--- 1/draft-ietf-ccamp-flexi-grid-fwk-03.txt 2015-05-18 02:17:04.206835870 -0700 +++ 2/draft-ietf-ccamp-flexi-grid-fwk-04.txt 2015-05-18 02:17:04.282837696 -0700 @@ -1,28 +1,28 @@ -Network Working Group O. Gonzalez de Dios, Ed. +CCAMP Working Group O. Gonzalez de Dios, Ed. Internet-Draft Telefonica I+D -Intended status: Standards Track R. Casellas, Ed. -Expires: August 27, 2015 CTTC +Intended status: Informational R. Casellas, Ed. +Expires: November 19, 2015 CTTC F. Zhang Huawei X. Fu ZTE D. Ceccarelli Ericsson I. Hussain Infinera - February 23, 2015 + May 18, 2015 Framework and Requirements for GMPLS-based control of Flexi-grid DWDM networks - draft-ietf-ccamp-flexi-grid-fwk-03 + draft-ietf-ccamp-flexi-grid-fwk-04 Abstract To allow efficient allocation of optical spectral bandwidth for high bit-rate systems, the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) has extended its Recommendations G.694.1 and G.872 to include a new dense wavelength division multiplexing (DWDM) grid by defining a set of nominal central frequencies, channel spacings and the concept of "frequency slot". In such an environment, a data plane connection is switched @@ -41,21 +41,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on August 27, 2015. + This Internet-Draft will expire on November 19, 2015. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -68,60 +68,60 @@ Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 2.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4 3. Overview of Flexi-grid Networks . . . . . . . . . . . . . . . 5 3.1. Flexi-grid in the Context of OTN . . . . . . . . . . . . 5 3.2. Flexi-grid Terminology . . . . . . . . . . . . . . . . . 6 3.2.1. Frequency Slots . . . . . . . . . . . . . . . . . . . 6 - 3.2.2. Media Channels . . . . . . . . . . . . . . . . . . . 8 - 3.2.3. Media Layer Elements . . . . . . . . . . . . . . . . 8 + 3.2.2. Media Layer Elements . . . . . . . . . . . . . . . . 8 + 3.2.3. Media Channels . . . . . . . . . . . . . . . . . . . 8 3.2.4. Optical Tributary Signals . . . . . . . . . . . . . . 9 3.2.5. Composite Media Channels . . . . . . . . . . . . . . 9 3.3. Hierarchy in the Media Layer . . . . . . . . . . . . . . 10 3.4. Flexi-grid Layered Network Model . . . . . . . . . . . . 10 3.4.1. DWDM Flexi-grid Enabled Network Element Models . . . 12 4. GMPLS Applicability . . . . . . . . . . . . . . . . . . . . . 12 4.1. General Considerations . . . . . . . . . . . . . . . . . 12 4.2. Consideration of TE Links . . . . . . . . . . . . . . . . 13 - 4.3. Consideration of LSPs in Flexi-grid . . . . . . . . . . . 16 - 4.4. Control Plane Modeling of Network Elements . . . . . . . 21 - 4.5. Media Layer Resource Allocation Considerations . . . . . 21 - 4.6. Neighbor Discovery and Link Property Correlation . . . . 25 - 4.7. Path Computation / Routing and Spectrum Assignment (RSA) 26 - 4.7.1. Architectural Approaches to RSA . . . . . . . . . . . 26 - 4.8. Routing and Topology Dissemination . . . . . . . . . . . 27 - 4.8.1. Available Frequency Ranges/Slots of DWDM Links . . . 28 - 4.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 28 - 4.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 28 - 4.8.4. Information Model . . . . . . . . . . . . . . . . . . 28 - 5. Control Plane Requirements . . . . . . . . . . . . . . . . . 30 - 5.1. Support for Media Channels . . . . . . . . . . . . . . . 30 - 5.1.1. Signaling . . . . . . . . . . . . . . . . . . . . . . 31 - 5.1.2. Routing . . . . . . . . . . . . . . . . . . . . . . . 31 - 5.2. Support for Media Channel Resizing . . . . . . . . . . . 32 + 4.3. Consideration of LSPs in Flexi-grid . . . . . . . . . . . 15 + 4.4. Control Plane Modeling of Network Elements . . . . . . . 20 + 4.5. Media Layer Resource Allocation Considerations . . . . . 20 + 4.6. Neighbor Discovery and Link Property Correlation . . . . 24 + 4.7. Path Computation / Routing and Spectrum Assignment (RSA) 25 + 4.7.1. Architectural Approaches to RSA . . . . . . . . . . . 25 + 4.8. Routing and Topology Dissemination . . . . . . . . . . . 26 + 4.8.1. Available Frequency Ranges/Slots of DWDM Links . . . 27 + 4.8.2. Available Slot Width Ranges of DWDM Links . . . . . . 27 + 4.8.3. Spectrum Management . . . . . . . . . . . . . . . . . 27 + 4.8.4. Information Model . . . . . . . . . . . . . . . . . . 27 + 5. Control Plane Requirements . . . . . . . . . . . . . . . . . 29 + 5.1. Support for Media Channels . . . . . . . . . . . . . . . 29 + 5.1.1. Signaling . . . . . . . . . . . . . . . . . . . . . . 30 + 5.1.2. Routing . . . . . . . . . . . . . . . . . . . . . . . 30 + 5.2. Support for Media Channel Resizing . . . . . . . . . . . 31 5.3. Support for Logical Associations of Multiple Media - Channels . . . . . . . . . . . . . . . . . . . . . . . . 32 - 5.4. Support for Composite Media Channels . . . . . . . . . . 32 + Channels . . . . . . . . . . . . . . . . . . . . . . . . 31 + 5.4. Support for Composite Media Channels . . . . . . . . . . 31 5.5. Support for Neighbor Discovery and Link Property - Correlation . . . . . . . . . . . . . . . . . . . . . . . 