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Network Working Group                                      G. Bernstein
Internet Draft                                        Grotto Networking
Intended status: Informational                                   Y. Lee
Expires: April 2010                                              Huawei
                                                         Ben Mack-Crane
                                                                 Huawei



                                                        October 7, 2009

       WSON Signal Characteristics and Network Element Compatibility
                           Constraints for GMPLS
              draft-bernstein-ccamp-wson-compatibility-01.txt


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   carefully, as they describe your rights and restrictions with respect
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Abstract

   While the current GMPLS WSON framework can deal with many types of
   wavelength switching systems there is a desire to extend the control
   plane to networks that include a combination of transparent optical
   and hybrid electro optical systems such as OEO switches,
   regenerators, and wavelength converters. Such networks are frequently
   referred to as translucent optical networks in the literature. Some
   of the systems use in such networks can be limited to processing WSON
   signals with specific characteristics or attributes. In addition,
   some of the network elements may be able to perform important
   optional processing functions such as regeneration on a signal and
   would need to be provisioned as part of optical path establishment.

   This document provides a WSON signal definition and attributes
   characterization based on ITU-T interface and signal class standards
   and describes the signal compatibility constraints of this extended
   set of network elements. The signal characterization, network element
   compatibility constraints and enhanced provisioning support enable
   GMPLS routing and signaling to control these devices and PCE to
   compute optical light-paths subject to signal compatibility
   attributes.



Table of Contents


   1. Introduction...................................................3
   2. Describing Optical Signals in WSONs............................3
      2.1. Optical Interfaces........................................4
      2.2. Optical Tributary Signals.................................4
      2.3. WSON Signal Characteristics...............................5
   3. Electro-Optical Systems........................................6
      3.1. Regenerators..............................................6
      3.2. OEO Switches..............................................9
      3.3. Wavelength Converters.....................................9
   4. Characterizing WSON Network Elements..........................10
      4.1. Input Constraints........................................10
      4.2. Output Constraints.......................................11
      4.3. Processing Capabilities..................................11
   5. Networking Scenarios and the Control Plane....................12


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      5.1. Fixed Regeneration Points................................12
      5.2. Shared Regeneration Pools................................13
      5.3. Reconfigurable Regenerators..............................13
      5.4. Relation to Translucent Networks.........................13
   6. Implications for GMPLS and PCE................................14
      6.1. Link and Network Element Extensions for GMPLS Routing....14
      6.2. Implications for GMPLS Signaling.........................15
      6.3. PCEP Extensions..........................................16
   7. Security Considerations.......................................17
   8. IANA Considerations...........................................17
   9. Acknowledgments...............................................17
   10. References...................................................18
      10.1. Normative References....................................18
      10.2. Informative References..................................19
   Author's Addresses...............................................19
   Intellectual Property Statement..................................20
   Disclaimer of Validity...........................................20

   1. Introduction

   The current GMPLS WSON formalism can deal with many types of
   wavelength switching systems. However, there is an implicit
   assumption that all signals used in a WSON are compatible with all
   network elements. This arises in practice for a number of reasons (a)
   in some WSONs only one class of signal is used throughout the
   network, or (b) only "relatively" transparent network elements are
   utilized in the WSON. Assumption (a) limits the inherent flexibility
   that carriers seek from a WSON and assumption (b) leaves out very
   common optical network elements including regenerators, OEO switches,
   and wavelength converters.

   Therefore there is a requirement to extend the GMPLS control plane to
   allow both multiple WSON signal types and common hybrid electro
   optical systems. In the following we characterize WSON signals in
   line with ITU-T standards, and add attributes describing signal
   compatibility constraints to WSON network elements. This way the
   control plane signaling and path computation functions can ensure
   "signal" compatibility between source, sink and any links or network
   elements as part of the path selection process, and configure devices
   appropriately via signaling as part of the connection provisioning
   process.

