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RSVP-TE Signaling Extensions in Support of Flexi-Grid Dense Wavelength Division Multiplexing (DWDM) Networks

The information below is for an old version of the document that is already published as an RFC.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 7792.
Authors Fatai Zhang , Xian Zhang , Adrian Farrel , Oscar Gonzalez de Dios , Daniele Ceccarelli
Last updated 2016-03-11 (Latest revision 2015-11-19)
Replaces draft-zhang-ccamp-flexible-grid-rsvp-te-ext
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
Additional resources Mailing list discussion
Stream WG state Submitted to IESG for Publication
Document shepherd Daniel King
Shepherd write-up Show Last changed 2015-09-23
IESG IESG state Became RFC 7792 (Proposed Standard)
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IANA IANA review state Version Changed - Review Needed
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CCAMP Working Group                                         Fatai Zhang 
Internet-Draft                                               Xian Zhang         
Intended status: Standards Track                                 Huawei 
                                                          Adrian Farrel 
                                                     Old Dog Consulting 
                                                 Oscar Gonzalez de Dios  
                                                          D. Ceccarelli 
Expires: May 19, 2016                                 November 20, 2015 

   RSVP-TE Signaling Extensions in support of Flexi-grid DWDM networks 


   This memo describes the extensions to the Resource reSerVation 
   Protocol Traffic Engineering (RSVP-TE) signaling protocol to support 
   Label Switched Paths (LSPs) in a GMPLS-controlled network that 
   includes devices using the flexible optical grid.  

Status of this Memo 

   This Internet-Draft is submitted to IETF 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-   

   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." 

   The list of current Internet-Drafts can be accessed at 

   The list of Internet-Draft Shadow Directories can be accessed at 

   This Internet-Draft will expire on May 19, 2016. 

   Copyright Notice 

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   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 
   ( in effect on the date of 
   publication of this document. Please review these documents 
   carefully, as they describe your rights and restrictions with 
   respect to this document. Code Components extracted from this 
   document must include Simplified BSD License text as described in 
   Section 4.e of the Trust Legal Provisions and are provided without 
   warranty as described in the Simplified BSD License.  

Table of Contents 

   1. Introduction ................................................ 2 
   2. Terminology ................................................. 3 
      2.1. Conventions used in this document .......................3 
   3. Requirements for Flexible Grid Signaling .....................3 
      3.1. Slot Width ............................................. 4 
      3.2. Frequency Slot ......................................... 4 
   4. Protocol Extensions ......................................... 5 
      4.1. Traffic Parameters...................................... 5 
         4.1.1. Applicability to Fixed Grid Networks ...............6 
      4.2. Generalized Label....................................... 6 
      4.3. Signaling Procedures.................................... 7 
   5. IANA Considerations ......................................... 7 
      5.1. RSVP Objects Class Types................................ 7 
   6. Manageability Considerations................................. 8 
   7. Implementation Status........................................ 8 
      7.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)8 
   8. Acknowledgments ............................................ 10 
   9. Security Considerations..................................... 10 
   10. References ................................................ 10 
      10.1. Normative References.................................. 10 
      10.2. Informative References................................ 10 
   11. Contributors' Addresses.................................... 11 
   12. Authors' Addresses .........................................12 

1. Introduction 

   [G.694.1] defines the Dense Wavelength Division Multiplexing (DWDM) 
   frequency grids for Wavelength Division Multiplexing (WDM) 
   applications. A frequency grid is a reference set of frequencies 
   used to denote allowed nominal central frequencies that may be used 
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   for defining applications that utilize WDM transmission. The channel 
   spacing is the frequency spacing between two allowed nominal central 
   frequencies. All of the wavelengths on a fiber use different central 
   frequencies and occupy a designated range of frequency.  

   Fixed grid channel spacing is selected from 12.5 GHz, 25 GHz, 50 GHz, 
   100 GHz and integer multiples of 100 GHz. But [G.694.1] also defines 
   "flexible grids", known as "flexi-grid". The terms "frequency slot" 
   (i.e., the frequency range allocated to a specific channel and 
   unavailable to other channels within a flexible grid) and "slot 
   width" (i.e., the full width of a frequency slot in a flexible grid) 
   are introduced in [G.694.1] to define a flexible grid.  

   [FLEX-FWK] defines a framework and the associated control plane 
   requirements for the Generalized Multi-Protocol Label Switching 
   (GMPLS) [RFC3945] based control of flexi-grid DWDM networks. 

