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GMPLS OSPF-TE Extensions in support of Flexi-grid DWDM networks
draft-ietf-ccamp-flexible-grid-ospf-ext-07

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft that was ultimately published as RFC 8363.
Authors Xian Zhang , Haomian Zheng , Ramon Casellas , Oscar Gonzalez de Dios , Daniele Ceccarelli
Last updated 2017-02-06 (Latest revision 2016-10-25)
Replaces draft-zhang-ccamp-flexible-grid-ospf-ext
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draft-ietf-ccamp-flexible-grid-ospf-ext-07
CCAMP Working Group                                          Xian Zhang        
Internet-Draft                                            Haomian Zheng 
Intended status: Standards Track                                 Huawei 
                                                         Ramon Casellas 
                                                                   CTTC 
                                                    O. Gonzalez de Dios 
                                                             Telefonica 
                                                          D. Ceccarelli 
                                                               Ericsson 
Expires: April 26, 2017                                October 26, 2016 
                                               
                                    
     GMPLS OSPF-TE Extensions in support of Flexi-grid DWDM networks 
                                      
              draft-ietf-ccamp-flexible-grid-ospf-ext-07.txt 

Abstract 

   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 the "frequency 
   slot". Corresponding techniques for data-plane connections are know 
   as flexi-grid.  

   Based on the characteristics of flexi-grid defined in G.694.1, RFC 
   7698 and 7699, this document describes the OSPF-TE extensions in 
   support of GMPLS control of networks that include devices that use 
   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-   
   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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   The list of current Internet-Drafts can be accessed at   
   http://www.ietf.org/ietf/1id-abstracts.txt. 

   The list of Internet-Draft Shadow Directories can be accessed at   
   http://www.ietf.org/shadow.html. 

  This Internet-Draft will expire on April 26, 2017. 

Copyright Notice 

   Copyright (c) 2016 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 
   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 ................................................. 3 
   2. Terminology .................................................. 3 
      2.1. Conventions Used in this Document ....................... 4 
   3. Requirements for Flexi-grid Routing .......................... 4 
      3.1. Available Frequency Ranges .............................. 4 
      3.2. Application Compliance Considerations ................... 5 
      3.3. Comparison with Fixed-grid DWDM Links ................... 6 
   4. Extensions ................................................... 7 
      4.1. ISCD Extensions for Flexi-grid .......................... 7 
         4.1.1. Switching Capability Specific Information (SCSI).... 8 
         4.1.2. An SCSI Example ................................... 10 
      4.2. Extensions to Port Label Restriction sub-TLV ........... 12 
   5. IANA Considerations ......................................... 13 
      5.1. New Switching Type ..................................... 13 
      5.2. New Sub-TLV ............................................ 14 
   6. Implementation Status ....................................... 14 
      6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)15 
   7. Acknowledgments ............................................. 16 
   8. Security Considerations ..................................... 16 
   9. Contributors' Addresses ..................................... 16 
   10. References ................................................. 17 
      10.1. Normative References .................................. 17 
 
 
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      10.2. Informative References ................................ 17 
   Authors' Addresses ............................................. 18 
    
    

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 should use different central frequencies and 
   occupy a fixed bandwidth of frequency. 

   Fixed grid channel spacing ranges from 12.5 GHz, 25 GHz, 50 GHz, 100 
   GHz to integer multiples of 100 GHz.  But [G.694.1] also defines 
   "flexible grids", also 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 used to define a flexible grid. 

   [RFC7698] defines a framework and the associated control plane 
   requirements for the GMPLS 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 [RFC7688] defines the requirements and OSPF-TE 
   extensions in support of GMPLS control of a WSON. 

   [RFC7792] describes requirements and protocol extensions for 
   signaling to set up LSPs in networks that support the flexi-grid, 
   and this document complements [RFC7792] by describing the 
   requirement and extensions for OSPF-TE routing in a flexi-grid 
   network. 

   This document complements the efforts to provide extensions to Open 
   Short Path First (OSPF) Traffic-Engineering (TE) protocol so as to 
   support GMPLS control of flexi-grid networks. 

2. Terminology  

   For terminology related to flexi-grid, please consult [RFC7698] and 
   [G.694.1]. 

 
 
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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 Flexi-grid Routing  

   The architecture for establishing LSPs in a Spectrum Switched 
   optical Network (SSON) is described in [RFC7698].  

