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Network Working Group                           Vijayanand Chandrasekar
INTERNET DRAFT                                   Individual Contributor
Intended Status: Standards Track                       August 16, 2019
Expires:  15 Febraury, 2020





            Advertising OTN Fixed Time slot constraints in OSPF
              draft-vijay-ccamp-ospf-otn-timeslot-00.txt

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   Abstract


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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019


   This document describes the extensions needed to OSPF for
   advertising the constraints that exists in some OTN switches while
   switching timeslots between ports. This advertisement would be
   needed for computing path of LSP through these switches taking into
   account the above mentioned constraint.

   This document proposes extensions to existing OSPF for advertising
   the timeslots available on each OTN port in a new sub-tlv and the
   connectivity matrix representing the capability of the device to
   cross connect these timeslots in another new sub-tlv

1. Introduction

       In [RFC7138], a mechanism for advertising the ODU multiplexing
   hierarchy is described. In [RFC7580], an optical node property TLV
   is defined as an extension to the OSPF opaque LSA defined in
   {RFC3630].
   .

       This document describes the use of OSPF-TE in carrying
   information about the details of OTN time slots available in each
   port of an OTN switch and the connectivity matrix describing the
   connectivity between the timeslots of the different ports.

2. Terminology

   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 RFC2119 [RFC2110].

   The reader is assumed to be familiar with the terminology in
   RFC7138[RFC7138],RFC5780[RFC7580] and RFC3630{RFC3630]


3. OSPF Extensions


       A new OTN timeslot sub-TLV and OTN Connectivity matrix sub-TLV
   are proposed in this document. The OTN timeslot sub-TLV will be used
   in conjunction with the SCSI described in section 4.1 of
   RFC7138[RFC7138]. The OTN connectivity matrix will be carried in the
   Optical node property TLV described in RFC7580[RFC7580]


   3.1 OTN Timeslot sub-TLV

       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 {TBD)                   |            Length             |
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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Pri  | Bitmap Length           | G | BitMap(variable length)   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          BitMap(variable length)                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Pri  | Bitmap Length           | G| BitMap(variable length)    |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |          BitMap(variable length)                              |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Type

         TBD

   Length

         Length of Sub-TLV

   Pri

         Priority level (0-7) at which the bitmap is advertised

   G: Timeslot granularity
        0 - 1.25 Gbps
        1 -  2.5 Gbps
        2 -  5 Gbps

         Priority (0-7) at which the bitmap is available

   Bitmap Length

         Length in bits of the bitmap following this



   BitMap

         The bitmap represents the timeslots available which is
   advertised through this sub-TLB. A 1 in the bit position represents
   that the timeslot is available , while a 0 represents that the
   timeslot is not available.The Bitmap is padded to the nearest byte
   boundary.



   3.2  Connectivity matrix sub-TLV


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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019

       The Connectivity matrix TLV is described 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( TBD)                 |         Length                |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Number of Link pairs                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Link Identifier                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Link Identifier                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Number of Bitmap pair pairs                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Bit Map Length                 | G | TimeSlot BitMap           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        BitMap(contd)                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Bit Map Length                 |G  | TimeSlot BitMap           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        BitMap(contd)                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                      .
                                      .
                                      .
                                      .
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Link Identifier                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        Link Identifier                        |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                  Number of Bitmap pair pairs                  |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Bit Map Length                 |G  | TimeSlot BitMap           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        BitMap(contd)                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |Bit Map Length                 |G  | TimeSlot BitMap           |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                        BitMap(contd)                          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



    Type

         TBD

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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019
   Length


         Length of Sub-TLV

   Number of Link pairs

         The number of pair of link identifiers advertised.

   Link Identifier


           An identifier for the port that is described


   Number of Bitmap pairs

         The number of pair of bitmaps advertised.


   Bit Map Length

         Length in bits of the bitmap

   G

         Timeslot granularity
         0:1.25 Gbps
         1:2.5  Gbps
         2:5 Gbps

    Timeslot BitmAp

         The BitMap representing the timeslots


4. Operational overview

       This section details the operation of the scheme proposed in
   this document.

        On some OTN switches there exists constraints on which OTN
   timeslots can be cross connected to which other OTN timeslots.
   Therefore, the node computing the path through such switches needs
   to be aware of the OTN timeslots which are available and to which
   other timeslots they can be cross connected.

        The OTN timeslot sub-TLV is advertised along with the SCSI
   defined in section 4.1 of RFC7138[RFC7138] as a separate sub-tlv of
   the link tlv. The SCSI in RFC7138[RFC7138] only advertises the
   number of timeslots available whereas this sub-TLV defines the exact
   timeslots which are available in the form a bitmap.
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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019


       The connectivity matrix sub-TLV is advertised in the node
   attribute TLV of the opaque LSA defined in RFC3630[RFC3630} in line
   with the connectivity matrix that is advertised in [RFC7580]. This
   advertisement describes exactly which timeslots of an OTN interface
   can be cross connected to which other timeslots of another OTN
   Interface. For every pair of link identifiers, multiple pairs of
   bitmaps are advertised, this denotes that timeslots, of the first
   interface in the interface identifier pair, identified in the first
   bitmap of the bitmap pair can be cross connected to timeslots, of
   the second interface in the interface identifier pair, identified in
   the second bitmap of the bitmap pair. Like this several interface
   pairs and their corresponding bitmap pairs can be advertised.
    For example, if on Interface I1 timeslots (t1,t3,t5) can be cross-
   connected to timeslots ( t2,t4,t6) on Interface I2 and ( t2,t4,t6)on
   Interface I1 can be cross-connected to  (t1,t3,t5) on Interface I2,
   then there will be one interface Identifier pair (I1,I2) advertised
   with two bitmap pairs corresponding to (t1,t3,t5), (t2,t4,t6) and (
   t2,t4,t6), ( t1,t3,t5)

      The above mentioned sub-TLVs together would help the node which
   is computing the path to determine which timeslot to select on each
   of the OTN ports to route the LSP on OTN switches which have
   restriction on cross connecting OTN timeslots.




5. Interoperability Considerations

       The feature described in this document would be operational only
   if all the OSPF routers in area support the extension described
   above.

6. Security considerations

      None

7. IANA Considerations

   IANA needs to allocate a new Type for the OTN timeslot sub-TLV
   described in section 3.1 and a new Type for the connectivity matrix
   sub-TLV described in section 3.2

8. Authors' Address

   Vijayanand Chandrasekar
   Individual Contributor

   Email: vijayanandc159@outlook.com

9. References
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INTERNET DRAFT   OTN fixed Timeslot constraints in OSPF    August 2019


9.1 Normative References

   [RFC7138], D. Ceccarelli, F. Zhang, S. Belotti, R. Rao and J. Drake,
   " Traffic Engineering Extensions to OSPF for GMPLS Control of
   Evolving G.709 Optical Transport Networks ",RFC7138,March 2014.

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

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

9.2 Informative references

    [RFC2110]  Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", RFC 2119, March 1997.

   [RFC5226] T. Narten and H. Alvestrand, "Guidelines for Writing an
   IANA Considerations Section in RFCs", RFC 5226.




























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