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Versions: (draft-doria-forces-protocol) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 RFC 5810

Network Working Group                                     A. Doria (Ed.)
Internet-Draft                                                      ETRI
Expires: September 6, 2006                                 R. Haas (Ed.)
                                                                     IBM
                                                     J. Hadi Salim (Ed.)
                                                                    Znyx
                                                       H. Khosravi (Ed.)
                                                                   Intel
                                                        W. M. Wang (Ed.)
                                           Zhejiang Gongshang University

                                                           March 5, 2006


                     ForCES Protocol Specification
                   draft-ietf-forces-protocol-07.txt


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Copyright Notice

   Copyright (C) The Internet Society (2006).





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Abstract

   This document specifies the Forwarding and Control Element Separation
   (ForCES) protocol.  ForCES protocol is used for communications
   between Control Elements(CEs) and Forwarding Elements (FEs) in a
   ForCES Network Element (ForCES NE).  This specification is intended
   to meet the ForCES protocol requirements defined in RFC3654.  Besides
   the ForCES protocol messages, the specification also defines the
   framework, the mechanisms, and the Transport Mapping Layer (TML)
   requirements for ForCES protocol.

Authors

   The participants in the ForCES Protocol Team, primary co-authors and
   co-editors, of this protocol specification, are:

   Ligang Dong (Zhejiang Gongshang University), Avri Doria (ETRI), Ram
   Gopal (Nokia), Robert Haas (IBM), Jamal Hadi Salim (Znyx), Hormuzd M
   Khosravi (Intel), and Weiming Wang (Zhejiang Gongshang University).
































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Table of Contents

   1.  Terminology and Conventions . . . . . . . . . . . . . . . . .   5
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   6
   3.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   8
   4.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . .  11
     4.1.  Protocol Framework  . . . . . . . . . . . . . . . . . . .  11
       4.1.1.  The PL layer  . . . . . . . . . . . . . . . . . . . .  13
       4.1.2.  The TML layer . . . . . . . . . . . . . . . . . . . .  14
       4.1.3.  The FEM/CEM Interface . . . . . . . . . . . . . . . .  14
     4.2.  ForCES Protocol Phases  . . . . . . . . . . . . . . . . .  15
       4.2.1.  Pre-association . . . . . . . . . . . . . . . . . . .  16
       4.2.2.  Post-association  . . . . . . . . . . . . . . . . . .  18
     4.3.  Protocol Mechanisms . . . . . . . . . . . . . . . . . . .  19
       4.3.1.  Transactions, Atomicity, Execution and Responses  . .  19
       4.3.2.  Scalability . . . . . . . . . . . . . . . . . . . . .  23
       4.3.3.  Heartbeat Mechanism . . . . . . . . . . . . . . . . .  23
       4.3.4.  FE Object and FE protocol LFBs  . . . . . . . . . . .  24
   5.  TML Requirements  . . . . . . . . . . . . . . . . . . . . . .  25
     5.1.  TML Parameterization  . . . . . . . . . . . . . . . . . .  26
   6.  Message encapsulation . . . . . . . . . . . . . . . . . . . .  27
     6.1.  Common Header . . . . . . . . . . . . . . . . . . . . . .  27
     6.2.  Type Length Value(TLV) Structuring  . . . . . . . . . . .  32
       6.2.1.  Nested TLVs . . . . . . . . . . . . . . . . . . . . .  32
       6.2.2.  Scope of the T in TLV . . . . . . . . . . . . . . . .  32
     6.3.  ILV . . . . . . . . . . . . . . . . . . . . . . . . . . .  32
   7.  Protocol Construction . . . . . . . . . . . . . . . . . . . .  34
     7.1.  Protocol Grammar  . . . . . . . . . . . . . . . . . . . .  34
       7.1.1.  Protocol BNF  . . . . . . . . . . . . . . . . . . . .  34
       7.1.2.  Protocol Visualization  . . . . . . . . . . . . . . .  42
     7.2.  Core ForCES LFBs  . . . . . . . . . . . . . . . . . . . .  45
       7.2.1.  FE Protocol LFB . . . . . . . . . . . . . . . . . . .  46
       7.2.2.  FE Object LFB . . . . . . . . . . . . . . . . . . . .  49
     7.3.  Semantics of message Direction  . . . . . . . . . . . . .  49
     7.4.  Association Messages  . . . . . . . . . . . . . . . . . .  49
       7.4.1.  Association Setup Message . . . . . . . . . . . . . .  49
       7.4.2.  Association Setup Response Message  . . . . . . . . .  51
       7.4.3.  Association Teardown Message  . . . . . . . . . . . .  52
     7.5.  Configuration Messages  . . . . . . . . . . . . . . . . .  53
       7.5.1.  Config Message  . . . . . . . . . . . . . . . . . . .  53
       7.5.2.  Config Response Message . . . . . . . . . . . . . . .  55
     7.6.  Query Messages  . . . . . . . . . . . . . . . . . . . . .  56
       7.6.1.  Query Message . . . . . . . . . . . . . . . . . . . .  57
       7.6.2.  Query Response Message  . . . . . . . . . . . . . . .  58
     7.7.  Event Notification Message  . . . . . . . . . . . . . . .  59
     7.8.  Packet Redirect Message . . . . . . . . . . . . . . . . .  61
     7.9.  Heartbeat Message . . . . . . . . . . . . . . . . . . . .  64
     7.10. Operation Summary . . . . . . . . . . . . . . . . . . . .  65



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   8.  Protocol Scenarios  . . . . . . . . . . . . . . . . . . . . .  68
     8.1.  Association Setup state . . . . . . . . . . . . . . . . .  68
     8.2.  Association Established state or Steady State . . . . . .  69
   9.  High Availability Support . . . . . . . . . . . . . . . . . .  72
     9.1.  Responsibilities for HA . . . . . . . . . . . . . . . . .  74
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  76
     10.1. No Security . . . . . . . . . . . . . . . . . . . . . . .  76
       10.1.1. Endpoint Authentication . . . . . . . . . . . . . . .  76
       10.1.2. Message authentication  . . . . . . . . . . . . . . .  77
     10.2. ForCES PL and TML security service  . . . . . . . . . . .  77
       10.2.1. Endpoint authentication service . . . . . . . . . . .  77
       10.2.2. Message authentication service  . . . . . . . . . . .  77
       10.2.3. Confidentiality service . . . . . . . . . . . . . . .  78
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  79
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  80
     12.1. Normative References  . . . . . . . . . . . . . . . . . .  80
     12.2. Informational References  . . . . . . . . . . . . . . . .  80
   Appendix A.  IANA Considerations  . . . . . . . . . . . . . . . .  81
     A.1.  Message Type Name Space . . . . . . . . . . . . . . . . .  81
     A.2.  Operation Type  . . . . . . . . . . . . . . . . . . . . .  82
     A.3.  Header Flags  . . . . . . . . . . . . . . . . . . . . . .  82
     A.4.  TLV Type Name Space . . . . . . . . . . . . . . . . . . .  83
     A.5.  LFB Class Id Name Space . . . . . . . . . . . . . . . . .  83
     A.6.  Association Setup Response  . . . . . . . . . . . . . . .  84
     A.7.  Association Teardown Message  . . . . . . . . . . . . . .  84
     A.8.  Configuration Request Result  . . . . . . . . . . . . . .  85
   Appendix B.  ForCES Protocol LFB schema . . . . . . . . . . . . .  86
     B.1.  Capabilities  . . . . . . . . . . . . . . . . . . . . . .  91
     B.2.  Attributes  . . . . . . . . . . . . . . . . . . . . . . .  91
   Appendix C.  Data Encoding Examples . . . . . . . . . . . . . . .  92
   Appendix D.  Use Cases  . . . . . . . . . . . . . . . . . . . . .  96
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . 112
   Intellectual Property and Copyright Statements  . . . . . . . . . 114


















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1.  Terminology and Conventions

   The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT,
   RECOMMENDED, MAY, and OPTIONAL in this document are to be interpreted
   as described in BCP 14, RFC 2119 [RFC2119].














































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2.  Introduction

   Forwarding and Control Element Separation (ForCES) defines an
   architectural framework and associated protocols to standardize
   information exchange between the control plane and the forwarding
   plane in a ForCES Network Element (ForCES NE).  RFC 3654 has defined
   the ForCES requirements, and RFC 3764 has defined the ForCES
   framework.  While there may be multiple protocols used within the
   overall ForCES architecture, the term "ForCES protocol" and
   "protocol" as used in this document refers to the protocol used to
   standardize the information exchange between Control Elements(CEs)
   and Forwarding Elements(FEs) only.  ForCES FE model [FE-MODEL]
   presents the capabilities, state and configuration of FEs within the
   context of the ForCES protocol, so that CEs can accordingly control
   the FEs in a standardizded way and by means of the ForCES protocol.

   This document defines the ForCES protocol specifications.  The ForCES
   protocol works in a master-slave mode in which FEs are slaves and CEs
   are masters.  Information exchanged between FEs and CEs makes
   extensive use of TLVs.  The protocol includes commands for transport
   of LFB configuration information, association setup, status and event
   notifications, etc.

   This specification does not define a transport mechanism for protocol
   messages, but does include a discussion of service primitives that
   must be provided by the underlying transport interface.

   Section 3 provides a glossary of terminology used in the
   specification.

   Section 4 provides an overview of the protocol including a discussion
   on the protocol framework, descriptions of the Protocol Layer (PL)
   and a Transport Mapping Layer (TML), as well as of the ForCES
   protocol mechanisms.

   While this document does not define the TML, Section 5 details the
   services that a TML must provide (TML requirements).

   The ForCES protocol defines a common header for all protocol
   messages.  The header is defined in Section 6.1, while the protocol
   messages are defined in Section 7.

   Section 8 describes several Protocol Scenarios and includes message
   exchange descriptions.

   Section 9 describes a mechanism in the protocol to support high
   availability mechanisms including redundancy and fail over.
   Section 10 defines the security mechanisms provided by the PL and



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   TML.


















































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3.  Definitions

   This document follows the terminology defined by the ForCES
   Requirements in [RFC3654] and by the ForCES framework in [RFC3746].
   The definitions below are repeated below for clarity.

   Addressable Entity (AE) - A physical device that is directly
   addressable given some interconnect technology.  For example, on IP
   networks, it is a device which can be reached using an IP address;
   and on a switch fabric, it is a device which can be reached using a
   switch fabric port number.

   Forwarding Element (FE) - A logical entity that implements the ForCES
   protocol.  FEs use the underlying hardware to provide per-packet
   processing and handling as directed/controlled by a CE via the ForCES
   protocol.

   Control Element (CE) - A logical entity that implements the ForCES
   protocol and uses it to instruct one or more FEs on how to process
   packets.  CEs handle functionality such as the execution of control
   and signaling protocols.

   Pre-association Phase - The period of time during which an FE Manager
   (see below) and a CE Manager (see below) are determining which FE(s)
   and CE(s) should be part of the same network element.

   Post-association Phase - The period of time during which an FE knows
   which CE is to control it and vice versa.  This includes the time
   during which the CE and FE are establishing communication with one
   another.

   FE Model - A model that describes the logical processing functions of
   an FE.

   FE Manager (FEM) - A logical entity responsible for generic FE
   management tasks.  It is used during pre-association phase to
   determine with which CE(s) an FE should communicate.  This process is
   called CE discovery and may involve the FE manager learning the
   capabilities of available CEs.  An FE manager may use anything from a
   static configuration to a pre-association phase protocol (see below)
   to determine which CE(s) to use.  Being a logical entity, an FE
   manager might be physically combined with any of the other logical
   entities such as FEs.

   CE Manager (CEM) - A logical entity responsible for generic CE
   management tasks.  It is particularly used during the pre-association
   phase to determine with which FE(s) a CE should communicate.  This
   process is called FE discovery and may involve the CE manager



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   learning the capabilities of available FEs.

   ForCES Network Element (NE) - An entity composed of one or more CEs
   and one or more FEs.  To entities outside a NE, the NE represents a
   single point of management.  Similarly, a NE usually hides its
   internal organization from external entities.

   High Touch Capability - This term will be used to apply to the
   capabilities found in some forwarders to take action on the contents
   or headers of a packet based on content other than what is found in
   the IP header.  Examples of these capabilities include NAT-PT,
   firewall, and L7 content recognition.

   Datapath -- A conceptual path taken by packets within the forwarding
   plane inside an FE.

   LFB (Logical Function Block) -- The basic building block that is
   operated on by the ForCES protocol.  The LFB is a well defined,
   logically separable functional block that resides in an FE and is
   controlled by the CE via ForCES protocol.  The LFB may reside at the
   FE's datapath and process packets or may be purely an FE control or
   configuration entity that is operated on by the CE.  Note that the
   LFB is a functionally accurate abstraction of the FE's processing
   capabilities, but not a hardware-accurate representation of the FE
   implementation.

   LFB (Logical Function Block) and LFB Instance -- LFBs are categorized
   by LFB Classes(or Types).  An LFB Instance represents an LFB Class
   (or Type) existence.  There may be multiple instances of the same LFB
   Class (or Type) in an FE.  An LFB Class is represented by an LFB
   Class ID, and an LFB Instance is represented by an LFB Instance ID.
   As a result, an LFB Class ID associated with an LFB Instance ID
   uniquely specify an LFB existence.

   LFB Metadata -- Metadata is used to communicate per-packet state from
   one LFB to another, but is not sent across the network.  The FE model
   defines how such metadata is identified, produced and consumed by the
   LFBs.  It defines the functionality but not how metadata is encoded
   within an implementation.

   LFB Attribute -- Operational parameters of the LFBs that must be
   visible to the CEs are conceptualized in the FE model as the LFB
   attributes.  The LFB attributes include, for example, flags, single
   parameter arguments, complex arguments, and tables that the CE can
   read or/and write via the ForCES protocol (see below).

   LFB Topology -- Representation of how the LFB instances are logically
   interconnected and placed along the datapath within one FE.



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   Sometimes it is also called intra-FE topology, to be distinguished
   from inter-FE topology.

   FE Topology -- A representation of how the multiple FEs within a
   single NE are interconnected.  Sometimes this is called inter-FE
   topology, to be distinguished from intra-FE topology (i.e., LFB
   topology).

   Inter-FE Topology -- See FE Topology.

   Intra-FE Topology -- See LFB Topology.

   ForCES Protocol - While there may be multiple protocols used within
   the overall ForCES architecture, the term "ForCES protocol" and
   "protocol" refer to the Fp reference point in the ForCES Framework in
   [RFC3746].  This protocol does not apply to CE-to-CE communication,
   FE-to-FE communication, or to communication between FE and CE
   managers.  Basically, the ForCES protocol works in a master-slave
   mode in which FEs are slaves and CEs are masters.  This document
   defines the specifications for this ForCES protocol.

   ForCES Protocol Layer (ForCES PL) -- A layer in ForCES protocol
   architecture that defines the ForCES protocol messages, the protocol
   state transfer scheme, as well as the ForCES protocol architecture
   itself (including requirements of ForCES TML (see below)).
   Specifications of ForCES PL are defined by this document.

   ForCES Protocol Transport Mapping Layer (ForCES TML) -- A layer in
   ForCES protocol architecture that uses the capabilities of existing
   transport protocols to specifically address protocol message
   transportation issues, such as how the protocol messages are mapped
   to different transport media (like TCP, IP, ATM, Ethernet, etc), and
   how to achieve and implement reliability, multicast, ordering, etc.
   The ForCES TML specifications are detailed in separate ForCES
   documents, one for each TML.
















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4.  Overview

   The reader is referred to the Framework document [RFC3746], and in
   particular sections 3 and 4, for an architectural overview and an
   explanation of how the ForCES protocol fits in.  There may be some
   content overlap between the framework document and this section in
   order to provide clarity.

4.1.  Protocol Framework

   Figure 1 below is reproduced from the Framework document for clarity.
   It shows a NE with two CEs and two FEs.

                            ---------------------------------------
                            | ForCES Network Element              |
     --------------   Fc    | --------------      --------------  |
     | CE Manager |---------+-|     CE 1   |------|    CE 2    |  |
     --------------         | |            |  Fr  |            |  |
           |                | --------------      --------------  |
           | Fl             |         |  |    Fp       /          |
           |                |       Fp|  |----------| /           |
           |                |         |             |/            |
           |                |         |             |             |
           |                |         |     Fp     /|----|        |
           |                |         |  /--------/      |        |
     --------------     Ff  | --------------      --------------  |
     | FE Manager |---------+-|     FE 1   |  Fi  |     FE 2   |  |
     --------------         | |            |------|            |  |
                            | --------------      --------------  |
                            |   |  |  |  |          |  |  |  |    |
                            ----+--+--+--+----------+--+--+--+-----
                                |  |  |  |          |  |  |  |
                                |  |  |  |          |  |  |  |
                                  Fi/f                   Fi/f

          Fp: CE-FE interface
          Fi: FE-FE interface
          Fr: CE-CE interface
          Fc: Interface between the CE Manager and a CE
          Ff: Interface between the FE Manager and an FE
          Fl: Interface between the CE Manager and the FE Manager
          Fi/f: FE external interface

   Figure 1: ForCES Architectural Diagram

   The ForCES protocol domain is found in the Fp Reference Point.  The
   Protocol Element configuration reference points, Fc and Ff also play
   a role in the booting up of the ForCES Protocol.  The protocol



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   element configuration (indicated by reference points Fc, Ff, and Fl)
   is out of scope of the ForCES protocol but is touched on in this
   document in discussion of FEM and CEM since it is an integral part of
   the protocol pre-association phase.

   Figure 2 below shows further breakdown of the Fp interface by example
   of an MPLS QoS enabled Network Element.

         -------------------------------------------------
         |       |       |       |       |       |       |
         |OSPF   |RIP    |BGP    |RSVP   |LDP    |. . .  |
         |       |       |       |       |       |       |
         -------------------------------------------------    CE
         |               ForCES Interface                |
         -------------------------------------------------
                                 ^   ^
                                 |   |
                         ForCES  |   |data
                         control |   |packets
                         messages|   |(e.g., routing packets)
                                 |   |
                                 v   v
         -------------------------------------------------
         |               ForCES Interface                |
         -------------------------------------------------    FE
         |       |       |       |       |       |       |
         |LPM Fwd|Meter  |Shaper |MPLS   |Classi-|. . .  |
         |       |       |       |       |fier   |       |
         -------------------------------------------------

   Figure 2: Examples of CE and FE functions

   The ForCES Interface shown in Figure 2 constitutes two pieces: the PL
   layer and the TML layer.

