   A flexi-grid LSP occupies a specific frequency slot, i.e., a 
   frequency range.  The process of computing a route and the 
   allocation of a frequency slot is referred to as RSA (Routing and 
   Spectrum Assignment).  [RFC7698] describes three types of 
   architectural approaches to RSA: combined RSA, separated RSA, and 
   distributed SA.  The first two approaches among them could be called 
   "centralized SA" because the spectrum (frequency slot) assignment is 
   performed by a single entity before the signaling procedure. 

   In the case of centralized SA, the assigned frequency slot is 
   specified in the RSVP-TE Path message during the signaling process.  
   In the case of distributed SA, only the requested 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 [RFC7698]. 

   The remainder of this section states the additional extensions on 
   the routing protocols in a flexi-grid network.  That is, the 
   additional information that must be collected and passed between 
   nodes in the network by the routing protocols in order to enable 
   correct path computation and signaling in support of LSPs within the 
   network.  

3.1. Available Frequency Ranges  

   In the case of flexi-grids, the central frequency steps from 193.1 
   THz with 6.25 GHz granularity. The calculation method of central 
   frequency and the frequency slot width of a frequency slot are 
   defined in [G.694.1], i.e., by using nominal central frequency n and 
   the slot width m. 

 
 
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   On a DWDM link, the allocated or in-use frequency slots must not 
   overlap with each other.  However, the border frequencies of two 
   frequency slots may be the same frequency, i.e., the upper bound of  
   a frequency slot and the lower bound of the directly adjacent 
   frequency slot are the same.  
    

                         Frequency Slot 1   Frequency Slot 2 
                           +-----------+-----------------------+  
                           |           |                       |  
      -9 -8 -7 -6 -5 -4 -3 -2 -1 0  1  2  3  4  5  6  7  8  9 10  11     
   ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 
                           ------------ ------------------------ 
                                 ^                 ^ 
                    Central F = 193.1THz    Central F = 193.1375 THz 
                     Slot width = 25 GHz    Slot width = 50 GHz 
    
                 Figure 1 - Two Frequency Slots on a Link 
    
   Figure 1 shows two adjacent frequency slots on a link.  The highest 
   frequency of frequency slot 1 denoted by n=2 is the lowest frequency 
   of slot 2.  In this example, it means that the frequency range from 
   n=-2 to n=10 is unavailable to other flexi-grid LSPs. Available 
   central frequencies are advertised for m=1, which means that for an 
   available central frequency n, the frequency slot from central 
   frequency n-1 to central frequency n+1 is available. 

   Hence, in order to clearly show which LSPs can be supported and what 
   frequency slots are unavailable, the available frequency ranges MUST 
   be advertised by the routing protocol for the flexi-grid DWDM links.  
   A set of non-overlapping available frequency ranges MUST be 
   disseminated in order to allow efficient resource management of 
   flexi-grid DWDM links and RSA procedures which are described in 
   Section 4.8 of [RFC7698]. 

3.2. Application Compliance Considerations 

   As described in [G.694.1], devices or applications that make use of 
   the flexi-grid may not be capable of supporting every possible slot 
   width or position (i.e., central frequency).  In other words, 
   applications or implementations may be defined where only a subset 
   of the possible slot widths and positions are required to be 
   supported. 

   For example, an application could be defined where the nominal 
   central frequency granularity is 12.5 GHz (by only requiring values 

 
 
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   of n that are even) and that only requires slot widths as a multiple 
   of 25 GHz (by only requiring values of m that are even).  

   Hence, in order to support all possible applications and 
   implementations the following information should be advertised for a 
   flexi-grid DWDM link:  

   o Channel Spacing (C.S.): as defined in [RFC7699] for flexi-grid, 
      is set to 5 to denote 6.25GHz. 

   o Central frequency granularity: a multiplier of C.S.. 

   o Slot width granularity: a multiplier of 2*C.S.. 

   o Slot width range: two multipliers of the slot width granularity, 
      each indicate the minimal and maximal slot width supported by a 
      port respectively.  

   The combination of slot width range and slot width granularity can 
   be used to determine the slot widths set supported by a port.  

3.3. Comparison with Fixed-grid DWDM Links  

   In the case of fixed-grid DWDM links, each wavelength has a pre-
   defined central frequency and each wavelength maps to a pre-defined 
   central frequency and the usable frequency range is implicit by the 
   channel spacing.  All the wavelengths on a DWDM link can be 
   identified with an identifier that mainly conveys its central 
   frequency as the label defined in [RFC6205], and the status of the 
   wavelengths (available or not) can be advertised through a routing 
   protocol. 