   2. Describing Optical Signals in WSONs

   As we will later see the new network elements that we wish to
   incorporate within the GMPLS control plane(OEO switches,
   regenerators, and wavelength converters) can impose constraints on
   the types of signals they can "process". Hence to enable the use of a


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   larger set of network elements the first step is to more precisely
   define and characterize our "optical signal".


   2.1. Optical Interfaces

   In wavelength switched optical networks (WSONs) our fundamental unit
   of switching is intuitively that of a "wavelength". The transmitters
   and receivers in these networks will deal with one wavelength at a
   time, while the switching systems themselves can deal with multiple
   wavelengths at a time. Hence we are generally concerned with
   multichannel dense wavelength division multiplexing (DWDM) networks
   with single channel interfaces. Interfaces of this type are defined
   in ITU-T recommendations [G.698.1] and [G.698.1]. Key non-impairment
   related parameters defined in [G.698.1] and [G.698.2] are:

   (a)   Minimum Channel Spacing (GHz)

   (b)   Bit-rate/Line coding (modulation) of optical tributary signals

   (c)   Minimum and Maximum central frequency

   We see that (a) and (c) above are related to properties of the link
   and have been modeled in [Otani], [WSON-FRAME], [WSON-Info] and (b)
   is related to the "signal".

   2.2. Optical Tributary Signals

   The optical interface specifications [G.698.1], [G.698.2], and
   [G.959.1] all use the concept of an Optical Tributary Signal which is
   defined as "a single channel signal that is placed within an optical
   channel for transport across the optical network". Note the use of
   the qualifier "tributary" to indicate that this is a single channel
   entity and not a multichannel optical signal. This is our candidate
   terminology for the entity that we will be controlling in our GMPLS
   extensions for WSONs.

   There are a currently a number of different "flavors" of optical
   tributary signals, known as "optical tributary signal classes". These
   are currently characterized by a modulation format and bit rate range
   [G.959.1]:

   (a)   optical tributary signal class NRZ 1.25G

   (b)   optical tributary signal class NRZ 2.5G

   (c)   optical tributary signal class NRZ 10G



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   (d)   optical tributary signal class NRZ 40G

   (e)   optical tributary signal class RZ 40G

   Note that with advances in technology more optical tributary signal
   classes may be added and that this is currently an active area for
   deployment and standardization. In particular at the 40G rate there
   are a number of non-standardized advanced modulation formats that
   have seen significant deployment including Differential Phase Shift
   Keying (DPSK) and Phase Shaped Binary Transmission (PSBT)[Winzer06].

   Note that according to [G.698.2] it is important to fully specify the
   bit rate of the optical tributary signal:

   "When an optical system uses one of these codes, therefore, it is
   necessary to specify both the application code and also the exact bit
   rate of the system. In other words, there is no requirement for
   equipment compliant with one of these codes to operate over the
   complete range of bit rates specified for its optical tributary
   signal class."

   Hence we see that modulation format (optical tributary signal class)
   and bit rate are key in characterizing the optical tributary signal.


2.3. WSON Signal Characteristics
   We refer an optical tributary signal defined in ITU-T G.698.1 and .2
   to as the signal in this document. This is an "entity" that can be
   put on an optical communications channel formed from links and
   network elements in a WSON. This corresponds to the "lambda" LSP in
   GMPLS. For signal compatibility purposes we will be interested in the
   following signal characteristics:

                    List 1. WSON Signal Characteristics

  1. Optical tributary signal class (modulation format).
  2. FEC: whether forward error correction is used in the digital stream
     and what type of error correcting code is used
  3. Center frequency (wavelength)
  4. Bit rate
  5. G-PID: General Protocol Identifier for the information format

   The first three items on this list can change as a WSON signal
   traverses a network with regenerators, OEO switches, or wavelength
   converters. An ability to control wavelength conversion already
   exists in GMPLS.


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   Bit rate and GPID would not change since they describe the encoded
   bit stream. A set of G-PID values are already defined for lambda
   switching in [RFC3471] and [RFC4328].

