Skip to main content

OSPF extensions for support wavelength range allocation in flexible grid supported network
draft-wang-ccamp-flexigrid-wavelength-range-ospf-00

The information below is for an old version of the document.
Document Type
This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Qilei Wang , Xihua Fu
Last updated 2012-02-28
RFC stream (None)
Formats
Additional resources
Stream Stream state (No stream defined)
Consensus boilerplate Unknown
RFC Editor Note (None)
IESG IESG state I-D Exists
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-wang-ccamp-flexigrid-wavelength-range-ospf-00
Network Working Group                                         Qilei Wang
Internet-Draft                                                  Xihua Fu
Intended status: Standards Track                         ZTE Corporation
Expires: September 1, 2012                                  Feb 29, 2012

OSPF extensions for support wavelength range allocation in flexible grid
                           supported network
        draft-wang-ccamp-flexigrid-wavelength-range-ospf-00.txt

Abstract

   This document addresses the requirements and routing protocol
   extension of wavelength range allocation in flexible grid supported
   network in order to help spectrum utilization in the process of path
   computation.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on September 1, 2012.

Copyright Notice

   Copyright (c) 2012 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.

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 1]
Internet-Draft         wavelength range allocation              Feb 2012

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Conventions used in this document . . . . . . . . . . . . . . . 4
   3.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Extension of routing protocol . . . . . . . . . . . . . . . . . 5
     4.1.  Relationship with WSON  . . . . . . . . . . . . . . . . . . 5
     4.2.  Extensions of OSPF Protocol to Support Wavelength
           Range Allocation  . . . . . . . . . . . . . . . . . . . . . 6
       4.2.1.  Wavelength Range Allocation by Bitrates . . . . . . . . 6
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 8
   6.  IANA considerations . . . . . . . . . . . . . . . . . . . . . . 8
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 8
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 8
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 9

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 2]
Internet-Draft         wavelength range allocation              Feb 2012

1.  Introduction

   In the latest version of ITU-T G.694.1, a new flexible grid
   technology is defined.  The flexible grid technology is also a dense
   wavelength division multiplexing and is different from traditional
   fixed grid technology.  Difference between fixed grid technology and
   flexible grid technology can be found in [G.694.1], the flexible grid
   technology allows mixed bit rates or mixed modulation formats
   transmission system to allocate frequency slots with different slot
   widths so that they can be optimized for the bandwidth requirements
   of a particular bit rate and modulation scheme of the individual
   channels.  As shown in Figure 1, there are three different channel
   spacing exist in one system.

       25GHz               50GHz                       75GHz
     +-------+       +---------------+       +-----------------------+
     |       |       |               |       |                       |
   __|_______|_______|_______________|_______|_______________________|_
     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
    193                            193.1                           193.2

              Figure 1: flexible grid wavelength utilization

   Traditional fixed grid doesn't allow system to allocate frequency
   slots with different widths, whereas flexible grid technology allows
   this.  The situation that different slot widths exist in the flexible
   grid network brings much disorder.  Spectrum fragments that can't be
   used anyone will appear in the network in the process of allocation
   of wavelength for a channel.  And this will result in the decline of
   spectrum utilization rate.  So in order to raise the spectrum
   utilization rate, spectrum utilization scheme such as scheme of
   wavelength assignment and use of slot position, wavelength range, can
   be done in advance, and this will help raise the spectrum utilization
   rate.  More advantage can be seen in section 2.

   This document mainly addresses the routing protocol extension support
   the advertisement of wavelength range (or spectrum block) allocation
   information, such as the wavelength range positions and specific
   restriction information which are related to this wavelength range
   and so on.  Certain policy would be involved here to help allocation
   wavelength range.  One wavelength range can only be used for path
   setup with specific attributes, for example, with specific bitrates
   and/or modulation format.

   When control plane uses path computation element to setup an end-to-

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 3]
Internet-Draft         wavelength range allocation              Feb 2012

   end path in flexible grid network, wavelength available information
   and restriction information should be considered in order to compute
   a suitable end-to-end path.  The restriction information can be
   derived by path computation element through routing advertisement,
   and the wavelength restriction information depicted in this document
   should also be considered in the flexible network.

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 [RFC2119].

