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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 RFC 6205

Network Working Group                                Tomohiro Otani(Ed.)
Internet Draft                                                     KDDI
Updates: 3471(if approved)                                   Dan Li(Ed.)
Category: Standards Track                                        Huawei

Expires: July 2011                                    January 11, 2011

     Generalized Labels for Lambda-Switching Capable Label Switching
                                 Routers



            draft-ietf-ccamp-gmpls-g-694-lambda-labels-11.txt


Status of this Memo

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

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   This Internet-Draft will expire on July 11, 2011.

Copyright Notice

   Copyright (c) 2010 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
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents




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   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before
   November 10, 2008. The person(s) controlling the copyright in
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   or to translate it into languages other than English.

Abstract

   Technology in the optical domain is constantly evolving and as a
   consequence new equipment providing lambda switching capability
   has been developed and is currently being deployed.

   Generalized MPLS (GMPLS) is a family of protocols that can be
   used   to operate networks built from a range of technologies
   including   wavelength (or lambda) switching. For this purpose,
   GMPLS defined   that a wavelength label only has significance
   between two neighbors   and global wavelength semantics are not
   considered.

   In order to facilitate interoperability in a network composed of
   next generation lambda switch-capable equipment, this document
   defines a standard lambda label format that is compliant with
   Dense Wavelength Division Multiplexing and Coarse Wavelength
   Division Multiplexing grids defined by the International
   Telecommunication Union Telecommunication Standardization Sector.
   The label format defined in this document can be used in GMPLS
   signaling and routing protocols.

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].



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1. Introduction

   As described in [RFC3945], Generalized MPLS (GMPLS) extends MPLS
   from supporting only packet (Packet Switching Capable - PSC)
   interfaces and switching to also include support for four new
   classes of interfaces and switching:

      o Layer-2 Switch Capable (L2SC)

      o Time-Division Multiplex (TDM)

      o Lambda Switch Capable (LSC)

      o Fiber-Switch Capable (FSC).

   A functional description of the extensions to MPLS signaling
   needed to support new classes of interfaces and switching is
   provided in [RFC3471].

   This document presents details that are specific to the use of
   GMPLS with Lambda Switch Capable (LSC) equipment. Technologies
   such as Reconfigurable Optical Add/Drop Multiplex (ROADM) and
   Wavelength Cross-Connect (WXC) operate at the wavelength
   switching level. [RFC3471] has defined that a wavelength label
   (section 3.2.1.1) "only has significance between two neighbors"
   and global wavelength semantics is not considered. In order to
   facilitate interoperability in a network composed of lambda
   switch-capable equipment, this document defines a standard lambda
   label format, which is compliant with both [G.694.1](Dense
   Wavelength Division Multiplexing (DWDM)-grid) or [G.694.2](Coarse
   Wavelength Division Multiplexing (CWDM)-grid).

2. Assumed Network Model and Related Problem Statement

   Figure 1 depicts an all-optically switched network consisting of
   different vendors' optical network domains. Vendor A's network
   consists of ROADM or WXC, and vendor B's network consists of a
   number of photonic cross-connect (PXC) and DWDM multiplexer &
   demultiplexer, otherwise both vendors' networks might be based on
   the same technology.

   In this case, the use of standardized wavelength label
   information is quite significant to establish a wavelength-based
   LSP. It is also an important constraint when conducting CSPF
   calculation for use by Generalized Multi-Protocol Label Switching
   (GMPLS) RSVP-TE signaling, [RFC3473]. The way the Constrained



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   Shortest Path First (CSPF) is performed is outside the scope of
   this document.

   It is needless to say, an LSP must be appropriately provisioned
   between a selected pair of ports not only within Domain A but
   also over multiple domains satisfying wavelength constraints.

   Figure 2 illustrates in detail the interconnection between Domain
   A and Domain B.