   [RFC6163] provides a framework for GMPLS and Path Computation 
   Element (PCE) control of Wavelength Switched Optical Networks 
   (WSONs), and [WSON-SIG] describes the requirements and protocol 
   extensions for signaling to set up Label Switched Paths (LSPs) in 

   This document describes the additional requirements and protocol 
   extensions to Resource reSerVation Protocol-Traffic Engineering 
   (RSVP-TE) [RFC3473] to set up LSPs in networks that support the 

2. Terminology  

   For terminology related to flexi-grid, please refer to [FLEX-FWK] 
   and [G.694.1]. 

2.1. Conventions used in this document 

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   document are to be interpreted as described in RFC-2119 [RFC2119]. 

3. Requirements for Flexible Grid Signaling   

   The architecture for establishing LSPs in a flexi-grid network is 
   described in [FLEX-FWK].  

   An optical spectrum LSP occupies a specific frequency slot, i.e., a 
   range of frequencies. The process of computing a route and the 
   allocation of a frequency slot is referred to as Routing and 
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   Spectrum Assignment (RSA). [FLEX-FWK] describes three architectural 
   approaches to RSA: combined RSA, separated RSA, and distributed SA. 
   The first two approaches are referred to as "centralized SA" because 
   both routing and spectrum (frequency slot) assignment are performed 
   by a centralized entity before the signaling procedure.  

   In the case of centralized SA, the assigned frequency slot is 
   specified in the RSVP-TE Path message during LSP setup. In the case 
   of distributed SA, the slot width of the flexi-grid LSP is specified 
   in the Path message, allowing the network elements to select the 
   frequency slot to be used when they process the RSVP-TE messages.  

   If the capability to switch or convert the whole optical spectrum 
   allocated to an optical spectrum LSP is not available at some nodes 
   along the path of the LSP, the LSP is subject to the Optical 
   "Spectrum Continuity Constraint" as described in [FLEX-FWK].  

   The remainder of this section states the additional requirements for 
   signaling in a flexi-grid network. 

3.1. Slot Width  

   The slot width is an end-to-end parameter representing how much 
   frequency resource is requested for a flexi-grid LSP. It is the 
   equivalent of optical bandwidth, although the amount of bandwidth 
   associated with a slot width will depend on the signal encoding. 

   Different LSPs may request different amounts of frequency resource 
   in flexible grid networks, so the slot width MUST be carried in the 
   signaling message during LSP establishment. This enables the nodes 
   along the LSP to know how much frequency resource has been requested 
   (in a Path message) and has been allocated (by a Resv message) for 
   the LSP.  

3.2. Frequency Slot  

   The frequency slot information identifies which part of the 
   frequency spectrum is allocated on each link for an LSP in a flexi-
   grid network.  

   This information MUST be present in a Resv message to indicate, hop-
   by-hop, the central frequency of the allocated resource. In 
   combination with the slot width indicated in a Resv message (see 
   Section 3.1) the central frequency carried in a Resv message 
   identifies the resources reserved for the LSP (known as the 
   frequency slot).  

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   The frequency slot can be represented by the two parameters as 

      Frequency slot = [(central frequency) - (slot width)/2] ~  
                       [(central frequency) + (slot width)/2]  

   As is common with other resource identifiers (i.e., labels) in GMPLS 
   signaling, it must be possible for the head-end node when sending a 
   Path message to suggest or require the central frequency to be used 
   for the LSP. Furthermore, for bidirectional LSPs, the Path message 
   MUST be able to specify the central frequency to be used for reverse 
   direction traffic.  

   As described in [G.694.1], the allowed frequency slots for the 
   flexible DWDM grid have a nominal central frequency (in THz) defined 

   193.1 + n * 0.00625 

   where n is zero or a positive or negative integer. 

   The slot width (in GHz) is defined as: 

   12.5 * m 

   where m is a positive integer. 

   It is possible that an implementation supports only a subset of the 
   possible slot widths and central frequencies. For example, an 
   implementation could be built where the nominal central frequency 
   granularity is 12.5 GHz (by only allowing values of n that are even) 
   and that only supports slot widths as a multiple of 25 GHz (by only 
   allowing values of m that are even).  

   Further details can be found in [FLEX-FWK].  

4. Protocol Extensions  

   This section defines the extensions to RSVP-TE signaling for GMPLS 
   [RFC3473] to support flexible grid networks.  

4.1. Traffic Parameters  

   In RSVP-TE, the SENDER_TSPEC object in the Path message indicates 
   the requested resource reservation. The FLOWSPEC object in the Resv 
   message indicates the actual resource reservation. 

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   As described in Section 3.1, the slot width represents how much 
   frequency resource is requested for a flexi-grid LSP. That is, it 
   describes the end-to-end traffic profile of the LSP. Therefore, the 
   traffic parameters for a flexi-grid LSP encode the slot width.  

