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Versions: 00 01 02                                                      
Internet Engineering Task Force                             R.Kunze, Ed.
Internet-Draft                                       Deutsche Telekom AG
Intended status: Informational                            G.Grammel, Ed.
Expires: May 3, 2012                                    H.Schmidtke, Ed.
                                                        Juniper Networks
                                                  GMG. G.Galimberti, Ed.
                                                                   Cisco
                                                        October 31, 2011


A framework for Management and Control of optical interfaces supporting
                                G.698.2
          draft-kunze-g-698-2-management-control-framework-01

Abstract

   This document provides a framework that describes a solution space
   for the control and management of optical interfaces according to the
   Black Link approach as specified by ITU-T [ITU.G698.2] and further
   revisions.  In particular, it examines topological elements and
   related network management measures.

   Optical Routing and Wavelength assignment based on WSON is out of
   scope.  This document concentrates on the management of optical
   interfaces.  The application of a dynamic control plane, e.g. for
   auto-discovery or for the distribtion of interface parameters, is
   complementary.  Anyway, this work is not in conflict with WSON but
   leverages and supports related work already done for management plane
   and control plane.

   The framework document will not address the client mapping into
   G.709.  This document only addresses the lower layers.  Furthermore,
   support for Fast Fault Detection, to e.g. trigger Protection
   Switching is provided by the WDM interface capability of the client
   interface (e.g.  ITU-T G.709) is out of scope for this work.
   Additionally the wavelength ordering process and the process how to
   determine the demand for a new wavelength from A to Z is out of
   scope.

Status of This Memo

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

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



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   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on May 3, 2012.

Copyright Notice

   Copyright (c) 2011 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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   described in the Simplified BSD License.






























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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Requirements Language  . . . . . . . . . . . . . . . . . .  5
   2.  Terminology and Definitions  . . . . . . . . . . . . . . . . .  5
   3.  Solution Space for optical interfaces using a DWDM Black
       Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Description of Client Network Layer - WDM connection . . .  7
       3.1.1.  Traditional WDM deployments  . . . . . . . . . . . . .  7
       3.1.2.  Black Link Deployments . . . . . . . . . . . . . . . .  8
   4.  Operational aspects using G.698 specified coloured
       interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     4.1.  Bringing into service  . . . . . . . . . . . . . . . . . . 10
     4.2.  Configuration Management . . . . . . . . . . . . . . . . . 11
     4.3.  In service (performance management)  . . . . . . . . . . . 11
     4.4.  Fault Clearance  . . . . . . . . . . . . . . . . . . . . . 11
   5.  Solutions managing and control the optical interface
       within BL sceanrios  . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  BL Separate Operation and Management Approaches  . . . . . 12
       5.1.1.  Direct connection to the management system . . . . . . 13
       5.1.2.  Indirect connection to the WDM management system . . . 15
     5.2.  Control Plane Considerations . . . . . . . . . . . . . . . 16
       5.2.1.  Stub Control Plane on the packet network . . . . . . . 17
       5.2.2.  Deployment of a common control plane . . . . . . . . . 17
       5.2.3.  Black Link deployment with an separate control
               plane  . . . . . . . . . . . . . . . . . . . . . . . . 18
   6.  Requirements for BL and FW deployments . . . . . . . . . . . . 18
     6.1.  Interoperability Aspects . . . . . . . . . . . . . . . . . 19
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 20
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 20
   9.  Security Considerations  . . . . . . . . . . . . . . . . . . . 20
   10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 20
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
     11.1. Normative References . . . . . . . . . . . . . . . . . . . 21
     11.2. Informative References . . . . . . . . . . . . . . . . . . 21
















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1.  Introduction

   The usage of the Black Link approach in carrier long haul and
   aggregation networks adds a further option for operators to
   facilitate their networks.  The integration of optical coloured
   interfaces into routers and other types of clients could lead to a
   lot of benefits regarding an efficient and optimized data transport
   for higher layer services.

