Network Working Group Sharfuddin Syed Rajan Rao Marco Sosa Biao Lu Internet Draft Infinera Intended status: Standard Track March 5, 2012 Expires: Sept 04 2012 A Framework for control of Flex Grid Networks draft-syed-ccamp-flexgrid-framework-ext-00.txt Abstract This document provides a framework for applying GMPLS architecture and protocols to Flex Grid. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." 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Table of Contents 1. Introduction...................................................2 2. Terminology....................................................3 3. Acronyms.......................................................3 4. Requirements and constraints...................................4 5. Use cases......................................................6 6. Protocol Implications..........................................9 7. Security Considerations........................................9 8. IANA Considerations............................................9 9. References.....................................................9 9.1. Normative References......................................9 9.2. Informative References....................................9 10. Acknowledgments ..............................................10 1. Introduction To enable scaling of existing transport systems to ultrahigh data rates of 1 Tbps and beyond, next generation systems providing super- channel switching capability are currently being developed. To allow efficient allocation of optical spectral bandwidth for such high bit rate systems, International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is extending the G.694.1 grid standard (termed ''Fixed-Grid'') to include flexible grid (termed ''Flex-Grid'') support. Expires September 5, 2012 [Page 2] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 2. Terminology A. Frequency Slot: The frequency range allocated to a slot [FLEX-GRID] It is a contiguous portion of the spectrum available for optical passband filter. B. Spectral Slice: Refers to a minimum granularity of a frequency slot (e.g. 12.5GHz). C. Slot width: The full width of a frequency slot in a flexible grid[FLEX- GRID]. The slot width is equal to number of spectral slices in the slot times the width of spectral slice. D. Super-channel: Super-channel is a collection of one or more frequency slots to be treated as unified entity for management and control plane (Ref to figure-1). E. Contiguous Spectrum Super-channel: Contiguous spectrum super-channel is a super-channel with a single frequency slot (Ref to figure-1). F. Split-Spectrum super-channel: Split-Spectrum super-channel is a super-channel with multiple frequency slots. Each frequency slot will be allocated an independent passband filter, irrespective of whether frequency slots are adjacent or not. Figure 1 Super-Channel (Refer to pdf version [5] of this draft for figures) 3. Acronyms OCG: Optical Carrier Group SCH: Super Channel OCH: Optical Channel Expires September 5, 2012 [Page 3] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 OCC: Optical Channel Carrier OTUk: Optical channel Transport Unit level k ODUk: Optical channel Data Unit Level k ODUj: Optical channel Data Unit Level j 4. Requirements and constraints This section covers the high level requirements for the support of super-channels over Flex-Grid Infrastructure. Specifically, the scope of requirements and constraints listed in this section covers the functionality that shall be supported by the control plane sub- system. The Features are listed as list of Requirements Tagged as Rn, for better traceability and coverage in other related drafts and/or for references by other related standards across other standard bodies. R1: Flexible size of super-channel The protocol shall allow the super-channels on the Flex-Grid to be of different size/width. The number of slices and the granularity of each slice shall be flexible. R2: Flexible mapping of super-channel The super-channels shall be allowed to be mapped to any spectrum location in the ITU Grid. The frequency slots allocation of super-channels on the ITU-Grid shall confirm to [FLEX GRID] R3: Contiguous Spectrum and Split Spectrum super-channel The protocol shall allow the use of super-channels which can be contiguous or non-contiguous. Example: consider a system supporting 500GHz super-channel. In case of contiguous spectrum, the super-channel is allocated with 40 slices of 12.5GHz granularity. This super-channel is placed directly on the Flex-Grid at any location. In case of split spectrum, the super-channel is divided into multiple members. Considering