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   This is depicted in Figure 3 below.

         +------------------------------------------------
         |               CE PL layer                     |
         +------------------------------------------------
         |              CE TML layer                     |
         +------------------------------------------------
                                   ^
                                   |
                      ForCES       |   (i.e  ForCES data + control
                      PL           |    packets )
                      messages     |
                      over         |
                      specific     |
                      TML          |
                      encaps       |
                      and          |
                      transport    |
                                   |
                                   v
         +------------------------------------------------
         |              FE TML layer                     |
         +------------------------------------------------
         |               FE PL layer                     |
         +------------------------------------------------

   Figure 3: ForCES Interface

   The PL layer is in fact the ForCES protocol.  Its semantics and
   message layout are defined in this document.  The TML Layer is
   necessary to connect two ForCES PL layers as shown in Figure 3 above.
   The TML is out of scope for this document but is within scope of
   ForCES.  This document defines requirements the PL needs the TML to
   meet.

   Both the PL and the TML layers are standardized by the IETF.  While
   only one PL layer is defined, different TMLs are expected to be
   standardized.  To interoperate the TML layer at the CE and FE are
   expected to conform to the same definition.

   On transmit, the PL layer delivers its messages to the TML layer.
   The TML layer delivers the message to the destination TML layer(s).
   On receive, the TML delivers the message to its destination PL
   layer(s).

4.1.1.  The PL layer

   The PL is common to all implementations of ForCES and is standardized



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   by the IETF as defined in this document.  The PL layer is responsible
   for associating an FE or CE to an NE.  It is also responsible for
   tearing down such associations.  An FE uses the PL layer to transmit
   various subscribed-to events to the CE PL layer as well as to respond
   to various status requests issued from the CE PL.  The CE configures
   both the FE and associated LFBs' operational parameters using the PL
   layer.  In addition the CE may send various requests to the FE to
   activate or deactivate it, reconfigure its HA parameterization,
   subscribe to specific events etc.  More details can be found in
   Section 7.

4.1.2.  The TML layer

   The TML layer transports the PL layer messages.  The TML is where the
   issues of how to achieve transport level reliability, congestion
   control, multicast, ordering, etc. are handled.  It is expected more
   than one TML will be standardized.  The various possible TMLs could
   vary their implementations based on the capabilities of underlying
   media and transport.  However, since each TML is standardized,
   interoperability is guaranteed as long as both endpoints support the
   same TML.  All ForCES Protocol Layer implementations MUST be portable
   across all TMLs, because all TMLs MUST have the top edge semantics
   defined in this document.

4.1.3.  The FEM/CEM Interface

   The FEM and CEM components, although valuable in the setup and
   configurations of both the PL and TML layers, are out of scope of the
   ForCES protocol.  The best way to think of them are as
   configurations/parameterizations for the PL and TML before they
   become active (or even at runtime based on implementation).  In the
   simplest case, the FE or CE read a static configuration file.  RFC
   3746 has a more detailed descriptions on how the FEM and CEM could be
   used.  The pre-association phase, where the CEM and FEM can be used,
   are described briefly in Section 4.2.1.

   An example of typical of things the FEM/CEM could configure would be
   TML specific parameterizations such as:

   a.  how the TML connection should happen (for example what IP
       addresses to use, transport modes etc);

   b.  Issuing the ID for the FE or CE would also be issued during the
       pre-association phase.

   c.  Security parameterization such as keys etc.





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   d.  Connection association parameters

   Example of this might be:

   o  simple parameters: send up to 3 association messages every 1
      second

   o  or more complex parameters: send up to 4 association messages with
      increasing exponential timeout

4.2.  ForCES Protocol Phases

   ForCES, in relation to NEs, involves two phases: the Pre-Association
   phase where configuration/initialization/bootup of the TML and PL
   layer happens, and the association phase where the ForCES protocol
   operates to manipulate the parameters of the FEs.


           FE start            CE configures
            -------+    +--->---->---->---->------->----+
                   |    |                               Y
                   Y    |                               |
                   |    |                               Y
                 +------+--+                        +--------+
                 | FE      |                        | FE     |
                 | DOWN    |                        | UP     |
                 | State   |                        | State  |
                 |         |                        |        |
                 +---------+                        +--------+
                      ^                                  Y
                      |                                  |
                      +-<---<------<-----<------<----<---+
                       CE configures or FE loses association


   Figure 4: The FE State Machine

   The FE can only be in one of two states as indicated above.  When the
   FE is in the DOWN state, it is not forwarding packets.  When the FE
   is in the UP state it may be forwarding packets depending on the
   configuration of its specific LFBs.

   CE configures FE states transitions by means of a so-called FEObject
   LFB, which is defined in [FE-MODEL] and also explained in Section
   4.3.3 of this document.  In FEObject LFB, FE state is defined as an
   attribute of the LFB, and CE configuration of the FE state equals CE
   configuration of this attribute.  Note that even in the FE DOWN
   state, the FEObject LFB itself is active.



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   On start up the FE is in the DOWN state unless it is explicitly
   configured by the CE to transition to the UP state via an FE Object
   admin action.  This must be done before configuring any other LFBs
   that affect packet forwarding.

   The FE transitions from the UP state to the DOWN state when it
   receives a FEObject Admin Down action or when it loses its
   association with the CE.  For the FE to properly complete the
   transition to the DOWN state, it MUST stop Packet forwarding and this
   may impact multiple LFBS.  How this is achieved is outside the scope
   of this specification.

   Note: in the case of loss of association, the FE can also be
      configured to not go to the DOWN state.

   For the FE to properly complete the transition to the DOWN state it
   must stop packet forwarding and that this may affect multiple LFBs.
   How this is achieved is outside the scope of this specification.

4.2.1.  Pre-association

   The ForCES interface is configured during the pre-association phase.
   In a simple setup, the configuration is static and is read from a
   saved configuration file.  All the parameters for the association
   phase are well known after the pre-association phase is complete.  A
   protocol such as DHCP may be used to retrieve the configuration
   parameters instead of reading them from a static configuration file.
   Note, this will still be considered static pre-association.  Dynamic
   configuration may also happen using the Fc, Ff and Fl reference
   points.  Vendors may use their own proprietary service discovery
   protocol to pass the parameters.  Essentially only guidelines are
   provided here and the details are left to the implementation.



















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   The following are scenarios reproduced from the Framework Document to
   show a pre-association example.


      <----Ff ref pt--->              <--Fc ref pt------->
      FE Manager      FE                CE Manager    CE
       |              |                 |             |
       |              |                 |             |
    (security exchange)               (security exchange)
      1|<------------>| authentication 1|<----------->|authentication
       |              |                 |             |
     (FE ID, attributes)              (CE ID, attributes)
      2|<-------------| request        2|<------------|request
       |              |                 |             |
      3|------------->| response       3|------------>|response
      (corresponding CE ID)          (corresponding FE ID)
       |              |                 |             |
       |              |                 |             |

   Figure 5: Examples of a message exchange over the Ff and Fc reference
   points


      <-----------Fl ref pt-------------->            |

      FE Manager      FE               CE Manager     CE
       |              |                 |             |
       |              |                 |             |
      (security exchange)               |             |
      1|<------------------------------>|             |
       |              |                 |             |
      (a list of CEs and their attributes)            |
      2|<-------------------------------|             |
       |              |                 |             |
      (a list of FEs and their attributes)            |
      3|------------------------------->|             |
       |              |                 |             |
       |              |                 |             |

   Figure 6: An example of a message exchange over the Fl reference
   point

   Before the transition to the association phase, the FEM will have
   established contact with a CEM component.  Initialization of the
   ForCES interface will have completed, and authentication as well as
   capability discovery may be complete.  Both the FE and CE would have
   the necessary information for connecting to each other for
   configuration, accounting, identification and authentication



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   purposes.  To summarize, at the completion of this stage both sides
   have all the necessary protocol parameters such as timers, etc.  The
   Fl reference point may continue to operate during the association
   phase and may be used to force a disassociation of an FE or CE.
   Because the pre-association phase is out of scope, these details are
   not discussed any further in this specification.  The reader is
   referred to the framework document [RFC3746] for a slightly more
   detailed discussion.

4.2.2.  Post-association

   In this phase, the FE and CE components communicate with each other
   using the ForCES protocol (PL over TML) as defined in this document.
   There are three sub-phases:

   o  Association Setup stage

   o  Established Stage

   o  Association Lost stage

4.2.2.1.  Association Setup stage

   The FE attempts to join the NE.  The FE may be rejected or accepted.
   Once granted access into the NE, capabilities exchange happens with
   the CE querying the FE.  Once the CE has the FE capability
   information, the CE can offer an initial configuration (possibly to
   restore state) and can query certain attributes within either an LFB
   or the FE itself.

   More details are provided in Section 8.

   On successful completion of this stage, the FE joins the NE and is
   moved to the Established State.

4.2.2.2.  Association Established stage

   In this stage the FE is continuously updated or queried.  The FE may
   also send asynchronous event notifications to the CE or synchronous
   heartbeat notifications if programmed to do so.  This continues until
   a termination occurs because of loss of connectivity or is initiated
   by either the CE or the FE.

   Refer to section on protocol scenarios, Section 8, for more details.

4.2.2.3.  Association Lost stage

   In this state, both or either the CE or FE declare the other side is



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   no longer associated.  The disconnection could be physically
   initiated by either party for administrative purposes but may also be
   driven by operational reasons such as loss of connectivity.

   It should be noted that loss of connectivity between TMLs is not
   necessarily indicative of loss of association between respective PL
   layers unless the programmed FE Protocol Object time limit is
   exceeded.  In other words if the TML repairs the transport loss
   before then, the association would still be valid.

   When an association is lost between a CE and FE, the FE continues to
   operate as instructed by the CE via the CE failover policy (for
   further discussion refer to Section 9 and Appendix B).

   For this version of the protocol (as defined in this document), the
   FE, upon re-association, MUST discard any state it has as invalid and
   retrieve new state.  This approach is motivated by a desire for
   simplicity (as opposed to efficiency).

4.3.  Protocol Mechanisms

   Various semantics are exposed to the protocol users via the PL header
   including: transaction capabilities, atomicity of transactions, two
   phase commits, batching/parallelization, high availability and
   failover as well as command windows.

   The EM (Execute Mode) flag, AT (Atomic Transaction) flag, and TP
   (Transaction Phase) flag as defined in Common Header Section (Section
   6.1) are relevant to these mechanisms.

4.3.1.  Transactions, Atomicity, Execution and Responses

   In the master-slave relationship the CE instructs one or more FEs on
   how to execute operations and how to report the results.

   This section details the different modes of execution that a CE can
   order the FE(s) to perform as defined in Section 4.3.1.1.  It also
   describes the different modes a CE can ask the FE(s) to use for
   formatting the responses after processing the operations as
   requested.  These modes relate to the transactional two phase
   commitment operations.

4.3.1.1.  Execution

   There are 3 execution modes that can be requested for a batch of
   operations spanning one or more LFB selectors in one protocol
   message.  The EM flag defined in Common Header Section (Section 6.1)
   selects the execution mode for a protocol message, as below:



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   a.  execute-all-or-none

   b.  execute-until-failure

   c.  continue-execute-on-failure

4.3.1.1.1.  execute-all-or-none

   When set to this mode, independent operations in a message targeted
   at one or more LFB selectors will all be executed if no failure
   occurs for any of the operations.  If there is any failure for any of
   the operations then none of the operations will be executed, i.e
   there is roll back for this mode of operation.

4.3.1.1.2.  continue-execute-on-failure

   If several independent operations are targeted at one or more LFB
   selectors, execution continues for all operations at the FE even if
   one or more operations fail.

4.3.1.1.3.  execute-until-failure

   In this mode all operations are executed on the FE sequentially until
   the first failure.  The rest of the operations are not executed but
   operations already completed are not undone, i.e. there is no roll
   back in this mode of operation.

4.3.1.2.  Transaction and Atomicity

4.3.1.2.1.  Transaction Definition

   A transaction is defined as a collection of one or more ForCES
   operations within one or more PL messages that MUST meet the ACIDity
   properties[ACID], defined as:

   Atomicity:   In a transaction involving two or more discrete pieces
                of information, either all of the pieces are committed
                or none are.

   Consistency:  A transaction either creates a new and valid state of
                data, or, if any failure occurs, returns all data to the
                state it was in before the transaction was started.

   Isolation:   A transaction in process and not yet committed must
                remain isolated from any other transaction.






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                Committed data is saved by the system such that, even in
                the event of a failure and a system restart, the data is
                available in its correct state.

   There are cases where the CE knows exact memory and implementation
   details of the FE such as in the case of an FE-CE pair from the same
   vendor where the FE-CE pair is tightly coupled.  In such a case, the
   transactional operations may be simplified further by extra
   computation at the CE.  This view is not discussed further other than
   to mention that it is not disallowed.

   As defined above, a transaction is always atomic and MAY be

   a.  Within an FE alone
       Example: updating multiple tables that are dependent on each
       other.  If updating one fails, then any that were already updated
       must be undone.

   b.  Distributed across the NE
       Example: updating table(s) that are inter-dependent across
       several FEs (such as L3 forwarding related tables).

4.3.1.2.2.  Transaction protocol

   By use of the execute mode as defined in Section 4.3.1.1, the
   protocol has provided a mechanism for transactional operations within
   one stand-alone message.  The 'execute-all-or-none' mode can meet the
   ACID requirements.

   For transactional operations of multiple messages within one FE or
   across FEs, a classical transactional protocol known as Two Phase
   Commit (2PC) [2PCREF] is supported by the protocol to achieve the
   transactional operations.

   The AT flag and the TP flag in Common Header (Section 6.1) are
   provided for 2PC based transactional operations spanning multiple
   messages.

   The AT flag, when set, indicates this message belongs to an Atomic
   Transaction.  All messages for a transaction operation must have the
   AT flag set.  If not set, it means the message is a stand-alone
   message and does not participate in any transaction operation that
   spans multiple messages.

   The TP flag indicates the Transaction Phase this message belongs to.
   There are four (4) possible phases for an transactional operation
   known as:




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      SOT (Start of Transaction)

      MOT (Middle of Transaction)

      EOT (End of Transaction)

      ABT (Abort)

   A transaction operation is started with a message the TP flag is set
   to Start of Transaction (SOT).  Multi-part messages, after the first
   one, are indicated by the Middle of Transaction flag (MOT).  The last
   message is indicated by by EOT.

      Any failure notified by the FE causes the CE to execute an Abort
      Transaction (ABT) to all FEs involved in the transaction, rolling
      back all previously executed operations in the transaction.

      The transaction commitment phase is signaled from the CE to the FE
      by an End of Transaction (EOT) configuration message.  The FE MUST
      respond to the CE's EOT message.  If no response is received from
      the FE within a specified timeout, the transaction MUST be aborted
      by the CE.

   Note that a transactional operation is generically atomic, therefore
   it requires that the execute modes of all messages in a transaction
   operation should always be kept the same and be set to 'execute-all-
   or-none'.  If the EM flag is set to other execute modes, it will
   result in a transaction failure.

   As noted above, a transaction may span multiple messages.  It is up
   to the CE to keep track of the different outstanding messages making
   up a transaction.  As an example, the correlator field could be used
   to mark transactions and a sequence field to label the different
   messages within the same atomic transaction, but this is out of scope
   and up to implementations.

4.3.1.2.3.  Recovery

   Any of the participating FEs, or the CE, or the associations between
   them, may fail after the EOT response message has been sent by the FE
   but before it has received all the responses, e.g. if the EOT
   response never reaches the CE.

   In this protocol revision, for sake of simplicity as indicated in
   Section 4.2.2.3, an FE losing an association would be required to get
   entirely new state from the newly associated CE upon a re-
   association.  The decision on what an FE should do after a lost
   association is dictated by the CE Failover policy (refer to Section 9



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   and Section 7.2).

4.3.2.  Scalability

   It is desirable that the PL layer not become the bottleneck when
   larger bandwidth pipes become available.  To pick a hypothetical
   example in today's terms, if a 100Gbps pipe is available and there is
   sufficient work then the PL layer should be able to take advantage of
   this and use all of the 100Gbps pipe.  Two mechanisms have been
   provided to achieve this.  The first one is batching and the second
   one is a command window.

   Batching is the ability to send multiple commands (such as Config) in
   one Protocol Data Unit (PDU).  The size of the batch will be affected
   by, amongst other things, the path MTU.  The commands may be part of
   the same transaction or may be part of unrelated transactions that
   are independent of each other.

   Command windowing allows for pipelining of independent transactions
   which do not affect each other.  Each independent transaction could
   consist of one or more batches.

4.3.2.1.  Batching

   There are several batching levels at different protocol hierarchies.

   o  multiple PL PDUs can be aggregated under one TML message

   o  multiple LFB classes and instances (as indicated in the LFB
      selector) can be addressed within one PL PDU

   o  Multiple operations can be addressed to a single LFB class and
      instance

4.3.2.2.  Command Pipelining

   The protocol allows any number of messages to be issued by the CE
   before the corresponding acknowledgments (if requested) have been
   returned by the FE.  Hence pipelining is inherently supported by the
   protocol.  Matching responses with requests messages can be done
   using the correlator field in the message header.

4.3.3.  Heartbeat Mechanism

   Heartbeats (HB) between FEs and CEs are traffic sensitive.  An HB is
   sent only if no PL traffic is sent between the CE and FE within a
   configured interval.  This has the effect of reducing the amount of
   HB traffic in the case of busy PL periods.



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   An HB can be sourced by either the CE or FE.  When sourced by the CE,
   a response can be requested (similar to the ICMP ping protocol).  The
   FE can only generate HBs in the case of being configured to do so by
   the CE.  Refer to Section 7.2.1 and Section 7.9 for details.

4.3.4.  FE Object and FE protocol LFBs

   All PL messages operate on LFB constructs as this provides more
   flexibility for future enhancements.  This means that maintenance and
   configurability of FEs, NE, as well as the ForCES protocol itself
   must be expressed in terms of this LFB architecture.  For this reason
   special LFBs are created to accommodate this need.

   In addition, this shows how the ForCES protocol itself can be
   controlled by the very same type of structures (LFBs) it uses to
   control functions such as IP forwarding, filtering, etc.

   To achieve this, the following specialized LFBs are introduced:

   o  FE Protocol LFB which is used to control the ForCES protocol.

   o  FE Object LFB which is used to controls attributes relative to the
      FE itself.  Such attributes include FEState [FE-MODEL], vendor,
      etc.

