. | |||
allocate in turn, a way we can ensure that the effective frequency | ||||
slot is valid is then by ensuring that the same "n" is allocated. | ||||
By forcing the same n, we avoid cases where the effective | ||||
frequency slot of the media channel is invalid (that is, the | ||||
resulting frequency slot cannot be described by its n and m | ||||
parameters). | ||||
Maybe this is a too hard restriction, since a node (or even a | o A downstream node cannot foresee what an upstream node will | |||
centralized/combined RSA entity) can make sure that the resulting | allocate. A way to ensure that the effective frequency slot is | |||
end to end (effective) frequency slot is valid, even if n is | valid along the length of the LSP is to ensure that the same value | |||
different locally. That means, the effective (end to end) | of n is allocated at each hop. By forcing the same value of n we | |||
frequency slot that characterizes the media channel is one and | avoid cases where the effective frequency slot of the media | |||
determined by its n and m, but are logical, in the sense that they | channel is invalid (that is, the resulting frequency slot cannot | |||
are the result of the intersection of local (filters) freq slots | be described by its n and m parameters). | |||
which may have different freq. slots | ||||
For Figure Figure 15 the effective slot is valid by ensuring that the | o This may be too restrictive, since a node (or even a centralized/ | |||
combined RSA entity) may be able ensure that the resulting end-to- | ||||
end effective frequency slot is valid even if n varies locally. | ||||
That means, the effective frequency slot that characterizes the | ||||
media channel from end to end is consistent and is determined by | ||||
its n and m values, but that the effective frequency slot and | ||||
those values are logical (i.e., do not map direct to the | ||||
physically assigned spectrum) in the sense that they are the | ||||
result of the intersection of locally-assigned frequency slots | ||||
applicable at local components (such as filters) each of which may | ||||
have assigned different frequency slots. | ||||
For Figure 15 the effective slot is made valid by ensuring that the | ||||
minimum m is greater than the requested m. The effective slot | minimum m is greater than the requested m. The effective slot | |||
(intersection) is the lowest m (bottleneck). | (intersection) is the lowest m (bottleneck). | |||
For Figure Figure 16 the effective slot is valid by ensuring that it | For Figure 16 the effective slot is made valid by ensuring that it is | |||
is valid at each hop in the upstream direction. The intersection | valid at each hop in the upstream direction. The intersection needs | |||
needs to be computed. Invalid slots could result otherwise. | to be computed because invalid slots could result otherwise. | |||
|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)) | |||
Figure 15: Distributed allocation with different m and same n | Figure 15: Distributed Allocation with Different m and Same n | |||
|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) | |||
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 OCh-P (i.e is a Network | Note, when a media channel is bound to one OTSi (i.e., is a network | |||
media channel), the EFS must be the one of the Och-P. The media | media channel), the EFS must be the one of the OTSi. The media | |||
channel setup by the LSP may contains the EFS of the network media | channel setup by the LSP may contains the EFS of the network media | |||
channel EFS. This is an endpoint property, the egress and ingress | channel EFS. This is an endpoint property: the egress and ingress | |||
SHOULD constrain the EFS to Och-P EFS . | have to constrain the EFS to be the OTSi EFS. | |||
5.6. Neighbor Discovery and Link Property Correlation | 4.6. Neighbor Discovery and Link Property Correlation | |||
Potential interworking problems between fixed-grid DWDM and flexible- | There are potential interworking problems between fixed-grid DWDM and | |||
grid DWDM nodes, may appear. Additionally, even two flexible-grid | flexi-grid DWDM nodes. Additionally, even two flexi-grid nodes may | |||
optical nodes may have different grid properties, leading to link | have different grid properties, leading to link property conflict | |||
property conflict. | with resulting limited interworking. | |||
Devices or applications that make use of the flexible-grid may not be | Devices or applications that make use of the flexi-grid might not be | |||
able to support every possible slot width. In other words, | able to support every possible slot width. In other words, different | |||
applications may be defined where different grid granularity can be | applications may be defined where each supports a different grid | |||
supported. Taking node F as an example, an application could be | granularity. Consider a node with an application where the nominal | |||