                                  |
      Domain A (or Vendor A)      |      Domain B (or Vendor B)
                                  |
     Node-1            Node-2     |         Node-6            Node-7
   +--------+        +--------+   |      +-------+ +-+     +-+ +-------+
   | ROADM  |        | ROADM  +---|------+  PXC  +-+D|     |D+-+  PXC  |
   | or WXC +========+ or WXC +---|------+       +-+W+=====+W+-+       |
   | (LSC)  |        | (LSC)  +---|------+ (LSC) +-+D|     |D+-+ (LSC) |
   +--------+        +--------+   |      |       +-|M|     |M+-+       |
       ||                ||       |      +++++++++ +-+     +-+ +++++++++
       ||     Node-3     ||       |       |||||||               |||||||
       ||   +--------+   ||       |      +++++++++             +++++++++
       ||===|  WXC   +===||       |      | DWDM  |             | DWDM  |
            | (LSC)  |            |      +--++---+             +--++---+
       ||===+        +===||       |         ||                    ||
       ||   +--------+   ||       |      +--++---+             +--++---+
       ||                ||       |      | DWDM  |             | DWDM  |
   +--------+        +--------+   |      +++++++++             +++++++++
   | ROADM  |        | ROADM  |   |       |||||||               |||||||
   | or WXC +========+ or WXC +=+ |  +-+ +++++++++ +-+     +-+ +++++++++
   | (LSC)  |        | (LSC)  | | |  |D|-|  PXC  +-+D|     |D+-+  PXC  |
   +--------+        +--------+ +=|==+W|-|       +-+W+=====+W+-+       |
     Node-4            Node-5     |  |D|-| (LSC) +-+D|     |D+-+ (LSC) |
                                  |  |M|-|       +-+M|     |M+-+       |
                                  |  +-+ +-------+ +-+     +-+ +-------+
                                  |        Node-8             Node-9

           Figure 1 Wavelength-based network model










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   +-------------------------------------------------------------+
   |          Domain A             |        Domain B             |
   |                               |                             |
   |           +---+     lambda 1  |         +---+               |
   |           |   |---------------|---------|   |               |
   |       WDM | N |     lambda 2  |         | N | WDM           |
   |      =====| O |---------------|---------| O |=====          |
   |  O        | D |        .      |         | D |        O      |
   |  T    WDM | E |        .      |         | E | WDM    T      |
   |  H   =====| 2 |     lambda n  |         | 6 |=====   H      |
   |  E        |   |---------------|---------|   |        E      |
   |  R        +---+               |         +---+        R      |
   |                               |                             |
   |  N        +---+               |         +---+        N      |
   |  O        |   |               |         |   |        O      |
   |  D    WDM | N |               |         | N | WDM    D      |
   |  E   =====| O |      WDM      |         | O |=====   E      |
   |  S        | D |=========================| D |        S      |
   |       WDM | E |               |         | E | WDM           |
   |      =====| 5 |               |         | 8 |=====          |
   |           |   |               |         |   |               |
   |           +---+               |         +---+               |
   +-------------------------------------------------------------+

     Figure 2 Interconnecting details between two domains

   In the scenario of Figure 1, consider the setting up of a
   bidirectional LSP from ingress switch 1 to egress switch 9 using
   GMPLS RSVP-TE. In order to satisfy wavelength continuity
   constraint, a fixed wavelength (lambda 1) needs to be used in
   domain A and domain B. A Path message will be used for signaling.
   The Path message will contain the Upstream_Label object and a
   Label_Set object; both containing the same value. The Label_set
   object shall contain a single sub-channel that must be the same
   as the Upstream_Label object. The Path setup will continue
   downstream to switch 9 by configuring each lambda switch based on
   the wavelength label. If a node has a tunable wavelength
   transponder, the tuning wavelength is considered as a part of
   wavelength switching operation.

   Not using a standardized label would add undue burden on the
   operator to enforce policy as each manufacturer may decide on a
   different representation and therefore each domain may have its
   own label formats. Moreover, manual provisioning may lead to
   misconfiguration if domain-specific labels are used.




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   Therefore, a wavelength label should be standardized in order to
   allow interoperability between multiple domains; otherwise
   appropriate existing labels are identified in support of
   wavelength availability. As identical wavelength information, the
   ITU-T frequency grid specified in [G.694.1] for DWDM and
   wavelength information in [G.694.2] for CWDM are used by Label
   Switching Routers (LSRs) and should be followed as a wavelength
   label.