the same example scenario, the 500GHz Expires September 5, 2012 [Page 4] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 super-channel can be divided into 2 member split spectrum channels. Each member is allocated a different flexible location on the Flex- Grid. Each frequency slot can be 250GHz, 20x12.5GHz slices allocated for frequency slot. R4: Co-routing of split-spectrum super-channel The protocol shall support the co-routing of frequency slots within the split-spectrum super-channels. Please refer to the Figure 5 and Use Case 3, depicting the co- routing of split-spectrum super-channels. R5: Flexible Modulation Formats for different super-channels on the same Flex-Grid Each super-channel mapped on to the Flex-Grid system shall have the capability to carry mixed modulation signals. R6: Fixed vs Flexible Grid super-channel interworking The Control Plane protocol shall handle nodes which support flex- grid functionality in addition to nodes that only support fixed grid functionality. This requirement is to enable introduction of flex-grid systems into existing fixed-grid network. This can also be used to deploy flex- grid system in certain segments of the network. Please also refer use case section of this document. R7: Support for the CDC based super-channels over Flex-Grid The super-channel over the Flex-Grid control plane frame work shall support CDC (Connectionless, Directionless and Contentionless) architecture. Further, flexibility of control shall be provided, such that, depending on deployment scenarios and application, a sub- set of CDC features are used on a given network segment. Hence, each type of ROADMs shall be supported. R8: Directionless/Contentionless super-channels The protocol shall allow for routing the super-channels in different fiber directions/degrees, based on the following criteria: a) Based on spectral slices b) Based on fibers/nodes Expires September 5, 2012 [Page 5] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 The super-channels with the same frequency slot mapping are not allowed to be provisioned over a given fiber direction. Please refer to the Figure 5 and Use Case 3, depicting the handling of same super-channel at a CDC node. R9: Resizing of super-channel bandwidth Depending on the spectral bandwidth changes, the protocol shall allow super-channels resizing. R10: super-channel LSP restoration The system shall support the super-channel based LSP restoration feature where the restored path is computed dynamically. During the restoration process, it shall be possible for the system to pick different frequency slots of super-channel, keeping the number and size of slices the same. Further, options for LSP restoration with pre-computed path (with or without resource reservation) shall be supported. Revertive and Non-Revertive restoration options shall be provided. R11: Embedded Control Channel for super-channel routing and signaling The system shall continue to use the standard mechanism for ECC defined in [ref: OSC based control channel], for OAM features required to be supported between network elements deploying super- channel over Flex-Grid. R12: Management Plane and Control Plane feature interaction for super-channel The system shall keep track of important bandwidth related parameters for the Flex-Grid based system. Important parameters include (but not limited to): a) Available Spectral Slices b) Provisioned super-channels along with provisioned spectral-slices 5. Use cases The use cases described in this section are for information only. The OTN hierarchy described in this section is sure to be discussed in ITU SG-15 Q6 & Q14. Within the scope of this frame-work document, the main focus is super-channel entity. The remaining layers are described to illustrate the relationship with the digital layers. Expires September 5, 2012 [Page 6] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 With respect to the mapping hierarchy in the OTN layers, multiple OCHs are mapped to the SCH, and multiple OCCs (Optical Channel Carriers) are mapped to an OCH. This hierarchy is depicted in Figure 2 below. Specifically, the following flexibility of number of instances that are mapped between the layers shall be supported. X number of OCC mapped to OCH Y number of OCH mapped to SCH Z number of SCH mapped to OCG Figure 2 Super-Channel mapping to OTN hierarchy ((Refer to pdf version [5] of this draft for figures) Example Use Case 1: Super-Channel with multiple OCHs and multiple carriers per OCHs. The following Figure 3 gives an example use case where multiple OCH are carrier over a single SCH. Please note that this is an example use case