defined where the nominal central frequency granularity is 12.5 GHz | central frequency granularity is 12.5 GHz and where slot widths are | |||
requiring slot widths being multiple of 25 GHz. Therefore the link | multiples of 25 GHz. In this case the link between two optical nodes | |||
between two optical nodes with different grid granularity must be | with different grid granularities must be configured to align with | |||
configured to align with the larger of both granularities. Besides, | the larger of both granularities. Furthermore, different nodes may | |||
different nodes may have different slot width tuning ranges. | have 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 least the following | |||
properties should be negotiated: | properties need to be negotiated: | |||
Grid capability (channel spacing) - Between fixed-grid and | o Grid capability (channel spacing) - Between fixed-grid and flexi- | |||
flexible-grid nodes. | grid nodes. | |||
Grid granularity - Between two flexible-grid nodes. | o Grid granularity - Between two flexi-grid nodes. | |||
Slot width tuning range - Between two flexible-grid nodes. | o Slot width tuning range - Between two flexi-grid nodes. | |||
5.7. Path Computation / Routing and Spectrum Assignment (RSA) | 4.7. Path Computation / Routing and Spectrum Assignment (RSA) | |||
Much like in WSON, in which if there is no (available) wavelength | In WSON, if there is no (available) wavelength converter in an | |||
converters in an optical network, an LSP is subject to the | optical network, an LSP is subject to the "wavelength continuity | |||
''wavelength continuity constraint'' (see section 4 of [RFC6163]), if | constraint" (see section 4 of [RFC6163]). Similarly in flexi-grid, | |||
the capability of shifting or converting an allocated frequency slot, | if the capability to shift or convert an allocated frequency slot is | |||
the LSP is subject to the Optical ''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 wavelength/spectrum converters | |||
(sparse translucent optical network) the wavelength/spectrum | (in what is called a "sparse translucent optical network") the | |||
continuity constraint should always be considered. When available, | wavelength/spectrum continuity constraint always has to be | |||
information regarding spectrum conversion capabilities at the optical | considered. When available, information regarding spectrum | |||
nodes may be used by RSA (Routing and Spectrum Assignment) | conversion capabilities at the optical nodes may be used by RSA | |||
mechanisms. | mechanisms. | |||
The RSA process determines a route and frequency slot for a 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 (SA) | |||
should determine the central frequency and slot width based on the | determines the central frequency and slot width based on the slot | |||
slot width and available central frequencies information of the | width and available central frequencies information of the | |||
transmitter and receiver, and the available frequency ranges | transmitter and receiver, and utilizing the available frequency | |||
information and available slot width ranges of the links that the | ranges information and available slot width ranges of the links that | |||
route traverses. | the route traverses. | |||
5.7.1. Architectural Approaches to RSA | 4.7.1. Architectural Approaches to RSA | |||
Similar to RWA for fixed grids, different ways of performing RSA in | Similar to RWA for fixed grids [RFC6163], different ways of | |||
conjunction with the control plane can be considered. The approaches | performing RSA in conjunction with the control plane can be | |||
included in this document are provided for reference purposes only; | considered. The approaches included in this document are provided | |||
other possible options could also be deployed. | for reference purposes only: other possible options could also be | |||
deployed. | ||||
5.7.1.1. Combined RSA (R&SA) | 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 | ||||
associated LSPs. | ||||
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 should have the | frequency slot assignment. The computation entity needs access to | |||
detailed network information, e.g. connectivity topology constructed | detailed network information, e.g., the connectivity topology of the | |||
by nodes/links information, available frequency ranges on each link, | nodes and links, the available frequency ranges on each link, the | |||
node capabilities, etc. | node capabilities, etc. | |||
The computation entity could reside either on a PCE or the ingress | The computation entity could reside on a dedicated PCE server, in the | |||
provisioning application that requests the service, or on the ingress | ||||
node. | node. | |||
5.7.1.2. 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 should get the connectivity topology to compute the | The first entity needs the connectivity topology to compute the | |||