   This document defines new C-Types for the SENDER_TSPEC and FLOWSPEC 
   objects to carry Spectrum Switched Optical Network (SSON) traffic 

   SSON SENDER_TSPEC: Class = 12, C-Type = TBD1.  

   SSON FLOWSPEC: Class = 9, C-Type = TBD2.  

   The SSON traffic parameters carried in both objects MUST have the 
   same format as shown in Figure 1.  

    0                   1                   2                   3 
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 
   |              m                |            Reserved           | 
                   Figure 1: The SSON Traffic Parameters 
   m (16 bits): a positive integer and the slot width is specified by 
   m*12.5 GHz.  

   The Reserved bits MUST be set to zero and ignored upon receipt. 

4.1.1. Applicability to Fixed Grid Networks 

   Note that the slot width (i.e., traffic parameters) of a fixed grid 
   defined in [G.694.1] can also be specified by using the SSON traffic 
   parameters. The fixed grid channel spacings (12.5 GHz, 25 GHz, 50 
   GHz, 100 GHz and integer multiples of 100 GHz) are also the 
   multiples of 12.5 GHz, so the m parameter can be used to represent 
   these slot widths.  

   Therefore, it is possible to consider using the new traffic 
   parameter object types in common signaling messages for flexi-grid 
   and legacy DWDM networks.  

4.2. Generalized Label  

   In the case of a flexible grid network, the labels that have been 
   requested or allocated as signaled in the RSVP-TE objects are 

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   encoded as described in [FLEX-LBL]. This new label encoding can 
   appear in any RSVP-TE object or sub-object that can carry a label.  

   As noted in Section 4.2 of [FLEX-LBL], the m parameter forms part of 
   the label as well as part of the traffic parameters.  

   As described in Section 4.3 of [FLEX-LBL], a "compound label", 
   constructed from a concatenation of the flexi-grid LABELs, is used 
   when signaling an LSP that uses multiple flexi-grid slots.  

4.3. Signaling Procedures  

   There are no differences between the signaling procedure described 
   for LSP control in [FLEX-FWK] and those required for use in a fixed-
   grid network [WSON-SIG]. Obviously, the TSpec, FlowSpec, and label 
   formats described in Sections 4.1 and 4.2 are used. The signaling 
   procedures for distributed SA and centralized SA can be applied.  

5. IANA Considerations 

5.1. RSVP Objects Class Types 

   This document introduces two new Class Types for existing RSVP 
   objects. IANA is requested to make allocations from the "Resource 
   ReSerVation Protocol (RSVP) Parameters" registry using the "Class 
   Names, Class Numbers, and Class Types" sub-registry. 

       Class Number  Class Name                            Reference 
       ------------  -----------------------               --------- 
       9             FLOWSPEC                              [RFC2205] 
                     Class Type (C-Type): 
                     (TBD2) SSON FLOWSPEC                  [This.I-D] 
       Class Number  Class Name                            Reference 
       ------------  -----------------------               --------- 
       12            SENDER_TSPEC                          [RFC2205] 
                     Class Type (C-Type): 
                     (TBD1) SSON SENDER_TSPEC              [This.I-D] 

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   IANA is requested to assign the same value for TBD1 and TBD2, and a 
   value of 8 is suggested.  
6. Manageability Considerations  

   This document makes minor modifications to GMPLS signaling, but does 
   not change the manageability considerations for such networks.  
   Clearly, protocol analysis tools and other diagnostic aids 
   (including logging systems and MIB modules) will need to be enhanced 
   to support the new traffic parameters and label formats. 
7. Implementation Status 

   [RFC Editor Note: Please remove this entire seciton prior to 
   publication as an RFC.] 

   This section records the status of known implementations of the 
   protocol defined by this specification at the time of posting of 
   this Internet-Draft, and is based on a proposal described in RFC 
   6982 [RFC6982].  The description of implementations in this section 
   is intended to assist the IETF in its decision processes in 
   progressing drafts to RFCs.  Please note that the listing of any 
   individual implementation here does not imply endorsement by the 
   IETF.  Furthermore, no effort has been spent to verify the 
   information presented here that was supplied by IETF contributors.  
   This is not intended as, and must not be construed to be, a catalog 
   of available implementations or their features.  Readers are advised 
   to note that other implementations may exist. 

   According to RFC 6982, "this will allow reviewers and working groups 
   to assign due consideration to documents that have the benefit of 
   running code, which may serve as evidence of valuable 
   experimentation and feedback that have made the implemented 
   protocols more mature.  It is up to the individual working groups to 
   use this information as they see fit." 

7.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) 

   Organization Responsible for the Implementation: 
      Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) 
      Optical Networks and Systems Department 

   Implementation Name and Details: 
      ADRENALINE testbed 

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   Brief Description: 
      Experimental testbed implementation of GMPLS/PCE control plane. 