   These LFBs are detailed in Section 7.2.

























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5.  TML Requirements

   The requirements below are expected to be delivered by the TML.  This
   text does not define how such mechanisms are delivered.  As an
   example they could be defined to be delivered via hardware or between
   2 or more TML processes on different CEs or FEs in protocol level
   schemes.

   Each TML must describe how it contributes to achieving the listed
   ForCES requirements.  If for any reason a TML does not provide a
   service listed below a justification needs to be provided.

   1.  Reliability
       As defined by RFC 3654, section 6 #6.

   2.  Security
       TML provides security services to the ForCES PL.  TML layer
       should support the following security services and describe how
       they are achieved.

       *  Endpoint authentication of FE and CE.

       *  Message Authentication

       *  Confidentiality service

   3.  Congestion Control
       The congestion control scheme used needs to be defined.  The
       congestion control mechanism defined by the TML should prevent
       the FE from being overloaded by the CE or the CE from being
       overwhelmed by traffic from the FE.  Additionally, the
       circumstances under which notification is sent to the PL to
       notify it of congestion must be defined.

   4.  Uni/multi/broadcast addressing/delivery if any
       If there is any mapping between PL and TML level Uni/Multi/
       Broadcast addressing it needs to be defined.

   5.  HA decisions
       It is expected that availability of transport links is the TML's
       responsibility.  However, on config basis, the PL layer may wish
       to participate in link failover schemes and therefore the TML
       must support this capability.
       Please refer to Section 9 for details.

   6.  Encapsulations used.
       Different types of TMLs will encapsulate the PL messages on
       different types of headers.  The TML needs to specify the



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       encapsulation used.

   7.  Prioritization
       It is expected that the TML will be able to handle up to 8
       priority levels needed by the PL layer and will provide
       preferential treatment.
       While the TML needs to define how this is achieved, it should be
       noted that the requirement for supporting up to 8 priority levels
       does not mean that the underlying TML MUST be capable of
       providing up to 8 actual priority levels.  In the event that the
       underlying TML layer does not have support for 8 priority levels,
       the supported priority levels should be divided between the
       available TML priority levels.  For example, if the TML only
       supports 2 priority levels, the 0-3 could go in one TML priority
       level, while 4-7 could go in the other.

   8.  Protection against DoS attacks
       As described in the Requirements RFC 3654, section 6

5.1.  TML Parameterization

   It is expected that it should be possible to use a configuration
   reference point, such as the FEM or the CEM, to configure the TML.

   Some of the configured parameters may include:

   o  PL ID

   o  Connection Type and associated data.  For example if a TML uses
      IP/TCP/UDP then parameters such as TCP and UDP ports, IP addresses
      need to be configured.

   o  Number of transport connections

   o  Connection Capability, such as bandwidth, etc.

   o  Allowed/Supported Connection QoS policy (or Congestion Control
      Policy)













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6.  Message encapsulation

   All PL layer PDUs start with a common header [Section 6.1] followed
   by a one or more TLVs [Section 6.2] which may nest other TLVs
   [Section 6.2.1].  All fields are in network byte order.

6.1.  Common Header

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |version| rsvd  | Message Type  |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Source ID                            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Destination ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          Correlator                           |
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                             Flags                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 7: Common Header

   The message is 32 bit aligned.


   Version (4 bit):
       Version number.  Current version is 1.

   rsvd (4 bit):
       Unused at this point.  A receiver should not interpret this
       field.  Senders MUST set it to zero and receivers MUST ignore
       this field.

   Message Type (8 bits):
       Commands are defined in Section 7.

   Length (16 bits):
       length of header + the rest of the message in DWORDS (4 byte
       increments).

   Source ID  (32 bit):







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   Dest ID (32 bit):

       *   Each of the source and Dest IDs are 32 bit IDs which are
           unique NE-wide and which recognize the termination points of
           a ForCES PL message.

       *   IDs allow multi/broad/unicast addressing with the following
           approach:

           a.  A split address space is used to distinguish FEs from
               CEs.  Even though in a large NE there are typically two
               or more orders of magnitude more FEs than CEs, the
               address space is split uniformly for simplicity.

           b.  The address space allows up to 2^30 (over a billion) CEs
               and the same amount of FEs.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |TS |                           sub-ID                          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

               Figure 8: ForCES ID Format

           c.  The 2 most significant bits called Type Switch (TS) are
               used to split the ID space as follows:

   TS        Corresponding ID range       Assignment
   --        ----------------------       ----------
   0b00      0x00000000 to 0x3FFFFFFF     FE IDs (2^30)
   0b01      0x40000000 to 0x7FFFFFFF     CE IDs (2^30)
   0b10      0x80000000 to 0xBFFFFFFF     reserved
   0b11      0xC0000000 to 0xFFFFFFEF     multicast IDs (2^30 - 16)
   0b11      0xFFFFFFF0 to 0xFFFFFFFC     reserved
   0b11      0xFFFFFFFD                   all CEs broadcast
   0b11      0xFFFFFFFE                   all FEs broadcast
   0b11      0xFFFFFFFF                   all FEs and CEs (NE) broadcast

               Figure 9: Type Switch ID Space


       *   Multicast or broadcast IDs are used to group endpoints (such
           as CEs and FES).  As an example one could group FEs in some
           functional group, by assigning a multicast ID.  Likewise,
           subgroups of CEs that act, for instance, in a back-up mode
           may be assigned a multicast ID to hide them from the FE.




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       *   This document does not discuss how a particular multicast ID
           is associated to a given group though it could be done via
           configuration process.  The list of IDs an FE owns or is part
           of are listed on the FE Object LFB.

   Correlator (64 bits)
       This field is set by the CE to correlate ForCES Request Messages
       with the corresponding Response messages from the FE.
       Essentially it is a cookie.  The Correlator is handled
       transparently by the FE, i.e. for a particular Request message
       the FE MUST assign the same correlator value in the corresponding
       Response message.  In the case where the message from the CE does
       not elicit a response, this field may not be useful.

       The Correlator field could be used in many implementations
       specific ways by the CE.  For example, the CE could split the
       Correlator into a 32-bit transactional identifier and 32-bit
       message sequence identifier.  Another example a 64 bit pointer to
       a context block.  All such implementation specific use of the
       Correlator is outside the scope of this specification.

   Flags(32 bits):
       Identified so far:


      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   |     |     |   | |   |                                   |
      |ACK| Pri |Rsr  |EM |A|TP |     Reserved                      |
      |   |     | vd. |   |T|   |                                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Figure 10: Header Flags

       - ACK: ACK indicator(2 bit)
           The ACK indicator flag is only used by the CE when sending a
           Config Message(Section 7.5.1) or a HB message (Section 7.9)
           to indicate to the message receiver whether or not a response
           is required by the sender.  Note that for all other messages
           than the Config Message or the HB Message this flag MUST be
           ignored.

           The flag values are defined as below:






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               'NoACK' (0b00) - to indicate that the message receiver
               MUST not to send any response message back to this
               message sender.

               'SuccessACK'(0b01) - to indicate the message receiver
               MUST send a response message back only when the message
               has been successfully processed by the receiver.

               'FailureACK'(0b10) - to indicate the message receiver
               MUST send a response message back only when there is was
               failure by the receiver in processing (executing) the
               message.  In other words, if the message can be processed
               successfully, the sender will not expect any response
               from the receiver.

               'AlwaysACK' (0b11) - to indicate the message receiver
               MUST send a response message.

           Note that in above definitions, the term success implies a
           complete execution without any failure of the message.
           Anything else than a complete successful execution is defined
           as a failure for the message processing.  As a result, for
           the execution modes (defined in Section 4.3.1.1) like
           execute-all-or-none, execute-until-failure, and continue-
           execute-on-failure, if any single operation among several
           operations in the same message fails, it will be treated as a
           failure and result in a response if the ACK indicator has
           been set to 'FailureACK' or 'AlwaysACK'.

           Also note that, other than in Config and HB Messages,
           requirements for responses of messages are all given in a
           default way rather than by ACK flags.  The default
           requirements of these messages and the expected responses are
           summarized below.  Detailed descriptions can be found in the
           individual message definitions:

           +   Association Setup Message always expects a response.

           +   Association Teardown Message, and Packet Redirect
               Message, never expect responses.

           +   Query Message always expects a response.

           +   Response messages never expect further responses.







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       - Pri: Priority (3 bits)
           ForCES protocol defines 8 different levels of priority (0-7).
           The priority level can be used to distinguish between
           different protocol message types as well as between the same
           message type.  For example, the REDIRECT PACKET message could
           have different priorities to distinguish between Routing
           protocols packets and ARP packets being redirected from FE to
           CE.  The Normal priority level is 1.

       - EM: Execution mode (2 bits)
           There are 3 execution modes refer to Section 4.3.1.1 for
           details.

               Reserved..................... (0b00)

               `execute-all-or-none` ....... (0b01)

               `execute-until-failure` ..... (0b10)

               `continue-execute-on-failure` (0b11)

       - AT  Atomic Transaction (1 bit)
           This flag indicates if the message is stand-alone message or
           one of multiple messages that belongs to 2PC transaction
           operations.  See Section 4.3.1.2.2 for details.

               Stand-alone message ......... (0b0)

               2PC transaction message ..... (0b1)

       - TP: Transaction phase (2 bits)
           A message from the CE to the FE within a transaction could be
           indicative of the different phases the transaction is in.
           Refer to Section 4.3.1.2.2 for details.

               SOT (start of transaction) ..... (0b00)

               MOT (Middle of transaction) .... (0b01)

               EOT (end of transaction) ........(0b10)

               ABT (abort) .....................(0b11)









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6.2.  Type Length Value(TLV) Structuring


   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | TLV Type                    | variable TLV Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            Value (Data of size TLV length)                    |
   ~                                                               ~
   ~                                                               ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 11: TLV Representation

   TLV Type (16):
                    The TLV type field is two octets, and indicates the
                    type of data encapsulated within the TLV.

   TLV Length (16):
                    The TLV Length field is two octets, and indicates
                    the length of this TLV including the TLV Type, TLV
                    Length, and the TLV data in octets.

   TLV Value (variable):
                    The TLV Value field carries the data.  For
                    extensibility, the TLV value may in fact be a TLV.
                    TLVs must be 32 bit aligned.

6.2.1.  Nested TLVs

   TLV values can be other TLVs.  This provides the benefits of protocol
   flexibility (being able to add new extensions by introducing new TLVs
   when needed).  The nesting feature also allows for an conceptual
   optimization with the XML LFB definitions to binary PL representation
   (represented by nested TLVs).

6.2.2.  Scope of the T in TLV

   The "Type" values in the TLV are global in scope.  This means that
   wherever TLVs occur in the PDU, a specific Type value refers to the
   same Type of TLV.  This is a design choice that was made to ease
   debugging of the protocol.

6.3.  ILV

   A slight variation of the TLV known as the ILV.  This sets the type



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   ("T") to be a 32-bit local index that refers to a ForCES element ID.
   The Length part of the ILV is fixed at 32 bits.

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Identifier                             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Length                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Value                                  |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 12: ILV Representation

   It should be noted that the "I" values are of local scope and are
   defined by the data declarations from the LFB definition.  Refer to
   Section 7.1.1.1.8 for discussions on usage of ILVs.


































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7.  Protocol Construction

7.1.  Protocol Grammar

   The protocol construction is formally defined using a BNF-like syntax
   to describe the structure of the PDU layout.  This is matched to a
   precise binary format later in the document.

   Since the protocol is very flexible and hierarchical in nature, it is
   easier at times to see the visualization layout.  This is provided in
   Section 7.1.2

7.1.1.  Protocol BNF

   The format used is based on RFC 2234.  The terminals of this grammar
   are flags, IDcount, IDs, KEYID, and encoded data, described after the
   grammar.

   1.  A TLV will have the word "-TLV" suffix at the end of its name

   2.  An ILV will have the word "-ILV" suffix at the end of its name

   3.  / is used to separate alternatives

   4.  parenthesized elements are treated as a single item

   5.  * before an item indicates 0 or more repetitions

   6.  1* before an item indicates 1 or more repetitions

   7.  [] around an item indicates that it is optional (equal to *1)

   The BNF of the PL level PDU is as follows:


















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   PL level PDU := MAINHDR [MAIN-TLV]
   MAIN-TLV := [LFBselect-TLV] / [REDIRECT-TLV] /
               [ASResult-TLV] / [ASTreason-TLV]
   LFBselect-TLV :=   LFBCLASSID LFBInstance OPER-TLV
   OPER-TLV := 1*PATH-DATA-TLV
   PATH-DATA-TLV := PATH  [DATA]
   PATH := flags IDcount IDs [SELECTOR]
   SELECTOR :=  KEYINFO-TLV
   DATA := FULLDATA-TLV / SPARSEDATA-TLV / RESULT-TLV /
          1*PATH-DATA-TLV
   KEYINFO-TLV := KEYID FULLDATA-TLV
   SPARSEDATA-TLV := encoded data that may have optionally
                     appearing elements
   FULLDATA-TLV := encoded data element which may nest
                   further FULLDATA-TLVs
   RESULT-TLV := Holds result code and optional FULLDATA-TLV


   Figure 13: BNF of PL level PDU

   o  MAINHDR defines a message type, Target FE/CE ID etc.  The MAINHDR
      also defines the content.  As an example the content of a "config"
      message would be different from an "association" message.

   o  MAIN-TLV is one of several TLVs that could follow the Mainheader.
      The appearance of these TLVs is message type specific.

   o  LFBCLASSID is a 32 bit unique identifier per LFB class defined at
      class Definition time.

   o  LFBInstance is a 32 bit unique instance identifier of an LFB class

   o  OPER-TLV uses the Type field in the TLV to uniquely identify the
      type of operation i.e one of {SET, GET, DEL,etc.} depending on the
      message type.

   o  PATH-DATA-TLV identifies the exact element targeted and may have
      zero or more paths associated with it.  The last PATH-DATA-TLV in
      the case of nesting of paths via the DATA construct in the case of
      SET requests and GET response is terminated by encoded data or
      response in the form of either FULLDATA-TLV or SPARSEDATA-TLV or
      RESULT-TLV.

   o  PATH provides the path to the data being referenced.

      *  flags (16 bits) are used to further refine the operation to be
         applied on the Path.  More on these later.




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      *  IDcount(16 bit): count of 32 bit IDs

      *  IDs: zero or more 32bit IDs (whose count is given by IDcount)
         defining the main path.  Depending on the flags, IDs could be
         field IDs only or a mix of field and dynamic IDs.  Zero is used
         for the special case of using the entirety of the containing
         context as the result of the path.

   o  SELECTOR is an optional construct that further defines the PATH.
      Currently, the only defined selector is the KEYINFO-TLV, used for
      selecting an array entry by the value of a key field.  The
      presence of a SELECTOR is correct only when the flags also
      indicate its presence.  A mismatch is a protocol format error.

   o  A KEYINFO TLV contains information used in content keying.

      *  A KeyID is used in a KEYINFO TLV.  It indicates which key for
         the current array is being used as the content key for array
         entry selection.

      *  The key's data is the data to look for in the array, in the
         fields identified by the key field.  The information is encoded
         according to the rules for the contents of a FULLDATA-TLV, and
         represent the field or fields which make up the key identified
         by the KEYID.

   o  DATA may contain a FULLDATA-TLV, SPARSEDATA-TLV, a RESULT-TLV or 1
      or more further PATH-DATA selection.  FULLDATA and SPARSEDATA are
      only allowed on SET requests, or on responses which return content
      information (GET-RESPONSE for example).  PATH-DATA may be included
      to extend the path on any request.

      *  Note: Nested PATH-DATA TLVs are supported as an efficiency
         measure to permit common subexpression extraction.

      *  FULLDATA and SPARSEDATA contain "the data" whose path has been
         selected by the PATH.  Refer to Section 7.1.1.1 for details.

   o  RESULT contains the indication of whether the individual SET
      succeeded.  If there is an indication for verbose response, then
      SET-RESPONSE will also contain the FULLDATA TLV showing the data
      that was set.  RESULT-TLV is included on the assumption that
      individual parts of a SET request can succeed or fail separately.

   In summary this approach has the following characteristic:

   o  There can be one or more LFB Class + InstanceId combination
      targeted in a message (batch)



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   o  There can one or more operations on an addressed LFB classid+
      instanceid combination (batch)

   o  There can be one or more path targets per operation (batch)

   o  Paths may have zero or more data values associated (flexibility
      and operation specific)

   It should be noted that the above is optimized for the case of a
   single classid+instance targeting.  To target multiple instances
   within the same class, multiple LFBselect are needed.

7.1.1.1.  Discussion on Grammar

   In the case of FULLDATA encoding, data is packed in such a way that a
   receiver of such data with knowledge of the path can correlate what
   it means by inferring in the LFB definition.  This is an optimization
   that helps reducing the amount of description for the data in the
   protocol.

   In other words:

   It is assumed that the type of the data can be inferred by the
   context in which data is used.  Hence, data will not include its type
   information.  The basis for the inference is typically the LFB class
   id and the path.

   It is expected that a substantial number of operations in ForCES will
   need to reference optional data within larger structures.  For this
   reason, the SPARSEDATA encoding is introduced to make it easier to
   encapsulate optionally appearing data elements.

7.1.1.1.1.  Data Packing Rules

   The scheme for encoding data used in this doc adheres to the
   following rules:

   o  The Value ("V" of TLV) of FULLDATA TLV will contain the data being
      transported.  This data will be as was described in the LFB
      definition.

   o  Variable sized data within a FULLDATA TLV will be encapsulated
      inside another FULLDATA TLV inside the V of the outer TLV.  For
      example of such a setup refer to Appendix D and Appendix C.

   o  In the case of FULLDATA TLVs:





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      *  When a table is referred to in the PATH (ids) of a PATH-DATA-
         TLV, then the FULLDATA's "V" will contain that table's row
         content prefixed by its 32 bit index/subscript.  OTOH, when
         PATH flags are 00, the PATH may contain an index pointing to a
         row in table; in such a case, the FULLDATA's "V" will only
         contain the content with the index in order to avoid ambiguity.

7.1.1.1.2.  Path Flags

   The following flags are currently defined:

   o  SELECTOR Bit: F_SELKEY indicates that a KEY Selector is present
      following this path information, and should be considered in
      evaluating the path.

   o  FIND-EMPTY Bit: This must not be set if the F_SEL_KEY bit is set.
      This must only be used on a create operation.  If set, this
      indicates that although the path identifies an array, the SET
      operation should be applied to the first unused element in the
      array.  The result of the operation will not have this flag set,
      and will have the assigned index in the path.