proper routes; the second entity should get the available frequency | proper routes. The second entity needs information about the | |||
ranges of the links and nodes' capabilities information to assign the | available frequency ranges of the links and the capabilities of the | |||
spectrum. | nodes in order to assign the spectrum. | |||
5.7.1.3. Routing and Distributed SA (R+DSA) | 4.7.1.3. Routing and Distributed SA (R+DSA) | |||
In this case, one 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 which meet the spectrum | |||
continuity constraint should be collected hop by hop along the route. | continuity constraint need to be collected hop-by-hop along the | |||
This procedure can be implemented by the GMPLS signaling protocol. | route. This procedure can be implemented by the GMPLS signaling | |||
protocol. | ||||
5.8. Routing / Topology dissemination | 4.8. Routing and Topology Dissemination | |||
In the case of combined RSA architecture, the computation entity | In the case of the combined RSA architecture, the computation entity | |||
needs to get the detailed network information, i.e. connectivity | needs the detailed network information, i.e., connectivity topology, | |||
topology, node capabilities and available frequency ranges of the | node capabilities, and available frequency ranges of the links. | |||
links. Route computation is performed based on the connectivity | Route computation is performed based on the connectivity topology and | |||
topology and node capabilities; spectrum assignment is performed | node capabilities, while spectrum assignment is performed based on | |||
based on the available frequency ranges of the links. The | the available frequency ranges of the links. The computation entity | |||
computation entity may get the detailed network information by the | may get the detailed network information via the GMPLS routing | |||
GMPLS routing protocol. Compared with [RFC6163], except wavelength- | protocol. | |||
specific availability information, the connectivity topology and node | ||||
capabilities are the same as WSON, which can be advertised by GMPLS | ||||
routing protocol (refer to section 6.2 of [RFC6163]. This section | ||||
analyses the necessary changes on link information brought by | ||||
flexible grids. | ||||
5.8.1. Available Frequency Ranges/slots of DWDM Links | For WSON, the connectivity topology and node capabilities can be | |||
advertised by the GMPLS routing protocol (refer to section 6.2 of | ||||
[RFC6163]. Except for wavelength-specific availability information, | ||||
the information for flexi-grid is the same as for WSON and can | ||||
equally be distributed by the GMPLS routing protocol. | ||||
This section analyses the necessary changes on link information | ||||
brought by flexible grids. | ||||
4.8.1. Available Frequency Ranges/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 6.25 GHz | |||
granularity. Different LSPs could make use of different slot widths | granularity. Different LSPs could make use of different slot widths | |||
on the same link. Hence, the available frequency ranges should be | on the same link. Hence, the available frequency ranges need to be | |||
advertised. | advertised. | |||
5.8.2. Available Slot Width Ranges of DWDM Links | 4.8.2. Available Slot Width Ranges of DWDM Links | |||
The available slot width ranges needs to be advertised, in | The available slot width ranges need to be advertised in combination | |||
combination with the Available frequency ranges, in order to verify | with the available frequency ranges, in order that the computing | |||
whether a LSP with a given slot width can be set up or not; this is | entity can verify whether an LSP with a given slot width can be set | |||
is constrained by the available slot width ranges of the media matrix | up or not. This is constrained by the available slot width ranges of | |||
Depending on the availability of the slot width ranges, it is | the media matrix. Depending on the availability of the slot width | |||
possible to allocate more spectrum than strictly needed by the LSP. | ranges, it is possible to allocate more spectrum than strictly needed | |||
by the LSP. | ||||
5.8.3. Spectrum Management | 4.8.3. Spectrum Management | |||
[Editors' note: the part on the hierarchy of the optical spectrum | The total available spectrum on a fiber can be described as a | |||
could be confusing, we can discuss it]. The total available spectrum | resource that can be partitioned. For example, a part of the | |||
on a fiber could be described as a resource that can be divided by a | spectrum could be assigned to a third party to manage, or parts of | |||
media device into a set of Frequency Slots. In terms of managing | the spectrum could be assigned by the operator for different classes | |||
spectrum, it is necessary to be able to speak about different | of traffic. This partitioning creates the impression that spectrum | |||
