path: root/doc/rfc/rfc7409.txt

Internet Engineering Task Force (IETF)                     E. Haleplidis
Request for Comments: 7409                          University of Patras
Category: Experimental                                        J. Halpern
ISSN: 2070-1721                                                 Ericsson
                                                           November 2014


           Forwarding and Control Element Separation (ForCES)
                         Packet Parallelization

Abstract

   Many network devices support parallel packet processing.  This
   document describes how Forwarding and Control Element Separation
   (ForCES) can model a network device's parallelization datapath using
   constructs defined by the ForCES model (RFC 5812) and controlled via
   the ForCES protocol (RFC 5810).

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  This document is a product of the Internet Engineering
   Task Force (IETF).  It represents the consensus of the IETF
   community.  It has received public review and has been approved for
   publication by the Internet Engineering Steering Group (IESG).  Not
   all documents approved by the IESG are a candidate for any level of
   Internet Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7409.
















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Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.





































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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Packet Parallelization  . . . . . . . . . . . . . . . . . . .   5
     2.1.  CoreParallelization LFB . . . . . . . . . . . . . . . . .   7
     2.2.  Parallelization Metadata  . . . . . . . . . . . . . . . .  10
   3.  Parallel Base Types . . . . . . . . . . . . . . . . . . . . .  11
     3.1.  Frame Types . . . . . . . . . . . . . . . . . . . . . . .  11
     3.2.  Data Types  . . . . . . . . . . . . . . . . . . . . . . .  11
     3.3.  Metadata Types  . . . . . . . . . . . . . . . . . . . . .  12
   4.  Parallel LFBs . . . . . . . . . . . . . . . . . . . . . . . .  12
     4.1.  Splitter  . . . . . . . . . . . . . . . . . . . . . . . .  12
       4.1.1.  Data Handling . . . . . . . . . . . . . . . . . . . .  13
       4.1.2.  Components  . . . . . . . . . . . . . . . . . . . . .  13
       4.1.3.  Capabilities  . . . . . . . . . . . . . . . . . . . .  13
       4.1.4.  Events  . . . . . . . . . . . . . . . . . . . . . . .  13
     4.2.  Merger  . . . . . . . . . . . . . . . . . . . . . . . . .  14
       4.2.1.  Data Handling . . . . . . . . . . . . . . . . . . . .  14
       4.2.2.  Components  . . . . . . . . . . . . . . . . . . . . .  15
       4.2.3.  Capabilities  . . . . . . . . . . . . . . . . . . . .  15
       4.2.4.  Events  . . . . . . . . . . . . . . . . . . . . . . .  16
     4.3.  CoreParallelization . . . . . . . . . . . . . . . . . . .  16
       4.3.1.  Data Handling . . . . . . . . . . . . . . . . . . . .  16
       4.3.2.  Components  . . . . . . . . . . . . . . . . . . . . .  16
       4.3.3.  Capabilities  . . . . . . . . . . . . . . . . . . . .  16
       4.3.4.  Events  . . . . . . . . . . . . . . . . . . . . . . .  17
   5.  XML for Parallel LFB Library  . . . . . . . . . . . . . . . .  17
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  25
     6.1.  LFB Class Names and LFB Class Identifiers . . . . . . . .  25
     6.2.  Metadata ID . . . . . . . . . . . . . . . . . . . . . . .  26
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  26
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  26
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  26
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  27
   Acknowledgments   . . . . . . . . . . . . . . . . . . . . . . . .  27
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  27













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1.  Introduction

   A lot of network devices can process packets in a parallel manner.
   The Forwarding and Control Element Separation (ForCES) model
   [RFC5812] presents a formal way to describe the Forwarding Plane's
   datapath with Logical Function Blocks (LFBs) using XML.  This
   document describes how packet parallelization can be described with
   the ForCES model.

   The modeling concept has been influenced by Cilk [Cilk].  Cilk is a
   programming language that has been in development since 1994 at the
   Massachusetts Institute of Technology (MIT) Laboratory.  Cilk allows
   programmers to identify elements that can be executed in parallel.
   The two Cilk concepts used in this document are "spawn" and "sync":
   spawn being the place where parallel tasks can start and sync being
   the place where the parallel task finishes and must collect all
   parallel output (see Section 1.2 for the definitions of both "task"
   and "task correclator").

   This document is Experimental; thus, the LFB Class IDs will not be
   included in the Standard Action's values.  Therefore, the LFB Class
   IDs must have a value larger than 65535, and the LFB names must begin
   with the prefix 'Ext-'.  However, for brevity, when we refer to the
   LFB Class names in the text of this document (not the formal
   definitions), the 'Ext-' prefix will be omitted.

1.1.  Requirements Language

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

1.2.  Definitions

   This document follows the terminology defined by the ForCES model in
   [RFC5812].  In particular, the reader is expected to be familiar with
   the following terms:

      FE

      CE

      FE Model

      LFB Class (or type)

      LFB Instance




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      LFB Model

      Element

      Attribute

      LFB Metadata

      ForCES Component

      LFB Class Library

   This document also introduces the following terms:

   Chunk:             Pieces of a packet.