3.  Overview

   Concerns were expressed in ITU-T document about mixing and matching a
   variety of bitrates and modulation formats on a single fiber
   completely freedom.  If flexible grid network allows completely
   freedom, indiscriminate positioning of the various channels with
   respect to each other, it is likely to lead to dramatically impaired
   system performance compared to a more careful choice of slot
   positioning / wavelength assignment.  Effects like XPM (Cross-phase
   modulation) will appear if network allows completely freedom,
   indiscriminate positioning of various channels.  Solution expressed
   by the ITU-T expert is that grouping of wavelength with the same
   bitrates and modulation formats is a sensible one.  This document
   addresses the requirements and protocol extension of the grouping of
   wavelength with the same attributes such as bitrates and/or
   modulation formats.  As signals of the same bitrates usually use the
   same modulation formation on a specific link, this document mainly
   pays attention to grouping of wavelength with the same bitrates and
   routing protocol extension is described in the next chapter.

   Some other advantages are also brought if operator split supported
   wavelength into several wavelength ranges and one wavelength range
   can be only used for path with specific attributes in the flexible
   grid network except what have been described above.  Grouping of
   wavelength of the same bitrates would help reduce fragments.
   Channels in the same wavelength range with the same bitrates looks
   almost like fixed grid technology, and they won't generate much
   fragments in the path setup and release because every channel use the
   same slot width.  It will also be convenient for operator to manage
   the flexible network if the operator groups the wavelength of the
   same bitrates.

   The whole wavelength that subsystems support can be partitioned into

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 4]
Internet-Draft         wavelength range allocation              Feb 2012

   several wavelength ranges, and one wavelength range can only be used
   for paths setup with the specific bit rate.  For example, a
   wavelength range which has a range of (m1, m2) can only be used for
   signal with 400Gbit/s to setup path, and m1 represents the start
   label of the wavelength range, m2 represents the end label of the
   wavelength range.  Also the wavelength can be partitioned according
   to the bitrates and/or modulation format if it is needed in some
   complex scenarios, that is to say a wavelength range can only be used
   for signal with the specific bitrates and/or modulation format to
   setup path.

   When control plane uses path computation element to setup an end-to-
   end path through flexible grid network, wavelength available
   information and restriction information should be taken into
   consideration in order to compute a suitable end-to-end path.  The
   wavelength range allocation information needs to be advertised by
   routing protocol in order to help the path computation.  Section 4
   describes the extension of OSPF routing protocol to advertise these
   wavelength range information in order to help with path computation.

4.  Extension of routing protocol

4.1.   Relationship with WSON

   As described in the introduction section, flexible grid is a new DWDM
   technology which is different from traditional fixed grid technology.
   It is described in newest version of ITU-T [G.694.1].  Flexible grid
   can make use of current WSON control plane technology to setup path,
   for example, routing protocol and signaling protocol.  Additional
   extensions may be needed because of new features introduced by
   flexible grid.  This Section addresses the routing extension of the
   features which is describe above base on the current WSON routing
   extension in IETF CCAMP.

   [draft-ietf-ccamp-general-constraint-encode] defines a new link sub-
   TLV called Port Label Restrictions sub-TLV.  Descriptions about Port
   Label Restrictions sub-TLV in this draft are referenced here: "Port
   label restrictions describe the label restrictions that the network
   element (node) and link may impose on a port.  These restrictions
   represent what labels may or may not be used on a link and are
   intended to be relatively static.  More dynamic information is
   contained in the information on available labels.  Port label
   restrictions are specified relative to the port in general or to a
   specific connectivity matrix for increased modeling flexibility" and
   "For example, Port Label Restrictions describes the wavelength
   restrictions that the link and various optical devices such as OXCs,
   ROADMs, and waveband multiplexers may impose on a port in WSON.

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 5]
Internet-Draft         wavelength range allocation              Feb 2012

   These restrictions represent what wavelength may or may not be used
   on a link and are relatively static."

   The wavelength range allocation information described in this
   document can be regarded as label restrictions which are imposed by
   network element (node) on a port, and the network element include
   various optical devices such as OXCs, ROADMs and waveband
   multiplexers and so on.  These wavelength range allocation
   restrictions represent what labels may or may not be used on a link
   or what labels can only be used for channel with specific bitrates
   and/or modulation format.  The restrictions described in this
   document can be seen as relative static and can be included in Port
   Label Restrictions sub-TLV.

4.2.  Extensions of OSPF Protocol to Support Wavelength Range Allocation

   Wavelength range allocation information should be known by path
   computation element if operators want to compute an end-to-end
   flexible grid network path.  As described in the previous section,
   Port Label Restrictions sub-TLV can be used to carry this wavelength
   range allocation restriction information.  Figure 1 is the format of
   Port Label Restrictions sub-TLV which is described in
   [draft-ietf-ccamp-general-constraint-encode] and definition of the
   parameters included in this sub-TLV can be found in this document.