   Figure 2 shows a link that supports a fixed-grid with 50 GHz channel 
   spacing.  The central frequencies of the wavelengths are pre-defined 
   by values of "n" and each wavelength occupies a fixed 50 GHz 
   frequency range as described in [G.694.1].  

 
 
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        W(-2)  |    W(-1)  |    W(0)   |    W(1)   |     W(2)  | 
   ...---------+-----------+-----------+-----------+-----------+----... 
         |   50 GHz  |  50 GHz   |  50 GHz   |   50 GHz  |  
    
       n=-2        n=-1        n=0         n=1         n=2               
   ...---+-----------+-----------+-----------+-----------+----------... 
                                 ^              
                    Central F = 193.1THz     
    
      Figure 2 - A Link Supports Fixed Wavelengths with 50 GHz Channel 
                                 Spacing 
    
   Unlike the fixed-grid DWDM links, on a flexi-grid DWDM link the slot 
   width of the frequency slot is flexible as described in section 3.1.  
   That is, the value of m in the following formula [G.694.1] is 
   uncertain before a frequency slot is actually allocated for a flexi-
   grid LSP.   

                Slot Width (GHz) = 12.5GHz * m 

   For this reason, the available frequency slot/ranges need to be 
   advertised for a flexi-grid DWDM link instead of the specific 
   "wavelengths" points that are sufficient for a fixed-grid link.  
   Moreover, thus advertisement is represented by the combination of 
   Central Frequency Granularity and Slot Width Granularity.  

4. Extensions 

   As described in [RFC7698], the network connectivity topology 
   constructed by the links/nodes and node capabilities are the same as 
   for WSON, and can be advertised by the GMPLS routing protocols 
   (refer to section 6.2 of [RFC6163]).  In the flexi-grid case, the 
   available frequency ranges instead of the specific "wavelengths" are 
   advertised for the link.  This section defines the GMPLS OSPF-TE 
   extensions in support of advertising the available frequency ranges 
   for flexi-grid DWDM links. 

4.1. ISCD Extensions for Flexi-grid 

         Value                       Type 

         -----                       ---- 

      152 (TBA by IANA)           Flexi-Grid-LSC 
 
 
 
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   Switching Capability and Encoding values MUST be used as follows: 

              Switching Capability = Flexi-Grid-LSC 

              Encoding Type = lambda [as defined in RFC3471] 

   When Switching Capability and Encoding fields are set to values as 
   stated above, the Interface Switching Capability Descriptor MUST be 
   interpreted as in [RFC4203] with the optional inclusion of one or 
   more Switching Capability Specific Information sub-TLVs.  

   As the "Max LSP Bandwidth at priority x" (x from 0 to 7) fields in 
   the generic part of the Interface Switching Capability Descriptor 
   [RFC4203] are not meaningful for flexi-grid DWDM links, the values 
   of these fields MUST be set to zero and MUST be ignored. The 
   Switching Capability Specific Information (SCSI) as defined below 
   provides the corresponding information for flexi-grid DWDM links. 

4.1.1. Switching Capability Specific Information (SCSI)  

   The technology specific part of the Flexi-grid ISCD should include 
   the available frequency spectrum resource as well as the max slot 
   widths per priority information. The format of this flex-grid SCSI, 
   the frequency available bitmap TLV, is depicted in the following 
   figure:  

     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 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |          Type  = 1            |           Length              | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   Priority    |                   Reserved                    | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | Max Slot Width at Priority 0  |           ...                 ~ 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    ~ Max Slot Width at Priority 7  |   Unreserved padding          | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | C.S.  |       Starting n              | No. of Effective. Bits|  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |       Bit Map                 ...                             ~ 
    ~      ...                              |  padding bits         ~ 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
 

   Type (16 bits): The type of this sub-TLV and is set to 1.   

 
 
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   Length (16 bits): The length of the value field of this sub-TLV. 

   Priority (8 bits): A bitmap used to indicate which priorities     
   are being advertised.  The bitmap is in ascending order, with the      
   leftmost bit representing priority level 0 (i.e., the highest) and      
   the rightmost bit representing priority level 7 (i.e., the      
   lowest).  A bit MUST be set (1) corresponding to each priority      
   represented in the sub-TLV, and MUST NOT be set (0) when the      
   corresponding priority is not represented.  At least one priority      
   level MUST be advertised that, unless overridden by local policy,      
   SHALL be at priority level 0. 

