INTERNET DRAFT                                           Tomohiro Otani
Updates: RFC 3471                                         Hongxiang Guo
Intended status: standard track                           KDDI R&D Labs
Expires: Nov. 27, 2008                                   Keiji Miyazaki
                                                           Fujitsu Lab.
                                                         Diego Caviglia
                                                           May 27, 2008

 Generalized Labels for G.694 Lambda-Switching Capable Label Switching

      Document: draft-ietf-ccamp-gmpls-g-694-lambda-labels-00.txt

Status of this Memo

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   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. However, RFC 3471 has
   defined that a wavelength label (section "only has
   significance between two neighbors" and global wavelength continuity
   is not considered. In order to achieve interoperability in a network
   composed of next generation lambda switch-capable equipment, this
   document defines a standard lambda label format, being compliant with
   ITU-T G.694. Moreover some consideration on how to ensure lambda
   continuity with RSVP-TE is provided. This document is a companion to
   the Generalized Multi-Protocol Label Switching (GMPLS) signaling. It
   defines the label format when Lambda Switching is requested in an all
   optical network.

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Table of Contents

   Status of this Memo................................................ 1
   Abstract........................................................... 1
   1. Introduction.................................................... 3
   2. Conventions used in this document............................... 3
   3. Assumed network model and related problem statement............. 3
   4. Label Related Formats........................................... 5
   5. Security consideration.......................................... 8
   6. Acknowledgement................................................. 8
   7. References...................................................... 8
   7.1. Normative References.......................................... 8
   7.2. Informative References........................................ 8
   Author's Address................................................... 9
   Intellectual property considerations............................... 9
   Copyright statement............................................... 10

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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

   This document presents details that are specific to the use of GMPLS
   with a new generation of 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. As such, the wavelength is important information
   that is necessary to set up a wavelength-based LSP appropriately and
   the wavelength defined in [G.694] is widely utilized.

2. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC-2119 [RFC2119].

3. Assumed network model and related problem statement

   Figure 1 depicts an all-optically switched network consisting of
   different vendor's optical network domains. Vendor A's network is a
   ring topology that consists of ROADM or WXC, and vendor B's network
   is a mesh topology consisting of PXCs and DWDMs, otherwise both
   vendors' networks are 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 RSVP-TE
   signaling. The way the CSPF is performed is outside the scope of this
   document, but defined in [GMPLS-CSPF].

   It is needless to say, a 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.

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      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.

      |          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  |         | 7 |=====   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 |=====          |
      |           |   |               |         |   |               |
      |           +---+               |         +---+               |

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           Figure 2 Interconnecting details between two domains.

   In the scenario of Figure 2, consider the setting up of a
   bidirectional LSP from ingress switch 1 to egress switch 4. 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 the signaling, the PATH message must contain the
   upstream label and a label set object; both containing the same
   lambda. The label set object is made by only one sub channel that
   must be same as the upstream label. The path setup will continue
   downstream to switch 4 by configuring each lambda switch based on the
   wavelength label. This label allows the correct switching of lambda
   switches and the label contents needs to be used over the inter-
   domain. As same above, the path setup will continue downstream to
   switch 7 by configuring lambda switch based on multiple wavelength
   labels. If the 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
   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 Dense WDM (DWDM) and
   wavelength information in [G.694.2] for Coarse WDM (CWDM) are used by
   LSRs and should be followed as a wavelength label.

4. 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 clarifications for the Wavelength label based
   on [G.694] and Label Set definition specific for LSC LSRs.

   4.1 Wavelength Labels

   In section 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.

   LSC equipment uses multiple wavelengths controlled by a single
   control channel. In such case, the label indicates the wavelength to
   be used for the LSP. This document proposes to standardize the
   wavelength label.  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]. In that sense, we can call G.694
   wavelength labels.

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   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 an 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.

   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 nm in this case.  Examples of CWDM
   wavelengths are 1470, 1490, etc. nm.

   The wavelength is calculated as follows

      Wavelength (nm) = 1470 nm + n * 20 nm

   The tables 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.

   4.2 DWDM Wavelength Label

   For the case of DWDM, the information carried in a Wavelength label

       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   |S|    Reserved   |              n                |

   (1) Grid: 3 bits

   The value for grid is set to 1 for ITU-T DWDM Grid as defined in

      |   Grid   |  Value  |
      |ITU-T DWDM|    1    |
      |ITU-T CWDM|    2    |

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      |Future use|  3 - 7  |

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

   DWDM channel spacing is defined as follows.

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

   (3) S: 1 bit

   Sign for the value of n, set to 1 for (-) and 0 for (+)

   (4) n: 16 bits

   The value used to compute the frequency as shown above.

   4.3 CWDM Wavelength Label

   For the case of CWDM, the information carried in a Wavelength label

       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 |     Reserved                            |       n       |

   (1) Grid: 3 bits

   The value for grid is set to 2 for ITU-T CWDM Grid as defined in

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

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   (2) Lambda: 8 bits

   The value used to compute the wavelength as shown above.

   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 above needs to be defined.

5. Security consideration

   This document introduces no new security considerations to [RFC3473].
   GMPLS security is described in section 11 of [RFC3471] and refers to
   [RFC3209] for RSVP-TE.

6. Acknowledgement

   The authors would like to express their thanks to Sidney Shiba,
   Richard Rabbat for originally initiating this work. They also thank
   Adrian Farrel, Lawrence Mao and Zafar Ali for the discussion.

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.

   [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
   and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC
   3209, December 2001.

   [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.

7.2. Informative References

   [GMPLS-CSPF] Otani, T., et al, "Considering Generalized Multiprotocol
   Label Switching Traffic Engineering Attributes During Path
   Computation", draft-otani-ccamp-gmpls-cspf-constraints-07.txt, Nov.

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

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

Author's Address

   Tomohiro Otani
   KDDI R&D Laboratories, Inc.
   2-1-15 Ohara Kamifukuoka Saitama, 356-8502, Japan
   Phone:  +81-49-278-7357

   Hongxiang Guo
   KDDI R&D Laboratories, Inc.
   2-1-15 Ohara Fujimino Saitama, 356-8502, Japan.
   Phone: +81-49-278-7864.

   Keiji Miyazaki
   Fujitsu Laboratories Ltd
   4-1-1 Kotanaka Nakahara-ku, Kawasaki Kanagawa, 211-8588, Japan
   Phone: +81-44-754-2765

   Diego Caviglia
   16153 Genova Cornigliano, ITALY
   Phone: +390106003736

Intellectual property considerations

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   The IETF invites any interested party to bring to its attention any
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   rights that may cover technology that may be required to implement

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   this standard. Please address the information to the IETF at ietf-

Copyright statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an

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