granularities of managed spectrum. For example, a part of the | is a hierarchy in view of Management and Control Plane: each | |||
spectrum could be assigned to a third party to manage. This need to | partition could be itself be partitioned. However, the hierarchy is | |||
partition creates the impression that spectrum is a hierarchy in view | created purely within a management system: it defines a hierarchy of | |||
of Management and Control Plane. The hierarchy is created within a | access or management rights, but there is no corresponding resource | |||
management system, and it is an access right hierarchy only. It is a | hierarchy within the fiber. | |||
management hierarchy without any actual resource hierarchy within | ||||
fiber. The end of fiber is a link end and presents a fiber port | ||||
which represents all of spectrum available on the fiber. Each | ||||
spectrum allocation appears as Link Channel Port (i.e., frequency | ||||
slot port) within fiber. | ||||
5.8.4. Information Model | The end of fiber is a link end and presents a fiber port which | |||
represents all of spectrum available on the fiber. Each spectrum | ||||
allocation appears as Link Channel Port (i.e., frequency slot port) | ||||
within fiber. Thus, while there is a hierarchy of ownership (the | ||||
Link Channel Port and corresponding LSP are located on a fiber and so | ||||
associated with a fiber port) there is no continued nesting hierarchy | ||||
of frequency slots within larger frequency slots. In its way, this | ||||
mirrors the fixed grid behavior where a wavelength is associated with | ||||
a port/fiber, but cannot be subdivided even though it is a partition | ||||
of the total spectrum available on the fiber. | ||||
Fixed DM grids can also be described via suitable choices of slots in | 4.8.4. Information Model | |||
a flexible DWDM grid. However, devices or applications that make use | ||||
of the flexible grid may not be capable of supporting every possible | This section defines an information model to describe the data that | |||
slot width or central frequency position. Following is the | represents the capabilities and resources available in an flexi-grid | |||
definition of information model, not intended to limit any IGP | network. It is not a data model and is not intended to limit any | |||
encoding implementation. For example, information required for | protocol solution such as an encoding for an IGP. For example, | |||
routing/path selection may be the set of available nominal central | information required for routing/path selection may be the set of | |||
frequencies from which a frequency slot of the required width can be | available nominal central frequencies from which a frequency slot of | |||
allocated. A convenient encoding for this information (may be as a | the required width can be allocated. A convenient encoding for this | |||
frequency slot or sets of contiguous slices) is further study in IGP | information is for further study in an IGP encoding document. | |||
encoding document. | ||||
Fixed DWDM grids can also be described via suitable choices of slots | ||||
in a flexible DWDM grid. However, devices or applications that make | ||||
use of the flexible grid may not be capable of supporting every | ||||
possible slot width or central frequency position. Thus, the | ||||
information model needs to enable: | ||||
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 | ||||
same network | ||||
interworking of flexgrid devices with different capabilities. | ||||
The information model is represented using Routing Backus-Naur Format | ||||
(RBNF) as defined in [RFC5511]. | ||||
<Available Spectrum in Fiber for frequency slot> ::= | <Available Spectrum in Fiber for frequency slot> ::= | |||
<Available Frequency Range-List> | <Available Frequency Range-List> | |||
<Available Central Frequency Granularity > | <Available Central Frequency Granularity > | |||
<Available Slot Width Granularity> | <Available Slot Width Granularity> | |||
<Minimal Slot Width> | <Minimal Slot Width> | |||
<Maximal Slot Width> | <Maximal Slot Width> | |||
<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 Spectrum Position><End Spectrum Position> | | ( <Start Spectrum Position> <End Spectrum Position> ) | | |||
<Sets of contiguous slices> | <Sets of contiguous slices> | |||
<Available Central Frequency Granularity> ::= n A— 6.25GHz, | <Available Central Frequency Granularity> ::= (2^n) x 6.25GHz | |||
where n is positive integer, such as 6.25GHz, 12.5GHz, 25GHz, 50GHz | where n is positive integer, giving rise to granularities | |||
or 100GHz | such as 6.25GHz, 12.5GHz, 25GHz, 50GHz, and 100GHz | |||
<Available Slot Width Granularity> ::= m A— 12.5GHz, | <Available Slot Width Granularity> ::= (2^m) x 12.5GHz | |||
where m is positive integer | where m is positive integer | |||
<Minimal Slot Width> ::= j x 12.5GHz, | <Minimal Slot Width> ::= j x 12.5GHz, | |||
j is a positive integer | j is a positive integer | |||