   Task:              Grouping of packets or chunks belonging to the
                      same packet that are processed in parallel.

   Task Correlator:   A 32-bit identifier that uniquely distinguishes
                      tasks.

   Split Type:        A parallel type where the packets are split into
                      chunks to be processed in parallel.  Each task in
                      a split type is composed only of chunks.

   Flood Type:        A parallel type where the packets are copied as-is
                      to downstream LFBs to be processed in parallel.
                      Each task in a flood type is composed only of
                      packets.

2.  Packet Parallelization

   This document addresses the following two types of packet
   parallelization:

   1.  Flood: Where a copy of a packet is sent to multiple LFBs to be
       processed in parallel.

   2.  Split: Where the packet will be split into chunks of equal size
       specified by the CE and sent to multiple LFB instances, probably
       of the same LFB class, to be processed in parallel.

   It must be noted that the process of copying the packet in the flood
   parallel type is implementation dependent and is loosely defined
   here.  An implementer may either decide to physically copy the packet
   and send all packets on the parallel paths or decide to logically
   copy the packet by simply sending, for example, pointers to the same



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   packet provided that the necessary interlocks are taken into account.
   The implementer has to take into account the device's characteristics
   to decide which approach fits best to the device.

   In the split parallel type, while harder, the implementer may also
   decide to logically split the packet and send, for example, pointers
   to parts of the packet, provided that the necessary interlocks are
   managed.  In addition, how chunks are distributed to the LFBs (e.g.,
   which chunk to which LFB) is implementation dependent.  For example,
   while usually chunks are sent to the same LFB class, the number of
   LFB instances may not be equal to the number of chunks.  It is up to
   the implementer to decide how these chunks will be sent, for example,
   in a round-robin fashion.

   This document introduces two LFBs that are used before and after the
   parallelization occurs:

   1.  Splitter: Similar to Cilk's spawn, a splitter is an LFB that will
       split the path of a packet that will be sent to multiple
       downstream LFBs to be processed in parallel.

   2.  Merger: Similar to Cilk's sync, a merger is an LFB that will
       receive packets or chunks of the same initial packet and merge
       them and the results into one packet.

   Both parallel packet distribution types can currently be achieved
   with the ForCES model.  The Splitter LFB has one group output that
   produces either chunks or packets to be sent to LFBs for processing,
   and the Merger LFB has one group input that expects either packets or
   chunks to aggregate all the parallel packets or chunks and produce a
   single packet.

   Figure 1 shows a simple example of a split parallel datapath along
   with the Splitter and Merger LFB.  The example in Figure 1 depicts
   multiple regular expression (regex) match LFBs that perform match
   operations on parts of the original packet.  Figure 2 shows an
   example of a flood parallel datapath along with the Splitter and
   Merger LFB.  The example in Figure 2 depicts a path that will
   classify an IPv4 packet while also performing metering; on the other
   path, the IPv4 Time to Live (TTL) field will be decremented.











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                      C1+M   +------------+  C1+M
                       +---->| Regex LFB  |----+
        +----------+   |     +------------+    |       +----------+
        |          |---+                       +------>|          |
     P  |          |  C2+M   +------------+  C2+M      |          | P
    --->| Splitter |-------->| Regex LFB  |----------->|  Merger  |--->
        |   LFB    |  CN+M   +------------+  CN+M      |   LFB    |
        |          |---+                       +------>|          |
        +----------+   |     +------------+    |       +----------+
                       +---->| Regex LFB  |----+
                             +------------+

                Figure 1: Simple Split Parallel Processing

        +----------+    +------------+    +-------+    +----------+
        |          |P+M | Classifier |P+M | Meter |P+M |          |
     P  |          |--->|     LFB    |--->|  LFB  |--->|          | P
    --->| Splitter |    +------------+    +-------+    |  Merger  |--->
        |   LFB    |                                   |   LFB    |
        |          |P+M       +------------+       P+M |          |
        |          |--------->|  IPv4 TTL  |---------->|          |
        +----------+          |  Decrement |           +----------+
                              |    LFB     |
                              +------------+

                Figure 2: Simple Flood Parallel Processing

   This version of the modeling framework does not allow for nested
   parallel datapath topologies.  This decision was reached by the
   authors and the ForCES working group, as there was no strong use case
   or need at decision time.  This led to a simpler metadata definition,
   which is required to be transported between the splitter and the
   corresponding merger.  If there is a need for nested parallel
   datapaths, a new version of a splitter and merger will need to be
   defined, as well as an augmentation to the defined metadata.

2.1.  CoreParallelization LFB

   One important element to a developer is the ability to define which
   LFBs can be used in a parallel mode, which LFBs can be parallelized
   with which, as well as the order in which parallel LFBs can be
   assembled.