      Example:  For a given LFB class, the path 2.5 might select an
         array in a structure.  If one wanted to set element 6 in this
         array, then the path 2.5.6 would define that element.  However
         if one wanted to create an element in the first empty spot in
         the array, the CE would then send the TLV with the FIND-EMPTY
         bit set with the path set to 2.5.

7.1.1.1.3.  Relation of operational flags with global message flags

   Global flags, such as the execution mode and the atomicity indicators
   defined in the header, apply to all operations in a message.  Global
   flags provide semantics that are orthogonal to those provided by the
   operational flags, such as the flags defined in Path Data.  The scope
   of operational flags is restricted to the operation.

7.1.1.1.4.  Content Path Selection

   The KEYINFO TLV describes the KEY as well as associated KEY data.
   KEYs, used for content searches, are restricted and described in the
   LFB definition.

7.1.1.1.5.  LFB select TLV

   The LFB select TLV is an instance of TLV defined in Section 6.2.  The
   definition is as below:




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    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |        Type = LFBselect       |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                          LFB Class ID                         |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        LFB Instance ID                        |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Operation TLV                          |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    ~                           ...                                 ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        Operation TLV                          |
    .                                                               .
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Figure 14: PL PDU layout

   Type:
       The type of the TLV is "LFBselect"

   Length:
       Length of the TLV including the T and L fields, in octets.

   LFB Class ID:
       This field uniquely recognizes the LFB class/type.

   LFB Instance ID:
       This field uniquely identifies the LFB instance.

   Operation TLV:
       It describes an operation nested in the LFB select TLV.  Note
       that usually there SHOULD be at least one Operation TLV present
       for an LFB select TLV, but for the Association Setup Message
       defined in Section 7.4.1. the Operation TLV is optional.  In this
       case there might not be an Operation TLV followed in the LFB
       select TLV.

7.1.1.1.6.  Operation TLV

   The Operation TLV is an instance of TLV defined in Section 6.2.  It
   is assumed that specific operations are identified by the Type code
   of the TLV.  Definitions for individual Types of operation TLVs are
   in corresponding message description sections followed.

   SET and GET Requests do not have result information (they are



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   requests).  SET and GET Responses have result information.  SET and
   GET Responses use SET-RESPONSE and GET-RESPONSE operation TLVs.

   For a GET response, individual GETs which succeed will have FULLDATA
   TLVs added to the leaf paths to carry the requested data.  For GET
   elements that fail, instead of the FULLDATA TLV there will be a
   RESULT TLV.

   For a SET response, each FULLDATA or or SPARSEDATA TLV in the
   original request will be replaced with a RESULT TLV in the response.
   If the request was for Ack-fail, then only those items which failed
   will appear in the response.  If the request was for ack-all, then
   all elements of the request will appear in the response with RESULT
   TLVs.

   Note that if a SET request with a structure in a FULLDATA is issued,
   and some field in the structure is invalid, the FE will not attempt
   to indicate which field was invalid, but rather will indicate that
   the operation failed.  Note further that if there are multiple errors
   in a single leaf path-data / FULLDATA, the FE can select which error
   it chooses to return.  So if a FULLDATA for a SET of a structure
   attempts to write one field which is read only, and attempts to set
   another field to an invalid value, the FE can return whatever error
   it likes.

   A SET operation on a variable length element with a length of 0 for
   the item is not the same as deleting it.  If the CE wishes to delete
   then the DEL operation should be used whether the path refers to an
   array element or an optional structure element.

7.1.1.1.7.  Result TLV

   The RESULT TLV is an instance of TLV defined in Section 6.2.  The
   definition is as below:

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |        Type = RESULT          |               Length          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       | Result Value  |                  Reserved                     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 15: Result TLV

   The defined Result Values are






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   0 =  success

   1 =  no such object

   2 =  permission denied (e.g., trying to configure an attribute that
        is read- only)

   3 =  invalid value (the encoded data could not validly be stored in
        the field)

   4 =  invalid array creation (when the subscript in an array create is
        not allowed)

   255 =  unspecified error (for when the FE can not decide what went
        wrong)

   others =  Reserved

7.1.1.1.8.  DATA TLV

   A FULLDATA TLV has "T"= FULLDATA, and a 16bit Length followed by the
   data value/contents.  Likewise, a SPARSEDATA TLV has "T" =
   SPARSEDATA, a 16bit Length followed by the data value/contents.  In
   the case of the SPARSEDATA each element in the Value part of the TLV
   will be further encapsulated in an ILV.  Rules:

   1.  Both ILVs and TLVs MUST 32 bit aligned.  Any padding bits used
       for the alignment MUST be zero on transmission and MUST be
       ignored upon reception.

   2.  FULLDATA TLV may be used at a particular path only if every
       element at that path level is present.  This requirement holds
       whether the fields are fixed or variable length, mandatory or
       optional.

       *  If a FULLDATA TLV is used, the encoder MUST layout data for
          each element in the same order in which the data was defined
          in the LFB specification.  This ensures the decoder is
          guaranteed to retrieve the data.

       *  In the case of a SPARSEDATA, it does not need to be ordered
          since the "I" in the ILV uniquely identifies the element.

   3.  Inside a FULLDATA TLV

       *  The values for atomic, fixed-length fields are given without
          any TLV or ILV encapsulation.




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       *  The values for atomic, variable-length fields are given inside
          FULLDATA TLVs.

   4.  Inside a SPARSE TLV

       *  the values for atomic fields may be given with ILVs (32-bit
          index, 32-bit length)

   5.  Any of the FULLDATA TLVs can contain an ILV but an ILV cannot
       contain a FULLDATA.  This is because it is hard to disambiguate
       ILV since an I is 32 bit and a T is 16 bit.

   6.  A FULLDATA can also contain a FULLDATA for variable sized
       elements.  The decoding disambiguation is assumed from rule #3
       above.

7.1.1.1.9.  SET and GET Relationship

   It is expected that a GET-RESPONSE would satisfy the following:

   o  it would have exactly the same path definitions as those sent in
      the GET.  The only difference being a GET-RESPONSE will contain
      FULLDATA TLVs.

   o  it should be possible to take the same GET-RESPONSE and convert it
      to a SET-REPLACE successfully by merely changing the T in the
      operational TLV.

   o  There are exceptions to this rule:

      1.  When a KEY selector is used with a path in a GET operation,
          that selector is not returned in the GET-RESPONSE; instead the
          cooked result is returned.  Refer to the examples using KEYS
          to see this.

      2.  When dumping a whole table in a GET, the GET-RESPONSE that
          merely edits the T to be SET will end up overwriting the
          table.

7.1.2.  Protocol Visualization

   The figure below shows a general layout of the PL PDU.  A main header
   is followed by one or more LFB selections each of which may contain
   one or more operation.







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   main hdr (Config in this case)
        |
        |
        +--- T = LFBselect
        |        |
        |        +-- LFBCLASSID
        |        |
        |        |
        |        +-- LFBInstance
        |        |
        |        +-- T = SET-CREATE
        |        |   |
        |        |   +--  // one or more path targets
        |        |        // with their data here to be added
        |        |
        |        +-- T  = DEL
        |        .   |
        |        .   +--  // one or more path targets to be deleted
        |
        |
        +--- T = LFBselect
        |        |
        |        +-- LFBCLASSID
        |        |
        |        |
        |        +-- LFBInstance
        |        |
        |        + -- T= SET-REPLACE
        |        |
        |        |
        |        + -- T= DEL
        |        |
        |        + -- T= SET-REPLACE
        |
        |
        +--- T = LFBselect
                |
                +-- LFBCLASSID
                |
                +-- LFBInstance
                .
                .
                .



   Figure 16: PL PDU logical layout




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   The figure below shows an example general layout of the operation
   within a targeted LFB selection.  The idea is to show the different
   nesting levels a path could take to get to the target path.



        T = SET-CREATE
        |  |
        |  +- T = Path-data
        |       |
        |       + -- flags
        |       + -- IDCount
        |       + -- IDs
        |       |
        |       +- T = Path-data
        |          |
        |          + -- flags
        |          + -- IDCount
        |          + -- IDs
        |          |
        |          +- T = Path-data
        |             |
        |             + -- flags
        |             + -- IDCount
        |             + -- IDs
        |             + -- T = KEYINFO
        |             |    + -- KEY_ID
        |             |    + -- KEY_DATA
        |             |
        |             + -- T = FULLDATA
        |                  + -- data
        |
        |
        T = SET-REPLACE
        |  |
        |  +- T = Path-data
        |  |  |
        |  |  + -- flags
        |  |  + -- IDCount
        |  |  + -- IDs
        |  |  |
        |  |  + -- T = FULLDATA
        |  |          + -- data
        |  +- T = Path-data
        |     |
        |     + -- flags
        |     + -- IDCount
        |     + -- IDs



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        |     |
        |     + -- T = FULLDATA
        |             + -- data
        T = DEL
           |
           +- T = Path-data
                |
                + -- flags
                + -- IDCount
                + -- IDs
                |
                +- T = Path-data
                   |
                   + -- flags
                   + -- IDCount
                   + -- IDs
                   |
                   +- T = Path-data
                      |
                      + -- flags
                      + -- IDCount
                      + -- IDs
                      + -- T = KEYINFO
                      |    + -- KEY_ID
                      |    + -- KEY_DATA
                      +- T = Path-data
                           |
                           + -- flags
                           + -- IDCount
                           + -- IDs


   Figure 17: Sample operation layout

7.2.  Core ForCES LFBs

   There are two LFBs that are used to control the operation of the
   ForCES protocol and to interact with FEs and CEs:

   o  FE Protocol LFB

   o  FE Object LFB

   Although these LFBs have the same form and interface as other LFBs,
   they are special in many respects: they have fixed well-known LFB
   Class and Instance IDs.  They are statically defined (no dynamic
   instantiation allowed) and their status cannot be changed by the
   protocol: any operation to change the state of such LFBs (for



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   instance, in order to disable the LFB) must result in an error.
   Moreover, these LFBs must exist before the first ForCES message can
   be sent or received.  All attributes in these LFBs must have pre-
   defined default values.  Finally, these LFBs do not have input or
   output ports and do not integrate into the intra-FE LFB topology.


7.2.1.  FE Protocol LFB

   The FE Protocol LFB is a logical entity in each FE that is used to
   control the ForCES protocol.  The FE Protocol LFB Class ID is
   assigned the value 0x1.  The FE Protocol LFB Instance ID is assigned
   the value 0x1.  There MUST be one and only one instance of the FE
   Protocol LFB in an FE.  The values of the attributes in the FE
   Protocol LFB have pre-defined default values that are specified here.
   Unless explicit changes are made to these values using Config
   messages from the CE, these default values MUST be used for correct
   operation of the protocol.

   The formal definition of the FE Protocol LFB can be found in
   Appendix B.

   The FE Protocol LFB consists of the following elements:

   o  FE Protocol capabilities (read-only):

      *  Supported ForCES protocol version(s) by the FE

      *  Any TML capability description(s)

   o  FE Protocol attributes (can be read and set):

      *  Current version of the ForCES protocol

      *  FE unicast ID

      *  FE multicast ID(s) list - this is a list of multicast IDs that
         the FE belongs to.  These IDs are configured by the CE.

      *  CE heartbeat policy - This policy, along with the parameter 'CE
         Heartbeat Dead Interval (CE HDI)' as described below defines
         the operating parameters for the FE to check the CE liveness.
         The policy values with meanings are listed as below:

            0 (default) - This policy specifies that the CE will send a
            Heartbeat Message to the FE(s) whenever the CE reaches a
            time interval within which no other PL messages were sent
            from the CE to the FE(s); refer to Section 4.3.3 for



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            details.  The CE HDI attribute as described below is tied to
            this policy.  If the FE has not received any PL messages
            within a CE HDI period it declares the connectivity lost.
            The CE independently chooses the time interval for sending
            the Heartbeat messages to FE(s) - care must be exercised to
            ensure the CE->FE HB interval is smaller than the assigned
            CE HDI.

            CE HDI SHOULD be at least 3 times as long as the HB
            interval.  Shorter rates MAY be appropriate in
            implementations working across a reliable internal
            interface.

            1 - The CE will not generate any HB messages.  This actually
            means CE does not want the FE to check the CE liveness.

            Others - reserved.

      *  CE Heartbeat Dead Interval (CE HDI) - The time interval the FE
         uses to check the CE liveness.  If FE has not received any
         messages from CE within this time interval, FE deduces lost
         connectivity which implies that the CE is dead or the
         association to the CE is lost.  Default value 30 s.

      *  FE heartbeat policy - This policy, along with the parameter 'FE
         Heartbeat Interval (FE HI)', defines the operating parameters
         for how the FE should behave so that the CE can deduce its
         liveness.  The policy values and the meanings are:

            0(default) - The FE should not generate any Heartbeat
            messages.  In this scenario, the CE is responsible for
            checking FE liveness by setting the PL header ACK flag of
            the message it sends to AlwaysACK.  The FE responds to CE
            whenever CE sends such Heartbeat Request Message.  Refer to
            Section 7.9 and Section 4.3.3 for details.

            1 - This policy specifies that FE must actively send a
            Heartbeat Message if it reaches the time interval assigned
            by the FE HI as long as no other messages were sent from FE
            to CE during that interval as described in Section 4.3.3.

            Others - Reserved.

      *  FE Heartbeat Interval (FE HI) - The time interval the FE should
         use to send HB as long as no other messages were sent from FE
         to CE during that interval as described in Section 4.3.3.  The
         default value for an FE HI is 500ms.




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      *  Primary CEID - The CEID that the FE is associated with.

      *  Backup CEs - The list of backup CEs an FE is associated with.
         Refer to Section 9 for details.

      *  FE restart policy - This specifies the behavior of the FE
         during an FE restart.  The restart may be from an FE failure or
         other reasons that have made FE down and then need to restart.
         The values are defined as below:

            0(default)- just restart the FE from scratch.  In this case,
            the FE should start from the pre-association phase.

            1 - restart the FE from an intermediate state.  In this
            case, the FE decides from which state it restarts.  For
            example, if the FE is able to retain enough information of
            pre-association phase after some failure, it then has the
            ability to start from the post-association phase in this
            case.

            Others - Reserved

      *  CE failover policy - This specifies the behavior of the FE
         during a CE failure and restart time interval, or when the FE
         loses the CE association.  It should be noted that this policy
         in the case of HA only takes effect after total failure to
         connect to a new CE.  A timeout parameter, the CE Timeout
         Interval (CE TI) is associated with this attribute.  Values of
         this policy are defined as below:

            0(default) - The FE should continue running and do what it
            can even without an associated CE.  This basically requires
            that the FE support CE Graceful restart.  Note that if the
            CE still has not been restarted or hasn't been associated
            back to the FE, after the CE TI has expired, the FE will go
            operationally down.

            1 - FE should go down to stop functioning immediately.

            2 - FE should go inactive to temporarily stop functioning.
            If the CE still has not been restarted after a time interval
            of specified by the CE TI, the FE will go down completely.

            Others - Reserved

      *  CE Timeout Interval (CE TI) - The time interval associated with
         the CE failover policy case '0' and '2'.  The default value is
         set to 300 seconds.  Note that it is advisable to set the CE TI



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         value much higher than the CE Heartbeat Dead Interval (CE HDI)
         since the effect of expiring this parameter is devastating to
         the operation of the FE.

7.2.2.  FE Object LFB

   The FE Object LFB is a logical entity in each FE and contains
   attributes relative to the FE itself, and not to the operation of the
   ForCES protocol.

   The formal definition of the FE Object LFB can be found in [FE-
   MODEL].  The model captures the high level properties of the FE that
   the CE needs to know to begin working with the FE.  The class ID for
   this LFB Class is also assigned in [FE-MODEL].  The singular instance
   of this class will always exist, and will always have instance ID 1
   within its class.  It is common, although not mandatory, for a CE to
   fetch much of the attribute and capability information from this LFB
   instance when the CE begins controlling the operation of the FE.

7.3.  Semantics of message Direction

   Recall: The PL protocol provides a master(CE)-Slave(FE) relationship.
   The LFBs reside at the FE and are controlled by CE.

   When messages go from the CE, the LFB Selector (Class and instance)
   refers to the destination LFB selection which resides in the FE.

   When messages go from the FE->CE, the LFB Selector (Class and
   instance) refers to the source LFB selection which resides in the FE.

7.4.  Association Messages

   The ForCES Association messages are used to establish and teardown
   associations between FEs and CEs.

7.4.1.  Association Setup Message

   This message is sent by the FE to the CE to setup a ForCES
   association between them.


   Message transfer direction:
      FE to CE

   Message Header:
      The Message Type in the header is set MessageType=
      'AssociationSetup'.  The ACK flag in the header MUST be ignored,
      and the association setup message always expects to get a response



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      from the message receiver (CE) whether the setup is successful or
      not.  The Correlator field in the header is set, so that FE can
      correlate the response coming back from CE correctly.  The Src ID
      (FE ID) may be set to O in the header which means that the FE
      would like the CE to assign an FE ID for the FE in the setup
      response message.

   Message body:
      The association setup message body optionally consists of one or
      more LFB select TLV as described in Section 7.1.1.1.5.  The
      association setup message only operates toward the FE Object and
      FE Protocol LFBs, therefore, the LFB class ID in the LFB select
      TLV only points to these two kinds of LFBs.

      The Operation TLV in the LFB select TLV is defined as a 'REPORT'
      operation.  More than one attribute may be announced in this
      message using REPORT operation to let the FE declare its
      configuration parameters in an unsolicited manner.  These may
      contain attributes like the Heart Beat Interval parameter, etc.
      The Operation TLV for event notification is is defined below.

   Operation TLV for Association Setup:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Type = REPORT              |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    PATH-DATA-TLV for REPORT                   |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 18: Operation TLV

   Type:
      Only one operation type is defined for the association setup
      message:

             Type = "REPORT" --- this type of operation is for FE to
             report something to CE.

   PATH-DATA-TLV for REPORT:
      This is generically a PATH-DATA-TLV format that has been defined
      in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
      definition.  The PATH-DATA-TLV for REPORT operation MAY contain
      FULLDATA-TLV(s) but SHALL NOT contain any RESULT-TLV in the data
      format.  The RESULT-TLV is defined in Section 7.1.1.1.7 and the
      FULLDATA-TLV is defined in Section 7.1.1.1.8.