   Max Slot Width (16 bits): This field indicates maximal frequency 
   slot width supported at a particular priority level.  This field 
   MUST be set to max frequency slot width supported in the unit of 
   2*C.S., for a particular priority level.  One field MUST be present 
   for each bit set in the Priority field, and is ordered to match the 
   Priority field.  Fields MUST NOT be present for priority levels that 
   are not indicated in the Priority field. 

   Unreserved Padding (16 bits): The Padding field is used to      
   ensure the 32 bit alignment of Max Slot Width fields.  When      
   present the Unreserved Padding field is 16 bits (2 byte) long.      
   When the number of priorities is odd, the Unreserved Padding field      
   MUST be included.  When the number of priorities is even, the      
   Unreserved Padding MUST be omitted. 

   C.S. (4 bits): As defined in [RFC7699] and it is currently set to 5. 

   Starting n (16 bits): as defined in [RFC7699] and this value denotes 
   the starting nominal central frequency point of the frequency 
   availability bitmap sub-TLV. 

   Number of Effective Bits (12 bits): Indicates the number of 
   effective bits in the Bit Map field. 

   Bit Map (variable):  Indicates whether a basic frequency slot, 
   characterized by a nominal central frequency and a fixed m value of 
   1, is available or not for flexi-grid LSP setup. The first nominal 
   central frequency is the value of starting n and with the subsequent 
   ones implied by the position in the bitmap. Note that when setting 
   to 1, it means that the corresponding central frequency is available 
   for a flexi-grid LSP with m=1; and when setting to 0, it means the 
   corresponding central frequency is unavailable. Note that a 
   centralized SA process will need to extend this to high values of m 
   by checking a sufficient large number of consecutive basic frequency 
   slots that are available. 
 
 
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   Padding Bits (variable): Padded after the Bit Map to make it a 
   multiple of four bytes if necessary.  Padding bits MUST be set to 0 
   and MUST be ignored on receipt. 

   The Reserved field MUST be set to zero on transmission and SHOULD be   
   ignored on receipt. 

   The starting n MAY be set to the lowest possible nominal central 
   frequency supported by the link. An example is provided in section 
   4.1.2. 

4.1.2. An SCSI Example 

   Figure 3 shows an example of the available frequency spectrum 
   resource of a flexi-grid DWDM link.  

      -9 -8 -7 -6 -5 -4 -3 -2 -1 0  1  2  3  4  5  6  7  8  9 10  11     
   ...+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--... 
                           |--Available Frequency Range--| 
    
                  Figure 3 - Flexi-grid DWDM Link Example 
                                      
   The symbol "+" represents the allowed nominal central frequency. The 
   symbol "--" represents a central frequency granularity of 6.25 GHz, 
   as currently be standardized in [G.694.1].  The number on the top of 
   the line represents the "n" in the frequency calculation formula 
   (193.1 + n * 0.00625).  The nominal central frequency is 193.1 THz 
   when n equals zero.  

   In this example, it is assumed that the lowest nominal central 
   frequency supported is n= -9 and the highest is n=11. Note they 
   cannot be used as a nominal central frequency for setting up a LSP, 
   but merely as the way to express the supported frequency range. 
   Using the encoding defined in Section 4.1.1, the relevant fields to 
   express the frequency resource availability can be filled as below:  

 
 
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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 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |          Type  = 1            |           Length              | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   Priority    |                   Reserved                    | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | Max Slot Width at Priority 0  |          ...                  ~ 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    ~ Max Slot Width at Priority 7  |   Unreserved padding          | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   5   |       Starting n (-9)         | No. of Effec. Bits(21)|  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |0|0|0|0|0|0|0|0|1|1|1|1|1|1|1|1|1|0|0|0|0|  padding bits (0s)  | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

   In the above example, the starting n is selected to be the lowest 
   nominal central frequency, i.e. -9. It is observed from the bit map 
   that n = -1 to 7 can be used to set up LSPs. Note other starting n 
   values can be chosen to represent the bit map, for example, the 
   first available nominal central frequency (a.k.a., the first 
   available basic frequency slot) can be chosen and the SCSI will be 
   expressed as the following:  

    

     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 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |          Type  = 1            |           Length              | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   Priority    |                   Reserved                    | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | Max Slot Width at Priority 0  |           ...                 ~ 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    ~ Max Slot Width at Priority 7  |   Unreserved padding          | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   5   |       Starting n (-1)         | No. of Effec. Bits(9)|  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |1|1|1|1|1|1|1|1|1|            padding bits (0s)                | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

 
 
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   This denotes that other than the advertised available nominal 
   central frequencies, the other nominal central frequencies within 
   the whole frequency range supported by the link are not available 
   for flexi-grid LSP set up. 