   To access the parallelization details, we opted for defining a new
   LFB class: the CoreParallelization LFB.  This choice was an
   alternative to making another change to the core FEObject LFB.  The
   CoreParallelization exists merely to define the capabilities for an
   FE's LFB parallelization.  A CE using the ForCES protocol [RFC5810]



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   can check the existence of this LFB class in the FEObject's
   SupportedLFBs component.  The existence of the CoreParallelization
   LFB will indicate to the CE that the specific FE supports
   parallelization.  There MUST be only one instance of the
   CoreParallelization LFB per FE.

   The topology of the parallel datapath can be deferred and manipulated
   from the FEObject LFB's LFBTopology.

   The CoreParallelization requires only one capability in order to
   specify each LFB that can be used in a parallel mode:

   o  The Name of the LFB.

   o  The Class ID of the LFB.

   o  The Version of the LFB.

   o  The number of instances that class can support in parallel.

   o  A list of LFB classes that can follow this LFB class in a pipeline
      for a parallel path.

   o  A list of LFB classes that can exist before this LFB class in a
      pipeline for a parallel path.

   o  A list of LFB classes that can process packets or chunks in
      parallel with this LFB class.

      <!-- Datatype -->
      <dataTypeDef>
         <name>ParallelLFBType</name>
         <synopsis>Table entry for parallel LFBs</synopsis>
         <struct>
            <component componentID="1">
               <name>LFBName</name>
               <synopsis>The name of an LFB Class</synopsis>
               <typeRef>string</typeRef>
            </component>
            <component componentID="2">
               <name>LFBClassID</name>
               <synopsis>The id of the LFB Class</synopsis>
               <typeRef>uint32</typeRef>
            </component>
            <component componentID="3">
               <name>LFBVersion</name>
               <synopsis>The version of the LFB Class used by this FE
               </synopsis>



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               <typeRef>string</typeRef>
            </component>
            <component componentID="4">
               <name>LFBParallelOccurrenceLimit</name>
               <synopsis>The upper limit of instances of the same
                  parallel LFBs of this class</synopsis>
               <optional />
               <typeRef>uint32</typeRef>
            </component>
            <component componentID="5">
               <name>AllowedParallelAfters</name>
               <synopsis>List of LFB Classes that can follow this LFB
                  in a parallel pipeline</synopsis>
               <optional />
               <array>
                  <typeRef>uint32</typeRef>
               </array>
            </component>
            <component componentID="6">
               <name>AllowedParallelBefores</name>
               <synopsis>List of LFB Classes that this LFB class can
                  follow in a parallel pipeline</synopsis>
               <optional />
               <array>
                  <typeRef>uint32</typeRef>
               </array>
            </component>
            <component componentID="7">
               <name>AllowedParallel</name>
               <synopsis>List of LFB Classes that this LFB class can run
                  in parallel with</synopsis>
               <array>
                  <typeRef>uint32</typeRef>
               </array>
            </component>
         </struct>
      </dataTypeDef>

      <!-- Capability -->
            <capability componentID="32">
               <name>ParallelLFBs</name>
               <synopsis>List of all supported parallel LFBs</synopsis>
               <array type="Variable-size">
                  <typeRef>ParallelLFBType</typeRef>
               </array>
            </capability>

           Figure 3: XML Definitions for CoreParallelization LFB



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2.2.  Parallelization Metadata

   It is expected that the splitting and merging mechanisms are an
   implementation issue.  This document plays the role of defining the
   operational parameters for the splitting and merging: namely, the
   size of the chunks, what happens if a packet or chunk has been marked
   as invalid, and whether the merge LFB should wait for all packets or
   chunks to arrive.  The following metadata set is defined as a struct:

   1.  ParallelType - Flood or split

   2.  TaskCorrelator - Identify packets or chunks that belonged to the
       initial packet that entered the Splitter LFB

   3.  ParallelNum - Sequence number of the packet or the chunk for a
       specific task

   4.  ParallelPartsCount - Total number of packets or chunks for a
       specific task

   This metadata is produced from the Splitter LFB, is opaque to LFBs in
   parallel paths, and is passed along to the Merger LFB without being
   consumed.

   In the case in which an LFB decides that a packet/chunk has to be
   dropped, the LFB MAY drop the packet/chunk, but the metadata MUST be
   sent to the Merger LFB's InvalidIn input port for merging purposes.

   Additional metadata produced by LFBs inside a datapath MAY be
   aggregated within the Merger LFB and sent on after the merging
   process.  In case of receiving the same metadata definition with
   multiple values, the Merger LFB MUST keep the first received from a
   valid packet or chunk.


















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3.  Parallel Base Types

3.1.  Frame Types

   One frame type has been defined in this library.

   +-----------+-------------------------------------------------------+
   | Frame     | Synopsis                                              |
   | Name      |                                                       |
   +-----------+-------------------------------------------------------+
   | Chunk     | A chunk is a frame that is part of an original larger |
   |           | frame.                                                |
   +-----------+-------------------------------------------------------+

                           Parallel Frame Types

3.2.  Data Types

   One data type has been defined in this library.