   To better illustrate the above PDU format, a tree structure for the
   format is shown below:



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               main hdr (eg type =  Association setup)
               |
               |
               +--- T = LFBselect
               |        |
               |        +-- LFBCLASSID = FE object
               |        |
               |        |
               |        +-- LFBInstance = 0x1
               |        |
               +--- T = LFBselect
               |
               +-- LFBCLASSID = FE Protocol object
               |
               |
               +-- LFBInstance = 0x1
               |
               +-- Path-data to one or more attributes
               including suggested HB parameters

   Figure 19: PDU Format

7.4.2.  Association Setup Response Message

   This message is sent by the CE to the FE in response to the Setup
   message.  It indicates to the FE whether the setup is successful or
   not, i.e. whether an association is established.


   Message transfer direction:
       CE to FE

   Message Header:
       The Message Type in the header is set MessageType=
       'AssociationSetupResponse'.  The ACK flag in the header MUST be
       ignored, and the setup response message never expects to get any
       more responses from the message receiver (FE).  The Correlator
       field in the header MUST be the same as that of the corresponding
       association setup message, so that the association setup message
       sender can correlate the response correctly.  The Dst ID in the
       header will be set to some FE ID value assigned by the CE if the
       FE had requested that in the setup message (by SrcID = 0).

   Message body:
       The association setup response message body only consists of one
       TLV, the Association Result TLV, the format of which is as
       follows:




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    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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |        Type = ASRresult       |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                  Association Setup Result                     |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 20: Message Body

   Type (16 bits):
       The type of the TLV is "ASRresult".

   Length (16 bits):
       Length of the TLV including the T and L fields, in octets.

   Association Setup Result (32 bits):
       This indicates whether the setup msg was successful or whether
       the FE request was rejected by the CE. the defined values are:

              0 = success

              1 = FE ID invalid

              2 = too many associations

              3 = permission denied

7.4.3.  Association Teardown Message

   This message can be sent by the FE or CE to any ForCES element to end
   its ForCES association with that element.


   Message transfer direction:
       CE to FE, or FE to CE (or CE to CE)

   Message Header:
       The Message Type in the header is set MessageType=
       "AssociationTeardown".  The ACK flag MUST be ignored The
       correlator field in the header MUST be set to zero and MUST be
       ignored by the receiver.

   Message Body:
       The association teardown message body only consists of one TLV,
       the Association Teardown Reason TLV, the format of which is as
       follows:





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     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |        Type = ASTreason       |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                      Teardown Reason                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 21: ASTreason TLV

   Type (16 bits):
       The type of the TLV is "ASTreason".

   Length (16 bits):
       Length of the TLV including the T and L fields, in octets.

   Teardown Reason (32 bits):
       This indicates the reason why the association is being
       terminated.  Several reason codes are defined as follows.

           0 - normal teardown by administrator

           1 - error - loss of heartbeats

           2 - error - out of bandwidth

           3 - error - out of memory

           4 - error - application crash

           255 - error - other or unspecified

7.5.  Configuration Messages

   The ForCES Configuration messages are used by CE to configure the FEs
   in a ForCES NE and report the results back to the CE.

7.5.1.  Config Message

   This message is sent by the CE to the FE to configure LFB attributes
   in the FE.  This message is also used by the CE to subscribe/
   unsubscribe to LFB events.

   As usual, a config message is composed of a common header followed by
   a message body that consists of one or more TLV data format.
   Detailed description of the message is as below.






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   Message transfer direction:
       CE to FE

   Message Header:
       The Message Type in the header is set MessageType= 'Config'.  The
       ACK flag in the header can be set to any value defined in
       Section 6.1, to indicate whether or not a response from FE is
       expected by the message ( the flag is set to 'NoACK' or
       'AlwaysACK'), or to indicate under which conditions a response is
       generated (the flag is set to 'SuccessACK' or 'FailureACK').  The
       default behavior for the ACK flag is set to always expect a full
       response from FE.  This happens when the ACK flag is not set to
       any defined value.  The correlator field in the message header
       MUST be set if a response is expected, so that CE can correlate
       the response correctly.  The correlator field can be ignored if
       no response is expected.

   Message body:
       The config message body MUST consist of at least one LFB select
       TLV as described in Section 7.1.1.1.5.  The Operation TLV in the
       LFB select TLV is defined below.

   Operation TLV for Config:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type                 |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        PATH-DATA-TLV                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 22: Operation TLV for Config

   Type:
       The operation type for config message. two types of operations
       for the config message are defined:

              Type = "SET" --- this operation is to set LFB attributes

              Type = "DEL" --- this operation to delete some LFB
              attributes

   PATH-DATA-TLV:
       This is generically a PATH-DATA-TLV format that has been defined
       in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
       definition.  The restriction on the use of PATH-DATA-TLV for SET
       operation is, it MUST contain either a FULLDATA or SPARSEDATA
       TLV(s), but MUST NOT contain any RESULT-TLV.  The restriction on
       the use of PATH-DATA-TLV for DEL operation is it MAY contain



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       FULLDATA or SPARSEDATA TLV(s), but MUST NOT contain any RESULT-
       TLV.  The RESULT-TLV is defined in Section 7.1.1.1.7 and FULLDATA
       and SPARSEDATA TLVs is defined in Section 7.1.1.1.8.

       *Note:  For Event subscription, the events will be defined by the
              individual LFBs.

   To better illustrate the above PDU format, a tree structure for the
   format is shown below:

          main hdr (eg type = config)
          |
          |
          +--- T = LFBselect
          |        |
          |        +-- LFBCLASSID = target LFB class
          |        |
          |        |
          |        +-- LFBInstance = target LFB instance
          |        |
          |        |
          |        +-- T = operation { SET }
          |        |   |
          |        |   +--  // one or more path targets
          |        |        // associated with FULL or SPARSEDATA TLV(s)
          |        |
          |        +-- T = operation { DEL }
          |        |   |
          |        |   +--  // one or more path targets


   Figure 23: PDU Format

7.5.2.  Config Response Message

   This message is sent by the FE to the CE in response to the Config
   message.  It indicates whether the Config was successful or not on
   the FE and also gives a detailed response regarding the configuration
   result of each attribute.


   Message transfer direction:
       FE to CE

   Message Header:
       The Message Type in the header is set MessageType= 'Config
       Response'.  The ACK flag in the header is always ignored, and the
       config response message never expects to get any further response



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       from the message receiver (CE).  The Correlator field in the
       header MUST keep the same as that of the config message to be
       responded, so that the config message sender can correlate the
       response with the original message correctly.

   Message body:
       The config message body MUST consist of at least one LFB select
       TLV as described in Section 7.1.1.1.5.  The Operation TLV in the
       LFB select TLV is defined below.

   Operation TLV for Config Response:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |          Type                 |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                        PATH-DATA-TLV                          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 24: Operation TLV for Config Response

   Type:
       The operation type for config response message.  Two types of
       operations for the config response message are defined:

              Type = "SET-RESPONSE" --- this operation is for the
              response of SET operation of LFB attributes

              Type = "DEL-RESPONSE" --- this operation is for the
              response of the DELETE operation of LFB attributes

   PATH-DATA-TLV:
       This is generically a PATH-DATA-TLV format that has been defined
       in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
       definition.  The restriction on the use of PATH-DATA-TLV for SET-
       RESPONSE operation is it MUST contain RESULT-TLV(s).  The
       restriction on the use of PATH-DATA-TLV for DEL-RESPONSE
       operation is it also MUST contain RESULT-TLV(s).  The RESULT-TLV
       is defined in Section 7.1.1.1.7.

7.6.  Query Messages

   The ForCES query messages are used by the CE to query LFBs in the FE
   for informations like LFB attributes, capabilities, statistics, etc.
   Query Messages include the Query Message and the Query Response
   Message.






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7.6.1.  Query Message

   A query message is composed of a common header and a message body
   that consists of one or more TLV data format.  Detailed description
   of the message is as below.


   Message transfer direction:
       from CE to FE.

   Message Header:
       The Message Type in the header is set to MessageType= 'Query'.
       The ACK flag in the header is always ignored, and a full response
       for a query message is always expected.  The Correlator field in
       the header is set, so that CE can locate the response back from
       FE correctly.

   Message body:
       The query message body MUST consist of at least one LFB select
       TLV as described in Section 7.1.1.1.5.  The Operation TLV in the
       LFB select TLV is defined below.


   Operation TLV for Query:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Type = GET                 |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    PATH-DATA-TLV for GET                      |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       Figure 25: TLV for Query

   Type:
       The operation type for query.  One operation type is defined:

              Type = "GET" --- this operation is to request to get LFB
              attributes.

   PATH-DATA-TLV for GET:
       This is generically a PATH-DATA-TLV format that has been defined
       in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
       definition.  The restriction on the use of PATH-DATA-TLV for GET
       operation is it MUST NOT contain any SPARSEDATA or FULLDATA TLV
       and RESULT-TLV in the data format.

   To better illustrate the above PDU format, a tree structure for the
   format is shown below:



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   main hdr (type = Query)
        |
        |
        +--- T = LFBselect
        |        |
        |        +-- LFBCLASSID = target LFB class
        |        |
        |        |
        |        +-- LFBInstance = target LFB instance
        |        |
        |        |
        |        +-- T = operation { GET }
        |        |   |
        |        |   +--  // one or more path targets
        |        |
        |        +-- T = operation { GET }
        |        |   |
        |        |   +--  // one or more path targets
        |        |

   Figure 26: PDU Format

7.6.2.  Query Response Message

   When receiving a query message, the receiver should process the
   message and come up with a query result.  The receiver sends the
   query result back to the message sender by use of the Query Response
   Message.  The query result can be the information being queried if
   the query operation is successful, or can also be error codes if the
   query operation fails, indicating the reasons for the failure.

   A query response message is also composed of a common header and a
   message body consists of one or more TLVs describing the query
   result.  Detailed description of the message is as below.


   Message transfer direction:
       from FE to CE.

   Message Header:
       The Message Type in the header is set to MessageType=
       'QueryResponse'.  The ACK flag in the header is ignored.  As a
       response itself, the message does not expect a further response
       anymore.  The Correlator field in the header MUST be the same as
       that of the associated query, so that the query message sender
       can keep track of the response.





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   Message body:
       The query response message body MUST consist of at least one LFB
       select TLV as described in Section 7.1.1.1.5.  The Operation TLV
       in the LFB select TLV is defined below.

   Operation TLV for Query Response:

    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |    Type = GET-RESPONSE         |               Length          |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |                    PATH-DATA-TLV for GET-RESPONSE             |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


       Figure 27: TLV for Query Response

   Type:
       The operation type for query response.  One operation type is
       defined:

              Type = "GET-RESPONSE" --- this operation is to response to
              get operation of LFB attributes.

   PATH-DATA-TLV for GET-RESPONSE:
       This is generically a PATH-DATA-TLV format that has been defined
       in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
       definition.  The PATH-DATA-TLV for GET-RESPONSE operation MAY
       contain SPARSEDATA TLV, FULLDATA TLV and/or RESULT-TLV(s) in the
       data encoding.  The RESULT-TLV is defined in Section 7.1.1.1.7
       and the SPARSEDATA and FULLDATA TLVs are defined in
       Section 7.1.1.1.8.

7.7.  Event Notification Message

   Event Notification Message is used by FE to asynchronously notify CE
   of events that happen in the FE.

   All events that can be generated in an FE are subscribable by CE.  A
   config message is used by CE to subscribe/unsubscribe for an event in
   FE.  To subscribe to an event is usually by specifying to the path of
   such an event as described by FE-Model and defined by LFB library.

   As usual, an Event Notification Message is composed of a common
   header and a message body that consists of one or more TLV data
   format.  Detailed description of the message is as below.






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   Message Transfer Direction:
      FE to CE

   Message Header:
      The Message Type in the message header is set to
      MessageType = 'EventNotification'.  The ACK flag in the header
      MUST be ignored by the CE, and the event notification message does
      not expect any response from the receiver.  The Correlator field
      in the header is also ignored because the response is not
      expected.

   Message Body:
      The event notification message body MUST consist of at least one
      LFB select TLV as described in Section 7.1.1.1.5.  The Operation
      TLV in the LFB select TLV is defined below.

   Operation TLV for Event Notification:


   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = REPORT              |               Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    PATH-DATA-TLV for REPORT                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 28: TLV for Event Notification

   Type:
      Only one operation type is defined for the event notification
      message:

             Type = "REPORT" --- this type of operation is for FE to
             report something to CE.

   PATH-DATA-TLV for REPORT:
      This is generically a PATH-DATA-TLV format that has been defined
      in "Protocol Grammar" section(Section 7.1) in the PATH-DATA BNF
      definition.  The PATH-DATA-TLV for REPORT operation MAY contain
      FULLDATA or SPARSEDATA TLV(s) but MUST NOT contain any RESULT-TLV
      in the data format.

   To better illustrate the above PDU format, a tree structure for the
   format is shown below:








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   main hdr (type = Event Notification)
        |
        |
        +--- T = LFBselect
        |        |
        |        +-- LFBCLASSID = target LFB class
        |        |
        |        |
        |        +-- LFBInstance = target LFB instance
        |        |
        |        |
        |        +-- T = operation { REPORT }
        |        |   |
        |        |   +--  // one or more path targets
        |        |        // associated with FULL/SPARSE DATA TLV(s)
        |        +-- T = operation { REPORT }
        |        |   |
        |        |   +--  // one or more path targets
        |        |        // associated with FULL/SPARSE DATA TLV(s)


   Figure 29: PDU Format

7.8.  Packet Redirect Message

   Packet redirect message is used to transfer data packets between CE
   and FE.  Usually these data packets are IP packets, though they may
   sometimes be associated with some metadata generated by other LFBs in
   the model.  They may also occasionally be other protocol packets,
   which usually happens when CE and FE are jointly implementing some
   high-touch operations.  Packets redirected from FE to CE are the data
   packets that come from forwarding plane, and usually are the data
   packets that need high-touch operations in CE,or packets for which
   the IP destination address is the NE.  Packets redirected from CE to
   FE are the data packets that come from the CE and that the CE decides
   to put into forwarding plane, i.e. an FE.

   Supplying such a redirect path between CE and FE actually leads to a
   possibility of this path being DoS attacked.  Attackers may
   maliciously try to send huge spurious packets that will be redirected
   by FE to CE, resulting in the redirect path becoming congested.
   ForCES protocol and the TML layer will jointly supply approaches to
   prevent such DoS attack.  To define a specific 'Packet Redirect
   Message' makes TML and CE able to distinguish the redirect messages
   from other ForCES protocol messages.

   By properly configuring related LFBs in FE, a packet can also be
   mirrored to CE instead of purely redirected to CE, i.e., the packet



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   is duplicated and one is redirected to CE and the other continues its
   way in the LFB topology.

   The Packet Redirect Message data format is formated as follows:

   Message Direction:
      CE to FE or FE to CE

   Message Header:
      The Message Type in the header is set to MessageType=
      'PacketRedirect'.  The ACK flags in the header MUST be ignored,
      and no response is expected by this message.  The correlator field
      is also ignored because no response is expected.

   Message Body:
      Consists of (at least) one or more than one TLV that describes
      packet redirection.  The TLV is specifically a Redirect TLV (with
      the TLV Type="Redirect").  Detailed data format of a Redirect TLV
      for packet redirect message is as below:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |        Type = Redirect        |               Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          LFB Class ID                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        LFB Instance ID                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Meta Data TLV                          |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Redirect Data TLV                      |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      Figure 30: Redirect_Data TLV

   LFB class ID:
      There are only two possible LFB classes here, the 'RedirectSink'
      LFB or the 'RedirectSource' LFB[FE-MODEL].  If the message is from
      FE to CE, the LFB class should be 'RedirectSink'.  If the message
      is from CE to FE, the LFB class should be 'RedirectSource'.

   Instance ID:
      Instance ID for the 'RedirectSink' LFB or 'RedirectSource' LFB.





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   Meta Data TLV:
      This is a TLV that specifies meta-data associated with followed
      redirected data.  The TLV is as follows:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = META-DATA           |               Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Meta Data ILV                          |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                           ...                                 ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Meta Data ILV                          |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 31: Redirected_Data TLV

   Meta Data ILV:
      This is an Identifier-Length-Value format that is used to describe
      one meta data.  The ILV has the format as:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Meta Data ID                           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Length                                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Meta Data Value                        |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      Figure 32: Meta Data ILV

      Where, Meta Data ID is an identifier for the meta data, which is
      statically assigned by the LFB definition.  This actually implies
      a Meta Data ID transcoding mechanism may be necessary if a
      metadata traverses several LFBs while these LFBs define the
      metadata with different Meta Data IDs.

      Usually there are two meta data that are necessary for CE-FE
      redirect operation.  One is the redirected data type (e.g., IP
      packet, TCP packet, or UDP Packet).  For an FE->CE redirect
      operation, redirected packet type meta data is usually a meta data
      specified by a Classifier LFB that filter out redirected packets
      from packet stream and sends the packets to Redirect Sink LFB.
      For an CE->FE redirect operation, the redirected packet type meta
      data is usually directly generated by CE.



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      Another meta data that should be associated with redirected data
      is the port number in a redirect LFB.  For a RedirectSink LFB, the
      port number meta data tells CE from which port in the lFB the
      redirected data come.  For a RedirectSource LFB, via the meta
      data, CE tells FE which port in the LFB the redirected data should
      go out.

   Redirect Data TLV
      This is a TLV describing one packet of data to be directed via the
      redirect operation.  The TLV format is as follows:

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Type = REDIRECTDATA        |               Length          |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                        Redirected Data                        |
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      Figure 33: Redirect Data TLV

   Redirected Data:
      This field presents the whole packet that is to be redirected.
      The packet should be 32bits aligned.

7.9.  Heartbeat Message

   The Heartbeat (HB) Message is used for one ForCES element (FE or CE)
   to asynchronously notify one or more other ForCES elements in the
   same ForCES NE on its liveness.

   A Heartbeat Message is sent by a ForCES element periodically.  The
   parameterization and policy definition for heartbeats for an FE is
   managed as attributes of the FE protocol LFB, and can be set by CE
   via a config message.  The Heartbeat message is a little different
   from other protocol messages in that it is only composed of a common
   header, with the message body left empty.  Detailed description of
   the message is as below.

   Message Transfer Direction:
       FE to CE, or CE to FE

   Message Header:
       The Message Type in the message header is set to MessageType =
       'Heartbeat'.  Section 4.3.3 describes the HB mechanisms used.
       The ACK flag in the header MUST be set to either 'NoACK' or
       'AlwaysACK' when the HB is sent.





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       *   When set to 'NoACK', the HB is not soliciting for a response.