      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    |RestrictionType|   Reserved/Parameter          |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     :      Additional Restriction Parameters per RestrictionType    :
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                 Figure 2: Port Label Restrictions sub-TLV

4.2.1.  Wavelength Range Allocation by Bitrates

   As described in section 3, signals on a single fiber with the same
   bitrates usually use the same modulation format, especially when the
   equipments come from one vendor.  So here operator can allocation
   wavelength into several wavelength ranges by bitrates.  In this
   section, OSPF protocol is extended to cover the wavelength range
   allocation information by bitrates.

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 6]
Internet-Draft         wavelength range allocation              Feb 2012

   The wavelength range allocation information by bitrates is needed in
   the process of path computation if an end-to-end path needs to be
   computed by path computation element and this information SHOULD be
   advertised by routing protocols.  Figure 3 gives a new kinds of Port
   Label Restrictions sub-TLV which mainly extent the Additional
   Restriction Parameters field to cover the wavelength ranges
   allocation information.  The parameters in the Additional Restriction
   Parameters field include Bit Rate which indicates the bitrates of the
   specific wavelength range and (Start Label, End Label) tuple which
   indicates the wavelength range.

      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    |RestrictionType|F|        Reserved             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                              Bit Rate                         |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     :                           Start Label                         :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     :                             End Label                         :
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                 Figure 3

   Definition of MatrixID and RestrictionType field can be found in the
   document [draft-ietf-ccamp-general-constraint-encode].  Value of
   RestrictionType needs to be assigned by IANA.

   When fixed grid network and flexible grid network exist on a single
   fiber, and an indication is needed to distinguish both of them.  "F"
   bit is introduced as an indication to distinguish fixed grid (F = 0)
   and flexible grid (F = 1).

   "Bit Rate" field indicates the bitrates of the specific wavelength
   range.

   The tuple (Start Label, End Label) indicates the wavelength range,
   and the label encoding format can be found in [RFC6205] when used to
   represent fixed grid, and in
   [draft-farrkingel-ccamp-flexigrid-lambda-label] when used to
   represent flexible grid.  Note: label encoding format in [RFC6205]
   can also be used by flexible grid, but it's an unresolved problem and
   needs further discussion.

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 7]
Internet-Draft         wavelength range allocation              Feb 2012

   In some situation, modulation format information may also be needed
   to help allocation wavelength range, as signals with the same
   bitrates on a single fiber can use different modulation format.  In
   this case, modulation formats information is needed to be carried in
   Port Label Restrictions sub-TLV.  Wavelength that is supported by
   subsystems can be partitioned to service traditional fixed grid
   technology.

5.  Security Considerations

   TBD

6.  IANA considerations

   TBD.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC6163]  Lee, Y., Bernstein, G., and W. Imajuku, "Framework for
              GMPLS and Path Computation Element (PCE) Control of
              Wavelength Switched Optical Networks (WSONs)", RFC 6163,
              April 2011.

7.2.  Informative References

   [G.694.1 v1]
              International Telecommunications Union, "Draft revised
              G.694.1 version 1.3".

   [flexible-grid-ospf-ext]
              Fatai Zhang, Xiaobing Zi, Ramon Casellas, O. Gonzalez de
              Dios, and D. Ceccarelli, "GMPLS OSPF-TE Extensions in
              support of Flexible-Grid in DWDM Networks",
              draft-zhang-ccamp-flexible-grid-ospf-ext-00.txt .

   [flexigrid-lambda-label]
              D. King, A. Farrel, Y. Li, F. Zhang, and R. Casellas,
              "Generalized Labels for the Flexi-Grid in Lambda-Switch-
              Capable (LSC) Label Switching Routers",
              draft-farrkingel-ccamp-flexigrid-lambda-label-01.txt .

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 8]
Internet-Draft         wavelength range allocation              Feb 2012

   [super-channel-label]
              Iftekhar Hussain, Abinder Dhillon, Zhong Pan, Marco Sosa
              and Bert Basch, Steve Liu, Andrew G. Malis, "Generalized
              Label for Super-Channel Assignment on Flexible Grid",
              draft-hussain-ccamp-super-channel-label-02.txt .

Authors' Addresses

   Qilei Wang
   ZTE Corporation

   Email: wang.qilei@zte.com.cn

   Xihua Fu
   ZTE Corporation
   ZTE Plaza, No.10, Tangyan South Road, Gaoxin District
   Xi'an  210012
   P.R.China

   Email: fu.xihua@zte.com.cn

Qilei Wang & Xihua Fu   Expires September 1, 2012               [Page 9]