   Carriers deploy their networks today as a combination of transport
   and packet infrastructure.  This ensures high available and flexible
   data transport.  Both network technologies are managed usually by
   different operational units using different management concepts.
   This is the status quo in many carrier networks today.  In the case
   of a black link deployment, where the coloured interface moves into
   the client (e.g. router), it is necessary to establish a management
   connection between the client providing the coloured interface and
   the corresponding EMS (Element Management System) of the transport
   network to ensure that the coloured interface parameters can be
   managed in the same way as traditional deployments allow this.

   The objective of this document is to provide a framework that
   describes the solution space for the control and management of WDM
   Black Links as specified by ITU-T [ITU.G698.2] and further revisions.
   In particular, it examines topological elements and related network
   management measures.

   Optical Routing and Wavelength assignment based on WSON is out of
   scope.  This document concentrates on the management of optical
   interfaces.  The application of a dynamic control plane, e.g. for
   auto-discovery or distribute interface parameters, is complementary.
   Anyway, this work is not in conflict with WSON but leverages and
   supports related work already done for management plane and control
   plane.

   Furthermore, support for Fast Fault Detection, to e.g. trigger
   Protection Switching is provided by the WDM interface capability of
   the client interface (e.g.  ITU-T G.709) is out of scope for this
   work.  Additionally the wavelength ordering process and the process
   how to determine the demand for a new wavelength from A to Z is out
   of scope.

   Note that Control and Management Plane are two separate entities that
   are handling the same information in different ways.  This document
   covers management as well as control plane considerations in
   different management cases of colored interfaces.





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1.1.  Requirements Language

   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 RFC 2119 [RFC2119].

2.  Terminology and Definitions

   Black Link: The Black Link [ITU.G698.2] allows supporting an optical
   transmitter/receiver pair of one or different vendors to inject a
   DWDM channel and run it over an optical network composed of
   amplifiers, filters, add-drop multiplexers from a different vendor.
   Therefore the standard defines the ingress and egress parameters for
   the optical interfaces at the reference points Ss and Rs.  In that
   case the DWDM network between the two colored interfaces is also
   referred to as Black Link.  G.698.2 provides an optical interface
   specification ensuring the realization of transversely compatible
   dense wavelength division multiplexing (DWDM) systems primarily
   intended for metro applications which include optical amplifiers and
   leads towards a multivendor DWDM optical transmission network.

   Coloured Interface: The term coloured interface defines the single
   channel optical interface that is used to bridge long distances and
   is directly connected with a DWDM system.  Coloured interfaces
   operate on a fix wavelength or within a wavelength band (tunability).
   Coloured interface is a generic term and relates to WDM systems in
   general, not just black link systems.

   Friendly Wavelength: A wavelength that is managed by the DWDM System.

   Alien Wavelength: A wavelength that is not managed and known by the
   WDM system.

   Forward error correction (FEC): FEC is an important way of improving
   the performance of high-capacity long haul optical transmission
   systems.  Employing FEC in optical transmission systems yields system
   designs that can accept relatively large BER (much more than 10-12)
   in the optical transmission line (before decoding).

   Administrative domain [G.805]: For the purposes of this
   Recommendation an administrative domain represents the extent of
   resources which belong to a single player such as a network operator,
   a service provider or an end-user.  Administrative domains of
   different players do not overlap amongst themselves.

   Intra-domain interface (IaDI) [G.870]: A physical interface within an
   administrative domain.




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   Inter-domain interface (IrDI) [G.870]: A physical interface that
   represents the boundary between two administrative domains.

   Vendor domain: tbd.

   Management Plane: Management Plane: The management plane supports
   FCAPS (Fault, Configuration, Accounting, Performance and Security
   Management) capabilities for carrier networks.

   Control Plane: The control plane supports signalling, path
   computation, routing, path provisioning and recovery.

   Client Network Layer: The client network layer is the layer above (on
   top) the WDM layer, from the perspective of the WDM layer.