only. In general, the system shall be capable of supporting flexible mapping where there is flexible number of carriers mapped into an OCH and a flexible number of OCHs mapped to a single Super- Channel. Figure 3 Super-Channel use case showing multiple OCH and multiple carriers per OCH(Refer to pdf version [5] of this draft for figures) Example Use Case 2: The following Figure 4 shows the case where multiple OCHs are carried over separate super-channels. These separate super-channel use case is used to realize the split-spectrum super-channel implementations. Further, these split-spectrum based super-channels can be co-routed together or can be diversely routed in the network. Figure 4: Split-Spectrum Super-Channel use case showing multiple OCH and multiple carriers per OCH (Refer to pdf version [5] of this draft for figures) Expires September 5, 2012 [Page 7] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 Example Use Case 3: Network Level Use Case of super-channel A network level diagram to illustrate the use of CDC based super- channel (contiguous spectrum and split-spectrum) is shown in Figure 5 below. In this scenario, N1 and N2 are digital/TDM nodes, where the client services originate. N2, N3, N4 and N5 are Optical/WDM nodes on which the super-channels are provisioned. Node N2 is CDC ROADM and Nodes N3, N4 and N5 are Colorless ROADMs only. Four super-channels are provisioned in this example network. Super- Channels S1 are contiguous spectrum super-channels, both using the same frequency slots, and are added/dropped at Node N2. The contention for the same super-channel (with exactly the same frequency slot mapping) is avoided by routing these super-channels in different degrees of the network. Alternatively, if these super- channels have to go through the same fiber path, then the frequency slots occupied on the Flex-Grid shall be different. Super-channels S2-1 and S2-2 illustrates the split-spectrum super- channel that is co-routed over the same fibers in the network. Super-channels S3-1 and S3-2 illustrates the split-spectrum super- channel that is diversely routed through Node N3 and Node N4. Figure 5: Super-Channel Network Level use case (Refer to pdf version [5] of this draft for figures) Example Use Case 4: Fixed and Flexible Grid Interworking - In Figure 6: o The Nodes N2 and N3 are Flex-Grid and Fixed grid capable nodes o The Nodes N1 and N4 are fixed grid capable nodes. - Fixed and Flexible support on the same interface o In Figure 6, this is represented by Link L3 - BW advertisement that include both fixed and flexible grid by Flex Grid capable nodes - Signaling support for both fixed and flex-grid. Figure 6: Use case for fixed and flex-grid interworking (Refer to pdf version [5] of this draft for figures) Expires September 5, 2012 [Page 8] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 6. Protocol Implications Support GMPLS Routing extensions to satisfy requirements in Section 3.0. Support GMPLS Signaling extensions to satisfy requirements in section 3.0. 7. Security Considerations 8. IANA Considerations IANA needs to assign a new Grid field value to represent ITU-T Flex- Grid. 9. References 9.1. Normative References [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 9.2. Informative References [1] ITU-T Recommendation G.694.1, "Spectral grids for WDM applications: DWDM frequency grid", June 2002 [2] [FLEX-GRID] Unpublished ITU-T Study Group-15 doc: G.694.1 [Rev-2, 12/2011] [3] [RFC 6163] Framework for GMPLS and Path Computation Element (PCE) Control of Wavelength Switched Optical Networks (WSONs) [4] draft-ietf-ccamp-rwa-info-13.txt: Routing and Wavelength Assignment Information Model for Wavelength Switched Optical Networks [5] draft-syed-ccamp-flexgrid-framework-ext.pdf - - Full version of this draft which contains figures. Expires September 5, 2012 [Page 9] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 10. Acknowledgments Expires September 5, 2012 [Page 10] Internet-Draft draft-syed-ccamp-flexgrid-framework-ext Mar-12 Authors' Addresses Sharfuddin Syed Infinera 140 Caspian Ct., Sunnyvale, CA 94089 Email: ssyed@infinera.com Rajan Rao Infinera 140 Caspian Ct., Sunnyvale, CA 94089 Email: rrao@infinera.com Marco Sosa Infinera 140 Caspian Ct., Sunnyvale, CA 94089 Email: msosa@infinera.com Biao Lu Infinera 140 Caspian Ct., Sunnyvale, CA 94089 Email: blu@infinera.com Contributor's List Radhakrishna Valiveti Email: rvaliveti@infinera.com Iftekhar Hussain Email: IHussain@infinera.com Abinder Dhillon Email: ADhillon@infinera.com Mike VanLeeuwen Email: MVanleeuwen@infinera.com Ping Pan Email: ppan@infinera.com Expires September 5, 2012 [Page 11]