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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: June 2011                                   December 13, 2010

      Generalized Labels for Lambda-Switching Capable Label Switching
                                 Routers



             draft-ietf-ccamp-gmpls-g-694-lambda-labels-10.txt


Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
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   This Internet-Draft will expire on June 13, 2011.

Copyright Notice

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   document authors.  All rights reserved.

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   include Simplified BSD License text as described in Section 4.e of



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   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 some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
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   it for publication as an RFC 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].

1. Introduction

   As described in [RFC3945], Generalized MPLS (GMPLS) extends MPLS
   from supporting only packet (Packet Switching Capable - PSC)



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   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 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.


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   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 is made by only one
   sub channel that must be 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.

   Therefore, a wavelength label should be standardized in order to
   allow interoperability between multiple domains; otherwise


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   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 standardize 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 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.


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   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].


   +----------+---------+
   |   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.


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   +----------+---------+
   | 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 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.

   (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:








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    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].


   +----------+---------+
   |   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 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


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   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.

   (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.

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



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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 4.2:


    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.

   Node 4 signals the LSP via a Path message including a Wavelength
   Label structured as defined in section 4.3:




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    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




























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