   +---------------+------------------------+--------------------------+
   | DataType Name | Type                   | Synopsis                 |
   +---------------+------------------------+--------------------------+
   | ParallelTypes | Atomic uchar.  Special | The type of              |
   |               | Values Flood (0),      | parallelization this     |
   |               | Split (1).             | packet will go through.  |
   +---------------+------------------------+--------------------------+

                            Parallel Data Types






















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3.3.  Metadata Types

   The following metadata structure with ID 16, using the ForCES model
   extension [RFC7408], is defined for the parallelization library:

   +--------------------+--------+----+--------------------------------+
   |   Metadata Name    |  Type  | ID |            Synopsis            |
   +--------------------+--------+----+--------------------------------+
   |    ParallelType    | uchar  | 1  |  The type of parallelization   |
   |                    |        |    | this packet will go through. 0 |
   |                    |        |    |    for flood, 1 for split.     |
   |                    |        |    |                                |
   |   TaskCorrelator   | uint32 | 2  |  An identification number to   |
   |                    |        |    |   specify that a packet or a   |
   |                    |        |    |   chunk belongs to the same    |
   |                    |        |    |         parallel task.         |
   |                    |        |    |                                |
   |    ParallelNum     | uint32 | 3  |    Defines the number of a     |
   |                    |        |    | specific packet or chunk of a  |
   |                    |        |    |         specific task.         |
   |                    |        |    |                                |
   | ParallelPartsCount | uint32 | 4  |  Defines the total number of   |
   |                    |        |    |    packets or chunks for a     |
   |                    |        |    |         specific task.         |
   +--------------------+--------+----+--------------------------------+

                      Metadata Structure for Merging

4.  Parallel LFBs

4.1.  Splitter

   The Splitter LFB takes part in parallelizing the processing datapath
   by sending either the same packet (Figure 2) or chunks (Figure 1) of
   the same packet to multiple LFBs.

                             +---------------+
                  SplitterIn |               | SplitterOut
                  ---------->| Splitter LFB  |------------->
                             |               |
                             +---------------+

                          Figure 4: Splitter LFB








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4.1.1.  Data Handling

   The Splitter LFB receives any kind of packet via the singleton input,
   Input.  Depending upon the CE's configuration of the ParallelType
   component, if the parallel type is of type flood (0), the same packet
   MUST be sent through all instances of the group output "SplitterOut".
   If the parallel type is of type split (1), then the packet will be
   split into same size chunks except for the last, which MAY be
   smaller, with the max size being defined by the ChunkSize component.
   Chunks MAY be sent out in a round-robin fashion through instances of
   the group output "ParallelOut" or in any other way defined by the
   implementer.  Each packet or chunk will be accompanied by the
   following metadata set as a struct:

   o  ParallelType - The parallel type: split or flood.

   o  ParallelID - Generated by the Splitter LFB to identify which
      chunks or packets belong to the same parallel task.

   o  ParallelNum - Each chunk or packet of a parallel ID will be
      assigned a number in order for the Merger LFB to know when it has
      gathered them all along with the ParallelPartsCount metadata.

   o  ParallelPartsCount - The number of chunks or packets for the
      specific task.

4.1.2.  Components

   The Splitter LFB has only two components.  The first is the
   ParallelType, a uint32 that defines how the packet will be processed
   by the Splitter LFB.  The second is the ChunkSize, a uint32 that
   specifies the size of each chunk when a packet is split into multiple
   same-size chunks.  The last chunk MAY be smaller than the value of
   the ChunkSize.

4.1.3.  Capabilities

   This LFB has only one capability specified; the MinMaxChunkSize is a
   struct of two uint32s to specify the minimum and maximum chunk size.

4.1.4.  Events

   This LFB has no events specified.








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4.2.  Merger

   The Merger LFB is the synchronization point for multiple packets or
   packet chunks of the same task emanating out of the parallel path, as
   illustrated in Figure 1 and Figure 2.

                               +-------------+
                      MergerIn |             |
                     --------->|             | MergerOut
                               | Merger LFB  |----------->
                     InvalidIn |             |
                     --------->|             |
                               +-------------+

                           Figure 5: Merger LFB

4.2.1.  Data Handling

   The Merger LFB receives either a packet or a chunk via the group
   input ParallelIn, along with the ParallelType metadata, the
   TaskCorrelator, the ParallelNum, and the ParallelPartsCount.

   In the case in which an upstream LFB has dropped a packet or a chunk,
   the Merger LFB MAY receive only the metadata, both the metadata and
   the packet, or the chunk through the InvalidIn group input port.  It
   SHOULD receive a metadata specifying the error code.  Currently
   defined metadata in the Base LFB Library [RFC6956] are the
   ExceptionID and the ValidateErrorID.

   If the MergeWaitType is set to false, the Merger LFB will initiate
   the merge process upon receiving the first packet.  If false, for
   each task identified by the task correlator, it will wait for all
   packets/chunks to arrive unless the MergeWaitTimeoutTimer timer
   expires.  If the MergeWaitTimeoutTimer has expired, the Merger MUST
   consider the rest of the packets/chunks that have not been received
   as invalid, and it MUST handle the packets according to the
   InvalidAction value.