<Maximal Slot Width> ::= k x 12.5GHz, | <Maximal Slot Width> ::= k x 12.5GHz, | |||
k is a positive integer (k >= j) | k is a positive integer (k >= j) | |||
Figure 17: Routing Information model | Figure 17: Routing Information Model | |||
6. Control Plane Requirements | 5. Control Plane Requirements | |||
The GMPLS based control plane of a flexi-grid networks provides | The control of a flexi-grid networks places additional requirements | |||
aditional requirements to GMPLS. In this section the features to be | on the GMPLS protocols. This section summarizes those requirements | |||
covered by GMPLS signaling for flexi-grid are identified. [Editor's | for signaling and routing. | |||
note: Only discussed requirements are included at this stage. | ||||
Routing requirements will come in the next version] | ||||
6.1. 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 SHALL be able to support Network | Consequently, the control plane will also be able to support Network | |||
Media Channels. | Media Channels. | |||
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 control plane protocols SHALL allow 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 (12.5GHz) to a maximum of the | |||
entire C-band with a slot width granularity of 12.5GHz. | entire C-band with a slot width granularity of 12.5GHz. | |||
The signaling procedure of the GMPLS control plane SHALL be able to | The signaling procedure SHALL be able to configure the minimum width | |||
configure the minimum width (m) of a flexi-grid LSP. In adition, the | (m) of a flexi-grid LSP. In addition, the signaling procedure SHALL | |||
control plane SHALL be able to configure local frecuency 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 L-band | |||
and S-band | and S-band. | |||
The signalling process of the control plane SHALL allow to collect | The signalling process SHALL be able to collect the local frequency | |||
the local frequency slot asigned at each link along the path | slot assigned at each link along the path. | |||
6.2. Support for Media Channel Resizing | The signaling procedures SHALL support all of the RSA architectural | |||
models (R&SA, R+SA, and R+DSA) within a single set of protocol | ||||
objects although some objects may only be applicable within on of the | ||||
models. | ||||
The control plane SHALL allow resizing (grow or shrink) the frequency | 5.1.2. Routing | |||
slot width of a media channel/network media channel. The resizing | ||||
MAY imply resizing the local frequency slots along the path of the | ||||
flexi-grid LSP. | ||||
6.3. Support for Logical Associations of multiple media channels | The routing protocol will support all functions as described in | |||
[RFC4202] and extend them to a flexi-grid data plane. | ||||
The routing protocol SHALL distribute sufficient information to | ||||
compute paths to enable the signaling procedure to establish LSPs as | ||||
described in the previous sections. This includes, at a minimum the | ||||
data described by the Information Model in Figure 17. | ||||
The routing protocol SHALL update its advertisements of available | ||||
resources and capabilities as the usage of resources in the network | ||||
varies with the establishment or tear-down of LSPs. These updates | ||||
SHOULD be amenable to damping and thresholds as in other traffic | ||||
engineering routing advertisements. | ||||
The routing protocol SHALL support all of the RSA architectural | ||||
models (R&SA, R+SA, and R+DSA) without any configuration or change of | ||||
behavior. Thus, the routing protocols SHALL be agnostic to the | ||||
computation and signaling model that is in use. | ||||
5.2. Support for Media Channel Resizing | ||||
The signaling procedures SHALL allow resizing (grow or shrink) the | ||||
frequency slot width of a media channel/network media channel. The | ||||
resizing MAY imply resizing the local frequency slots along the path | ||||
of the flexi-grid LSP. | ||||
The routing protocol SHALL update its advertisements of available | ||||
resources and capabilities as the usage of resources in the network | ||||
varies with the resizing of LSP. These updates SHOULD be amenable to | ||||
damping and thresholds as in other traffic engineering routing | ||||
advertisements. | ||||
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 | |||
logically associated | that are logically associated. | |||
5.4. Support for Composite Media Channels | ||||
As described in Section 3.2.5 and Section 4.3, a media channel may be | ||||
composed of multiple network media channels. | ||||
The signaling procedures SHOULD include support for signaling a | ||||
single control plane LSP that includes information about multiple | ||||
network media channels that will comprise the single compound media | ||||
channel. | ||||
The signaling procedures SHOULD include a mechanism to associate | ||||
separately signaled control plane LSPs so that the end points may | ||||
correlate them into a single compound media channel. | ||||