   If a LSP with slot width m equals to 1 is set up using this link, 
   say using n= -1, then the SCSI information is updated to be the 
   following:  

     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 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |          Type  = 1            |           Length              | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   Priority    |                   Reserved                    | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | Max Slot Width at Priority 0  |           ...                 ~ 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    ~ Max Slot Width at Priority 7  |   Unreserved padding          | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |   5   |       Starting n (-1)         | No. of Effec. Bits(9)|  
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |0|0|1|1|1|1|1|1|1|            padding bits (0s)                | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    

4.2. Extensions to Port Label Restriction sub-TLV 

   As described in Section 3.2, a port that supports flexi-grid may 
   support only a restricted subset of the full flexible grid.  The 
   Port Label Restriction sub-TLV is defined in [RFC7579].  It can be 
   used to describe the label restrictions on a port and is carried in 
   the top-level Link TLV as specified in [RFC7580].  A new restriction 
   type, the flexi-grid Restriction Type, is defined here to specify 
   the restrictions on a port to support flexi-grid. 

 
 
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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 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    | MatrixID      | RstType = 5   | Switching Cap |   Encoding    | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |  C.S. |     C.F.G     |    S.W.G      |     Reserved          | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
    |      Min Slot Width           |        Reserved               | 
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 
     
   MatrixID (8 bits): As defined in [RFC7579]. 

   RstType (Restriction Type, 8 bits): Takes the value of 5 to indicate 
   the restrictions on a port to support flexi-grid. 

   Switching Cap (Switching Capability, 8 bits): As defined in 
   [RFC7579], MUST be consistent with the one specified in ISCD as 
   described in Section 4.1.  

   Encoding (8 bits): As defined in [RFC7579], must be consistent with 
   the one specified in ISCD as described in Section 4.1. 

   C.S. (4 bits): As defined in [RFC7699] and for flexi-grid is 5 to 
   denote 6.25GHz. 

   C.F.G (Central Frequency Granularity, 8 bits): A positive integer.  
   Its value indicates the multiple of C.S., in terms of central 
   frequency granularity. 

   S.W.G (Slot Width Granularity, 8 bits): A positive integer.  Its 
   value indicates the multiple of 2*C.S., in terms of slot width 
   granularity. 

   Min Slot Width (16 bits): A positive integer.  Its value indicates 
   the multiple of 2*C.S. (GHz), in terms of the supported minimal slot 
   width. 

   The Reserved field MUST be set to zero on transmission and SHOULD be   
   ignored on receipt. 

5. IANA Considerations 

5.1. New Switching Type  

   Upon approval of this document, IANA will make the assignment in the   
   "Switching Types" section of the "GMPLS Signaling Parameters"   

 
 
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   registry located at http://www.iana.org/assignments/gmpls-sig-
   parameters: 

      Value      Name                          Reference 

      ---------  --------------------------    ---------- 

      152 (*)     Flexi-Grid-LSC     [This.I-D] 

      (*) Suggested value 

5.2. New Sub-TLV 

   This document defines one new sub-TLV that are carried in the 
   Interface Switching Capability Descriptors [RFC4203] with Signal 
   Type Flexi-Grid-LSC. 

   Upon approval of this document, IANA will create and maintain a new   
   sub-registry, the "Types for sub-TLVs of Flexi-Grid-LSC SCSI (Switch 
   Capability-Specific Information)" registry under the "Open Shortest 
   Path First (OSPF) Traffic Engineering TLVs" registry, see 
   http://www.iana.org/assignments/ospf-traffic-eng-tlvs/ospf-traffic-
   eng-tlvs.xml, with the sub-TLV types as follows: 

   This document defines new sub-TLV types as follows: 

    

      Value      Sub-TLV                       Reference 
      ---------  --------------------------    ---------- 
      0           Reserved                     [This.I-D] 
      1       Frequency availability bitmap    [This.I-D] 
    
6. Implementation Status 

   [RFC Editor Note: Please remove this entire section 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 
   7942.  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 
 
 
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   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 7942, "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. 

