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Versions: (draft-zhang-ccamp-flexible-grid-ospf-ext) 00 01 02 03 04 05 06 07 08 09 Draft is active
In: IESG-wait
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: August 17, 2017                               February 17, 2017


     GMPLS OSPF-TE Extensions in support of Flexi-grid DWDM networks

              draft-ietf-ccamp-flexible-grid-ospf-ext-09.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 known
   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 August 17, 2017.

Copyright Notice

   Copyright (c) 2017 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 ............................................ 13
   6. Implementation Status ....................................... 14
      6.1. Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)14
   7. Acknowledgments ............................................. 15
   8. Security Considerations ..................................... 15
   9. Contributors' Addresses ..................................... 16
   10. References ................................................. 16
      10.1. Normative References .................................. 16


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      10.2. Informative References ................................ 17
   Authors' Addresses ............................................. 17



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.

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.

   On a DWDM link, the allocated or in-use frequency slots do 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



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   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 are
   advertised by the routing protocol for the flexi-grid DWDM links.  A
   set of non-overlapping available frequency ranges are 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
   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).




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   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 are advertised
   for a flexi-grid DWDM link instead of the specific "wavelengths"
   points that are sufficient for a fixed-grid link.  Moreover, this
   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 using
   opaque LSAs [RFC3630] in the case of OSPF-TE [RFC4203] (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 is
   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 includes 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 k  |   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.

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


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   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 is set (1) corresponding to each priority
   represented in the sub-TLV, and clear (0) for each priority not
   represented in the sub-TLV.   At least one priority level MUST be
   advertised. If only one priority level is advertised, it MUST be at
   priority level 0.

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

   Max Slot Width at priority k(16 bits): This field indicates maximal
   frequency slot width supported at a particular priority level, up to
   8.  This field is 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 be present for priority
   levels that are 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 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.  This field MUST be set to 0 and MUST be
   ignored on receipt.

   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



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   by checking a sufficient large number of consecutive basic frequency
   slots that are available.

   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.

   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:

     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 k  |   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)  |


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    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   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 k  |   Unreserved padding          ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   5   |       Starting n (-1)         | No. of Effec. Bits(9)|
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |1|1|1|1|1|1|1|1|1|            padding bits (0s)                |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   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:












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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 k  |   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 field 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.

     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.


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   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"
   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:


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   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
   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.



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      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

      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.





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9. Contributors' Addresses

   Adrian Farrel
   Juniper Networks
   Email: afarrel@juniper.net

   Fatai Zhang
   Huawei Technologies
   Email: zhangfatai@huawei.com


   Lei Wang,
   Beijing University of Posts and Telecommunications
   Email: wang.lei@bupt.edu.cn


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


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.



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   [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.

   [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


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   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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