   Note that a number of "pre-standard" or proprietary modulation
   formats and FEC codes are commonly used in WSONs. For some digital
   bit streams the presence  of FEC can be detected, e.g., in [G.707]
   this is indicated in the signal itself via the FEC status indication
   (FSI) byte, while in [G.709] this can be inferred from whether the
   FEC field of the OTUk is all zeros or not.


   3. Electro-Optical Systems

   This section describes how Electro-Optical Systems (e.g., OEO
   switches, wavelength converters, and regenerators) interact with the
   WSON signal characteristics defined in List 1 in Section 2.3. OEO
   switches, wavelength converters and regenerators all share a similar
   property: they can be more or less "transparent" to an "optical
   signal" depending on their functionality and/or implementation.
   Regenerators have been fairly well characterized in this regard so we
   start by describing their properties.


3.1. Regenerators
   The various approaches to regeneration are discussed in ITU-T G.872
   Annex A [G.872]. They map a number of functions into the so-called
   1R, 2R and 3R categories of regenerators as summarized in Table 1
   below:


















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   Table 1 Regenerator functionality mapped to general regenerator
   classes from [G.872].

   ---------------------------------------------------------------------
   1R | Equal amplification of all frequencies within the amplification
      | bandwidth. There is no restriction upon information formats.
      +-----------------------------------------------------------------
      | Amplification with different gain for frequencies within the
      | amplification bandwidth. This could be applied to both single-
      | channel and multi-channel systems.
      +-----------------------------------------------------------------
      | Dispersion compensation (phase distortion). This analogue
      | process can be applied in either single-channel or multi-
      | channel systems.
   ---------------------------------------------------------------------
   2R | Any or all 1R functions. Noise suppression.
      +-----------------------------------------------------------------
      | Digital reshaping (Schmitt Trigger function) with no clock
      | recovery. This is applicable to individual channels and can be
      | used for different bit rates but is not transparent to line
      | coding (modulation).
   --------------------------------------------------------------------
   3R | Any or all 1R and 2R functions. Complete regeneration of the
      | pulse shape including clock recovery and retiming within
      | required jitter limits.
   --------------------------------------------------------------------

   From the previous table we can see that 1R regenerators are generally
   independent of signal modulation format (also known as line coding),
   but may work over a limited range of wavelength/frequencies.  We see
   that 2R regenerators are generally applicable to a single digital
   stream and are dependent upon modulation format (line coding) and to
   a lesser extent are limited to a range of bit rates (but not a
   specific bit rate). Finally, 3R regenerators apply to a single
   channel, are dependent upon the modulation format and generally
   sensitive to the bit rate of digital signal, i.e., either are
   designed to only handle a specific bit rate or need to be programmed
   to accept and regenerate a specific bit rate.  In all these types of
   regenerators the digital bit stream contained within the optical or
   electrical signal is not modified.

   However, in the most common usage of regenerators the digital bit
   stream may be slightly modified for performance monitoring and fault
   management purposes. SONET, SDH and G.709 all have a digital signal
   "envelope" designed to be used between "regenerators" (in this case
   3R regenerators). In SONET this is known as the "section" signal, in
   SDH this is known as the "regenerator section" signal, in G.709 this
   is known as an OTUk (Optical Channel Transport Unit-k).  These


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   signals reserve a portion of their frame structure (known as
   overhead) for use by regenerators. The nature of this overhead is
   summarized in Table 2.

       Table 2. SONET, SDH, and G.709 regenerator related overhead.


