Internet DRAFT - draft-haleplidis-forces-packet-parallelization

draft-haleplidis-forces-packet-parallelization







Internet Engineering Task Force                            E. Haleplidis
Internet-Draft                                      University of Patras
Intended status: Standards Track                              J. Halpern
Expires: May 20, 2014                                           Ericsson
                                                       November 16, 2013


                     ForCES Packet Parallelization
           draft-haleplidis-forces-packet-parallelization-04

Abstract

   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).  RFC5812 has defined
   the ForCES Model provides a formal way to represent the capabilities,
   state, and configuration of forwarding elements within the context of
   the ForCES protocol, so that control elements (CEs) can control the
   FEs accordingly.  More specifically, the model describes the logical
   functions that are present in an FE, what capabilities these
   functions support, and how these functions are or can be
   interconnected.

   Many network devices support parallel packet processing.  This
   document describes how ForCES can model a network device's
   parallelization datapath.

Status of This Memo

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

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

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 20, 2014.

Copyright Notice





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   Copyright (c) 2013 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.

Table of Contents

   1.  Terminology and Conventions . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Packet Parallelization  . . . . . . . . . . . . . . . . . . .   4
   4.  Parallel Base Types . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Frame Types . . . . . . . . . . . . . . . . . . . . . . .   9
     4.2.  Data Types  . . . . . . . . . . . . . . . . . . . . . . .   9
     4.3.  MetaData Types  . . . . . . . . . . . . . . . . . . . . .  10
   5.  Parallel LFBs . . . . . . . . . . . . . . . . . . . . . . . .  10
     5.1.  Splitter  . . . . . . . . . . . . . . . . . . . . . . . .  10
       5.1.1.  Data Handling . . . . . . . . . . . . . . . . . . . .  10
       5.1.2.  Components  . . . . . . . . . . . . . . . . . . . . .  11
       5.1.3.  Capabilities  . . . . . . . . . . . . . . . . . . . .  11
       5.1.4.  Events  . . . . . . . . . . . . . . . . . . . . . . .  11
     5.2.  Merger  . . . . . . . . . . . . . . . . . . . . . . . . .  11
       5.2.1.  Data Handling . . . . . . . . . . . . . . . . . . . .  11
       5.2.2.  Components  . . . . . . . . . . . . . . . . . . . . .  12
       5.2.3.  Capabilities  . . . . . . . . . . . . . . . . . . . .  13
       5.2.4.  Events  . . . . . . . . . . . . . . . . . . . . . . .  13
   6.  XML for Parallel LFB library  . . . . . . . . . . . . . . . .  13
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  19
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  20
     8.1.  LFB Class Names and LFB Class Identifiers . . . . . . . .  20
     8.2.  Metadata ID . . . . . . . . . . . . . . . . . . . . . . .  20
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  21
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  21
     10.2.  Informative References . . . . . . . . . . . . . . . . .  21
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  21

1.  Terminology and Conventions




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1.1.  Requirements Language

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

1.2.  Definitions

   This document follows the terminology defined by the ForCES Model in
   [RFC5812].  The required definitions are repeated below for clarity.

      FE Model - The FE model is designed to model the logical
      processing functions of an FE.  The FE model proposed in this
      document includes three components; the LFB modeling of individual
      Logical Functional Block (LFB model), the logical interconnection
      between LFBs (LFB topology), and the FE-level attributes,
      including FE capabilities.  The FE model provides the basis to
      define the information elements exchanged between the CE and the
      FE in the ForCES protocol [RFC5810].

      LFB (Logical Functional Block) Class (or type) - A template that
      represents a fine-grained, logically separable aspect of FE
      processing.  Most LFBs relate to packet processing in the data
      path.  LFB classes are the basic building blocks of the FE model.

      LFB Instance - As a packet flows through an FE along a data path,
      it flows through one or multiple LFB instances, where each LFB is
      an instance of a specific LFB class.  Multiple instances of the
      same LFB class can be present in an FE's data path.  Note that we
      often refer to LFBs without distinguishing between an LFB class
      and LFB instance when we believe the implied reference is obvious
      for the given context.

      LFB Model - The LFB model describes the content and structures in
      an LFB, plus the associated data definition.  XML is used to
      provide a formal definition of the necessary structures for the
      modeling.  Four types of information are defined in the LFB model.
      The core part of the LFB model is the LFB class definitions; the
      other three types of information define constructs associated with
      and used by the class definition.  These are reusable data types,
      supported frame (packet) formats, and metadata.

      Element - Element is generally used in this document in accordance
      with the XML usage of the term.  It refers to an XML tagged part
      of an XML document.  For a precise definition, please see the full
      set of XML specifications from the W3C. This term is included in
      this list for completeness because the ForCES formal model uses
      XML.



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      Attribute - Attribute is used in the ForCES formal modeling in
      accordance with standard XML usage of the term, i.e., to provide
      attribute information included in an XML tag.

      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, but not how the per-packet state is
      implemented within actual hardware.  Metadata is sent between the
      FE and the CE on redirect packets.

      ForCES Component - A ForCES Component is a well-defined, uniquely
      identifiable and addressable ForCES model building block.  A
      component has a 32-bit ID, name, type, and an optional synopsis
      description.  These are often referred to simply as components.
      LFB Component - An LFB component is a ForCES component that
      defines the Operational parameters of the LFBs that must be
      visible to the CEs.

