Internet DRAFT - draft-keten-mpls-expbit
draft-keten-mpls-expbit
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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Internet-Draft MPLS EXP/TC BIT EXPANSION September 2016
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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