   Level of Maturity: 
      Implemented as extensions to a mature GMLPS/PCE control plane. 
      It is limited to research / prototyping stages, but it has been 
      used successfully for more than the last five years. 

      Support for the Tspec, FlowSpec, and label formats as described  
      version 03 of this document.  Label format support extends to the 
      following RSVP-TE objects and sub-objects: 

         - Generalized Label Object 
         - Suggested Label Object 
         - Upstream Label Object 
         - ERO Label Subobjects 

      It is expected that this implementation will evolve to follow the 
      evolution of this document. 


   Implementation Experience: 
      Implementation of this document reports no issues. 
      General implementation experience has been reported in a number 
      of journal papers. Contact Ramon Casellas for more information or 


   Contact Information: 
      Ramon Casellas: 

      No report. 

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8. Acknowledgments 

   This work was supported in part by the FP-7 IDEALIST project under 
   grant agreement number 317999. 
9. Security Considerations 

   This document introduces no new security considerations to [RFC3473]. 
   See also [RFC5920] for a discussion of security considerations for 
   GMPLS signaling. 
10. References 

10.1. Normative References 

   [RFC2119] S. Bradner, "Key words for use in RFCs to indicate 
             requirements levels", RFC 2119, March 1997.  

   [RFC3473] L. Berger, Ed., "Generalized Multi-Protocol Label 
             Switching (GMPLS) Signaling Resource ReserVation Protocol-
             Traffic Engineering (RSVP-TE) Extensions", RFC 3473, 
             January 2003. 

   [G.694.1] ITU-T Recommendation G.694.1 (revision 2), "Spectral grids 
             for WDM applications: DWDM frequency grid", February 2012. 

   [FLEX-LBL] King, D., Farrel, A. and Y. Li, "Generalized Labels for 
             the Flexi-Grid in Lambda Switched Capable (LSC) Label 
             Switching Routers", draft-ietf-ccamp-flexigrid-lambda-
             label, work in progress.  

10.2. Informative References 

   [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching 
             (GMPLS)" Architecture, RFC3945, October 2004. 

   [RFC2205] Braden, R., Zhang L., Berson, S., Herzog, S. and S. Jamin, 
             "Resource ReServation Protocol (RSVP) - Version 1, 
             Functional Specification", RFC2205, September 1997. 

   [RFC5920] L. Fang et al., "Security Framework for MPLS and GMPLS 
             Networks", RFC 5920, July 2010. 

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   [RFC6163] Y. Lee, G. Bernstein and W. Imajuku, "Framework for GMPLS 
             and Path Computation Element (PCE) Control of Wavelength 
             Switched Optical Networks (WSONs)", RFC 6163, April 2011. 

   [RFC6982] Sheffer, Y. and A. Farrel, "Improving Awareness of Running 
             Code: The Implementation Status Section", RFC 6982, July 

   [RFC Editor Note: This reference can be removed when Section 7 is 

   [FLEX-FWK] Gonzalez de Dios, O, Casellas R., Zhang, F., Fu, X., 
             Ceccarelli, D., and I. Hussain, "Framework and 
             Requirements for GMPLS based control of Flexi-grid DWDM 
             networks", draft-ietf-ccamp-flexi-grid-fwk, work in 

   [WSON-SIG] G. Bernstein, Sugang Xu, Y. Lee, G. Martinelli and 
             Hiroaki Harai, "Signaling Extensions for Wavelength 
             Switched Optical Networks", draft-ietf-ccamp-wson-
             signaling, work in progress. 

11. Contributors' Addresses 

   Ramon Casellas  
   Av. Carl Friedrich Gauss n7  
   Castelldefels, Barcelona 08860  
   Felipe Jimenez Arribas 
   Telefonica Investigacion y Desarrollo 
   Emilio Vargas 6 
   Madrid,   28045 
   Yi Lin 
   Huawei Technologies Co., Ltd. 
   F3-5-B R&D Center, Huawei Base, 
   Bantian, Longgang District 
   Shenzhen 518129 P.R.China 
   Phone: +86-755-28972914 
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   Qilei Wang 
   Haomian Zheng 
   Huawei Technologies
12. Authors' Addresses 

   Fatai Zhang 
   Huawei Technologies 
   Xian Zhang 
   Huawei Technologies 
   Adrian Farrel 
   Old Dog Consulting 
   Oscar Gonzalez de Dios 
   Telefonica Investigacion y Desarrollo 
   Emilio Vargas 6 
   Madrid,   28045 
   Phone: +34 913374013 
   Daniele Ceccarelli 
   Via A. Negrone 1/A 
   Genova - Sestri Ponente 

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