    +-----------------------------------------------------------------+
    |Function          |       SONET/SDH      |     G.709 OTUk        |
    |                  |       Regenerator    |                       |
    |                  |       Section        |                       |
    |------------------+----------------------+-----------------------|
    |Signal            |       J0 (section    |  Trail Trace          |
    |Identifier        |       trace)         |  Identifier (TTI)     |
    |------------------+----------------------+-----------------------|
    |Performance       |       BIP-8 (B1)     |  BIP-8 (within SM)    |
    |Monitoring        |                      |                       |
    |------------------+----------------------+-----------------------|
    |Management        |       D1-D3 bytes    |  GCC0 (general        |
    |Communications    |                      |  communications       |
    |                  |                      |  channel)             |
    |------------------+----------------------+-----------------------|
    |Fault Management  |       A1, A2 framing |  FAS (frame alignment |
    |                  |       bytes          |  signal), BDI(backward|
    |                  |                      |  defect indication)BEI|
    |                  |                      |  (backward error      |
    |                  |                      |  indication)          |
    +------------------+----------------------+-----------------------|
    |Forward Error     |       P1,Q1 bytes    |  OTUk FEC             |
    |Correction (FEC)  |                      |                       |
    +-----------------------------------------------------------------+


   In the previous table we see support for frame alignment, signal
   identification, and FEC. What this table also shows by its omission
   is that no switching or multiplexing occurs at this layer. This is a
   significant simplification for the control plane since control plane
   standards require a multi-layer approach when there are multiple
   switching layers, but not for "layering" to provide the management
   functions of Table 2. That is, many existing technologies covered by
   GMPLS contain extra management related layers that are essentially
   ignored by the control plane (though not by the management plane!).
   Hence, the approach here is to include regenerators and other devices
   at the WSON layer unless they provide higher layer switching and then
   a multi-layer or multi-region approach [RFC5212] is called for.
   However, this can result in regenerators having a dependence on the
   client signal type.



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   Hence we see that depending upon the regenerator technology we may
   have the following constraints imposed by a regenerator device:

              Table 3. Regenerator Compatibility Constraints

   +--------------------------------------------------------+
   |      Constraints            |   1R   |   2R   |   3R   |
   +--------------------------------------------------------+
   | Limited Wavelength Range    |    x   |    x   |    x   |
   +--------------------------------------------------------+
   | Modulation Type Restriction |        |    x   |    x   |
   +--------------------------------------------------------+
   | Bit Rate Range Restriction  |        |    x   |    x   |
   +--------------------------------------------------------+
   | Exact Bit Rate Restriction  |        |        |    x   |
   +--------------------------------------------------------+
   | Client Signal Dependence    |        |        |    x   |
   +--------------------------------------------------------+


   Note that Limited Wavelength Range constraint is already modeled in
   GMPLS for WSON and that Modulation Type Restriction constraint
   includes FEC.


3.2. OEO Switches
   A common place where optical-to-electrical-to-optical (OEO)
   processing may take place is in WSON switches that utilize (or
   contain) regenerators. A vendor may add regenerators to a switching
   system for a number of reasons. One obvious reason is to restore
   signal quality either before or after optical processing (switching).
   Another reason may be to convert the signal to an electronic form for
   switching then reconverting to an optical signal prior to egress from
   the switch. In this later case the regeneration is applied to adapt
   the signal to the switch fabric regardless of whether or not it is
   needed from a signal quality perspective.

   In either case these optical switches have essentially the same
   compatibility constraints as those we described for regenerators in
   Table 3.


3.3. Wavelength Converters
   In [WSON-FRAME] the motivation for utilizing wavelength converters
   was discussed. In essence a wavelength converter would take one or


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   more optical channels on specific wavelengths and convert them to
   corresponding new specific wavelengths. Currently all optical
   wavelength converters exist but have not been widely deployed, hence
   the majority of wavelength converters are based on demodulation to an
   electrical signal and then re-modulation onto a new optical carrier,
   i.e., an OEO process. This process is very similar to that used for a
   regenerator except that the output optical wavelength will be
   different from the input optical wavelength. Hence in general
   wavelength converters have signal processing restrictions that are
   essentially the same as those we described for regenerators in Table
   3 with perhaps an additional input frequency range restriction and
   output frequency range  restriction. By additional we mean more
   restrictive than the range of the WDM link. Such a restriction has
   already been modeled in [WSON-Frame] and [WSON-Info].