       *   When set to 'AlwaysACK', the HB Message sender is always
           expecting a response from its receiver.  According the HB
           policies defined in Section 7.2.1, only the CE can send such
           a HB message to query FE liveness.  For simplicity and
           because of the minimal nature of the HB message, the response
           to a HB message is another HB message, i.e. no specific HB
           response message is defined.  Whenever an FE receives a HB
           message marked with 'AlwaysACK' from the CE, the FE MUST send
           a HB message back immediately.  The HB message sent by the FE
           in response to the 'AlwasyACK' MUST modify the source and
           destination IDs so that the ID of the FE is the source ID and
           the CEID of the sender is the destination ID, and MUST change
           the ACK information to 'NoACK'.  A CE MUST NOT respond to an
           HB message with 'AlwasyACK' set.

       The correlator field in the HB message header SHOULD be set
       accordingly when a response is expected so that a receiver can
       correlate the response correctly.  The correlator field MAY be
       ignored if no response is expected.

   Message Body:
       The message body is empty for the Heartbeat Message.

7.10.  Operation Summary

   The following table summarizes the TLVs that compose messages, and
   the applicabiity of operation TLVs to the messages.






















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   +---------------------------+-----------+---------------------------+
   |          Messages         |    TLVs   |         Operations        |
   +---------------------------+-----------+---------------------------+
   |     Association Setup     | LFBselect |           REPORT          |
   |                           |           |                           |
   |     Association Setup     | ASRresult |            None           |
   |          Response         |           |                           |
   |                           |           |                           |
   |    Association Teardown   | ASTreason |            None           |
   |                           |           |                           |
   |           Config          | LFBselect |          SET, DEL         |
   |                           |           |                           |
   |      Config Response      | LFBselect |       SET-RESPONSE,       |
   |                           |           |        DEL-RESPONSE       |
   |                           |           |                           |
   |           Query           | LFBselect |            GET            |
   |                           |           |                           |
   |       Query Response      | LFBselect |        GET-RESPONSE       |
   |                           |           |                           |
   |     Event Notification    | LFBselect |           REPORT          |
   |                           |           |                           |
   |      Packet Redirect      |  Redirect |            None           |
   |                           |           |                           |
   |         Heartbeat         |    None   |            None           |
   +---------------------------+-----------+---------------------------+

   The following table summarises the applicability of the FULL/SPARSE
   DATA TLV and the RESULT TLV to the Operation TLVs.























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       +--------------+--------------+----------------+------------+
       |  Operations  | FULLDATA TLV | SPARSEDATA TLV | RESULT TLV |
       +--------------+--------------+----------------+------------+
       |      SET     |      MAY     |       MAY      |  MUST NOT  |
       |              |              |                |            |
       | SET-RESPONSE |      MAY     |    MUST NOT    |    MUST    |
       |              |              |                |            |
       |      DEL     |      MAY     |       MAY      |  MUST NOT  |
       |              |              |                |            |
       | DEL-RESPONSE |      MAY     |    MUST NOT    |    MUST    |
       |              |              |                |            |
       |      GET     |   MUST NOT   |    MUST NOT    |  MUST NOT  |
       |              |              |                |            |
       | GET-RESPONSE |     MUST     |    MUST NOT    |     MAY    |
       |              |              |                |            |
       |    REPORT    |      MAY     |    MUST NOT    |  MUST NOT  |
       +--------------+--------------+----------------+------------+


































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8.  Protocol Scenarios

8.1.  Association Setup state

   The associations among CEs and FEs are initiated via Association
   setup message from the FE.  If a setup request is granted by the CE,
   a successful setup response message is sent to the FE.  If CEs and
   FEs are operating in an insecure environment then the security
   associations have to be established between them before any
   association messages can be exchanged.  The TML will take care of
   establishing any security associations.

   This is typically followed by capability query, topology query, etc.
   When the FE is ready to start forwarding data traffic, it sends an FE
   UP Event message to the CE.  When the CE is ready, it repsonds by
   enabling the FE by setting the FEStatus to Adminup [Refer to [FE-
   MODEL] for details].  This indicates to the FE to start forwarding
   data traffic.  At this point the association establishment is
   complete.  These sequences of messages are illustrated in the Figure
   below.































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           FE PL                  CE PL

             |                       |
             |   Asso Setup Req      |
             |---------------------->|
             |                       |
             |   Asso Setup Resp     |
             |<----------------------|
             |                       |
             | LFBx Query capability |
             |<----------------------|
             |                       |
             | LFBx Query Resp       |
             |---------------------->|
             |                       |
             | FEO Query (Topology)  |
             |<----------------------|
             |                       |
             | FEO Query Resp        |
             |---------------------->|
             |                       |
             |  Config FEO Adminup   |
             |<----------------------|
             |                       |
             | FEO Config-Resp       |
             |---------------------->|
             |                       |
             | FEO UP Event          |
             |---------------------->|
             |                       |


   Figure 34: Message exchange between CE and FE to establish an NE
   association

   On successful completion of this state, the FE joins the NE.

8.2.  Association Established state or Steady State

   In this state the FE is continously updated or queried.  The FE may
   also send asynchronous event notifications to the CE or synchronous
   heartbeat messages.  This continues until a termination (or
   deactivation) is initiated by either the CE or FE.  The figure below
   helps illustrate this state.







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           FE PL                          CE PL

             |                              |
             |    Heart Beat                |
             |<---------------------------->|
             |                              |
             |   Heart Beat                 |
             |----------------------------->|
             |                              |
             | Config-set LFBy (Event sub.) |
             |<-----------------------------|
             |                              |
             |     Config Resp LFBy         |
             |----------------------------->|
             |                              |
             |  Config-set LFBx Attr        |
             |<-----------------------------|
             |                              |
             |     Config Resp  LFBx        |
             |----------------------------->|
             |                              |
             |Config-Query LFBz (Stats)     |
             |<--------------------------- -|
             |                              |
             |    Query Resp LFBz           |
             |----------------------------->|
             |                              |
             |    FE Event Report           |
             |----------------------------->|
             |                              |
             |  Config-Del LFBx Attr        |
             |<-----------------------------|
             |                              |
             |     Config Resp LFBx         |
             |----------------------------->|
             |                              |
             |    Packet Redirect LFBx      |
             |----------------------------->|
             |                              |
             |    Heart Beat                |
             |<-----------------------------|
             .                              .
             .                              .
             |                              |

   Figure 35: Message exchange between CE and FE during steady-state
   communication




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   Note that the sequence of messages shown in the figure serve only as
   examples and the messages exchange sequences could be different from
   what is shown in the figure.  Also, note that the protocol scenarios
   described in this section do not include all the different message
   exchanges which would take place during failover.  That is described
   in the HA section 8.













































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9.  High Availability Support


   The ForCES protocol provides mechanisms for CE redundancy and
   failover, in order to support High Availability as defined in
   [RFC3654].  FE redundancy and FE to FE interaction is currently out
   of scope of this draft.  There can be multiple redundant CEs and FEs
   in a ForCES NE.  However, at any one time only one Primary CE can
   control the FEs though there can be multiple secondary CEs.  The FE
   and the CE PL are aware of the primary and secondary CEs.  This
   information (primary, secondary CEs) is configured in the FE and in
   the CE PLs during pre-association by the FEM and the CEM
   respectively.  Only the primary CE sends Control messages to the FEs.

   Two HA modes are defined in the ForCES protocol, Report Primary Mode
   and Report All Mode.  The Report Primary Mode is the default mode of
   the protocol, in which the FEs only associate with one CE (primary)
   at a time.  The Report All mode is for future study and not part of
   the current protocol version.  In this mode, the FE would establish
   association with multiple CEs (primary and secondary) and report
   events, packets, Heart Beats to all the CEs.  However, only the
   primary CE would configure/control the FE in this mode as well.  This
   would help with keeping state between CEs synchronized, although it
   would not guarantee synchronization.

   The HA Modes are configured during Association setup phase, though
   currently only Report Primary Mode can be configured.  A CE-to-CE
   synchronization protocol would be needed to support fast failover as
   well as address some of the corner cases, however this will not be
   defined by the ForCES protocol as it is out of scope for this
   specification.

   During a communication failure between the FE and CE (which is caused
   due to CE or link reasons, i.e. not FE related), either the TML on
   the FE will trigger the FE PL regarding this failure or it will be
   detected using the HB messages between FEs and CEs.  The
   communication failure, regardless of how it is detected, MUST be
   considered as a loss of association between the CE and corresponding
   FE.  In the Report Primary mode, as there should be no other existing
   CE-FE associations, the FE PL MUST at this point establish
   association with the secondary CE.  Once the process has started, if
   the original primary CE comes alive and starts sending commands
   message to the FE, the FE MUST ignore those messages.  If the
   original CE begins a new association phase with the FE then the FE
   MUST send an Association Setup Response message with Result = 2
   indicating that there are too many associations.  It will be up to
   CE-CE communications, out of scope for this specification, to
   determine what what, if any changes should be made to FE



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   configuration following the recovery process.

   An explicit message (Config message setting Primary CE attribute in
   ForCES Protocol object) from the primary CE, can also be used to
   change the Primary CE for an FE during normal protocol operation.

   Also note that the FEs in a ForCES NE could also use a multicast
   CEID, i.e. they are associated with a group of CEs (this assumes the
   use of a CE-CE synchronization protocol, which is out of scope for
   this specification).  In this case the loss of association would mean
   that communication with the entire multicast group of CEs has been
   lost.  The mechanisms described above will apply for this case as
   well during the loss of association.  If, however, the secondary CE
   was also using the multicast CEID that was lost, then the FE will
   need to form a new association using a different CEID.  If the
   capability exists, the FE MAY first attempt to form a new association
   with original primary CE using a different non multicast CEID.

   These two scenarios, Report Primary (default), Report Primary
   (currently unsupported), are illustrated in the Figure 36 and
   Figure 37 below.



         FE                   CE Primary        CE Secondary
         |                       |                    |
         |  Asso Estb,Caps exchg |                    |
       1 |<--------------------->|                    |
         |                       |                    |
         |       All msgs        |                    |
       2 |<--------------------->|                    |
         |                       |                    |
         |                       |                    |
         |                   FAILURE                  |
         |                                            |
         |         Asso Estb,Caps exchange            |
       3 |<------------------------------------------>|
         |                                            |
         |              Event Report (pri CE down)    |
       4 |------------------------------------------->|
         |                                            |
         |                   All Msgs                 |
       5 |<------------------------------------------>|


   Figure 36: CE Failover for Report Primary Mode





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        FE                   CE Primary         CE Secondary
         |                       |                    |
         | Asso Estb,Caps exchg  |                    |
       1 |<--------------------->|                    |
         |                       |                    |
         |         Asso Estb,Caps|exchange            |
       2 |<----------------------|------------------->|
         |                       |                    |
         |     All msgs          |                    |
       3 |<--------------------->|                    |
         |                       |                    |
         |    packet redirection,|events, HBs         |
       4 |-----------------------|------------------->|
         |                       |                    |
         |                   FAILURE                  |
         |                                            |
         |             Event Report (pri CE down)     |
       5 |------------------------------------------->|
         |                                            |
         |                  All Msgs                  |
       6 |<------------------------------------------>|


   Figure 37: CE Failover for Report All mode

9.1.  Responsibilities for HA

   TML level - Transport level:

   1.  The TML controls logical connection availability and failover.

   2.  The TML also controls peer HA management.

   At this level, control of all lower layers, for example transport
   level (such as IP addresses, MAC addresses etc) and associated links
   going down are the role of the TML.

   PL Level:
   For all other functionality including configuring the HA behavior
   during setup, the CEIDs are used to identify primary, secondary CEs,
   protocol Messages used to report CE failure (Event Report), Heartbeat
   messages used to detect association failure, messages to change
   primary CE (config - move), and other HA related operations described
   before are the PL responsibility.

   To put the two together, if a path to a primary CE is down, the TML
   would take care of failing over to a backup path, if one is
   available.  If the CE is totally unreachable then the PL would be



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   informed and it will take the appropriate actions described before.


















































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10.  Security Considerations

   ForCES architecture identifies several levels of security in
   [RFC3746].  ForCES PL uses security services provided by the ForCES
   TML layer.  TML layer provides security services such as endpoint
   authentication service, message authentication service and
   confidentiality service.  Endpoint authentication service is invoked
   at the time of pre-association connection establishment phase and
   message authentication is performed whenever FE or CE receives a
   packet from its peer.

   The following are the general security mechanisms that needs to be in
   place for ForCES PL layer.

   o  Security mechanisms are session controlled - that is, once the
      security is turned ON depending upon the chosen security level (No
      Security, Authentication only, Confidentiality), it will be in
      effect for the entire duration of the session.

   o  Operator should configure the same security policies for both
      primary and backup FE's and CE's (if available).  This will ensure
      uniform operations, and to avoid unnecessary complexity in policy
      configuration.

   o  ForCES PL endpoints SHOULD pre-established connections with both
      primary and backup CE's.  This will reduce the security messages
      and enable rapid switchover operations for HA.

10.1.  No Security

   When "No security" is chosen for ForCES protocol communication, both
   endpoint authentication and message authentication service needs to
   be performed by ForCES PL layer.  Both these mechanism are weak and
   does not involve cryptographic operation.  Operator can choose "No
   security" level when the ForCES protocol endpoints are within a
   single box.

   In order to have interoperable and uniform implementation across
   various security levels, each CE and FE endpoint MUST implement this
   level.  The operations that are being performed for "No security"
   level is required even if lower TML security services are being used.

10.1.1.  Endpoint Authentication

   Each CE and FE PL layer maintains set of associations list as part of
   configuration.  This is done via CEM and FEM interfaces.  FE MUST
   connect to only those CE's that are configured via FEM similarly, a
   CE should accept the connection and establish associations for the



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   FE's which are configured via CEM.  CE should validate the FE
   identifier before accepting the connection during the pre-association
   phase.

10.1.2.  Message authentication

   When CE or FE generates initiates a message, the receiving endpoint
   MUST validate the initiator of the message by checking the common
   header CE or FE identifiers.  This will ensure proper protocol
   functioning.  This extra processing step is recommend even if the
   underlying TLM layer security services.

10.2.  ForCES PL and TML security service

   This section is applicable if operator wishes to use the TML security
   services.  ForCES TML layer MUST support one or more security service
   such as endpoint authentication service, message authentication
   service, confidentiality service as part of TML security layer
   functions.  It is the responsibility of the operator to select
   appropriate security service and configure security policies
   accordingly.  The details of such configuration is outside the scope
   of ForCES PL and is depending upon the type of transport protocol,
   nature of connection.

   All these configurations should be done prior to starting the CE and
   FE.

   When certificates-based authentication is being used at TML layer,
   the certificate can use ForCES specific naming structure as
   certificate names and accordingly the security policies can be
   configured at CE and FE.

10.2.1.  Endpoint authentication service

   When TML security services are enabled.  ForCES TML layer performs
   endpoint authentication.  Security association is established between
   CE and FE and is transparent to the ForCES PL layer.

   It is recommended that an FE, after establishing the connection with
   the primary CE, should establish the security association with the
   backup CE (if available).  During the switchover operation CE's
   security state associated with each SA's are not transferred.  SA
   between primary CE and FE and backup CE and FE are treated as two
   separate SA's.

10.2.2.  Message authentication service

   This is TML specific operation and is transparent to ForCES PL layer.



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   For details refer to Section 5.

10.2.3.  Confidentiality service

   This is TML specific operation and is transparent to ForCES PL layer.
   For details refer to Section 5.













































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11.  Acknowledgments

   The authors of this draft would like to acknowledge and thank the
   ForCES Working Group and especially the following: Furquan Ansari,
   Alex Audu, Steven Blake, Shuchi Chawla Alan DeKok, Ellen M.
   Deleganes, Xiaoyi Guo, Yunfei Guo, Evangelos Haleplidis, Joel M.
   Halpern (who should probably be listed among the authors), Zsolt
   Haraszti, Fenggen Jia, John C. Lin, Alistair Munro, Jeff Pickering,
   T. Sridhlar, Guangming Wang, Chaoping Wu, and Lily L. Yang, for their
   contributions.  We would also like to thank David Putzolu, and
   Patrick Droz for their comments and suggestions on the protocol and
   for their infinite patience.







































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12.  References

12.1.  Normative References

   [FE-MODEL]
              Yang, L., Halpern, J., Gopal, R., DeKok, A., Haraszti, Z.,
              and S. Blake, "ForCES Forwarding Element Model",
              Feb. 2005.

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

   [RFC2434]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 2434,
              October 1998.

   [RFC2629]  Rose, M., "Writing I-Ds and RFCs using XML", RFC 2629,
              June 1999.

   [RFC3654]  Khosravi, H. and T. Anderson, "Requirements for Separation
              of IP Control and Forwarding", RFC 3654, November 2003.

   [RFC3746]  Yang, L., Dantu, R., Anderson, T., and R. Gopal,
              "Forwarding and Control Element Separation (ForCES)
              Framework", RFC 3746, April 2004.

12.2.  Informational References

   [2PCREF]  Gray, J., "Notes on database operating systems. In
             Operating Systems: An Advanced Course. Lecture Notes in
             Computer Science, Vol. 60, pp. 394-481, Springer-Verlag",
             1978.

   [ACID]    Haerder, T. and A. Reuter, "Principles of Transaction-
             Orientated Database Recovery", 1983.
















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Appendix A.  IANA Considerations

   Following the policies outlined in "Guidelines for Writing an IANA
   Considerations Section in RFCs" (RFC 2434 [RFC2434]), the following
   name spaces are defined in ForCES.

   o  Message Type Name Space Section 7.1.1

   o  Operation Type Name Space Section 7.1.1.1.6

   o  Header Flags Section 6.1

   o  TLV Type Section 7.1.1

   o  LFB Class ID Section 7.1.1.1.5

   o  Result: Association Setup Response Section 7.4.2

   o  Reason: Association Teardown Message Section 7.4.3

   o  Configuration Request: Operation Result Section 7.5.1

A.1.  Message Type Name Space

   The Message Type is an 8 bit value.  The following is the guideline
   for defining the Message Type namespace

   Message Types 0x00 - 0x0F
      Message Types in this range are part of the base ForCES Protocol.
      Message Types in this range are allocated through an IETF
      consensus action.  [RFC2434]
      Values assigned by this specification:

       0x00 ............... Reserved
       0x01 ............... AssociationSetup
       0x02 ............... AssociationTeardown
       0x03 ............... Config
       0x04 ............... Query
       0x05 ............... EventNotification
       0x06 ............... PacketRedirect
       0x07 - 0x0E ........ Reserved
       0x0F ............... Hearbeat
       0x11 ............... AssociationSetupRepsonse
       0x12 ............... Reserved
       0x13 ............... ConfigRepsonse
       0x14 ............... QueryResponse





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   Message Types 0x20 - 0x7F
      Message Types in this range are Specification Required [RFC2434]
      Message Types using this range must be documented in an RFC or
      other permanent and readily available references.