   Transponder: A Transponder is a network element that performs O/E/O
   (Optical /Electrical/Optical) conversion.  In this document it is
   referred only transponders with 3R (rather than 2R or 1R
   regeneration) as defined in [ITU.G.872]

3.   Solution Space for optical interfaces using a DWDM Black Link

   Basically the management of optical interfaces using a Black Link
   deals with aspects needed for setup, tear down and maintenance of
   wavelengths and all related optical parameters, which are demanded by
   a client network layer (the layer above WDM) or by a different
   administrative domain.  The following types of WDM networks are
   considered for a management of optical interfaces using a black link:

   a.  Passive WDM

   b.  Legacy point to point WDM systems

   c.  Legacy WDM systems with OADMs

   d.  Transparent optical networks supporting specific IPoDWDM
       functions, interfaces or protocols

   Table 1 provides a list of tasks, which are related to BL management,
   It is indicated which domain (optical or client) is responsible for a
   task.  The relevance of a task for each type of WDM network is also
   indicated.









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   +---------------------------------------+---------+----+----+---+---+
   |                  Task                 |  Domain |  a |  b | c | d |
   +---------------------------------------+---------+----+----+---+---+
   |   determination of centre frequency   |  client |  R |  R | R | R |
   |  configuration of centre frequency at | optical | NR | NR | R | R |
   |               colored IF              |         |    |    |   |   |
   |     path computation of wavelength    | optical | NR | NR | R | R |
   |         routing of wavelength         | optical | NR | NR | R | R |
   |    wavelength setup across optical    |  client |  ? |  ? | R | R |
   |                network                |         |    |    |   |   |
   |     detection of wavelength fault     | optical |  R |  R | R | R |
   |   fault isolation, identification of  | optical | NR |  R | R | R |
   |              root failure             |         |    |    |   |   |
   | repair actions within optical network | optical |  R |  R | R | R |
   |   protection switching of wavelength  | optical | NR | NR | R | R |
   |       restoration of wavelength       | optical | NR | NR | R | R |
   +---------------------------------------+---------+----+----+---+---+

                   Note: R = relevant, NR = not relevant

              Table 1: List of tasks related to BL management

   Furthermore the following deployment cases will be considered:

   a.  Exclusive Black Link deployment

   b.  Black Link deplyoment in combination with grey client network
       interfaces

   Case b) is motivated by the usage of legacy equipment using the
   traditional connection as described in Figure 1 combined with the BL
   approach.

3.1.  Description of Client Network Layer - WDM connection

3.1.1.  Traditional WDM deployments

   The ordinary connection of a client layer network towards a WDM
   system is based today on client interfaces (grey) bridging short or
   intermediate distances between client and WDM system.  The Optical
   Signal incoming into the WDM system must be converted (OEO
   conversion) to corresponding WDM wavelength grid and the power level
   that is applicable for the WDM transmission path.  This conversion is
   done by a component termed as transponder (see Figure 1).

   After that OEO conversion the signal complies with the parameters
   that are specified for a certain WDM link.




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   Figure 1 shows the traditional Client - WDM interconnection using
   transponders for wavelength conversion.  IrDI and IaDI as defined in
   Section 2 specifying the different demarcation areas related to
   external and internal connections


               IrDI                            IaDI
                |                                |
                .                                .
                |   +----------------------------|---+
                .   |     +    WDM Domain     +  .   |
                |   |     |\                 /|  |   |
   +------+     .   |     | \     |\        / |  .   |          +------+
   |  CL  |-->--+---+--T/-|OM|----|/-------|OD|--+-\T+------->--| CL   |
   |      |--<--+---+--T/-|  |----- /|-----|  |--.-\T+-------<--|      |
   +------+     |   |     | /       \|      \ |  |   |          +------+
                .   |     |/                 \|  .   |
                |   |     +                   +  |   |
                .   +----------------------------.---+
                |                                |

           CL = Client
           T/ = Transponder
           OM = Optical Mux
           OD = Optical Demux


         Figure 1: Inter and Intra-Domain Interface Identification

   This document refers only on the IaDI Interface as specified in ITU-T
   G.698.2 as transversely compatible and multi-vendor interface within
   one administrative domain controlled by the network operator.  This
   administrative domain can contain several vendor domains (vendor A
   for the DWDM sub-network, and vendors B1 and B2 at the transmitter
   and receiver terminal side).

   The management and control of WDM and client layer is done by
   different control and management solutions.  Different operational
   units are responsible for client and WDM layer.