The signaling procedures MAY include a mechanism to dynamically vary | ||||
the composition of a composite media channel by allowing network | ||||
media channels to be added to or removed from the whole. | ||||
The routing protocols MUST provide sufficient information for the | ||||
computation of paths and slots for composite media channels using any | ||||
of the three RSA architectural models (R&SA, R+SA, and R+DSA). | ||||
5.5. Support for Neighbor Discovery and Link Property Correlation | ||||
The control plane MAY include support for neighbor discovery such | ||||
that an flexi-grid network can be constructed in a "plug-and-play" | ||||
manner. | ||||
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 | ||||
correlation SHOULD include at least the identities of the node and | ||||
the identities they apply to the link. Other properties such as the | ||||
link characteristics described for the routing information model in | ||||
Figure 17 SHOULD also be correlated. | ||||
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 | ||||
control channel. | ||||
6. IANA Considerations | ||||
This framework document makes no requests for IANA action. | ||||
7. Security Considerations | 7. Security Considerations | |||
TBD | 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 | ||||
substantial reason to expect the security considerations to be any | ||||
different. | ||||
8. Contributing Authors | A good overview of the security considerations for a GMPLS-based | |||
control plane can be found in [RFC5920]. | ||||
Qilei Wang | [RFC6163] includes a section describing security considerations for | |||
ZTE | WSON, and it is reasonable to infer that these considerations apply | |||
Ruanjian Avenue, Nanjing, China | and may be exacerbated in a flexi-grid SSON system. In particular, | |||
wang.qilei@zte.com.cn | the detailed and granular information describing a flexi- grid | |||
network and the capabilities of nodes in that network could put | ||||
stress on the routing protocol or the out-of-band control channel | ||||
used by the protocol. An attacker might be able to cause small | ||||
variations in the use of the network or the available resources | ||||
(perhaps by modifying the environment of a fiber) and so trigger the | ||||
routing protocol to make new flooding announcements. This situation | ||||
is explicitly mitigated in the requirements for the routing protocol | ||||
extensions where it is noted that the protocol must include damping | ||||
and configurable thresholds as already exist in the core GMPLS | ||||
routing protocols. | ||||
Malcolm Betts | 8. Manageability Considerations | |||
ZTE | ||||
malcolm.betts@zte.com.cn | GMPLS systems already contain a number of management tools. | |||
o MIB modules exist to model the control plane protocols and the | ||||
network elements [RFC4802], [RFC4803], and there is early work to | ||||
provide similar access through YANG. The features described in | ||||
these models are currently designed to represent fixed-label | ||||
technologies such as optical networks using the fixed grid: | ||||
extensions may be needed in order to represent bandwidth, | ||||
frequency slots, and effective frequency slots in flexi- grid | ||||
networks. | ||||
o There are protocol extensions within GMPLS signaling to allow | ||||
control plane systems to report the presence of faults that affect | ||||
LSPs [RFC4783], although it must be carefully noted that these | ||||
mechanisms do not constitute an alarm mechanism that could be used | ||||
to rapidly propagate information about faults in a way that would | ||||
allow the data plane to perform protection switching. These | ||||
mechanisms could easily be enhanced with the addition of | ||||
technology-specific reasons codes if any are needed. | ||||
o The GMPLS protocols, themselves, already include fault detection | ||||
and recovery mechanisms (such as the PathErr and Notify messages | ||||
in RSVP-TE signaling as used by GMPLS [RFC3473]. It is not | ||||
anticipated that these mechanisms will need enhancement to support | ||||
flexi-grid although additional reason codes may be needed to | ||||
describe technology-specific error cases. | ||||
o [RFC7260] describes a framework for the control and configuration | ||||
of data plane Operations, Administration, and Management (OAM). | ||||
It would not be appropriate for the IETF to define or describe | ||||
data plane OAM for optical systems, but the framework described in | ||||
RFC 7260 could be used (with minor protocol extensions) to enable | ||||
data plane OAM that has been defined by the originators of the | ||||
flexi-grid data plane technology (the ITU-T). | ||||
o The Link Management Protocol [RFC4204] is designed to allow the | ||||
two ends of a network link to coordinate and confirm the | ||||
configuration and capabilities that they will apply to the link. | ||||
This protocol is particularly applicable to optical links where | ||||