3. Label Related Formats

   To deal with the widening scope of MPLS into the optical and time
   domains, several new forms of "label" have been defined in
   [RFC3471]. This section contains a definition of a Wavelength
   label based on [G.694.1] or [G.694.2] for use by LSC LSRs.

3.1. Wavelength Labels

   In section 3.2.1.1 of [RFC3471], a Wavelength label is defined to
   have significance between two neighbors, and the receiver may
   need to convert the received value into a value that has local
   significance.

   We do not need to define a new type as the information stored is
   either a port label or a wavelength label. Only the wavelength
   label as below needs to be defined.

   LSC equipment uses multiple wavelengths controlled by a single
   control channel. In a case, the label indicates the wavelength to
   be used for the LSP. This document defines a standardized
   wavelength label format.  As an example of wavelength values, the
   reader is referred to [G.694.1] which lists the frequencies from
   the ITU-T DWDM frequency grid.  The same can be done for CWDM
   technology by using the wavelength defined in [G.694.2].

   Since the ITU-T DWDM grid is based on nominal central frequencies,
   we need to indicate the appropriate table, the channel spacing in
   the grid and a value n that allows the calculation of the
   frequency. That value can be positive or negative.

   The frequency is calculated as such in [G.694.1]:

        Frequency (THz) = 193.1 THz + n * channel spacing (THz)

   Where "n" is a two's-complement integer (positive, negative or 0)
   and "channel spacing" is defined to be 0.0125, 0.025, 0.05 or 0.1



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   THz. When wider channel spacing such as 0.2 THz is utilized, the
   combination of narrower channel spacing and the value "n" can
   provide proper frequency with that channel spacing. Channel
   spacing is not utilized to indicate the LSR capability but only
   to specify a frequency in signaling.

   For the other example of the case of the ITU-T CWDM grid, the
   spacing between different channels was defined to be 20nm, so we
   need to pass the wavelength value in nanometers(nm) in this case.
   Examples of CWDM wavelengths are 1471, 1491, etc. nm.

   The wavelength is calculated as follows

        Wavelength (nm) = 1471 nm + n * 20 nm

   Where "n" is a two's-complement integer (positive, negative or 0).
   The grids listed in [G.694.1] and [G.694.2] are not numbered and
   change with the changing frequency spacing as technology advances,
   so an index is not appropriate in this case.

3.2. DWDM Wavelength Label

   For the case of lambda switching (LSC) of DWDM, the information
   carried in a Wavelength label is:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid | C.S   |    Identifier   |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   (1) Grid: 3 bits

   The value for grid is set to 1 for ITU-T DWDM Grid as defined in
   [G.694.1].












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   +----------+---------+
   |   Grid   |  Value  |
   +----------+---------+
   | Reserved |    0    |
   +----------+---------+
   |ITU-T DWDM|    1    |
   +----------+---------+
   |ITU-T CWDM|    2    |
   +----------+---------+
   |Future use|  3 - 7  |
   +----------+---------+

   (2) C.S.(channel spacing): 4 bits

   DWDM channel spacing is defined as follows.


   +----------+---------+
   | C.S(GHz) |  Value  |
   +----------+---------+
   | Reserved |    0    |
   +----------+---------+
   |    100   |    1    |
   +----------+---------+
   |    50    |    2    |
   +----------+---------+
   |    25    |    3    |
   +----------+---------+
   |    12.5  |    4    |
   +----------+---------+
   |Future use|  5 - 15 |
   +----------+---------+

   (3) Identifier: 9 bits

   The identifier field in lambda label format is used to
   distinguish different lasers (in one node) when they can transmit
   the same frequency lambda. The identifier field is a per-node
   assigned and scoped value. This field MAY change on a per-hop
   basis. In all cases but one, a node MAY select any value,
   including zero (0), for this field. Once selected, the value MUST
   NOT change until the LSP is torn down and the value MUST be used
   in all LSP related messages, e.g., in Resv messages and label RRO
   subobjects. The sole special case occurs when this label format
   is used in a label ERO subobject. In this case, the special value



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   of zero (0) means that the referenced node MAY assign any
   Identifier field value, including zero (0), when establishing the
   corresponding LSP. When non-zero value is assigned to the
   identifier field in a label ERO subobject, the referenced node
   MUST use the assigned value for the identifier field in the
   corresponding LSP related messages.