3.1.2.  Black Link Deployments

   In case of a black link deployment Figure 2 the DWDM transceiver is
   located directly at the client and the grey interfaces will be saved.
   In that case a solution must be found to manage that coloured
   interface in the same way as in the traditional case.  This
   requirement must be fulfilled especially in the cases where legacy
   equipment and Black Link Wavelength interfaces will be used in



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   parallel or together and the operational situation is unchanged.

   Figure 2 shows a set of reference points, for the linear "black-link"
   approach, for single-channel connection (Ss and Rs) between
   transmitters (Tx) and receivers (Rx).  Here the WDM network elements
   include an OM and an OD (which are used as a pair with the opposing
   element), one or more optical amplifiers and may also include one or
   more OADMs.


        |==================== Black Link =======================|

           +-------------------------------------------------+
       Ss  |              DWDM Network Elements              | Rs
  +---+ |  |  | \                                       / |  |  | +---+
  Tx L1----|->|   \    +------+            +------+   /   |--|--->Rx L1
  +---+    |  |    |   |      |  +------+  |      |  |    |  |    +---+
  +---+    |  |    |   |      |  |      |  |      |  |    |  |    +---+
  Tx L2----|->| OM |-|>|------|->| OADM |--|------|->| OD |--|--->Rx L2
  +---+    |  |    |   |      |  |      |  |      |  |    |  |    +---+
  +---+    |  |    |   |      |  +------+  |      |  |    |  |    +---+
  Tx L3----|->|   /    | DWDM |    |  ^    | DWDM |   \   |--|--->Rx L3
  +---+    |  | /      | Link +----|--|----+ Link |     \ |  |    +---+
           +-----------+           |  |           +----------+
                                +--+  +--+
                                |        |
                                v        |
                              +---+    +---+
                              RxLx     TxLx
                              +---+    +---+
       Ss = reference point at the DWDM network element tributary output
       Rs = reference point at the DWDM network element tributary input
       Lx = Lambda x
       OM = Optical Mux
       OD = Optical Demux
       OADM = Optical Add Drop Mux


   from Fig. 5.1/G.698.2

                        Figure 2: Linear Black Link

   Independent from the WDM networks that are considered the usage of
   colored interfaces must perform as well in mixed setups with both
   legacy and colored interface equipment using the BL.






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4.  Operational aspects using G.698 specified coloured interfaces

   A Comparison of the black link with the traditional operation
   scenarios provides an insight of similarities and distinctions in
   operation and management.  The following four use cases provide an
   overview about operation and maintenance processes.

4.1.  Bringing into service

   It is necessary to differentiate between two operational issues
   setting up a wavelength path within an optical network.  The first is
   the preparation of the link if no optical circuit on the system
   exits.  This configuration is then the first task of the transport
   management.  Therefore it is necessary:

   a.  to define/calculate the path of the connection

   b.  to configure all involved network elements and

   c.  to verify software versions and alarms.

   This task could be done manually supported by the EMS/NMS of the
   optical transport network or automated.

   The second step is to setup the circuit.  From the operation point of
   view it is the same task in a black link scenario and in a
   traditional environment.  The circuit must be setup logically at
   first.  In the traditional case, where no control plane is in use
   this is a task of the operational staff as well.  It must be known
   what type of framing is used to setup the link and which nodes are
   involved.  Furthermore it must be decided and specified if an
   alternative path has to be configured for protection.  An additional
   wavelength path could be specified for protection purposes.

   From this point now the operational stuff needs access to the client
   to configure the optical interface.  The optical interface must be
   patched to the right ingress port of the optical transport node (e.g.
   ROADM or OADM/OM) and must be known in the inventory of the transport
   management system.

   The transport staff must know for example the router name, the
   interface type, name and address to ensure to configure the right
   interface.  This is needed in the transponder case as well.  After
   configuring all parameters the connection will be monitored for a
   certain time period.  If monitoring is successful then the connection
   will be announced in the IGP and is in use then.

   The only difference in case of a black link scenario is that the



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   coloured interface that moved into the client is belongs to the
   optical path (creation and termination of the optical wavelength
   path) and must be configured ideally by the optical transport
   operation stuff too.