   4. Characterizing WSON Network Elements

   In this section we characterize WSON network elements by the three
   key functional components: Input constraints, Output constraints and
   Processing Capabilities.

                             WSON Network Element

                          +-----------------------+
          WSON Signal     |      |         |      |    WSON Signal
                          |      |         |      |
        --------------->  |      |         |      | ----------------->
                          |      |         |      |
                          +-----------------------+
                          <-----> <-------> <----->

                          Input   Processing Output

                       Figure 1 WSON Network Element

   4.1. Input Constraints

   Section 3 discussed the basic properties regenerators, OEO switches
   and wavelength converters from these we have the following possible
   types of input constraints and properties:

   1. Acceptable Modulation formats

   2. Client Signal (GPID) restrictions

   3. Bit Rate restrictions

   4. FEC coding restrictions


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   5. Configurability: (a) none, (b) self-configuring, (c) required

   We can represent these constraints via simple lists. Note that the
   device may need to be "provisioned" via signaling or some other means
   to accept signals with some attributes versus others. In other cases
   the devices maybe relatively transparent to some attributes, e.g.,
   such as a 2R regenerator to bit rate. Finally, some devices maybe
   able to auto-detect some attributes and configure themselves, e.g., a
   3R regenerator with bit rate detection mechanisms and flexible phase
   locking circuitry. To account for these different cases we've added
   item 5, which describes the devices configurability.

   Note that such input constraints also apply to the final destination,
   sink or termination, of the WSON signal.

   4.2. Output Constraints

   None of the network elements considered here modifies either the bit
   rate or the basic type of the client signal. However, they may modify
   the modulation format or the FEC code. Typically we'd see the
   following types of output constraints:

   1. Output modulation is the same as input modulation (default)

   2. A limited set of output modulations is available

   3. Output FEC is the same as input FEC code (default)

   4. A limited set of output FEC codes is available

   Note that in cases (2) and (4) above, where there is more than one
   choice in the output modulation or FEC code then the network element
   will need to be configured on a per LSP basis as to which choice to
   use.

   4.3. Processing Capabilities

   A general WSON network element (NE) can perform a number of signal
   processing functions including:

     (A) Regeneration (possibly different types)

     (B) Fault and Performance Monitoring

     (C) Wavelength Conversion

     (D) Switching



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   Items (C) and (D) are already covered in GMPLS and [WSON-Frame].

   An NE may or may not have the ability to perform regeneration (of the
   one of the types previously discussed). In addition some nodes may
   have limited regeneration capability, i.e., a shared pool, which may
   be applied to selected signals traversing the NE. Hence to describe
   the regeneration capability of a link or node we have at a minimum:

   1. Regeneration capability: (a)fixed, (b) selective, (c) none

   2. Regeneration type: 1R, 2R, 3R

   3. Regeneration pool properties for the case of selective
      regeneration (ingress & egress restrictions, availability)

   Note that the properties of shared regenerator pools would be
   essentially the same at that of wavelength converter pools modeled in
   [WSON-Frame].

   Item (B), fault and performance monitoring, is typically outside the
   scope of the control plane. However, when the operations are to be
   performed on an LSP basis or as part of an LSP then the control plane
   can be of assistance in their configuration. Per LSP, per node, fault
   and performance monitoring examples include setting up a "section
   trace" (a regenerator overhead identifier) between two nodes, or
   intermediate optical performance monitoring at selected nodes along a
   path.

   5. Networking Scenarios and the Control Plane

   In the following we look at various networking scenarios involving
   regenerators, OEO switches and wavelength converters. We group these
   scenarios roughly by type and number of extensions to the GMPLS
   control plane that would be required.

   5.1. Fixed Regeneration Points

   In the simplest networking scenario involving regenerators, the
   regeneration is associated with a WDM link or entire node and is not
   optional, i.e., all signals traversing the link or node will be
   regenerated. This includes OEO switches since they provide
   regeneration on every port.