32 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 - 7. Security Considerations . . . . . . . . . . . . . . . . . . . 33 - 8. Manageability Considerations . . . . . . . . . . . . . . . . 33 - 9. Contributing Authors . . . . . . . . . . . . . . . . . . . . 34 - 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 37 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 37 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 37 - 11.2. Informative References . . . . . . . . . . . . . . . . . 38 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39 + Correlation . . . . . . . . . . . . . . . . . . . . . . . 31 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 + 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32 + 8. Manageability Considerations . . . . . . . . . . . . . . . . 32 + 9. Contributing Authors . . . . . . . . . . . . . . . . . . . . 33 + 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 36 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 36 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 36 + 11.2. Informative References . . . . . . . . . . . . . . . . . 37 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38 1. Introduction The term "Flexible grid" (flexi-grid for short) as defined by the International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Study Group 15 in the latest version of [G.694.1], refers to the updated set of nominal central frequencies (a frequency grid), channel spacing and optical spectrum management/allocation considerations that have been defined in order to allow an efficient and flexible allocation and configuration of @@ -138,22 +138,23 @@ optical spectrum frequency ranges or frequency slots with typical channel separations of 50 GHz, a flexible grid network can select its media channels with a more flexible choice of slot widths, allocating as much optical spectrum as required. 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 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 of a media channel is given by the properties of the associated - frequency slot. In this layered network, the media channel can - transport more than one Optical Tributary Signals. + frequency slot. In this layered network, a media channel can + transport more than one Optical Tributary Signals (OTSi), as defined + later in this document. A Wavelength Switched Optical Network (WSON), addressed in [RFC6163], is a term commonly used to refer to the application/deployment of a GMPLS-based control plane for the control (provisioning/recovery, etc.) of a fixed grid wavelength division multiplexing (WDM) network in which media (spectrum) and signal are jointly considered. This document defines the framework for a GMPLS-based control of flexi-grid enabled dense wavelength division multiplexing (DWDM) networks (in the scope defined by ITU-T layered Optical Transport @@ -179,44 +180,46 @@ FS: Frequency Slot FSC: Fiber-Switch Capable LSR: Label Switching Router NCF: Nominal Central Frequency OCh: Optical Channel - OCh-P: Optical Channel Payload + + OTN: Optical Transport Network + OTSi: Optical Tributary Signal - OTSiG: OTSi Group is the set of OTSi signals + OTSiG: OTSi Group is a set of OTSi OCC: Optical Channel Carrier PCE: Path Computation Element ROADM: Reconfigurable Optical Add-Drop Multiplexer SSON: Spectrum-Switched Optical Network SWG: Slot Width Granularity 3. Overview of Flexi-grid Networks 3.1. Flexi-grid in the Context of OTN [G.872] describes, from a network level, the functional architecture - of Optical Transport Networks (OTN). The OTN is decomposed into - independent layer networks with client/layer relationships among - them. A simplified view of the OTN layers is shown in Figure 1. + of an OTN. It is decomposed into independent layer networks with + client/layer relationships among them. A simplified view of the OTN + layers is shown in Figure 1. +----------------+ | Digital Layer | +----------------+ | Signal Layer | +----------------+ | Media Layer | +----------------+ Figure 1: Generic OTN Overview @@ -238,52 +241,47 @@ This section presents the definition of the terms used in flexi-grid networks. More detail about these terms can be found in the ITU-T Recommendations [G.694.1], [G.872]), [G.870], [G.8080], and [G.959.1-2013]. Where appropriate, this documents also uses terminology and lexicography from [RFC4397]. 3.2.1. Frequency Slots - This subsection is focused on the frequency slot related terms. + This subsection is focused on the frequency slot and related terms. o Frequency Slot [G.694.1]: The frequency range allocated to a slot within the flexible grid and unavailable to other slots. A frequency slot is defined by its nominal central frequency and its slot width. - o Effective Frequency Slot [G.870]: The effective frequency slot of - a media channel is that part of the frequency slots of the filters - along the media channel that is common to all of the filters' - frequency slots. Note that both the Frequency Slot and Effective - Frequency Slot are both local terms. - 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 expression f = 193.1 THz + n x 0.00625 THz where 193.1 THz is ITU-T "anchor frequency" for transmission over the C band, and n is a positive or negative integer including 0. -5 -4 -3 -2 -1 0 1 2 3 4 5 <- values of n ...