   The two last steps could be automated in a case of black link setup.
   After patching the router towards the first transport node a
   management connection will be established over a different control
   channel using an extended UNI to exchange configuration information
   (see chapter xyz)

   Due to the fully tuneable interfaces used in the Black Link scenario
   it is possible to define a second wavelength for restoration/
   resilience that can be tested and stored in backup profile.  In fault
   cases this wavelength can be used to recover the service.

4.2.  Configuration Management

   tbd.

4.3.  In service (performance management)

   tbd.

4.4.  Fault Clearance

   tbd.

5.  Solutions managing and control the optical interface within BL
    sceanrios

   Operation and management of WDM systems is traditionally seen as a
   homogenous group of tasks that could be carried out best when a
   single management system or an umbrella management system is used.
   Each WDM vendor provides a management system that also administrates
   the wavelengths.

   This old operational approach was based on a high amount/rate of
   connection oriented traffic in carrier networks.  This behaviour has
   been changed completely.  Today IP is the dominating traffic in the
   network and from the operating perspective it is more beneficial to
   use a common management and operation approach.  Due to a long
   history of operational separation it must be possible to manage and
   operate the optical interface using a Black Link with the traditional
   approach too.

   Therefore from the operational point of view in a pure Black Link or
   in a mixed setup with legacy equipment (transponders) there are two



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   approaches to manage and operate optical interfaces.

   1.  Separate operation and management of client and Transport network

       a.  Direct link to the management from the client system to the
       optical domain (e.g.  EMS, OSS)

       b.  Indirect link to the management system; using a protocol
       between the peer node and the directly connected WDM system node
       to exchange management information with the optical domain

   2.  Common operation and management of client and Transport network

   The first option keeps the status quo in large carrier networks as
   mentioned above.  In that case it must be ensured that the full FCAPS
   Management (Fault, Configuration, Accounting, Performance and
   Security) capabilities are supported.  This means from the management
   staff point of view nothing changes.  The transceiver/receiver
   optical interface will be part of the optical management domain and
   will be managed from the transport management staff.

   The second option should be favoured if the underlying WDM transport
   network is mainly used to interconnect IP nodes and the service
   creation and restoration will be done on higher layers (e.g.  IP/
   MPLS).  Then it is more beneficial have a higher level of integration
   and a common management will be more efficient.

5.1.  BL Separate Operation and Management Approaches























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5.1.1.  Direct connection to the management system

   As depicted in Figure 3 one possibility to manage the optical
   interface within the client is a direct connection to the management
   system of the optical domain.  This ensures manageability as usual.



                        +-----+
                        | OSS |
                        |_____|
                        /_____/
                           |
                           |
                           |
                       +---+---+
                +----->+  EMS  |
               /       |       |
              /        +-------+
             /             | MI
       SNMP /              |                DCN Network
       --------------------+-------------------------------
          /         +------+-----------------------+
         /          |     +|     WDM Domain   +    |
        /           |     |\                 /|    |
   +---+--+         |     | \     |\        / |    |          +------+
   |  CL  |-/C------+--- -|OM|----|/-------|OD|--- +-------/C-|  CL  |
   |      |-/C------+--- -|  |----- /|-----|  |----+-------/C-|      |
   +------+         |     | /       \|      \ |    |          +------+
                    |     |/                 \|    |
                    |     +                   +    |
                    +------------------------------+

           CL = Client
           /C = Coloured Interface
           OM = Optical Mux
           OD = Optical Demux
           EMS = Element Management System
           MI= Management Interface



              Figure 3: Connecting BL on Transport Management

   The exchange of management information between client and management
   system assumes that some form of a direct link exists between the
   client node and the WDM management system (e.g.  EMS).  This may be
   an Ethernet Link or a DCN connection.



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   It must be ensured that the optical interface can be managed in a
   standardized way to enable interoperable solutions between different
   optical interface vendors and vendors of the optical network
   management software.  RFC 3591 [RFC3591] defines manage objects for
   the optical interface type but does not cover the scenarios described
   by this framework document.  Therefore an extension to this MIB for
   the optical interface has been drafted in [Black-Link-MIB].  In that
   case SNMP is used to exchange data between client and management
   system of the WDM domain.