   (4) n: 16 bits

   n is a two's-complement integer to take either a negative, zero
   or a positive value. The value used to compute the frequency as
   shown above.

3.3. CWDM Wavelength Label

   For the case of lambda switching (LSC) of CWDM, the information
   carried in a Wavelength label is:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid | C.S   |    Identifier   |                n              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The structure of the label in the case of CWDM is the same as
   that of DWDM case.

   (1) Grid: 3 bits

   The value for grid is set to 2 for ITU-T CWDM Grid as defined in
   [G.694.2].
















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   +----------+---------+
   |   Grid   |  Value  |
   +----------+---------+
   | Reserved |    0    |
   +----------+---------+
   |ITU-T DWDM|    1    |
   +----------+---------+
   |ITU-T CWDM|    2    |
   +----------+---------+
   |Future use|  3 - 7  |
   +----------+---------+

   (2) C.S.(channel spacing): 4 bits

   CWDM channel spacing is defined as follows.


   +----------+---------+
   | C.S(nm)  |  Value  |
   +----------+---------+
   | Reserved |    0    |
   +----------+---------+
   |    20    |    1    |
   +----------+---------+
   |Future use|  2 - 15 |
   +----------+---------+

   (3) Identifier: 9 bits

   The identifier field in lambda label format is used to
   distinguish different lasers (in one node) when they can transmit
   the same frequency lambda. The identifier field is a per-node
   assigned and scoped value. This field MAY change on a per-hop
   basis. In all cases but one, a node MAY select any value,
   including zero (0), for this field. Once selected, the value MUST
   NOT change until the LSP is torn down and the value MUST be used
   in all LSP related messages, e.g., in Resv messages and label RRO
   subobjects. The sole special case occurs when this label format
   is used in a label ERO subobject. In this case, the special value
   of zero (0) means that the referenced node MAY assign any
   Identifier field value, including zero (0), when establishing the
   corresponding LSP. When non-zero value is assigned to the
   identifier field in a label ERO subobject, the referenced node
   MUST use the assigned value for the identifier field in the
   corresponding LSP related messages.



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   (4) n: 16 bits

   n is a two's-complement integer. The value used to compute the
   wavelength as shown above.

4. Security Considerations

   This document introduces no new security considerations to
   [RFC3471] and [RFC3473]. For a general discussion on MPLS and
   GMPLS related security issues, see the MPLS/GMPLS security
   framework [RFC5920].

5. IANA Considerations

   IANA maintains the "Generalized Multi-Protocol Label Switching
   (GMPLS) Signaling Parameters" registry. IANA is requested to add
   three new subregistries to track the codepoints (Grid and C.S.)
   used in the DWDM and CWDM Wavelength Labels, which are described
   in the following sections.

5.1. Grid Subregistry

   Initial entries in this subregistry are as follows:

   Value   Grid                         Reference
   -----   -------------------------    ----------
     0     Reserved                     [This.I-D]
     1     ITU-T DWDM                   [This.I-D]
     2     ITU-T CWDM                   [This.I-D]
    3-7    Not assigned at this time    [This.I-D]

   New values are assigned according to Standards Action.

5.2. DWDM Channel Spacing Subregistry

   Initial entries in this subregistry are as follows:












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   Value   Channel Spacing (GHz)        Reference
   -----   -------------------------    ----------
     0     Reserved                     [This.I-D]
     1     100                          [This.I-D]
     2     50                           [This.I-D]
     3     25                           [This.I-D]
     4     12.5                         [This.I-D]
    5-15   Not assigned at this time    [This.I-D]

   New values are assigned according to Standards Action.

5.3. CWDM Channel Spacing Subregistry

   Initial entries in this subregistry are as follows:

   Value   Channel Spacing (nm)         Reference
   -----   -------------------------    ----------
   0       Reserved                     [This.I-D]
   1       20                           [This.I-D]
   2-15    Not assigned at this time    [This.I-D]

   New values are assigned according to Standards Action.

6. Acknowledgments

   The authors would like to thank Adrian Farrel, Lou Berger,
   Lawrence Mao, Zafar Ali and Daniele Ceccarelli for the discussion
   and their comments.