+--+--+--+--+--+--+--+--+--+--+- ^ 193.1 THz <- anchor frequency Figure 2: Anchor Frequency and Set of Nominal Central Frequencies o Nominal Central Frequency Granularity: This is the spacing between - allowed nominal central frequencies and it is set to 6.25 GHz. + allowed nominal central frequencies and it is set to 6.25 GHz + [G.694.1]. o Slot Width Granularity (SWG): 12.5 GHz, as defined in [G.694.1]. o Slot Width: The slot width determines the "amount" of optical 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 ------------- ------------------- @@ -300,31 +298,28 @@ * 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. + * The nominal central frequency is 193.1 THz when n equals to + 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. + o Effective Frequency Slot [G.870]: The effective frequency slot of + a media channel is that part of the frequency slots of the filters + along the media channel that is common to all of the filters' + frequency slots. Note that both the Frequency Slot and Effective + Frequency Slot are local terms. Frequency Slot 1 ------------- | | -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... Frequency Slot 2 ------------------- | | @@ -333,78 +328,76 @@ =============================================== Effective Frequency Slot ------------- | | -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 ..--+--+--+--+--X--+--+--+--+--+--+--+--+--+--+--+--... Figure 4: Effective Frequency Slot -3.2.2. Media Channels +3.2.2. Media Layer Elements + + o Media Element: A media element directs an optical signal or + 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. + + 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. + +3.2.3. Media Channels This section defines concepts such as (Network) Media Channel; the mapping to GMPLS constructs (i.e., LSP) is detailed in Section 4. o Media Channel: A media association that represents both the topology (i.e., path through the media) and the resource (frequency slot) that it occupies. As a topological construct, it 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. 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. - -3.2.3. Media Layer Elements - - o Media Element: A media element directs an optical signal or - 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. - - 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. + as a media channel that transports a single OTSi, defined next. 3.2.4. Optical Tributary Signals 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. - o OTSi Group (OTSiG): The set of OTSi signals that are carried by a - 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. + o OTSi Group (OTSiG): The set of OTSi that are carried by a group of + network media channels. Each OTSi is carried by one network media + 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. + carried by one network media channel. This group of OTSi are + 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. @@ -421,68 +414,67 @@ 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. + support two network media channels, each of them carrying one OTSi. Media Channel Frequency Slot +-------------------------------X------------------------------+ | | | Frequency Slot Frequency Slot | - | +------------X-----------+ +----------X-----------+ | - | | Opt Tributary Signal | | Opt Tributary Signal | | + | +------------X----------+ +----------X-----------+ | + | | OTSi | | OTSi | | | | 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 + 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 | + single OTSi (see Figure 6) + | OTSi | O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O | | | Channel Port Network Media Channel Channel Port | O - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O | | +--------+ +-----------+ +--------+ | \ (1) | | (1) | | (1) / | | \----|-----------------|-----------|-------------------|-----/ | +--------+ Link Channel +-----------+ Link Channel +--------+ Media Channel Media Channel Media Channel Matrix Matrix Matrix The symbol (1) indicates a Matrix Channel Figure 6: Simplified Layered Network Model - A particular example of Optical Tributary Signal is the OCh-P. - Figure 7 shows this specific example as defined in G.805 [G.805]. + Note that a particular example of OTSi is the OCh-P. Figure 7 shows + this specific example as defined in G.805 [G.805]. OCh AP Trail (OCh) OCh AP O- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - O | | --- OCh-P OCh-P --- \ / source sink \ / + + | OCh-P OCh-P Network Connection OCh-P | O TCP - - - - - - - - - - - - - - - - - - - - - - - - - - -TCP O | | @@ -493,23 +485,20 @@ | \ (1) | OCh-P LC | (1) | OCh-P LC | (1) / | | \----|-----------------|-----------|-----------------|------/ | +--------+ Link Channel +-----------+ Link Channel +---------+ Media Channel Media Channel Media Channel Matrix Matrix Matrix The symbol (1) indicates a Matrix Channel Figure 7: Layered Network Model According to G.805 - By definition, a network media channel supports only a single Optical - Tributary Signal. - 3.4.1. DWDM Flexi-grid Enabled Network Element Models A flexible grid network is constructed from subsystems that include WDM links, tunable transmitters, and receivers, (i.e, media elements including media layer switching elements that are media matrices) as well as electro-optical network elements. This is just the same as in a fixed grid network except that each element has flexible grid characteristics. As stated in Clause 7 of [G.694.1] the flexible DWDM grid has a @@ -541,43 +530,42 @@ between the architectural concept/construct of media channel and its control plane representations (e.g., as a TE link). 4.1. General Considerations The GMPLS control of the media layer deals with the establishment of media channels that are switched in media channel matrices. GMPLS labels are used to locally represent the media channel and its associated frequency slot. Network media channels are considered a particular case of media channels when the end points are - transceivers (that is, source and destination of an Optical Tributary - Signal) + transceivers (that is, source and destination of an OTSi). 4.2. Consideration of TE Links From a theoretical / abstract point of view, a fiber can be modeled as having a frequency slot that ranges from minus infinity to plus infinity. This representation helps understand the relationship between frequency slots and ranges. The frequency slot is a local concept that applies within a component or element. When applied to a media channel, we are referring to its effective frequency slot as defined in [G.872]. - The association of the three components a filter, a fiber, and a - filter, is a media channel in its most basic form. From the control - plane perspective this may modeled as a (physical) TE-link with a - contiguous optical spectrum. This can be represented by saying that - the portion of spectrum available at time t0 depends on which filters - are placed at the ends of the fiber and how they have been - configured. Once filters are placed we have a one-hop media channel. - In practical terms, associating a fiber with the terminating filters - determines the usable optical spectrum. + The association sequence of the three components (i.e., a filter, a + fiber, and a filter), is a media channel in its most basic form. + From the control plane perspective this may modeled as a (physical) + TE-link with a contiguous optical spectrum. This can be represented + by saying that the portion of spectrum available at time t0 depends + on which filters are placed at the ends of the fiber and how they + have been configured. Once filters are placed we have a one-hop + media channel. In practical terms, associating a fiber with the + terminating filters determines the usable optical spectrum. ---------------+ +-----------------+ | | +--------+ +--------+ | | | | +--------- ---o| =============================== o--| | | Fiber | | | --\ /-- ---o| | | o--| \/ | | | | | /\ ---o| =============================== o--| --/ \-- @@ -590,29 +578,30 @@ --------+ +-------- |--------------------------------------| LSR | TE link | LSR |--------------------------------------| +--------+ +-------- Figure 8: (Basic) Media Channel and TE Link Additionally, when a cross-connect for a specific frequency slot is - considered, the underlying media support is still a media channel, - augmented, so to speak, with a bigger association of media elements - and a resulting effective slot. When this media channel is the - result of the association of basic media channels and media layer - matrix cross-connects, this architectural construct can be + considered, the resulting media support of joining basic media + channels is still a media channel, i.e., a longer association + sequence of media elements and its effective frequency slot. In + other words, It is possible to "concatenate" several media channels + (e.g., patch on intermediate nodes) to create a single media channel. + + The architectural construct resulting of the association sequence of + basic media channels and media layer matrix cross-connects can be represented as (i.e., corresponds to) a Label Switched Path (LSP) - from a control plane perspective. In other words, It is possible to - "concatenate" several media channels (e.g., Patch on intermediate - nodes) to create a single media channel. + from a control plane perspective. ----------+ +------------------------------+ +--------- | | | | +------+ +------+ +------+ +------+ | | | | +----------+ | | | | --o| ========= o--| |--o ========= o-- | | Fiber | | | --\ /-- | | | Fiber | | --o| | | o--| \/ |--o | | o-- | | | | | /\ | | | | | --o| ========= o--***********|--o ========= o-- @@ -702,21 +691,21 @@ |------------------| |----------------| LSR | TE link | LSR | TE link | LSR |------------------| |----------------| -----+ +---------------+ +----- 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 Incoming Interface of the Egress LSR In Figure 12 a Network Media Channel is represented as terminated at - the DWDM side of the transponder. This is commonly named as OCh- + the network side of the trnaponders. This is commonly names as OTSi- trail connection. |--------------------- Network Media Channel ----------------------| +----------------------+ +----------------------+ | | | +------+ +------+ +------+ +------+ | | +----+ | | | | +----+ | |OTSi OTSi| o-| |-o | +-----+ | o-| |-o |sink src | | | | | ===+-+ +-+==| | | | | O---|R @@ -788,39 +777,39 @@ | | link | | link | Matrix |o- - - - - - - - - - o| Matrix |o- - - - - - +--------------+ +--------------+ | +---------+ | | | Media | | |o----| Channel |-----o| | | | Matrix | +---------+ - Figure 14: MRN/MLN Topology View with TE Link / FA + Figure 14: Topology View with TE Link / FA Note that there is only one media layer switch matrix (one implementation is a FlexGrid ROADM) in SSON, while a signal layer LSP (Network Media Channel) is established mainly for the purpose of management and control of individual optical signals. Signal layer LSPs with the same attributes (such as source and destination) can be grouped into one media-layer LSP (media channel): this has advantages in spectral efficiency (reduce guard band between adjacent OChs in one FSC channel) and LSP management. However, assuming some network elements perform signal layer switching in an SSON, there must be enough guard band between adjacent OTSis in any media channel to - compensate filter concatenation effect and other effects caused by - signal layer switching elements. In such a situation, the separation - of the signal layer from the media layer does not bring any benefit - in spectral efficiency or in other aspects, but makes the network - switch and control more complex. If two OTSis must be switched to - different ports, it is better to carry them by diferent FSC channels, - and the media layer switch is enough in this scenario. + compensate for the filter concatenation effects and other effects + caused by signal layer switching elements. In such a situation, the + separation of the signal layer from the media layer does not bring + any benefit in spectral efficiency or in other aspects, but makes the + network switch and control more complex. If two OTSis must be + switched to different ports, it is better to carry them by diferent + FSC channels, and the media layer switch is enough in this scenario. As discussed in Section 3.2.5, a media channel may be constructed 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]. o In the first case, a single LSP may be established in the control plane. The signaling messages include information for all of the @@ -970,22 +959,22 @@ o A downstream node cannot foresee what an upstream node will allocate. A way to ensure that the effective frequency slot is valid along the length of the LSP is to ensure that the same value of n is allocated at each hop. By forcing the same value of n we avoid cases where the effective frequency slot of the media channel is invalid (that is, the resulting frequency slot cannot be described by its n and m parameters). 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. + combined RSA entity) may be able to 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 @@ -1220,36 +1209,36 @@ 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]. - ::= + ::= ::= [] ::= ( ) | ::= (2^n) x 6.25GHz - where n is positive integer, giving rise to granularities + where n is a non negative integer, giving rise to granularities such as 6.25GHz, 12.5GHz, 25GHz, 50GHz, and 100GHz ::= (2^m) x 12.5GHz where m is positive integer ::= j x 12.5GHz, j is a positive integer ::= k x 12.5GHz, k is a positive integer (k >= j) @@ -1288,22 +1277,22 @@ be able to configure local frequency slots. The control plane architecture SHOULD allow for the support of L-band and S-band. The signalling process SHALL be able to collect the local frequency slot assigned at each link along the path. 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. + objects although some objects may only be applicable within one of + the models. 5.1.2. Routing 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. @@ -1487,28 +1476,26 @@ Optics CTO Via Trento 30 20059 Vimercate (Milano) Italy +39 039 6863033 sergio.belotti@alcatel-lucent.com Yao Li Nanjing University wsliguotou@hotmail.com Fei Zhang - ZTE - Zijinghua Road, Nanjing, China - zhang.fei3@zte.com.cn + Huawei + zhangfei7@huawei.com Lei Wang - ZTE - East Huayuan Road, Haidian district, Beijing, China - wang.lei131@zte.com.cn + wang.lei@bupt.edu.cn + Guoying Zhang China Academy of Telecom Research No.52 Huayuan Bei Road, Beijing, China zhangguoying@ritt.cn Takehiro Tsuritani KDDI R&D Laboratories Inc. 2-1-15 Ohara, Fujimino, Saitama, Japan tsuri@kddilabs.jp