   Note that a software update of the interface components of the client
   does not lead obligatory to an update of the software of the EMS and
   vice versa.






































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5.1.2.  Indirect connection to the WDM management system

   The alternative as shown in Figure 4 can be used in cases where a
   more automated relationship between transport node and router is
   aspired.  In that case a combination of rudimentary control plane
   features and manual management will be used.  It is a first step into
   a more control plane oriented operation model.


                        +-----+
                        | OSS |
                        |_____|
                        /_____/
                           |
                           |
                           |
                       +---+---+
                       | EMS   |
                       |       |
                       +-------+
                           | MI
                           |
                           |
           LMP(XML) +------+-----------------------+
       +------------+---+ +|                  +    |
       |            |   | |\                 /|    |
   +---+--+         |   +-+ \     |\        / |    |          +------+
   |  CL  |-/C------+--- -|OM|----|/-------|OD|--- +-------/C-|  CL  |
   |      |-/C------+--- -|  |----- /|-----|  |----+-------/C-|      |
   +------+         |     | /       \|      \ |    |          +------+
                    |     |/                 \|    |
                    |     +                   +    |
                    +------------------------------+


           CL = Client
           /C = Coloured Interface
           OM = Optical Mux
           OD = Optical Demux
                   EMS= Element Management System
           MI= Management Interface


      Figure 4: Direct connection between peer node and first optical
                               network node

   For information exchange between client and the direct connected node
   of the optical transport network LMP as specified in RFC 4209



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   [RFC4209] can (should) be used.  This extension of LMP may be used
   between a peer node and an adjacent optical network node as depicted
   in Figure 4.

   Recently LMP based on RFC 4209 does not support the transmission of
   configuration data (information).  This functionality has to be added
   to the existing extensions of the protocol.  The use LMP-WDM assumes
   that some form of a control channel exists between the client node
   and the WDM equipment.  This may be a dedicated lambda, an Ethernet
   Link, or a DCN.  It is proposed to use an out of band signalling over
   a separate link or DCN to ensure a high availability.

5.2.  Control Plane Considerations

   Basically it is not mandatory necessary to run a control plane in
   Black Link scenarios at least not in simple black link case where
   clients will be connected point to point using a simple WDM
   infrastructure (multiplexer and amplifier).  As a first step it is
   possible to configure the entire link using the standard management
   system and a direct connection of the router or client to the EMS of
   the transport network.  Configuration information will be exchanged
   via a network management protocol.  This could be SNMP(see sections
   Section 5.1.1).

   Looking at the control plane the following two scenarios may be
   considered:

   a.  A control plane is only used on the packet layer, transport in
       further managed using a traditional management system EMS/NMS.Its
       called Stub-Control plane.

   b.  A common control plane for transport and client network; this
       implies a single operation unit responsible for both client and
       transport network management.

   c.  A separate control plane for client and optical network without
       any interaction

   As mentioned in chapter Section 5.1.2 some control plane features
   like LMP in an enhanced version could be used.

   In such simple scenario it is imaginable to use only LMP to exchange
   information between the nodes of the optical domain.  LMP must be run
   between the both end-points of the link and between the edge node and
   the first optical network node.






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5.2.1.  Stub Control Plane on the packet network

   Stub control plane means here that a control plane is used in the
   packet network only and the optical transport uses a management
   system for configuration.  The type of control plane that is used in
   that case doesnt matter.  It could be an IP or IP/MPLS control plane
   for example.

   This scenario is used when no fully control plane is supported by the
   optical transport network.  In this case an extended version of LMP
   for example could be used to monitor the link between transport
   management system and the client hosting the optical interfaces.
   This makes it possible to exchange configuration parameters towards
   the node hosting the coloured interface and on the other side send
   important FCAP information towards the transport management system.

   An additional control plane is not needed initially.  A communication
   channel (out of band) must be used to automate the configuration and
   setup process.