   If one packet or chunk has been received through the InvalidIn port,
   then the merging procedure will handle the packets/chunks according
   to the InvalidAction value.  If the InvalidAction component has been
   set to 0, then if one packet or chunk is not valid, all will be
   dropped or else the process will initiate.  Once the merging process
   has been completed, the resulting packet will be sent via the
   singleton output port MergerOut.






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   If the Merger LFB receives different values for the same metadata
   from different packets or chunks that have the same task correlator,
   then the Merger LFB will use the first metadata from a packet or
   chunk that entered the LFB through the MergerIn input port.

4.2.2.  Components

   This LFB has the following components specified:

   1.  InvalidAction: A uchar defining what the Merge LFB will do if an
       invalid chunk or packet is received.  If set to 0 (DropAll), the
       merge will be considered invalid and all chunks or packets will
       be dropped.  If set to 1 (Continue), the merge will continue.

   2.  MergeWaitTimeoutTimer: A uint32 defining the amount of time, in
       milliseconds, that the Merger will wait for all packets or chunks
       within the same task to arrive before considering them invalid.
       The MergeWaitTimeoutTimer starts as soon as the first chunk or
       packet of a parallel task arrives.

   3.  MergeWaitType: A boolean.  If true, the Merger LFB will wait for
       all packets or chunks to be received prior to performing the
       merge.  If false, when one packet or a chunk with a response is
       received by the merge LFB, it will start with the merge process.

   4.  InvalidMergesCounter: A uint32 that counts the number of merges
       where there is at least one packet or chunk that entered the
       Merger LFB through the InvalidIn input port.

   5.  InvalidTotalCounter: A uint32 that counts the number of merges
       where all packets/chunks entered the Merger LFB through the
       InvalidIn input port.


   6.  InvalidIDCounters: A struct of two arrays.  Each array has a
       uint32 per row.  Each array counts the number of invalid merges
       where at least one packet or chunk entered through InvalidID per
       error ID.  The first array is the InvalidExceptionID and the
       second is the InvalidValidateErrorID.

4.2.3.  Capabilities

   This LFB has no capabilities specified.








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4.2.4.  Events

   This LFB specifies only two events.  The first detects whether the
   InvalidMergesCounter has exceeded a specific value, and the second
   detects whether the InvalidAllCounter has exceeded a specific value.
   Both error reports will send the respective counter value.  Event
   Filters can be used to limit the number of messages

4.3.  CoreParallelization

   A core LFB that specifies that the FE supports parallelization
   instead of updating the FEObject LFB

4.3.1.  Data Handling

   The CoreParallelization does not handle data.

4.3.2.  Components

   This LFB has no components specified.

4.3.3.  Capabilities

   This LFB has only one capability specified.  The ParallelLFBs is a
   table which lists all the LFBs that can be parallelized.  Each row of
   the table contains:

   1.  LFBName: A string.  The Name of the parallel LFB.

   2.  LFBClassID: A uint32.  The Class ID of the parallel LFB.

   3.  LFBVersion: A string.  The Version of the parallel LFB.

   4.  LFBParallelOccurrenceLimit: A uint32.  The upper limit of
       instances of the same parallel LFBs of this class.


   5.  AllowedParallelAfters: A table of uint32s (LFB Class IDs).  A
       list of LFB classes that can follow this LFB class in a pipeline
       for a parallel path.

   6.  AllowedParallelBefores: A table of uint32s (LFB Class IDs).  A
       list of LFB classes that can exist before this LFB class in a
       pipeline for a parallel path.

   7.  AllowedParallel: A table of uint32s (LFB Class IDs).  A list of
       LFB classes that can process packets or chunks in parallel with
       this LFB class.



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4.3.4.  Events

   This LFB specifies no events.

5.  XML for Parallel LFB Library

  <?xml version="1.0" encoding="UTF-8"?>
  <LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
     provides="Parallel">
    <load library="BaseTypeLibrary" location="BaseTypeLibrary.LFB"/>
    <frameDefs>
      <frameDef>
        <name>Chunk</name>
        <synopsis>A chunk is a frame that is part of an original
              larger frame</synopsis>
      </frameDef>
    </frameDefs>
    <dataTypeDefs>
      <dataTypeDef>
        <name>ParallelTypes</name>
        <synopsis>The type of parallelization this packet will go
              through</synopsis>
        <atomic>
          <baseType>uchar</baseType>
          <specialValues>
            <specialValue value="0">
              <name>Flood</name>
              <synopsis>The packet/chunk has been sent as a whole
                       to multiple recipients</synopsis>
            </specialValue>
            <specialValue value="1">
              <name>Split</name>
              <synopsis>The packet/chunk has been split into
                       multiple chunks and sent to recipients</synopsis>
            </specialValue>
          </specialValues>
        </atomic>
      </dataTypeDef>
      <dataTypeDef>
        <name>ParallelLFBType</name>
        <synopsis>Table entry for parallel LFBs</synopsis>
        <struct>
          <component componentID="1">
            <name>LFBName</name>
            <synopsis>The name of an LFB Class</synopsis>
            <typeRef>string</typeRef>