   There maybe input constraints and output constraints on the
   regenerators. Hence the path selection process will need to know from
   an IGP or other means the regenerator constraints so that it can
   choose a compatible path. For impairment aware routing and wavelength
   assignment (IA-RWA) the path selection process will also need to know


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   which links/nodes provide regeneration. Even for "regular" RWA, this
   regeneration information is useful since wavelength converters
   typically perform regeneration and the wavelength continuity
   constraint can be relaxed at such a point.

   Signaling does not need to be enhanced to include this scenario since
   there are no reconfigurable regenerator options on input, output or
   with respect to processing.

   5.2. Shared Regeneration Pools

   In this scenario there are nodes with shared regenerator pools within
   the network in addition to fixed regenerators of the previous
   scenario. These regenerators are shared within a node and their
   application to a signal is optional. There are no reconfigurable
   options on either input or output. The only processing option is to
   "regenerate" a particular signal or not.

   Regenerator information in this case is used in path computation to
   select a path that ensures signal compatibility and IA-RWA criteria.

   To setup an LSP that utilizes a regenerator from a node with a shared
   regenerator pool we need to be able to indicate that regeneration is
   to take place at that particular node along the signal path. Such a
   capability currently does not exist in GMPLS signaling.

   5.3. Reconfigurable Regenerators

   In this scenario we have regenerators that require configuration
   prior to use on an optical signal. We discussed previously that this
   could be due to a regenerator that must be configured to accept
   signals with different characteristics, for regenerators with a
   selection of output attributes, or for regenerators with additional
   optional processing capabilities.

   As in the previous scenarios we will need information concerning
   regenerator properties for selection of compatible paths and for IA-
   RWA computations. In addition during LSP setup we need to be able
   configure regenerator options at a particular node along the path.
   Such a capability currently does not exist in GMPLS signaling.

   5.4. Relation to Translucent Networks

   In the literature networks that contain both transparent network
   elements such as reconfigurable optical add drop multiplexers
   (ROADMs) and electro-optical network elements such regenerators or
   OEO switches are frequently referred to as Translucent optical
   networks [Trans07]. Earlier work suggesting GMPLS extensions for


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   translucent optical networks can be found in [Yang05] while a more
   comprehensive evaluation of differing GMPLS control plane approaches
   to translucent networks can be found in [Sambo09].

   Three main types of translucent optical networks have been discussed:

   1. Transparent "islands" surrounded by regenerators. This is
      frequently seen when transitioning from a metro optical sub-
      network to a long haul optical sub-network.

   2. Mostly transparent networks with a limited number of OEO
      ("opaque") nodes strategically placed. This takes advantage of the
      inherent regeneration capabilities of OEO switches. In the
      planning of such networks one has to determine the optimal
      placement of the OEO switches [Sen08].

   3. Mostly transparent networks with a limited number of optical
      switching nodes with "shared regenerator pools" that can be
      optionally applied to signals passing through these switches.
      These switches are sometimes called translucent nodes.

   All three of these types of translucent networks fit within either
   the networking scenarios of sections 5.1. and 5.2.  above. And hence,
   can be accommodated by the GMPLS extensions suggested in this
   document.



   6. Implications for GMPLS and PCE


6.1. Link and Network Element Extensions for GMPLS Routing
   Other drafts  [WSON-FRAME],[WSON-Info] provide NE models that include
   switching asymmetry and port wavelength constraints here we add
   parameters to our existing node and link models to take into account
   input constraints, output constraints, and the signal processing
   capabilities of a NE.

   Input Constraints:

  1. Permitted optical tributary signal classes: A list of optical
     tributary signal classes that can be processed by this network
     element or carried over this link. [configuration type]
  2. Acceptable FEC codes [configuration type]





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  3. Acceptable Bit Rate Set: A list of specific bit rates or bit rate
     ranges that the device can accommodate. Coarse bit rate info is
     included with the optical tributary signal class restrictions.
  4. Acceptable G-PID list: A list of G-PIDs corresponding to the
     "client" digital streams that is compatible with this device.