   This model could be seen as an evolutionary step into the direction
   of a GMPLS Control plane and only the edge node and the first core
   node need to run this protocol.  The wavelength that should be used
   by the coloured interface can be assigned manually.If the connection
   comes up the IGP announces it and the metric will be adapted that the
   link is in operation.

   This horizontal communication is needed to virtually integrate the
   optical part of the interface towards the optical transport system
   keeping the status quo as today.In case of more static networks using
   the current paradigm of network design this model has a lot benefits.
   It keeps the network simple and adds some beneficial features to the
   network to automate the operational processes and make operation
   easier.

5.2.2.  Deployment of a common control plane

   The deployment of coloured interfaces is leading to some changes
   related to the control plane models and has some impact on the
   existing interfaces especially in the case of an overlay model where
   the edge node requests resources from the core node and the edges
   node do not participate in the routing protocol instance that runs
   among the core nodes.  RFC 4208 [RFC4208] defines the GMPLS UNI that
   will be used between edge and core node.  In case of a black link
   deployment this UNI moves into the client that hosts the coloured
   interface.  This means that the overlay starts at the same node that
   is as well part of the transport infrastructure starting and
   terminating the wavelength channel.



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   Lets differentiate between topology/signalling information that must
   or could be exchanged and configuration parameters needed to setup a
   wavelength path like wavelength, modulation scheme, FEC and other
   important parameters.  RSVP-TE could be used for the signalling and
   the reservation of the wavelength path.  But there is more
   information needed in case of a wavelength path setup.  Now there are
   two possibilities to proceed:

   a.  Using RSVP-TE only for the signalling and LMP as described above
       to exchange information to configure the optical interface within
       the edge node or

   b.  RSVP-TE will be used to transport additional information

   c.  Leaking IGP information instead of exchanging this information
       needed from the optical network to the edge node (overlay will be
       transformed to a border-peer model)

   In any case the classic overlay moves into the edge node or client
   and in any case of using the overlay model additional parameters need
   to be exchanged between edge node and optical core node.  The
   following issues must be solved:

   Communication between peering edge nodes using an out of band control
   channel.  The two node have to exchange their optical capabilities
   (LMP:do we need to extend LMP in that case), FEC Modulation scheme,
   etc must be the same.  It would be helpful to define some common
   profiles that will be supported.  Only if the profiles match with
   both interface capabilities it is possible start signalling.

   Due to the bidirectional wavelength path that must be setup it is
   obligatory that the upstream edge node inserts a wavelength value
   into the path message for the wavelength path towards the upstream
   node itself.  But in the case of an overlay model the client has not
   the information which wavelength must should be selected and this
   information must be exchanged between edge and the core node.

   Other points

5.2.3.  Black Link deployment with an separate control plane

   tbd.

6.  Requirements for BL and FW deployments

   This section raises requirements from the carrier perspective and
   will be removed in a separate requirements draft if necessary.




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6.1.  Interoperability Aspects

   For carrier network deployments, interoperability is a key
   requirement.  Today it is state-of-the-art to interconnect e.g.
   clients from different vendors and a WDM transport system using
   short-reach, grey interfaces.  Applying the Black Link (BL) concept,
   clients (e.g. routers) now become directly connected via transport
   interfaces which must be interoperable to each other.



                     <========= Black Link =========>
                      +---------------------------+
                      |   Black Link (vendor A)   |
   +-----------+      |   +                   +   |      +-----------+
   |CL #1      |     -+---|\                 /|---+-     | CL #2     |
   |    +------+-+    |   | \   +-------+   / |   |    +-+------+    |
   |  --|  Tx    |    |   |  |  |       |  |  |   |    |   Rx   |--  |
   |  --|(vendor +--+-+---|OM|--  OADM  |--|OD|---+-+--+(vendor |--  |
   |  --|   X)   | Ss |   |  |  |       |  |  |   | RS |   Y)   |--  |
   |    +------+-+    |   | /   +-------+   \ |   |    +-+------+    |
   |           |     -+---|/                 \|---+-     |           |
   |(vendor B1)|      |   +                   +   |      |(vendor B2)|
   +-----------+      |                           |      +-----------+
                      +---------------------------+