   Message Types 0x80 - 0xFF
      Message Types in this range are reserved for vendor private
      extensions and are the responsibility of individual vendors.  IANA
      management of this range of the Message Type Name Space is
      unnecessary.

A.2.  Operation Type

   The Operation Type name space is 16 bits long.  The following is the
   guideline for managing the Operation Type Name Space.

   Operation Type 0x0000-0x00FF
      Operation Types in this range are allocated through an IETF
      consensus process.  [RFC2434].
      Values assigned by this specification:

                 0x0000           Reserved
                 0x0001           SET
                 0x0002           SET-RESPONSE
                 0x0003           DEL
                 0x0004           DEL-RESPONSE
                 0x0005           GET
                 0x0006           GET-RESPONSE
                 0x0007           REPORT

   Operation Type 0x0100-0x7FFF
      Operation Types using this range must be documented in an RFC or
      other permanent and readily available references.  [RFC2434].

   Operation Type 0x8000-0xFFFF
      Operation Types in this range are reserved for vendor private
      extensions and are the responsibility of individual vendors.  IANA
      management of this range of the Operation Type Name Space is
      unnecessary.

A.3.  Header Flags

      The Header flag field is 32 bits long Header flags are part of the
      ForCES base protocol.  Header flags are allocated through an IETF
      consensus action [RFC2434].






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A.4.  TLV Type Name Space

   The TLV Type name space is 16 bits long.  The following is the
   guideline for managing the TLV Type Name Space.

   TLV Type 0x0000-0x00FF
      TLV Types in this range are allocated through an IETF consensus
      process.  [RFC2434].
      Values assigned by this specification:

                 0x0000           Reserved
                 0x0001           MAIN_TLV
                 0x0002           REDIRECT-TLV
                 0x0010           ASResult-TLV
                 0x0011           ASTreason-TLV
                 0x1000           LFBselect-TLV
                 0x0101           OPER-TLV
                 0x0110           PATH-DATA-TLV
                 0x0111           KEYINFO-TLV
                 0x0112           FULLDATA-TLV
                 0x0113           SPARSEDATA-TLV
                 0x0114           RESULT-TLV

   TLV Type 0x0200-0x7FFF
      TLV Types using this range must be documented in an RFC or other
      permanent and readily available references.  [RFC2434].

   TLV Type 0x8000-0xFFFF
      TLV Types in this range are reserved for vendor private extensions
      and are the responsibility of individual vendors.  IANA management
      of this range of the TLV Type Name Space is unnecessary.

A.5.  LFB Class Id Name Space

   The LFB Class ID name space is 32 bits long.  The following is the
   guideline for managing the TLV Result Name Space.

   LFB Class ID 0x00000000-0x0000FFFF
      LFB Class IDs in this range are allocated through an IETF
      consensus process.  [RFC2434].
      Values assigned by this specification:

                 0x00000000       Reserved
                 0x00000001       FE Protocol LFB
                 0x00000002       FE Object LFB






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   LFB Class ID 0x00010000-0x7FFFFFFF
      LFB Class IDs in this range are Specification Required [RFC2434]
      LFB Class ID using this range must be documented in an RFC or
      other permanent and readily available references.  [RFC2434].

   LFB Class Id 0x80000000-0xFFFFFFFFF
      LFB Class IDs in this range are reserved for vendor private
      extensions and are the responsibility of individual vendors.  IANA
      management of this range of the LFB Class ID Space is unnecessary.

A.6.  Association Setup Response

   The Association Setup Response name space is 16 bits long.  The
   following is the guideline for managing the Association Setup
   Response Name Space.

   Association Setup Response 0x0000-0x00FF
      Association Setup Responses in this range are allocated through an
      IETF consensus process.  [RFC2434].
      Values assigned by this specification:

          0x0000   Success
          0x0001   FE ID Invalid
          0x0002   Too many associations
          0x0003   Permission Denied

   Association Setup Response 0x0100-0x0FFF
      Association Setup Responses in this range are Specification
      Required [RFC2434] Values using this range must be documented in
      an RFC or other permanent and readily available references.
      [RFC2434].

   Association Setup Response 0x80000000-0xFFFFFFFFF
      Association Setup Responses in this range are reserved for vendor
      private extensions and are the responsibility of individual
      vendors.  IANA management of this range of the Association Setup
      Responses Name Space is unnecessary.

A.7.  Association Teardown Message

   The Association Teardown Message name space is 32 bits long.  The
   following is the guideline for managing the TLV Result Name Space.

   Association Teardown Message 0x00000000-0x0000FFFF
      Association Teardown Messages in this range are allocated through
      an IETF consensus process.  [RFC2434].
      Values assigned by this specification:




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           0x00000000        Normal - Teardown by Administrator
           0x00000001        Error  - Out of Memory
           0x00000002        Error  - Application Crash
           0x000000FF        Error  - Unspecified

   Association Teardown Message 0x00010000-0x7FFFFFFF
      Association Teardown Messages in this range are Specification
      Required [RFC2434] Association Teardown Messages using this range
      must be documented in an RFC or other permanent and readily
      available references.  [RFC2434].

   LFB Class Id 0x80000000-0xFFFFFFFFF
      Association Teardown Messages in this range are reserved for
      vendor private extensions and are the responsibility of individual
      vendors.  IANA management of this range of the Association
      Teardown Message Name Space is unnecessary.

A.8.  Configuration Request Result

   The Configuration Request name space is 32 bits long.  The following
   is the guideline for managing the Configuration Request Name Space.

   Configuration Request 0x0000-0x00FF
      Configuration Requests in this range are allocated through an IETF
      consensus process.  [RFC2434].
      Values assigned by this specification:

       0x0000      Success
       0x0001      FE ID Invalid
       0x0003      Permission Denied

   Configuration Request 0x0100-0x7FFF
      Configuration Requests in this range are Specification Required
      [RFC2434] Configuration Requests using this range must be
      documented in an RFC or other permanent and readily available
      references.  [RFC2434].

    0x8000-0xFFFF
      Configuration Requests in this range are reserved for vendor
      private extensions and are the responsibility of individual
      vendors.  IANA management of this range of the Configuration
      Request Name Space is unnecessary.









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Appendix B.  ForCES Protocol LFB schema

   The schema described below conforms to the LFB schema described in
   ForCES Model draft[FE-MODEL]

   <LFBLibrary xmlns="http://ietf.org/forces/1.0/lfbmodel"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation=
       "http://ietf.org/forces/1.0/lfbmodel
        file:/home/hadi/xmlj1/lfbmodel.xsd" provides="FEPO">
   <!-- XXX  -->
     <dataTypeDefs>
        <dataTypeDef>
           <name>CEHBPolicyValues</name>
                  <synopsis>
                      The possible values of CE heartbeat policy
                  </synopsis>
              <atomic>
              <baseType>uchar</baseType>
              <specialValues>
                 <specialValue value="0">
                   <name>CEHBPolicy0</name>
                   <synopsis>
                       The CE heartbeat policy 0, refer to
                       <xref target="FPL_sum" /> for details
                   </synopsis>
                   </specialValue>
                 <specialValue value="1">
                    <name>CEHBPolicy1</name>
                    <synopsis>
                        The CE heartbeat policy 1, refer to
                        <xref target="FPL_sum" /> for details
                    </synopsis>
                 </specialValue>
               </specialValues>
               </atomic>
         </dataTypeDef>

         <dataTypeDef>
            <name>FEHBPolicyValues</name>
                 <synopsis>
                     The possible values of FE heartbeat policy
                </synopsis>
              <atomic>
              <baseType>uchar</baseType>
              <specialValues>
                <specialValue value="0">
                  <name>FEHBPolicy0</name>



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                  <synopsis>
                    The FE heartbeat policy 0, refer to
                    <xref target="FPL_sum" /> for details
                  </synopsis>
                </specialValue>
                <specialValue value="1">
                   <name>FEHBPolicy1</name>
                   <synopsis>
                      The FE heartbeat policy 1, refer to
                      <xref target="FPL_sum" /> for details
                   </synopsis>
                  </specialValue>
               </specialValues>
               </atomic>
         </dataTypeDef>

         <dataTypeDef>
         <name>FERestartPolicyValues</name>
               <synopsis>
                   The possible values of FE restart policy
               </synopsis>
              <atomic>
              <baseType>uchar</baseType>
              <specialValues>
                 <specialValue value="0">
                   <name>FERestartPolicy0</name>
                   <synopsis>
                      The FE restart policy 0, refer to
                      <xref target="FPL_sum" /> for details
                   </synopsis>
                   </specialValue>
                   <specialValue value="1">
                     <name>FERestartPolicy1</name>
                     <synopsis>
                      The FE restart policy 1, refer to
                      <xref target="FPL_sum" /> for details
                     </synopsis>
                   </specialValue>
               </specialValues>
               </atomic>
         </dataTypeDef>

         <dataTypeDef>
         <name>CEFailoverPolicyValues</name>
               <synopsis>
                   The possible values of CE failover policy
               </synopsis>
              <atomic>



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              <baseType>uchar</baseType>
              <specialValues>
                <specialValue value="0">
                   <name>CEFailoverPolicy0</name>
                   <synopsis>
                      The CE failover policy 0, refer to
                      <xref target="FPL_sum" /> for details
                   </synopsis>
                 </specialValue>
               <specialValue value="1">
                  <name>CEFailoverPolicy1</name>
                  <synopsis>
                      The CE failover policy 1, refer to
                      <xref target="FPL_sum" /> for details
                  </synopsis>
                </specialValue>
                <specialValue value="2">
                   <name>CEFailoverPolicy2</name>
                   <synopsis>
                      The CE failover policy 2, refer to
                      <xref target="FPL_sum" /> for details
                   </synopsis>
                  </specialValue>
               </specialValues>
               </atomic>
         </dataTypeDef>
     </dataTypeDefs>

     <LFBClassDefs>
       <LFBClassDef LFBClassID="2">
         <name>FEPO</name>
         <id>1</id>
         <synopsis>
            The FE Protocol Object
         </synopsis>
         <version>1.0</version>
         <derivedFrom>baseclass</derivedFrom>

     <attributes>
           <attribute elementID="1" access="read-only">
             <name>CurrentRunningVersion</name>
             <synopsis>Currently running ForCES version</synopsis>
             <typeRef>u8</typeRef>
           </attribute>
           <attribute elementID="2" access="read-only">
             <name>FEID</name>
             <synopsis>Unicast FEID</synopsis>
             <typeRef>uint32</typeRef>



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           </attribute>
           <attribute elementID="3" access="read-write">
              <name>MulticastFEIDs</name>
              <synopsis>
                 the table of all multicast IDs
              </synopsis>
              <array type="variable-size">
               <typeRef>uint32</typeRef>
              </array>
           </attribute>
           <attribute elementID="4" access="read-write">
             <name>CEHBPolicy</name>
             <synopsis>
              The CE Heartbeat Policy
             </synopsis>
             <typeRef>CEHBPolicyValues</typeRef>
           </attribute>
           <attribute elementID="5" access="read-write">
             <name>CEHDI</name>
             <synopsis>
               The CE Heartbeat Dead Interval in millisecs
             </synopsis>
             <typeRef>uint32</typeRef>
           </attribute>
           <attribute elementID="6" access="read-write">
             <name>FEHBPolicy</name>
             <synopsis>
               The FE Heartbeat Policy
             </synopsis>
             <typeRef>FEHBPolicyValues</typeRef>
           </attribute>
           <attribute elementID="7" access="read-write">
             <name>FEHI</name>
             <synopsis>
               The FE Heartbeat Interval in millisecs
             </synopsis>
             <typeRef>uint32</typeRef>
           </attribute>
           <attribute elementID="8" access="read-write">
             <name>CEID</name>
             <synopsis>
                The Primary CE this FE is associated with
             </synopsis>
             <typeRef>uint32</typeRef>
           </attribute>
           <attribute elementID="9" access="read-write">
              <name>BackupCEs</name>
              <synopsis>



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                 The table of all backup CEs other than the primary
              </synopsis>
              <array type="variable-size">
               <typeRef>uint32</typeRef>
              </array>
           </attribute>
           <attribute elementID="10" access="read-write">
             <name>FERestartPolicy</name>
             <synopsis>
                The FE Restart Policy
             </synopsis>
             <typeRef>FERestartPolicyValues</typeRef>
           </attribute>

           <attribute elementID="11" access="read-write">
             <name>CEFailoverPolicy</name>
             <synopsis>
               The CE Failover Policy
             </synopsis>
     <typeRef>CEFailoverPolicyValues</typeRef>
           </attribute>

           <attribute elementID="12" access="read-write">
             <name>CETI</name>
             <synopsis>
               The CE Timeout Interval in millisecs
             </synopsis>
             <typeRef>uint32</typeRef>
           </attribute>
         </attributes>
        <capabilities>
           <capability elementID="30" access="read-only">
              <name>SupportableVersions</name>
              <synopsis>
                 the table of ForCES versions that FE supports
              </synopsis>
              <array type="variable-size">
               <typeRef>u8</typeRef>
              </array>
           </capability>
         </capabilities>
       </LFBClassDef>
     </LFBClassDefs>
   </LFBLibrary>







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B.1.  Capabilities

   At the moment only the SupportableVersions capability is owned by
   this LFB.

   Supportable Versions enumerates all ForCES versions that an FE
   supports.

B.2.  Attributes

   All Attributes are explained in Section 7.2.1.








































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Appendix C.  Data Encoding Examples

   In this section a few examples of data encoding are discussed. these
   example, however, do not show any padding.

   ==========
   Example 1:
   ==========

   Structure with three fixed-lengthof, mandatory fields.

           struct S {
           uint16 a
           uint16 b
           uint16 c
           }

   (a) Describing all fields using SPARSEDATA

           Path-Data TLV
             Path to an instance of S ...
             SPARSEDATA TLV
               ElementIDof(a), lengthof(a), valueof(a)
               ElementIDof(b), lengthof(b), valueof(b)
               ElementIDof(c), lengthof(c), valueof(c)

   (b) Describing a subset of fields

           Path-Data TLV
             Path to an instance of S ...
             SPARSEDATA TLV
               ElementIDof(a), lengthof(a), valueof(a)
               ElementIDof(c), lengthof(c), valueof(c)

   Note: Even though there are non-optional elements in structure S,
   since one can uniquely identify elements, one can selectively send
   element of structure S (eg in the case of an update from CE to FE).

   (c) Describing all fields using a FULLDATA TLV

           Path-Data TLV
             Path to an instance of S ...
             FULLDATA TLV
               valueof(a)
               valueof(b)
               valueof(c)





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   ==========
   Example 2:
   ==========

   Structure with three fixed-lengthof fields, one mandatory, two
   optional.

           struct T {
           uint16 a
           uint16 b (optional)
           uint16 c (optional)
           }

   This example is identical to Example 1, as illustrated below.

   (a) Describing all fields using SPARSEDATA

           Path-Data TLV
             Path to an instance of S ...
             SPARSEDATA TLV
               ElementIDof(a), lengthof(a), valueof(a)
               ElementIDof(b), lengthof(b), valueof(b)
               ElementIDof(c), lengthof(c), valueof(c)

   (b) Describing a subset of fields using SPARSEDATA

           Path-Data TLV
             Path to an instance of S ...
             SPARSEDATA TLV
               ElementIDof(a), lengthof(a), valueof(a)
               ElementIDof(c), lengthof(c), valueof(c)

   (c) Describing all fields using a FULLDATA TLV

           Path-Data TLV
             Path to an instance of S ...
             FULLDATA TLV
               valueof(a)
               valueof(b)
               valueof(c)

   Note: FULLDATA TLV _cannot_ be used unless all fields are being
   described.

   ==========
   Example 3:
   ==========




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   Structure with a mix of fixed-lengthof and variable-lengthof fields,
   some mandatory, some optional.

           struct U {
           uint16 a
           string b (optional)
           uint16 c (optional)
           }

   (a) Describing all fields using SPARSEDATA

           Path to an instance of U ...
           SPARSEDATA TLV
             ElementIDof(a), lengthof(a), valueof(a)
             ElementIDof(b), lengthof(b), valueof(b)
             ElementIDof(c), lengthof(c), valueof(c)

   (b) Describing a subset of fields using SPARSEDATA

           Path to an instance of U ...
           SPARSEDATA TLV
             ElementIDof(a), lengthof(a), valueof(a)
             ElementIDof(c), lengthof(c), valueof(c)

   (c) Describing all fields using FULLDATA TLV

           Path to an instance of U ...
             FULLDATA TLV
               valueof(a)
               FULLDATA TLV
                 valueof(b)
               valueof(c)

   Note: The variable-length field requires the addition of a FULLDATA
   TLV within the outer FULLDATA TLV as in the case of element b above.

   ==========
   Example 4:
   ==========

   Structure containing an array of another structure type.

           struct V {
           uint32 x
           uint32 y
           struct U z[]
           }




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   (a) Encoding using SPARSEDATA, with two instances of z[], also
   described with SPARSEDATA, assuming only the 10th and 15th subscript
   of z[] are encoded.

           path to instance of V ...
           SPARSEDATA TLV
           ElementIDof(x), lengthof(x), valueof(x)
           ElementIDof(y), lengthof(y), valueof(y)
           ElementIDof(z), lengthof(all below)
             ElementID = 10 (i.e index 10 from z[]), lengthof(all below)
                 ElementIDof(a), lengthof(a), valueof(a)
                 ElementIDof(b), lengthof(b), valueof(b)
             ElementID = 15 (index 15 from z[]), lengthof(all below)
                 ElementIDof(a), lengthof(a), valueof(a)
                 ElementIDof(c), lengthof(c), valueof(c)

   Note the holes in the elements of z (10 followed by 15).  Also note
   the gap in index 15 with only elements a and c appearing but not b.

