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          </component>
          <component componentID="2">
            <name>LFBClassID</name>
            <synopsis>The ID of the LFB Class</synopsis>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="3">
            <name>LFBVersion</name>
            <synopsis>The version of the LFB Class used by this FE
               </synopsis>
            <typeRef>string</typeRef>
          </component>
          <component componentID="4">
            <name>LFBParallelOccurrenceLimit</name>
            <synopsis>The upper limit of instances of the same
                  parallel LFBs of this class</synopsis>
            <optional/>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="5">
            <name>AllowedParallelAfters</name>
            <synopsis>List of LFB Classes that can follow this LFB
                  in a parallel pipeline</synopsis>
            <optional/>
            <array>
              <typeRef>uint32</typeRef>
            </array>
          </component>
          <component componentID="6">
            <name>AllowedParallelBefores</name>
            <synopsis>List of LFB Classes that this LFB Class can
                  follow in a parallel pipeline</synopsis>
            <optional/>
            <array>
              <typeRef>uint32</typeRef>
            </array>
          </component>
          <component componentID="7">
            <name>AllowedParallel</name>
            <synopsis>List of LFB Classes that this LFB Class can be run
                  in parallel with</synopsis>
            <array>
              <typeRef>uint32</typeRef>
            </array>
          </component>
        </struct>
      </dataTypeDef>
    </dataTypeDefs>



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    <metadataDefs>
      <metadataDef>
        <name>ParallelMetadataSet</name>
        <synopsis>A metadata set for parallelization-related LFBs
           </synopsis>
        <metadataID>32</metadataID>
        <struct>
          <component componentID="1">
            <name>ParallelType</name>
            <synopsis>The type of parallelization this packet/chunk
                    has gone through</synopsis>
            <typeRef>ParallelTypes</typeRef>
          </component>
          <component componentID="2">
            <name>TaskCorrelator</name>
            <synopsis>An identification number to specify that
                    packets or chunks originate from the same packet.
                 </synopsis>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="3">
            <name>ParallelNum</name>
            <synopsis>Defines the number of the specific packet or
                    chunk of the specific parallel ID.</synopsis>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="4">
            <name>ParallelPartsCount</name>
            <synopsis>Defines the total number of packets or chunks
                    for the specific parallel ID.</synopsis>
            <typeRef>uint32</typeRef>
          </component>
        </struct>
      </metadataDef>
    </metadataDefs>
    <LFBClassDefs>
      <LFBClassDef LFBClassID="65537">
        <name>Ext-Splitter</name>
        <synopsis>A Splitter LFB takes part in parallelizing the
              processing datapath.  It will either send the same packet
              or chunks of one packet to multiple LFBs</synopsis>
        <version>1.0</version>
        <inputPorts>
          <inputPort>
            <name>SplitterIn</name>
            <synopsis>An input port expecting any kind of frame
                 </synopsis>
            <expectation>



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              <frameExpected>
                <ref>Arbitrary</ref>
              </frameExpected>
            </expectation>
          </inputPort>
        </inputPorts>
        <outputPorts>
          <outputPort group="true">
            <name>SplitterOut</name>
            <synopsis>A parallel output port that sends the same
                    packet to all output instances or chunks of the same
                    packet to output instances.  Each chunk is sent only
                    once by the LFB.</synopsis>
            <product>
              <frameProduced>
                <ref>Arbitrary</ref>
                <ref>Chunk</ref>
              </frameProduced>
              <metadataProduced>
                <ref>ParallelMetadataSet</ref>
              </metadataProduced>
            </product>
          </outputPort>
        </outputPorts>
        <components>
          <component componentID="1" access="read-write">
            <name>ParallelType</name>
            <synopsis>The type of parallelization this packet will
                    go through</synopsis>
            <typeRef>ParallelTypes</typeRef>
          </component>
          <component componentID="2" access="read-write">
            <name>ChunkSize</name>
            <synopsis>The size of a chunk when a packet is split
                    into multiple chunks of the same size</synopsis>
            <typeRef>uint32</typeRef>
          </component>
        </components>
        <capabilities>
          <capability componentID="31">
            <name>MinMaxChunkSize</name>
            <synopsis>The minimum and maximum size of a chunk
                    capable of split by this LFB</synopsis>
            <struct>
              <component componentID="1">
                <name>MinChunkSize</name>
                <synopsis>Minimum chunk size</synopsis>
                <optional/>



