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RSVP-TE Signaling Extensions in support of Flexible Grid
draft-zhang-ccamp-flexible-grid-rsvp-te-ext-02

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This is an older version of an Internet-Draft whose latest revision state is "Replaced".
Authors Fatai Zhang , Xian Zhang , Adrian Farrel , Oscar Gonzalez de Dios , Daniele Ceccarelli
Last updated 2013-06-24
Replaced by draft-ietf-ccamp-flexible-grid-rsvp-te-ext, draft-ietf-ccamp-flexible-grid-rsvp-te-ext, RFC 7792
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draft-zhang-ccamp-flexible-grid-rsvp-te-ext-02
Network Working Group                                       Fatai Zhang 
Internet-Draft                                               Xian Zhang         
Intended status: Standards Track                                 Huawei 
                                                          Adrian Farrel 
                                                     Old Dog Consulting 
                                                 Oscar Gonzalez de Dios  
                                                             Telefonica 
                                                          D. Ceccarelli 
                                                               Ericsson 
Expires: December 24, 2013                                June 25, 2013 
                                      

                                     
        RSVP-TE Signaling Extensions in support of Flexible Grid  
                                      
             draft-zhang-ccamp-flexible-grid-rsvp-te-ext-02.txt 

Abstract 

   This memo describes the extensions to RSVP-TE signaling to support 
   Label Switched Paths in a GMPLS-controlled network that includes 
   devices using the new 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-   
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   Internet-Drafts are draft documents valid for a maximum of six 
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   The list of Internet-Draft Shadow Directories can be accessed at   
   http://www.ietf.org/shadow.html. 

   This Internet-Draft will expire on December 24, 2013. 

    

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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.................................... 6 
   5. IANA Considerations ......................................... 7 
      5.1. RSVP Objects Class Types................................ 7 
   6. Manageability Considerations................................. 7 
   7. Security Considerations...................................... 7 
   8. References .................................................. 7 
      8.1. Normative References.................................... 7 
      8.2. Informative References.................................. 8 
   9. Contributors' Address........................................ 8 
   10. Authors' Addresses ..........................................9 
    
    

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 
   for defining applications. 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 fixed bandwidth 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 to define a flexible grid.  

   [FLEX-FWK] defines a framework and the associated control plane 
   requirements for the GMPLS based control of flexi-grid DWDM networks. 

 
 
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   [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 
   WSONs.  

   This document describes the additional requirements and protocol 
   extensions for signaling to set up LSPs in networks that support the 
   flexi-grid.  

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", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 
   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].  

   A 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 RSA (Routing and 
   Spectrum Assignment). [FLEX-FWK] describes three types of 
   architecture 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 centralized entity before the signaling 
   procedure.  

   In the case of centralized SA, the assigned frequency slot is 
   specified in the 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 involved network elements to select 
   the frequency slot to be used.  

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

 
 
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   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 
   equivalent of optical bandwidth, although the amount of bandwidth 
   associated with a slot width will depend on the encoding. 

   Different LSPs may request different amounts of frequency resource 
   in flexible grid networks, so the slot width needs to 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 a flexi-LSP.  

   This information is required in 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).  

   The frequency slot can be represented by the two parameters as 
   follows:  

      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 LSP 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 
   by: 

   193.1 + n * 0.00625 

   where n is zero or a positive or negative integer. 
 
 
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   The slot width (in GHz) is defined as: 

   12.5 * m 

   where m is a positive integer. 

   It is possible that implementing a subset of the possible slot 
   widths and central frequencies are supported. For example, an 
   implementation could built where the nominal central frequency 
   granularity is 12.5 GHz (by only requiring 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. 

   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 
   parameters: 

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

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

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

 
 
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    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 (8 bits): 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 multiple 
   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 
   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.    

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 Section 3 are used. The signaling procedures 
   for distributed SA and centralized SA can be applied.  

     

 
 
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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] 
    
   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. Security Considerations 

   This document introduces no new security considerations to [RFC3473]. 
    
8. References 

8.1. Normative References 

   [RFC2119] S. Bradner, "Key words for use in RFCs to indicate 
             requirements levels", RFC 2119, March 1997.  
 
 
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   [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-farrkingel-ccamp-flexigrid-
             lambda-label, work in progress.  

8.2. Informative References 

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

   [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. 

   [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-ogrcetal-cammp-flexi-grid-fwk, work in 
             progress. 

   [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. 

9. Contributors' Address 

   Ramon Casellas  
   CTTC  
   Av. Carl Friedrich Gauss n7  
   Castelldefels, Barcelona 08860  
   Spain  
    
   Email: ramon.casellas@cttc.es
    

 
 
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   Felipe Jimenez Arribas 
   Telefonica Investigacion y Desarrollo 
   Emilio Vargas 6 
   Madrid,   28045 
   Spain 
   Email: felipej@tid.es
    
   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 
   Email: yi.lin@huawei.com
    
10. Authors' Addresses 

   Fatai Zhang 
   Huawei Technologies 
   Email: zhangfatai@huawei.com
    
   Xian Zhang 
   Huawei Technologies 
   Email: zhang.xian@huawei.com
    
   Adrian Farrel 
   Old Dog Consulting 
   Email: adrian@olddog.co.uk
    
   Oscar Gonzalez de Dios 
   Telefonica Investigacion y Desarrollo 
   Emilio Vargas 6 
   Madrid,   28045 
   Spain 
    
   Phone: +34 913374013 
   Email: ogondio@tid.es
    
   Daniele Ceccarelli 
   Ericsson 
   Via A. Negrone 1/A 
   Genova - Sestri Ponente 
   Italy 
   Email: daniele.ceccarelli@ericsson.com
    
 
 
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