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Independent Submission                                       U. Keten
Internet Draft                                       Turk Telekom A.S.
Intended status: Proposed Standard                   September 15, 2016
Expires: February 2017



                         MPLS EXP/TC BIT EXPANSION
                      draft-keten-mpls-expbit-02.txt




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   This Internet-Draft will expire on FEB 14, 2016.

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Abstract

   This document specifies the new label/header architecture for a new
   Multiprotocol Label Switching and proposes a new Label Standard.
   With this new architecture the aim is to provide more QoS options.

Table of Contents


   1. Introduction ................................................ 3
   2. Conventions used in this document............................ 3
   3. Overview and Current Encoding of the Label Stack............. 4
   4. New Proposed Encoding of the Label Stack..................... 4
   5. More QoS parameters ......................................... 5
   6. Backwards Compatability...................................... 5
   7. Formal Syntax ............................................... 5
   8. Security Considerations...................................... 5
   9. IANA Considerations ......................................... 5
   10. Conclusions ................................................ 5
   11. References ................................................. 6
      11.1. Normative References................................... 6
      11.2. Informative References................................. 6
   12. Acknowledgments ............................................ 6


























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1. Introduction

         This internet draft outlines a proposed change for the MPLS
         architecture as defined in RFC 3031 and the MPLS Label Stack
         Encoding RFC 3032 to suit the need of differentiated services
         and their requirements for more differentiated QoS.

         Current services require more specific QoS parameters then the
         8 possibilities provided by the 3 bit in the EXP/COS/TC field.

         3 bits is not enough to differentiate in our current service
         oriented environment.

         With this Proposed Standard a possibility of 32 QoS settings
         can be achieved.









2. 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].

   In this document, these words will appear with that interpretation
   only when in ALL CAPS. Lower case uses of these words are not to be
   interpreted as carrying significance described in RFC 2119.

   In this document, the characters ">>" preceding an indented line(s)
   indicates a statement using the key words listed above. This
   convention aids reviewers in quickly identifying or finding the
   portions of this RFC covered by these keywords.









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3. Overview and Current Encoding of the Label Stack

      The current label stack as described in RFC 3032 is represented
      as a sequence of "label stack entries".
      Each label stack entry is represented by 4 octets.

      This is shown in Figure 1:

   Octets  0             1              2             3              4

   Bits   1 2 3 4 5 6 7 8

   Label   -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+-+-+-+-
   Stack  |             Label               |  EXP   |S|      TTL     |
   Entry   -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+-+-+-+-

     Figure 1

      Label:       Label Value, 20 bit
      EXP/TC/COS:  3 bits defined as TC, RFC 5462
      S:           Bottom of Stack, 1 bit
      TTL:         Time to Live, 8 bits

4. New Proposed Encoding of the Label Stack

      The New label stack described is represented as the same sequence
      of "label stack entries" as in RFC 3032. However the assigned 8
      bits to TTL have been deducted by 2, to a total of 6 bits and
      added to a new complimentary QoS X stack which will be a 2 bits
      entry.

     This is shown in Figure 2.



  Octets 0             1              2             3              4
  Bits  1 2 3 4 5 6 7 8

   Label   -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+-+-+-+-
   Stack  |             Label               |  EXP   |S| X |  TTL     |
   Entry   -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+-+-+-+-

     Figure 2

      Label:       Label Value, 20 bit
      EXP/TC/COS:  5 bits defined in New Proposed Format
      S:           Bottom of Stack, 1 bit
      X:           Complimentary QoS bits
      TTL:         Time to Live, 6 bits


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5. More QoS parameters

   With the addition of 2 more complimentary bits as the X stack, more
   QoS parameters can be set to suit the needs of current IP Internet
   services.

   MPLS networks will not need such large TTL's, taking the 2
   most-significant-bits from the TTL and giving them a different
   purpose could have more meaning.


6. Backwards Compatability

   Assumed is that these most-significant-bits bits will "never" be
   decremented. For consideration is that certain OAM mechanisms do rely
   on TTL decrementing to zero to trap frames. This is to specify that
   OAM protocols in this new architecture would never set these
   "extended" TC bits. Intended is to use these as extra "trash" tiers.
   Alternatively, these could be considered as "premium" trash tiers
   and hopping too much is grounds to have your extended TC "downgraded".

   In terms of implementation as a software upgrade in existing gear,
   this should be doable. NPU/FPGA/NFV-based solutions could add this
   functionality with a software upgrade. Semi-programmable ASICs could
   do this with some reconfiguration/programming.
   Only fully baked-in ASICs would have difficulty implementing this.


7. Formal Syntax

   The following syntax specification uses the augmented Backus-Naur
   Form (BNF) as described in RFC-2234 [RFC2234].



8. Security Considerations

   There are no security considerations.



9. IANA Considerations

   This document has no actions for IANA.



10. Conclusions

   With this document a necessary and easy change is advised. More
   diverse QoS settings will enable a more service oriented network.







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11. References

11.1. Normative References

   [1]  Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol
         Label Switching Architecture", RFC 3031, January 2001.

   [2]  Rosen, E., Tappan, D. Fedorkow G., Y. Rekhter,  D. Farinacci,
         T. Li, A. Conta "MPLS Label Stack Encoding", RFC 3032,
         January 2001

   [3]  Bradner, S.,"Key words for use in RFCs to Indicate Requirement
         Levels", BCP 14, RFC 2119, March 1997.

   [4]  L. Andersson, Acreo AB, R. Asati, Multiprotocol Label
         Switching (MPLS) Label Stack Entry:"EXP" Field Renamed to
         "Traffic Class" Field,RFC 5462, February 2009





11.2. Informative References

   No Informative References



12. Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.





Authors' Addresses

   Umut Keten
   Turk Telekom A.S.
   Ankara GM

   Phone: +90 553 349 9669
   Email: umut.keten@turktelekom.com.tr



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