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                <typeRef>uint32</typeRef>
              </component>
              <component componentID="2">
                <name>MaxChunkSize</name>
                <synopsis>Maximum chunk size</synopsis>
                <typeRef>uint32</typeRef>
              </component>
            </struct>
          </capability>
        </capabilities>
      </LFBClassDef>
      <LFBClassDef LFBClassID="65538">
        <name>Ext-Merger</name>
        <synopsis>A Merger LFB receives multiple packets or multiple
              chunks of the same packet and merge them into one merged
              packet</synopsis>
        <version>1.0</version>
        <inputPorts>
          <inputPort group="true">
            <name>MergerIn</name>
            <synopsis>A parallel input port that accepts packets
                    or chunks from all output instances</synopsis>
            <expectation>
              <frameExpected>
                <ref>Arbitrary</ref>
                <ref>Chunk</ref>
              </frameExpected>
              <metadataExpected>
                <ref>ParallelMetadataSet</ref>
              </metadataExpected>
            </expectation>
          </inputPort>
          <inputPort group="true">
            <name>InvalidIn</name>
            <synopsis>When a packet is sent out of an error port of
                    an LFB in a parallel path, it will be sent to this
                    output port in the Merger LFB</synopsis>
            <expectation>
              <frameExpected>
                <ref>Arbitrary</ref>
                <ref>Chunk</ref>
              </frameExpected>
              <metadataExpected>
                <one-of>
                  <ref>ExceptionID</ref>
                  <ref>ValidateErrorID</ref>
                </one-of>
              </metadataExpected>



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            </expectation>
          </inputPort>
        </inputPorts>
        <outputPorts>
          <outputPort>
            <name>MergerOut</name>
            <synopsis>An output port expecting any kind of frame
                 </synopsis>
            <product>
              <frameProduced>
                <ref>Arbitrary</ref>
              </frameProduced>
            </product>
          </outputPort>
        </outputPorts>
        <components>
          <component componentID="1" access="read-write">
            <name>InvalidAction</name>
            <synopsis>What the Merge LFB will do if an invalid
                    chunk or packet is received</synopsis>
            <atomic>
              <baseType>uchar</baseType>
              <specialValues>
                <specialValue value="0">
                  <name>DropAll</name>
                  <synopsis>Drop all packets or chunks
                          </synopsis>
                </specialValue>
                <specialValue value="1">
                  <name>Continue</name>
                  <synopsis>Continue with the merge</synopsis>
                </specialValue>
              </specialValues>
            </atomic>
          </component>
          <component componentID="2" access="read-write">
            <name>MergeWaitType</name>
            <synopsis>Whether the Merge LFB will wait for all
                    packets or chunks to be received prior to sending
                    out a response</synopsis>
            <typeRef>boolean</typeRef>
          </component>
          <component componentID="3" access="read-write">
            <name>MergeWaitTimeoutTimer</name>
            <synopsis>The time that the Merger will wait
            for all packets or chunks within the same task to arrive
            before considering them invalid.</synopsis>
            <typeRef>uint32</typeRef>



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          </component>
          <component componentID="4" access="read-reset">
            <name>InvalidMergesCounter</name>
            <synopsis>Counts the number of merges where there is at
                    least one packet/chunk that entered the Merger LFB
                    through the InvalidIn input port</synopsis>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="5" access="read-reset">
            <name>InvalidTotalCounter</name>
            <synopsis>Counts the number of merges where all
                    packets/chunks entered the Merger LFB through the
                    InvalidIn input port</synopsis>
            <typeRef>uint32</typeRef>
          </component>
          <component componentID="6" access="read-reset">
            <name>InvalidIDCounters</name>
            <synopsis>Counts the number of invalid merges where at
                    least one packet/chunk entered through InvalidID per
                    error ID</synopsis>
            <struct>
              <component componentID="1">
                <name>InvalidExceptionID</name>
                <synopsis>Per Exception ID</synopsis>
                <array>
                  <typeRef>uint32</typeRef>
                </array>
              </component>
              <component componentID="2">
                <name>InvalidValidateErrorID</name>
                <synopsis>Per Validate Error ID</synopsis>
                <array>
                  <typeRef>uint32</typeRef>
                </array>
              </component>
            </struct>
          </component>
        </components>
        <events baseID="30">
          <event eventID="1">
            <name>ManyInvalids</name>
            <synopsis>An event that specifies if there are too many
                    invalids</synopsis>
            <eventTarget>
              <eventField>InvalidCounter</eventField>
            </eventTarget>
            <eventGreaterThan/>
            <eventReports>



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              <eventReport>
                <eventField>InvalidMergesCounter</eventField>
              </eventReport>
            </eventReports>
          </event>
          <event eventID="2">
            <name>ManyTotalInvalids</name>
            <synopsis>An event that specifies if there are too many
                    invalids</synopsis>
            <eventTarget>
              <eventField>InvalidTotalCounter</eventField>
            </eventTarget>
            <eventGreaterThan/>
            <eventReports>
              <eventReport>
                <eventField>InvalidTotalCounter</eventField>
              </eventReport>
            </eventReports>
          </event>
        </events>
      </LFBClassDef>
      <LFBClassDef LFBClassID="65539">
        <name>Ext-CoreParallelization</name>
        <synopsis>A core LFB that specifies that the FE supports
          parallelization instead of updating the FEObject
          LFB</synopsis>
        <version>1.0</version>
        <capabilities>
          <capability componentID="10">
            <name>ParallelLFBs</name>
            <synopsis>A table that lists all the LFBs that can be
                parallelized</synopsis>
            <array>
              <typeRef>ParallelLFBType</typeRef>
            </array>
          </capability>
        </capabilities>
      </LFBClassDef>
    </LFBClassDefs>
  </LFBLibrary>

                      Figure 6: Parallel LFB Library









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6.  IANA Considerations

6.1.  LFB Class Names and LFB Class Identifiers

   LFB classes defined by this document do not belong to LFBs defined by
   Standards Action.  As such, the corresponding values assigned in the
   "Logical Functional Block (LFB) Class Names and Class Identifiers"
   registry at <http://www.iana.org/assignments/forces> are above 65535.