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Appendix D.  Use Cases

   Assume LFB with following attributes for the following use cases.



   foo1, type u32, ID = 1

   foo2, type u32, ID = 2

   table1: type array, ID = 3
           elements are:
           t1, type u32, ID = 1
           t2, type u32, ID = 2  // index into table 2
           KEY: nhkey, ID = 1, V = t2

   table2: type array, ID = 4
           elements are:
           j1, type u32, ID = 1
           j2, type u32, ID = 2
           KEY: akey, ID = 1, V = { j1,j2 }

   table3: type array, ID = 5
           elements are:
           someid, type u32, ID = 1
           name, type string variable sized, ID = 2

   table4: type array, ID = 6
           elements are:
           j1, type u32, ID = 1
           j2, type u32, ID = 2
           j3, type u32, ID = 3
           j4, type u32, ID = 4
           KEY: mykey, ID = 1, V = { j1}

   table5: type array, ID = 7
           elements are:
           p1, type u32, ID = 1
           p2, type array, ID = 2, array elements of type-X

   Type-X:
           x1, ID 1, type u32
           x2, ID2 , type u32
                   KEY: tkey, ID = 1, V = { x1}



   All examples will show an attribute suffixed with "v" or "val" to



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   indicate the value of the referenced attribute. example for attribute
   foo2, foo1v or foo1value will indicate the value of foo1.  In the
   case where F_SEL** are missing (bits equal to 00) then the flags will
   not show any selection.

   All the examples only show use of FULLDATA for data encoding;
   although SPARSEDATA would make more sense in certain occasions, the
   emphasis is on showing the message layout.  Refer to Appendix C for
   examples that show usage of both FULLDATA and SPARSEDATA.

   1.   To get foo1


   OPER = GET-TLV
           Path-data TLV: IDCount = 1, IDs = 1
   Result:
   OPER = GET-RESPONSE-TLV
           Path-data-TLV:
                   flags=0, IDCount = 1, IDs = 1
                   FULLDATA-TLV L = 4+4, V =  foo1v


   2.   To set foo2 to 10

   OPER = SET-REPLACE-TLV
           Path-data-TLV:
                   flags = 0,  IDCount = 1, IDs = 2
                   FULLDATA TLV: L = 4+4, V=10

   Result:
   OPER = SET-RESPONSE-TLV
           Path-data-TLV:
                   flags = 0,  IDCount = 1, IDs = 2
                   RESULT-TLV

   3.   To dump table2

   OPER = GET-TLV
           Path-data-TLV:
                   IDCount = 1, IDs = 4
   Result:
   OPER = GET-RESPONSE-TLV
           Path-data-TLV:
                   flags = 0, IDCount = 1, IDs = 4
                   FULLDATA=TLV: L = XXX, V=
                           a series of: index, j1value,j2value  entries
                           representing the entire table




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        Note:  One should be able to take a GET-RESPONSE-TLV and convert
           it to a SET-REPLACE-TLV.  If the result in the above example
           is sent back in a SET-REPLACE-TLV, (instead of a GET-
           RESPONSE_TLV) then the entire contents of the table will be
           replaced at that point.

   4.   Multiple operations Example.  To create entry 0-5 of table2
        (Error conditions are ignored)

   OPER = SET-CREATE-TLV
           Path-data-TLV:
                   flags = 0 , IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                       FULLDATA-TLV containing j1, j2 value for entry 0
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 1
                       FULLDATA-TLV containing j1, j2 value for entry 1
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                       FULLDATA-TLV containing j1, j2 value for entry 2
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 3
                       FULLDATA-TLV containing j1, j2 value for entry 3
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 4
                       FULLDATA-TLV containing j1, j2 value for entry 4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 5
                       FULLDATA-TLV containing j1, j2 value for entry 5





















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   Result:
   OPER = SET-RESPONSE-TLV
           Path-data-TLV:
                   flags = 0 , IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 1
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 3
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 4
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 5
                       RESULT-TLV


   5.   Block operations (with holes) example.  Replace entry 0,2 of
        table2

   OPER = SET-REPLACE-TLV
           Path-data TLV:
                   flags =  0 , IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                       FULLDATA-TLV containing j1, j2 value for entry 0
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                       FULLDATA-TLV containing j1, j2 value for entry 2

   Result:
   OPER = SET-REPLACE-TLV
           Path-data TLV:
                   flags =  0 , IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                       RESULT-TLV
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                       RESULT-TLV




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   6.   Getting rows example.  Get first entry of table2.

   OPER = GET-TLV
           Path-data TLV:
                   IDCount = 2, IDs=4.0

   Result:
   OPER = GET-RESPONSE-TLV
           Path-data TLV:
                   IDCount = 2, IDs=4.0
                   FULLDATA TLV, Length = XXX, V =
                           j1value,j2value entry

   7.   Get entry 0-5 of table2.





































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   OPER = GET-TLV
           Path-data-TLV:
                   flags = 0, IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 1
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 3
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 5


   Result:
   OPER = GET-RESPONSE-TLV
           Path-data-TLV:
                   flags = 0, IDCount = 1, IDs=4
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 0
                       FULLDATA-TLV containing j1value j2value
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 1
                       FULLDATA-TLV containing j1value j2value
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 2
                       FULLDATA-TLV containing j1value j2value
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 3
                       FULLDATA-TLV containing j1value j2value
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 4
                       FULLDATA-TLV containing j1value j2value
                   PATH-DATA-TLV
                       flags = 0, IDCount = 1, IDs = 5
                       FULLDATA-TLV containing j1value j2value


   8.   Create a row in table2, index 5.









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   OPER = SET-CREATE-TLV
           Path-data-TLV:
                   flags = 0, IDCount = 2, IDs=4.5
                   FULLDATA TLV, Length = XXX
                           j1value,j2value

   Result:
   OPER = SET-RESPONSE-TLV
           Path-data TLV:
                   flags = 0, IDCount = 1, IDs=4.5
                   RESULT-TLV


   9.   An example of "create and give me an index" Assuming one asked
        for verbose response back in the main message header.


   OPER = SET-CREATE-TLV
           Path-data -TLV:
                   flags = FIND-EMPTY, IDCount = 1, IDs=4
                   FULLDATA TLV, Length = XXX
                           j1value,j2value

   Result
   If 7 were the first unused entry in the table:
   OPER = SET-RESPONSE
           Path-data TLV:
                   flags = 0, IDCount = 2, IDs=4.7
                   RESULT-TLV indicating success, and
                           FULLDATA-TLV, Length = XXX j1value,j2value


   10.  Dump contents of table1.


   OPER = GET-TLV
           Path-data TLV:
                   flags = 0, IDCount = 1, IDs=3

   Result:
   OPER = GET-RESPONSE-TLV
           Path-data TLV
                   flags = 0, IDCount = 1, IDs=3
                   FULLDATA TLV, Length = XXXX
                           (depending on size of table1)
                           index, t1value, t2value
                           index, t1value, t2value
                           .



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                           .
                           .


   11.  Using Keys.  Get row entry from table4 where j1=100.  Recall, j1
        is a defined key for this table and its keyid is 1.




   OPER = GET-TLV
           Path-data-TLV:
                   flags = F_SELKEY  IDCount = 1, IDs=6
                   KEYINFO-TLV = KEYID=1, KEY_DATA=100

   Result:
   If j1=100 was at index 10
   OPER = GET-RESPONSE-TLV
           Path-data TLV:
                   flags = 0, IDCount = 1, IDs=6.10
                   FULLDATA TLV, Length = XXXX
                           j1value,j2value, j3value, j4value


   12.  Delete row with KEY match (j1=100, j2=200) in table 2.  Note
        that the j1,j2 pair are a defined key for the table 2.


   OPER = DEL-TLV
           Path-data TLV:
                   flags = F_SELKEY  IDCount = 1, IDs=4
                   KEYINFO TLV:  {KEYID =1 KEY_DATA=100,200}

   Result:
   If (j1=100, j2=200) was at entry 15:
   OPER = DELETE-RESPONSE-TLV
           Path-data TLV:
                   flags = 0  IDCount = 2, IDs=4.15
                   RESULT-TLV (with FULLDATA if verbose)


   13.  Dump contents of table3.  It should be noted that this table has
        a column with element name that is variable sized.  The purpose
        of this use case is to show how such an element is to be
        encoded.






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   OPER = GET-TLV
           Path-data-TLV:
                   flags = 0 IDCount = 1, IDs=5

   Result:
   OPER = GET-RESPONSE-TLV
        Path-data TLV:
           flags = 0  IDCount = 1, IDs=5
               FULLDATA TLV, Length = XXXX
                   index, someidv, TLV: T=FULLDATA, L = 4+strlen(namev),
                          V = namev
                   index, someidv, TLV: T=FULLDATA, L = 4+strlen(namev),
                          V = namev
                   index, someidv, TLV: T=FULLDATA, L = 4+strlen(namev),
                          V = namev
                   index, someidv, TLV: T=FULLDATA, L = 4+strlen(namev),
                          V = namev
                   .
                   .
                   .


   14.  Multiple atomic operations.

        Note 1:  This emulates adding a new nexthop entry and then
           atomically updating the L3 entries pointing to an old NH to
           point to a new one.  The assumption is both tables are in the
           same LFB

        Note2:  Main header has atomic flag set and the request is for
           verbose/full results back; Two operations on the LFB
           instance, both are SET operations.



















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   //Operation 1: Add a new entry to table2 index #20.
   OPER = SET-CREATE-TLV
           Path-TLV:
                   flags = 0, IDCount = 2,  IDs=4.20
                   FULLDATA TLV, V= j1value,j2value

   // Operation 2: Update table1 entry which
   // was pointing with t2 = 10 to now point to 20
   OPER = SET-REPLACE-TLV
           Path-data-TLV:
                   flags = F_SELKEY, IDCount = 1, IDs=3
                   KEYINFO = KEYID=1 KEY_DATA=10
                   Path-data-TLV
                           flags = 0  IDCount = 1, IDs=2
                           FULLDATA TLV, V= 20

   Result:
   //first operation, SET
   OPER = SET-RESPONSE-TLV
           Path-data-TLV
                   flags = 0 IDCount = 3, IDs=4.20
                   RESULT-TLV code = success
                           FULLDATA TLV, V = j1value,j2value
   // second opertion SET - assuming entry 16 was updated
   OPER = SET-RESPONSE-TLV
           Path-data TLV
                   flags = 0 IDCount = 2, IDs=3.16
                   Path-Data TLV
                           flags = 0  IDCount = 1, IDs = 2
                           SET-RESULT-TLV code = success
                                   FULLDATA TLV, Length = XXXX v=20
   // second opertion SET
   OPER = SET-RESPONSE-TLV
           Path-data TLV
                   flags = 0 IDCount = 1, IDs=3
                   KEYINFO = KEYID=1 KEY_DATA=10
                   Path-Data TLV
                           flags = 0  IDCount = 1, IDs = 2
                           SET-RESULT-TLV code = success
                                   FULLDATA TLV, Length = XXXX v=20



   15.  Selective setting.  On table 4 -- for indices 1, 3, 5, 7, and 9.
        Replace j1 to 100, j2 to 200, j3 to 300.  Leave j4 as is.

   PER = SET-REPLACE-TLV
       Path-data TLV



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           flags = 0, IDCount = 1, IDs = 6
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 1
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   FULLDATA TLV, Length = XXXX, V = {100}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   FULLDATA TLV, Length = XXXX, V = {200}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   FULLDATA TLV, Length = XXXX, V = {300}
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 3
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   FULLDATA TLV, Length = XXXX, V = {100}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   FULLDATA TLV, Length = XXXX, V = {200}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   FULLDATA TLV, Length = XXXX, V = {300}
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 5
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   FULLDATA TLV, Length = XXXX, V = {100}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   FULLDATA TLV, Length = XXXX, V = {200}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   FULLDATA TLV, Length = XXXX, V = {300}
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 7
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   FULLDATA TLV, Length = XXXX, V = {100}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   FULLDATA TLV, Length = XXXX, V = {200}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   FULLDATA TLV, Length = XXXX, V = {300}
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 9
               Path-data TLV



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                   flags = 0, IDCount = 1, IDs = 1
                   FULLDATA TLV, Length = XXXX, V = {100}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   FULLDATA TLV, Length = XXXX, V = {200}
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   FULLDATA TLV, Length = XXXX, V = {300}


   Non-verbose response mode shown:

   OPER = SET-RESPONSE-TLV
       Path-data TLV
           flags = 0, IDCount = 1, IDs = 6
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 1
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   RESULT-TLV
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 3
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   RESULT-TLV
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 5
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   RESULT-TLV



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           Path-data TLV
               flags = 0, IDCount = 1, IDs = 7
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   RESULT-TLV
           Path-data TLV
               flags = 0, IDCount = 1, IDs = 9
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 1
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 2
                   RESULT-TLV
               Path-data TLV
                   flags = 0, IDCount = 1, IDs = 3
                   RESULT-TLV

   16.  Manipulation of table of table examples.  Get x1 from table10
        row with index 4, inside table5 entry 10


   operation = GET-TLV
           Path-data-TLV
                   flags = 0  IDCount = 5, IDs=7.10.2.4.1

   Results:
   operation = GET-RESPONSE-TLV
           Path-data-TLV
                   flags = 0  IDCount = 5, IDs=7.10.2.4.1
                   FULLDATA TLV: L=XXXX, V = {x1 value}


   17.  From table5's row 10 table10, get X2s based on on the value of
        x1 equaling 10 (recall x1 is KeyID 1)











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   operation = GET-TLV
           Path-data-TLV
                   flag = F_SELKEY, IDCount=3, IDS = 7.10.2
                   KEYINFO TLV, KEYID = 1, KEYDATA = 10
                   Path-data TLV
                           IDCount = 1, IDS = 2 //select x2

   Results:
   If x1=10 was at entry 11:
   operation = GET-RESPONSE-TLV
           Path-data-TLV
                   flag = 0, IDCount=5, IDS = 7.10.2.11
                   Path-data TLV
                           flags = 0  IDCount = 1, IDS = 2
                           FULLDATA TLV: L=XXXX, V = {x2 value}


   18.  Further example of manipulating a table of tables


   Consider table 6 which is defined as:
   table6: type array, ID = 8
           elements are:
           p1, type u32, ID = 1
           p2, type array, ID = 2, array elements of type type-A

   type-A:
           a1, type u32, ID 1,
           a2, type array ID2 ,array elements of type type-B

   type-B:
           b1, type u32, ID 1
           b2, type u32, ID 2

   If for example one wanted to set by replacing:
   table6.10.p1 to 111
   table6.10.p2.20.a1 to 222
   table6.10.p2.20.a2.30.b1 to 333

   in one message and one operation.

   There are two ways to do this:
      a) using nesting
      b) using a flat path data







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   A. Method using nesting
      in one message with a single operation

   operation = SET-REPLACE-TLV
           Path-data-TLV
                   flags = 0  IDCount = 2, IDs=6.10
                   Path-data-TLV
                           flags = 0, IDCount = 1, IDs=1
                           FULLDATA TLV: L=XXXX,
                                   V = {111}
                   Path-data-TLV
                           flags = 0  IDCount = 2, IDs=2.20
                           Path-data-TLV
                                   flags = 0, IDCount = 1, IDs=1
                                   FULLDATA TLV: L=XXXX,
                                           V = {222}
                           Path-data TLV :
                                   flags = 0, IDCount = 3, IDs=2.30.1
                                   FULLDATA TLV: L=XXXX,
                                           V = {333}
   Result:
   operation = SET-RESPONSE-TLV
           Path-data-TLV
                   flags = 0  IDCount = 2, IDs=6.10
                   Path-data-TLV
                           flags = 0, IDCount = 1, IDs=1
                           RESULT-TLV
                   Path-data-TLV
                           flags = 0  IDCount = 2, IDs=2.20
                           Path-data-TLV
                                   flags = 0, IDCount = 1, IDs=1
                                   RESULT-TLV
                           Path-data TLV :
                                   flags = 0, IDCount = 3, IDs=2.30.1
                                   RESULT-TLV
















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   B. Method using a flat path data in
      one message with a single operation

   operation = SET-REPLACE-TLV
           Path-data TLV :
                   flags = 0, IDCount = 3, IDs=6.10.1
                   FULLDATA TLV: L=XXXX,
                           V = {111}
           Path-data TLV :
                   flags = 0, IDCount = 5, IDs=6.10.1.20.1
                   FULLDATA TLV: L=XXXX,
                           V = {222}
           Path-data TLV :
                   flags = 0, IDCount = 7, IDs=6.10.1.20.1.30.1
                   FULLDATA TLV: L=XXXX,
                           V = {333}
   Result:
   operation = SET-REPLACE-TLV
           Path-data TLV :
                   flags = 0, IDCount = 3, IDs=6.10.1
                   RESULT-TLV
           Path-data TLV :
                   flags = 0, IDCount = 5, IDs=6.10.1.20.1
                   RESULT-TLV
           Path-data TLV :
                   flags = 0, IDCount = 7, IDs=6.10.1.20.1.30.1
                   RESULT-TLV


   19.  Get a whole LFB (all its attributes, etc.).

        For example:  at startup a CE might well want the entire FE
           OBJECT LFB.  So, in a request targeted at class 1, instance
           1, one might find:



   operation = GET-TLV
           Path-data-TLV
                   flags = 0  IDCount = 0

   result:
   operation = GET-RESPONSE-TLV
           Path-data-TLV
                   flags = 0  IDCount = 0
                   FULLDATA encoding of the FE Object LFB





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Authors' Addresses

   Ligang Dong
   Zhejiang Gongshang University
   149 Jiaogong Road
   Hangzhou  310035
   P.R.China

   Phone: +86-571-88071024
   Email: donglg@mail.zjgsu.edu.cn


   Avri Doria
   ETRI
   Lulea University of Technology
   Lulea
   Sweden

   Phone: +46 73 277 1788
   Email: avri@acm.org


   Ram Gopal
   Nokia
   5, Wayside Road
   Burlington, MA  310035
   USA

   Phone: +1-781-993-3685
   Email: ram.gopal@nokia.com


   Robert Haas
   IBM
   Saumerstrasse 4
   8803 Ruschlikon
   Switzerland

   Phone:
   Email: rha@zurich.ibm.com











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   Jamal Hadi Salim
   Znyx
   Ottawa, Ontario
   Canada

   Phone:
   Email: hadi@znyx.com


   Hormuzd M Khosravi
   Intel
   2111 NE 25th Avenue
   Hillsboro, OR  97124
   USA

   Phone: +1 503 264 0334
   Email: hormuzd.m.khosravi@intel.com


   Weiming Wang
   Zhejiang Gongshang University
   149 Jiaogong Road
   Hangzhou  310035
   P.R.China

   Phone: +86-571-88057712
   Email: wmwang@mail.zjgsu.edu.cn
























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