6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) 

      Organization Responsible for the Implementation: CTTC - Centre 
   Tecnologic de Telecomunicacions de Catalunya (CTTC), Optical 
   Networks and Systems Department, http://wikiona.cttc.es. 

      Implementation Name and Details: ADRENALINE testbed,       
   http://networks.cttc.es/experimental-testbeds/ 

      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. 

      Coverage: Support for the 64 bit label [RFC7699] for flexi-grid 
   as described in this document, with available label set encoded as 
   bitmap. 

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

      Licensing: Proprietary 

      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 see http://networks.cttc.es/publications/?         
   search=GMPLS&research_area=optical-networks-systems 

 
 
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      Contact Information: Ramon Casellas: ramon.casellas@cttc.es 

      Interoperability: No report. 

7. Acknowledgments 

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

   This work was supported in part by NSFC Project 61201260. 

8. Security Considerations 

   This document extends [RFC4203] and [RFC7580] to carry flex-grid 
   specific information in OSPF Opaque LSAs. This document does not 
   introduce any further security issues other than those discussed in 
   [RFC3630], [RFC4203]. To be more specific, the security mechanisms 
   described in [RFC2328] which apply to Opaque LSAs carried in OSPF 
   still apply. An analysis of the OSPF security is provided in 
   [RFC6863] and applies to the extensions to OSPF in this document as 
   well.  

9. Contributors' Addresses 

   Adrian Farrel 
   Old Dog Consulting 
   Email: adrian@olddog.co.uk 
    

   Fatai Zhang 
   Huawei Technologies 
   Email: zhangfatai@huawei.com 
    

   Lei Wang,   
   ZTE  
   Email: wang.lei@bupt.edu.cn 
    

   Guoying Zhang,   
   China Academy of Information and Communication Technology 
   Email: zhangguoying@ritt.cn 
    

 
 
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10. References 

10.1. Normative References 

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

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

   [RFC4203] K. Kompella, Y. Rekhter, " OSPF Extensions in Support of           
             Generalized Multi-Protocol Label Switching (GMPLS)",              
             October 2005. 

   [RFC7579] Bernstein, G., Lee, Y., Li, D., and W. Imajuku, "General 
             Network Element Constraint Encoding for GMPLS Controlled 
             Networks", RFC 7579, June 2015. 

   [RFC7580] F. Zhang, Y. Lee, J. Han, G. Bernstein and Y. Xu, "OSPF-TE 
             Extensions for General Network Element Constraints ", RFC 
             7580, June 2015. 

   [RFC6205] T. Otani and D. Li, "Generalized Labels for Lambda-Switch-
             Capable (LSC) Label Switching Routers", RFC 6205, March 
             2011. 

   [RFC7699] King, D., Farrel, A. and Y. Li, "Generalized Labels for 
             the Flexi-Grid in Lambda Switch Capable (LSC) Label 
             Switching Routers", RFC7699, September 2015. 

10.2. Informative References 

   [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. 

   [RFC7792] F.Zhang et al, "RSVP-TE Signaling Extensions in support of 
             Flexible-grid", RFC 7792, November 2015. 

   [RFC7698] 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', RFC 7698, August 2015. 

   [RFC7688] Y. Lee and G. Bernstein, "GMPLS OSPF Enhancement for 
             Signal and Network Element Compatibility for Wavelength 
             Switched Optical Networks ", RFC7688, August 2015.  
 
 
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   [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. 

   [RFC3630] D. Katz, K. Kompella, D. Yeung, " Traffic Engineering              
             (TE) Extensions to OSPF Version 2", September 2003. 

   [RFC6863] Hartman, S. and D. Zhang, "Analysis of OSPF Security 
             According to the Keying and Authentication for Routing 
             Protocols (KARP) Design Guide", RFC 6863, March 2013. 

    
   Authors' Addresses 
    
   Xian Zhang  
   Huawei Technologies  
   Email: zhang.xian@huawei.com 

   Haomian Zheng 
   Huawei Technologies 
   Email: zhenghaomian@huawei.com 
    
   Ramon Casellas, Ph.D. 
   CTTC 
   Spain 
   Phone: +34 936452916 
   Email: ramon.casellas@cttc.es 
    
   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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