   This specification includes the following LFB class names and LFB
   class identifiers:

   +-------+---------------------+-------+-----------------+---------+
   | LFB   |  LFB Class Name     |  LFB  |  Description    |   Ref   |
   | Class |                     |Version|                 |         |
   | ID    |                     |       |                 |         |
   +-------+---------------------+-------+-----------------+---------+
   | 65537 |   Ext-Splitter      |  1.0  | A Splitter LFB  |   RFC   |
   |       |                     |       |  will send      |   7409  |
   |       |                     |       |either the same  |         |
   |       |                     |       |   packet or     |         |
   |       |                     |       | chunks of one   |         |
   |       |                     |       |   packet to     |         |
   |       |                     |       | multiple LFBs.  |         |
   +-------+---------------------+-------+-----------------+---------+
   | 65538 |    Ext-Merger       |   1.0 |  A Merger LFB   |   RFC   |
   |       |                     |       |    receives     |   7409  |
   |       |                     |       |    multiple     |         |
   |       |                     |       |   packets or    |         |
   |       |                     |       |    multiple     |         |
   |       |                     |       | chunks of the   |         |
   |       |                     |       |  same packet    |         |
   |       |                     |       |   and merges    |         |
   |       |                     |       | them into one.  |         |
   +-------+---------------------+-------+-----------------+---------+
   | 65539 | Ext-                |   1.0 | A core LFB to   |   RFC   |
   |       | CoreParallelization |       | signify the     |   7409  |
   |       |                     |       | parallelization |         |
   |       |                     |       |   capability    |         |
   +-------+---------------------+-------+-----------------+---------+

     Logical Functional Block (LFB) Class Names and Class Identifiers









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6.2.  Metadata ID

   The Metadata ID namespace is 32-bits long.  Values assigned by this
   specification are:

             +------------+---------------------+-----------+
             |   Value    |         Name        | Reference |
             +------------+---------------------+-----------+
             | 0x00000010 | ParallelMetadataSet |  RFC 7409 |
             +------------+---------------------+-----------+

                Metadata ID Assigned by this Specification

7.  Security Considerations

   This document does not alter either the ForCES model [RFC5812] or the
   ForCES protocol [RFC5810].  As such, it has no impact on their
   security considerations.  This document simply defines the
   operational parameters and capabilities of LFBs that perform
   parallelization and not how parallelization is implemented.  Finally,
   this document does not attempt to analyze the presence or possibility
   of security interactions created by allowing parallel operations on
   packets.  Any such issues, if they exist, are for the designers of
   the particular data path, not the general mechanism.

8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5810]  Doria, A., Hadi Salim, J., Haas, R., Khosravi, H., Wang,
              W., Dong, L., Gopal, R., and J. Halpern, "Forwarding and
              Control Element Separation (ForCES) Protocol
              Specification", RFC 5810, March 2010,
              <http://www.rfc-editor.org/info/rfc5810>.

   [RFC5812]  Halpern, J. and J. Hadi Salim, "Forwarding and Control
              Element Separation (ForCES) Forwarding Element Model", RFC
              5812, March 2010,
              <http://www.rfc-editor.org/info/rfc5812>.

   [RFC6956]  Wang, W., Haleplidis, E., Ogawa, K., Li, C., and J.
              Halpern, "Forwarding and Control Element Separation
              (ForCES) Logical Function Block (LFB) Library", RFC 6956,
              June 2013, <http://www.rfc-editor.org/info/rfc6956>.



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   [RFC7408]  Haleplidis, E., "Forwarding and Control Element Separation
              (ForCES) Model Extension", RFC 7408, November 2014,
              <http://www.rfc-editor.org/info/rfc7408>.

8.2.  Informative References

   [Cilk]     Massachusetts Institute of Technology, "The Cilk Project",
              <http://supertech.csail.mit.edu/cilk/>.

Acknowledgments

   The authors would like to thank Edward Crabbe for the initial
   discussion that led to the creation of this document.  They also
   thank Jamal Hadi Salim and Dave Hood for comments and discussions and
   Adrian Farrel for his AD review that made this document better.
   Finally, the authors thank Francis Dupont for his Gen-Art review and
   Magnus Nystroem for his security review both of which refined this
   document to its final shape.

Authors' Addresses

   Evangelos Haleplidis
   University of Patras
   Department of Electrical and Computer Engineering
   Patras  26500
   Greece

   EMail: ehalep@ece.upatras.gr


   Joel Halpern
   Ericsson
   P.O. Box 6049
   Leesburg, VA  20178
   United States

   Phone: +1 703 371 3043
   EMail: joel.halpern@ericsson.com













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