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.

   [RFC3471] Berger, L., "Generalized Multi-Protocol Label Switching
             (MPLS) Signaling Functional Description", RFC 3471,
             January 2003.

   [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
             (MPLS) Signaling - Resource ReserVation Protocol Traffic
             Engineering (RSVP-TE) Extensions", RFC 3473, January
             2003.





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   [RFC3945] Mannie, E., Ed., "Generalized Multiprotocol Label
             Switching (GMPLS) Architecture", RFC 3945, October 2004.

7.2. Informative References

   [G.694.1] ITU-T Recommendation G.694.1, "Spectral grids for WDM
             applications: DWDM frequency grid", June 2002.

   [G.694.2] ITU-T Recommendation G.694.2, "Spectral grids for WDM
             applications: CWDM wavelength grid", December 2003.

   [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
             Networks", RFC 5920, July 2010.



































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8. Authors' Address

   Tomohiro Otani
   KDDI Corporation
   2-3-2 Nishishinjuku Shinjuku-ku
   Tokyo, 163-8003, Japan
   Phone:  +81-3-3347-6006
   Email:  tm-otani@kddi.com

   Richard Rabbat
   Google, Inc.
   1600 Amphitheatre Pkwy
   Mountain View, CA 94043
   Email: rabbat@alum.mit.edu

   Sidney Shiba
   Email: sidney.shiba@att.net

   Hongxiang Guo
   Email: hongxiang.guo@gmail.com

   Keiji Miyazaki
   Fujitsu Laboratories Ltd
   4-1-1 Kotanaka Nakahara-ku,
   Kawasaki Kanagawa, 211-8588, Japan
   Phone: +81-44-754-2765
   Email: miyazaki.keiji@jp.fujitsu.com

   Diego Caviglia
   Ericsson
   16153 Genova Cornigliano, ITALY
   Phone: +390106003736
   Email: diego.caviglia@ericsson.com

   Dan Li
   Huawei Technologies
   F3-5-B R&D Center, Huawei Base,
   Shenzhen 518129 China
   Phone: +86 755-289-70230
   Email: danli@huawei.com

   Takehiro Tsuritani
   KDDI R&D Laboratories Inc.
   2-1-15 Ohara Fujimino-shi
   Saitama, 356-8502, Japan
   Phone:  +81-49-278-7806
   Email:  tsuri@kddilabs.jp


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9. Appendix A. DWDM Example

   Considering the network displayed in figure 1 it is possible to
   show an example of LSP set up using the lambda labels.

   Node 1 receives the request for establishing an LSP from itself
   to Node 9. The ITU-T grid to be used is the DWDM one, the channel
   spacing is 50Ghz and the wavelength to be used is 193,35 THz.

   Node 1 signals the LSP via a Path message including a Wavelength
   Label structured as defined in section 3.2:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid |  C.S  |   Identifier    |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   Grid = 1 : ITU-T DWDM grid

   C.S. = 2 : 50 GHz channel spacing

   n    = 5 :

        Frequency (THz) = 193.1 THz + n * channel spacing (THz)

        193.35 (THz) = 193.1 (THz) + n* 0.05 (THz)

        n = (193.35-193.1)/0.05 = 5

10. Appendix B. CWDM Example

   The network displayed in figure 1 can be used also to display an
   example of signaling using the Wavelength Label in a CWDM
   environment.

   This time the signaling of an LSP from Node 4 to Node 7 is
   considered. Such LSP exploits the CWDM ITU-T grid with a 20nm
   channel spacing and is to established using wavelength equal to
   1331 nm.





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   Node 4 signals the LSP via a Path message including a Wavelength
   Label structured as defined in section 3.3:


    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |Grid |  C.S  |   Identifier    |              n                |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Where:

   Grid = 2 : ITU-T CWDM grid

   C.S. = 1 : 20 nm channel spacing

   n    = -7 :

        Wavelength (nm) = 1471 nm + n * 20 nm

        1331 (nm) = 1471 (nm) + n * 20 nm

        n = (1331-1471)/20 = -7

























T. Otani et al.           Expires July 2011                  [Page 16]


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