   Note that since the bit rate of the signal does not change over the
   LSP. We can make this an LSP parameter and hence this information
   would be available for any NE that needs to use it for configuration.
   Hence we do not need "configuration type" for the NE with respect to
   bit rate.

   Output Constraints:

   1. Output modulation: (a)same as input, (b) list of available types

   2. FEC options: (a) same as input, (b) list of available codes

   Processing Capabilities:

   1. Regeneration: (a) 1R, (b) 2R, (c) 3R, (d)list of selectable
      regeneration types

   2. Fault and Performance Monitoring (a)GPID particular capabilities
      TBD, (b) optical performance monitoring capabilities TBD.

   Note that such parameters could be specified on an (a) Network
   element wide basis, (b) a per port basis, (c) on a per regenerator
   basis.  Typically such information has been on a per port basis,
   e.g., the GMPLS interface switching capability descriptor [RFC4202].
   However, in [WSON-FRAME] we give examples of shared wavelength
   converters within a switching system, and hence this would be on a
   subsystem basis. The exact form would be defined in the [WSON-Info]
   and [WSON-Encoding] drafts.

   6.2. Implications for GMPLS Signaling

   We saw in section 2.3. that a WSON signal at any point along its path
   can be characterized by the (a) modulation format, (b) FEC, (c)
   wavelength, (d)bit rate, and (d)G-PID.

   Currently G-PID, wavelength (via labels), and bit rate (via bandwidth
   encoding) are supported in [RFC3471] and [RFC3473]. These RFCs can
   accommodate the wavelength changing at any node along the LSP and can
   provide explicit control of wavelength converters.



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   In the fixed regeneration point scenario (section 5.1. ) no
   enhancements are required to signaling since there are no additional
   configuration options for the LSP at a node.

   In the case of shared regeneration pools (section 5.2. ) we need to
   be able to indicate to a node that it should perform regeneration on
   a particular signal. Viewed another way, for an LSP we want to
   specify that certain nodes along the path perform regeneration.  Such
   a capability currently does not exist in GMPLS signaling.

   The case of configurable regenerators (section 5.3. ) is very similar
   to the previous except that now there are potentially many more items
   that we may want to configure on a per node basis for an LSP.

   Note that the techniques of [RFC5420] which allow for additional LSP
   attributes and their recording in an RRO object could be extended to
   allow for additional LSP attributes in an ERO. This could allow one
   to indicate where optional 3R regeneration should take place along a
   path, any modification of LSP attributes such as modulation format,
   or any enhance processing such as performance monitoring.



   6.3. PCEP Extensions

   When requesting a path computation to PCE, the PCC should be able to
   indicate the following:

   o  The GPID type of an LSP

   o  The signal attributes at the transmitter (at the source): (i)
      modulation type; (ii) FEC type

   o  The signal attributes at the receiver (at the sink): (i)
      modulation type; (ii) FEC type

   The PCE should be able to respond to the PCC with the following:

   o  The conformity of the requested optical characteristics associated
      with the resulting LSP with the source, sink and NE along the LSP.

   o  Additional LSP attributes modified along the path (e.g.,
      modulation format change, etc.)







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   7. Security Considerations

   This document has no requirement for a change to the security models
   within GMPLS and associated protocols. That is the OSPF-TE, RSVP-TE,
   and PCEP [RFC5540] security models could be operated unchanged.

   Furthermore the additional information distributed in order to extend
   GMPLS capabilities to the additional network elements discussed in
   this document represents a disclosure of network capabilities that an
   operator may wish to keep private. Consideration should be given to
   securing this information.

   8. IANA Considerations

   This document makes no request for IANA actions.

   9. Acknowledgments

   This document was prepared using 2-Word-v2.0.template.dot.