the characteristics of the network devices may considerably affect | ||||
how the link is used and where misconfiguration of mis-fibering | ||||
could make physical interoperability impossible. LMP could easily | ||||
be extended to collect and report information between the end | ||||
points of links in a flexi-grid network. | ||||
9. Contributing Authors | ||||
Adrian Farrel | ||||
Old Dog Consulting | ||||
adrian@olddog.co.uk | ||||
Daniel King | ||||
Old Dog Consulting | ||||
daniel@olddog.co.uk | ||||
Xian Zhang | Xian Zhang | |||
Huawei | Huawei | |||
zhang.xian@huawei.com | zhang.xian@huawei.com | |||
Cyril Margaria | Cyril Margaria | |||
Juniper Networks | Juniper Networks | |||
cmargaria@juniper.net | 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 | Sergio Belotti | |||
Alcatel Lucent | Alcatel Lucent | |||
Optics CTO | Optics CTO | |||
Via Trento 30 20059 Vimercate (Milano) Italy | Via Trento 30 20059 Vimercate (Milano) Italy | |||
+39 039 6863033 | +39 039 6863033 | |||
sergio.belotti@alcatel-lucent.com | sergio.belotti@alcatel-lucent.com | |||
Yao Li | Yao Li | |||
Nanjing University | Nanjing University | |||
wsliguotou@hotmail.com | wsliguotou@hotmail.com | |||
skipping to change at page 29, line 25 | skipping to change at page 36, line 15 | |||
China Academy of Telecom Research | China Academy of Telecom Research | |||
No.52 Huayuan Bei Road, Beijing, China | No.52 Huayuan Bei Road, Beijing, China | |||
zhangguoying@ritt.cn | zhangguoying@ritt.cn | |||
Takehiro Tsuritani | Takehiro Tsuritani | |||
KDDI R&D Laboratories Inc. | KDDI R&D Laboratories Inc. | |||
2-1-15 Ohara, Fujimino, Saitama, Japan | 2-1-15 Ohara, Fujimino, Saitama, Japan | |||
tsuri@kddilabs.jp | tsuri@kddilabs.jp | |||
Lei Liu | Lei Liu | |||
KDDI R&D Laboratories Inc. | U.C. Davis, USA | |||
2-1-15 Ohara, Fujimino, Saitama, Japan | leiliu@ucdavis.edu | |||
le-liu@kddilabs.jp | ||||
Eve Varma | Eve Varma | |||
Alcatel-Lucent | Alcatel-Lucent | |||
+1 732 239 7656 | +1 732 239 7656 | |||
eve.varma@alcatel-lucent.com | eve.varma@alcatel-lucent.com | |||
Young Lee | Young Lee | |||
Huawei | Huawei | |||
Jianrui Han | Jianrui Han | |||
skipping to change at page 30, line 17 | skipping to change at page 37, line 7 | |||
Marco Sosa | Marco Sosa | |||
Infinera | Infinera | |||
Biao Lu | Biao Lu | |||
Infinera | Infinera | |||
Abinder Dhillon | Abinder Dhillon | |||
Infinera | Infinera | |||
Felipe Jimenez Arribas | Felipe Jimenez Arribas | |||
TelefA^3nica I+D | Telefonica I+D | |||
Andrew G. Malis | Andrew G. Malis | |||
Verizon | Huawei | |||
agmalis@gmail.com | ||||
Adrian Farrel | ||||
Old Dog Consulting | ||||
Daniel King | ||||
Old Dog Consulting | ||||
Huub van Helvoort | Huub van Helvoort | |||
Hai Gaoming BV | ||||
The Neterlands | ||||
huubatwork@gmail.com | ||||
9. Acknowledgments | 10. Acknowledgments | |||
The authors would like to thank Pete Anslow for his insights and | The authors would like to thank Pete Anslow for his insights and | |||
clarifications. This work was supported in part by the FP-7 IDEALIST | clarifications. | |||
project under grant agreement number 317999. | ||||
10. References | This work was supported in part by the FP-7 IDEALIST project under | |||
grant agreement number 317999. | ||||
10.1. Normative References | 11. References | |||
11.1. Normative References | ||||
[G.694.1] International Telecomunications Union, "ITU-T | [G.694.1] International Telecomunications Union, "ITU-T | |||
Recommendation G.694.1, Spectral grids for WDM | Recommendation G.694.1, Spectral grids for WDM | |||
applications: DWDM frequency grid", November 2012. | applications: DWDM frequency grid", November 2012. | |||
[G.709] International Telecomunications Union, "ITU-T | ||||
Recommendation G.709, Interfaces for the Optical Transport | ||||
Network (OTN).", March 2009. | ||||
[G.800] International Telecomunications Union, "ITU-T | [G.800] International Telecomunications Union, "ITU-T | |||
Recommendation G.800, Unified functional architecture of | Recommendation G.800, Unified functional architecture of | |||
transport networks.", February 2012. | transport networks.", February 2012. | |||
[G.805] International Telecomunications Union, "ITU-T | [G.805] International Telecomunications Union, "ITU-T | |||
Recommendation G.805, Generic functional architecture of | Recommendation G.805, Generic functional architecture of | |||
transport networks.", March 2000. | transport networks.", March 2000. | |||
[G.8080] International Telecomunications Union, "ITU-T | [G.8080] International Telecomunications Union, "ITU-T | |||
Recommendation G.8080/Y.1304, Architecture for the | Recommendation G.8080/Y.1304, Architecture for the | |||
skipping to change at page 31, line 37 | skipping to change at page 38, line 21 | |||
networks, draft v0.16 2012/09 (for discussion)", 2012. | networks, draft v0.16 2012/09 (for discussion)", 2012. | |||
[G.959.1-2013] | [G.959.1-2013] | |||
International Telecomunications Union, "Update of ITU-T | International Telecomunications Union, "Update of ITU-T | |||