           CL = Client
           /C = Coloured Interface
           OM = Optical Mux
           OD = Optical Demux
                   EMS= Element Management System
           MI= Management Interface


                    Figure 5: Interoperability aspects

   In practice, a network operator may not use five different vendors
   when implementing black link systems.  A simplified use case could be
   to choose the same vendor B for the client equipment on both sides
   (i.e. vendor B1 = vendor B2 = vendor B) and to choose the same vendor
   X for the Tx and Rx (i.e. vendor X = vendor Y) thus enabling to use
   universal pluggable modules for the optical transmitters and
   receivers.

   An even more simplified use case could be to choose the same vendor B
   for all client equipment and Tx/Rx (i.e.  B = B1 = X = B2 = Y) thus
   having only two vendors for the whole set-up, namely vendor A and



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   vendor B, but to give up the possibility to use universal pluggable
   modules.

   Other vendor combinations could also be realized (e.g. vendor X =
   vendor Y = vendor A).

7.  Acknowledgements

   The author would like to thank Ulrich Drafz for the very good
   teamwork during the last years and the initial thoughts related to
   the packet optical integration.  Furthermore the author would like to
   thank all people involved within Deutsche Telekom for the support and
   fruitful discussions.

8.  IANA Considerations

   This memo includes no request to IANA.

9.  Security Considerations

   This document has no requirement for a change to the security models
   within GMPLS, associated protocols and management interfaces.  As
   well as the LMP security models could be operated unchanged.

10.  Contributors

               Arnold Mattheus
                 Deutsche Telekom
                 Darmstadt
                 Germany
                 email arnold.Mattheus@telekom.de

               Manuel Paul
                 Deutsche Telekom
                 Berlin
                 Germany
                 email Manuel.Paul@telekom.de

               Josef Roese
                 Deutsche Telekom
                 Darmstadt
                 Germany
                 email j.roese@telekom.de

                             Frank Luennemann
                 Deutsche Telekom
                 Muenster
                             Germany



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                 email Frank.Luennemann@telekom.de


11.  References

11.1.  Normative References

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

   [ITU.G698.2]      International Telecommunications Union, "Amplified
                     multichannel dense wavelength division multiplexing
                     applications with single channel optical
                     interfaces", ITU-T Recommendation G.698.2,
                     November 2009.

   [ITU.G709]        International Telecommunications Union, "Interface
                     for the Optical Transport Network (OTN)", ITU-
                     T Recommendation G.709, March 2003.

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

   [RFC3591]         Lam, H-K., Stewart, M., and A. Huynh, "Definitions
                     of Managed Objects for the Optical Interface Type",
                     RFC 3591, September 2003.

   [RFC4204]         Lang, J., "Link Management Protocol (LMP)",
                     RFC 4204, October 2005.

   [RFC4209]         Fredette, A. and J. Lang, "Link Management Protocol
                     (LMP) for Dense Wavelength Division Multiplexing
                     (DWDM) Optical Line Systems", RFC 4209,
                     October 2005.

11.2.  Informative References

   [Black-Link-MIB]  Internet Engineering Task Force, "A SNMP MIB to
                     manage the optical colored interfaces of a DWDM
                     network", draft-galimbe-kunze-g-698-2-snmp-
                     mib draft-galimbe-kunze-g-698-2-snmp-mib,
                     July 2011.








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Authors' Addresses

   Ruediger Kunze (editor)
   Deutsche Telekom AG
   Berlin,   10589
   DE

   Phone: +49 30 3497 3152
   EMail: ruediger.kunze@telekom.de


   Gert Grammel (editor)
   Juniper Networks
   ddddd
   dddd,   1234
   US

   Phone: +1 45552
   EMail: ggrammel@juniper.net


   Hans-Juergen Schmidtke (editor)
   Juniper Networks
   dddd,   1234
   US

   Phone: +1 45552
   EMail: hschmidtke@juniper.net


   Gabriele Galimberti (editor)
   Cisco
   Via Philips,12
   20052 - Monza
   Italy

   Phone: +390392091462
   EMail: ggalimbe@cisco.com













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