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   10. References

   10.1. Normative References

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

   [RFC4202] Kompella, K. and Y. Rekhter, "Routing Extensions in Support
             of Generalized Multi-Protocol Label Switching (GMPLS)", RFC
             4202, October 2005.

   [RFC4328] Papadimitriou, D., "Generalized Multi-Protocol Label
             Switching (GMPLS) Signaling Extensions for G.709 Optical
             Transport Networks Control", RFC 4328, January 2006.

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

   [RFC5212] Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureux,
             M., and D. Brungard, "Requirements for GMPLS-Based Multi-
             Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July
             2008.

   [RFC5540] J.P. Vasseur and J.L. Le Roux (Editors), "Path Computation
             Element (PCE) Communication Protocol (PCEP)", RFC 5540,
             March 2009.

   [WSON-FRAME] Y. Lee, G. Bernstein, W. Imajuku, "Framework for GMPLS
             and PCE Control of Wavelength Switched Optical Networks
             (WSON)", draft-ietf-ccamp-rwa-wson-framework-02.txt, March
             2009.

   [WSON-Info] Y. Lee, G. Bernstein, D. Li, W. Imajuku, "Routing and
             Wavelength Assignment Information for Wavelength Switched
             Optical Networks", draft-bernstein-ccamp-wson-info-03.txt,
             March, 2009.

   [WSON-Encoding] G. Bernstein, Y. Lee, D. Li, W. Imajuku, "Routing and
             Wavelength Assignment Information Encoding for Wavelength
             Switched Optical networks", work in progress, draft-ietf-
             ccamp-rwa-wson-encode-01.txt, March 2009.








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   10.2. Informative References

   [Otani]  T. Otani, H. Guo, K. Miyazaki, D. Caviglia, "Generalized
             Labels for G.694 Lambda-Switching Capable Label Switching
             Routers (LSR)", work in progress, draft-ietf-ccamp-gmpls-g-
             694-lambda-labels-04.txt

   [G.872]  ITU-T Recommendation G.872, Architecture of optical
             transport networks, November 2001.

   [G.959.1] ITU-T Recommendation G.959.1, Optical Transport Network
             Physical Layer Interfaces, March 2006.

   [Imp-Frame] G. Bernstein, Y. Lee, D. Li, G. Martinelli, "A Framework
             for the Control and Measurement of Wavelength Switched
             Optical Networks (WSON) with Impairments", Work in
             Progress, draft-ietf-ccamp-wson-impairments-00.txt.

   [Sambo09] N. Sambo, N. Andriolli, A. Giorgetti, L. Valcarenghi, I.
             Cerutti, P. Castoldi, and F. Cugini, "GMPLS-controlled
             dynamic translucent optical networks," Network, IEEE,  vol.
             23, 2009, pp. 34-40.

   [Sen08]   A. Sen, S. Murthy, and S. Bandyopadhyay, "On Sparse
             Placement of Regenerator Nodes in Translucent Optical
             Network," Global Telecommunications Conference, 2008. IEEE
             GLOBECOM 2008. IEEE, 2008, pp. 1-6.

   [Trans07] Gangxiang Shen and Rodney S. Tucker, "Translucent optical
             networks: the way forward [Topics in Optical
             Communications]," Communications Magazine, IEEE, vol. 45,
             2007, pp. 48-54.

   [Yang05]  Xi Yang and B. Ramamurthy, "Dynamic routing in translucent
             WDM optical networks: the intradomain case," Lightwave
             Technology, Journal of,  vol. 23, 2005, pp. 955-971.


Author's Addresses

   Greg M. Bernstein
   Grotto Networking
   Fremont California, USA

   Phone: (510) 573-2237
   Email: gregb@grotto-networking.com




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   Young Lee
   Huawei Technologies
   1700 Alma Drive, Suite 100
   Plano, TX 75075
   USA

   Phone: (972) 509-5599 (x2240)
   Email: ylee@huawei.com

   T. Benjamin Mack-Crane
   Huawei Technologies
   Downers Grove, Illinois

   Email: tmackcrane@huawei.com


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