Recommendation G.959.1, Optical transport network physical | Recommendation G.959.1, Optical transport network physical | |||
layer interfaces (to appear in July 2013)", 2013. | layer interfaces (to appear in July 2013)", 2013. | |||
[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, March 1997. | Requirement Levels", BCP 14, RFC 2119, March 1997. | |||
[RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching | [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in | |||
(GMPLS) Architecture", RFC 3945, October 2004. | Support of Generalized Multi-Protocol Label Switching | |||
(GMPLS)", RFC 4202, October 2005. | ||||
[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, October 2005. | (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005. | |||
[RFC5150] Ayyangar, A., Kompella, K., Vasseur, JP., and A. Farrel, | [RFC5511] Farrel, A., "Routing Backus-Naur Form (RBNF): A Syntax | |||
"Label Switched Path Stitching with Generalized | Used to Form Encoding Rules in Various Routing Protocol | |||
Multiprotocol Label Switching Traffic Engineering (GMPLS | Specifications", RFC 5511, April 2009. | |||
TE)", RFC 5150, February 2008. | ||||
[RFC6163] Lee, Y., Bernstein, G., and W. Imajuku, "Framework for | 11.2. Informative References | |||
GMPLS and Path Computation Element (PCE) Control of | ||||
Wavelength Switched Optical Networks (WSONs)", RFC 6163, | ||||
April 2011. | ||||
10.2. Informative References | [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching | |||
(GMPLS) Signaling Resource ReserVation Protocol-Traffic | ||||
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. | ||||
[RFC4204] Lang, J., "Link Management Protocol (LMP)", RFC 4204, | ||||
October 2005. | ||||
[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, February 2006. | Architecture", RFC 4397, February 2006. | |||
[RFC4606] Mannie, E. and D. Papadimitriou, "Generalized Multi- | ||||
Protocol Label Switching (GMPLS) Extensions for | ||||
Synchronous Optical Network (SONET) and Synchronous | ||||
Digital Hierarchy (SDH) Control", RFC 4606, August 2006. | ||||
[RFC4783] Berger, L., "GMPLS - Communication of Alarm Information", | ||||
RFC 4783, December 2006. | ||||
[RFC4802] Nadeau, T. and A. Farrel, "Generalized Multiprotocol Label | ||||
Switching (GMPLS) Traffic Engineering Management | ||||
Information Base", RFC 4802, February 2007. | ||||
[RFC4803] Nadeau, T. and A. Farrel, "Generalized Multiprotocol Label | ||||
Switching (GMPLS) Label Switching Router (LSR) Management | ||||
Information Base", RFC 4803, February 2007. | ||||
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS | ||||
Networks", RFC 5920, July 2010. | ||||
[RFC6163] Lee, Y., Bernstein, G., and W. Imajuku, "Framework for | ||||
GMPLS and Path Computation Element (PCE) Control of | ||||
Wavelength Switched Optical Networks (WSONs)", RFC 6163, | ||||
April 2011. | ||||
[RFC6344] Bernstein, G., Caviglia, D., Rabbat, R., and H. van | ||||
Helvoort, "Operating Virtual Concatenation (VCAT) and the | ||||
Link Capacity Adjustment Scheme (LCAS) with Generalized | ||||
Multi-Protocol Label Switching (GMPLS)", RFC 6344, August | ||||
2011. | ||||
[RFC7139] Zhang, F., Zhang, G., Belotti, S., Ceccarelli, D., and K. | ||||
Pithewan, "GMPLS Signaling Extensions for Control of | ||||
Evolving G.709 Optical Transport Networks", RFC 7139, | ||||
March 2014. | ||||
[RFC7260] Takacs, A., Fedyk, D., and J. He, "GMPLS RSVP-TE | ||||
Extensions for Operations, Administration, and Maintenance | ||||
(OAM) Configuration", RFC 7260, June 2014. | ||||
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 | Don Ramon de la Cruz 82-84 | |||
Madrid 28045 | Madrid 28045 | |||
Spain | Spain | |||
Phone: +34913128832 | Phone: +34913128832 | |||
Email: oscar.gonzalezdedios@telefonica.com | Email: oscar.gonzalezdedios@telefonica.com | |||
skipping to change at page 32, line 44 | skipping to change at page 40, line 24 | |||
Huawei | Huawei | |||
Huawei Base, Bantian, Longgang District | Huawei Base, Bantian, Longgang District | |||
Shenzhen 518129 | Shenzhen 518129 | |||
China | China | |||
Phone: +86-755-28972912 | Phone: +86-755-28972912 | |||
Email: zhangfatai@huawei.com | Email: zhangfatai@huawei.com | |||
Xihua Fu | Xihua Fu | |||
ZTE | ZTE | |||
Ruanjian Avenue | ZTE Plaza,No.10,Tangyan South Road, Gaoxin District | |||
Nanjing | Xi'An | |||
China | China | |||
Email: fu.xihua@zte.com.cn | Email: fu.xihua@zte.com.cn | |||
Daniele Ceccarelli | Daniele Ceccarelli | |||
Ericsson | Ericsson | |||
Via Calda 5 | Via Calda 5 | |||
Genova | Genova | |||
Italy | Italy | |||
Phone: +39 010 600 2512 | Phone: +39 010 600 2512 | |||
Email: daniele.ceccarelli@ericsson.com | Email: daniele.ceccarelli@ericsson.com | |||
Iftekhar Hussain | Iftekhar Hussain | |||
End of changes. 208 change blocks. | ||||
702 lines changed or deleted | 1026 lines changed or added | |||
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