      LFB Class Library - The LFB class library is a set of LFB classes
      that has been identified as the most common functions found in
      most FEs and hence should be defined first by the ForCES Working
      Group.

2.  Introduction

   A lot of network devices can process packets in a parallel manner.
   The 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 modelling concept has been influenced by Cilc [Cilc].  Cilc is a
   programming language that has been developed since 1994 at the MIT
   Laboratory to allow programmers to identify elements that can be
   executed in parallel.  The two Cilc concepts used in this document is
   spawn and sync.  Spawn being the place where parallel work can start
   and sync being the place where the parallel work finishes and must
   collect all parallel output.

3.  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.




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   2.  Split - where the packet will be split in equal size chunks
       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 depended and is loosely defined here.
   An implementor may either decide to physical copy the packet and send
   all packets on the parallel paths, or may decide to logically copy
   the packet by simply sending for example pointers of the same packet
   provided that the necessary interlocks are taken into account.  The
   implementor has to take into account the device's characteristics to
   decide which approach fits bets to the hardware.

   Additionally in the split parallel type, while harder, the
   implementor 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.

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

   1.  Splitter - similar to Cilc's spawn.  An LFB that will split the
       path of a packet and be sent to multiple LFBs to be processed in
       parallel.

   2.  Merger - similar to Cilc's sync.  An LFB that will receive
       packets or chunks of the same initial packet and merge them into
       one.

   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 an simple example of a split parallel
   datapath along with the splitter and merger LFB.  Figure 2 shows an
   example of a flood parallel datapath along with the splitter and
   merger LFB.

                            +------------+
                      +---->| Regex LFB  |----+
       +----------+   |     +------------+    |       +----------+
       |          |---+                       +------>|          |
       |          |         +------------+            |          |
   --->| Splitter |-------->| Regex LFB  |----------->|  Merger  |--->
       |   LFB    |         +------------+            |   LFB    |
       |          |---+                       +------>|          |
       +----------+   |     +------------+    |       +----------+



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                      +---->| Regex LFB  |----+
                            +------------+

                Figure 1: Simple split parallel processing

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

                Figure 2: Simple flood parallel processing

   This version of the modelling 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 the time.  This led to a more simple metadata definition
   needed 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 be needed to be defined as well
   as an augmentation to the defined metadata.

   One important element to a developer is the ability to define which
   LFBs can be used in a parallel mode, with which other LFBs can they
   be parallelized with and the order of the LFBs can be assembled.
   This information must be accessible in the core LFBs and therefore
   this document needs to append one more capability in the FEObject
   LFB.  The topology of the parallel datapath can be deferred and
   manipulated from the FEObject LFB's LFBTopology.

   The FEObject LFB currently specifies the LFBtopology and supported
   LFBs in an FE.  In order to support parallelization the following
   component is needed 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.




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   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>
                <typeRef>string</typeRef>
             </component>
             <component componentID="4">
                <name>LFBParallelOccurenceLimit</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>



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                <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 be 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 Definition for FEObjectLFB extension

   While the ForCES model cannot describe how the splitting or the
   merging is actually done as that is an implementation issue of the
   actual LFB, however this document defines operational parameters to
   control 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.  Additionally this document defines metadata, which contain
   necessary information to assist the merging procedure.  The following
   metadata set as a struct is defined:

   1.  ParallelType - Flood or split

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

   3.  ParallelNum - Number of packet or chunk for specific Correlator.

   4.  ParralelPartsCount - Total number of packets or chunks for
       specific Correlator.



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

   In case of a packet/chunk being branded invalid by an LFB in a
   parallel path, it MUST be sent by an output port of said LFB

   An LFB inside a parallel path decides that a packet or a chunk has to
   be dropped it MAY drop it 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.

4.  Parallel Base Types

4.1.  Frame Types

   One frame type has been defined in this library.

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

                           Parallel Frame Types

4.2.  Data Types

   One data type has been defined in this library.

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

                            Parallel Data Types





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4.3.  MetaData Types

   The following metadata structure with ID 16, using the ForCES model
   extension [I-D.ietf-forces-model-extension], 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.           |
   |                      |        |     |                             |
   |      Correlator      | uint32 |  2  | An identification number to |
   |                      |        |     |   specify that packets or   |
   |                      |        |     |  chunks belong to the same  |
   |                      |        |     |        parallel work.       |
   |                      |        |     |                             |
   |     ParallelNum      | uint32 |  3  |  Defines the number of the  |
   |                      |        |     | specific packet or chunk of |
   |                      |        |     |  the specific parallel ID.  |
   |                      |        |     |                             |
   |  ParallelPartsCount  | uint32 |  4  | Defines the total number of |
   |                      |        |     |  packets or chunks for the  |
   |                      |        |     |    specific parallel ID.    |
   +----------------------+--------+-----+-----------------------------+

                      Metadata Structure for Merging

5.  Parallel LFBs

5.1.  Splitter

   A splitter LFB takes part in parallelizing the processing datapath by
   sending either the same packet or chunks of the same packet to
   multiple LFBs.

5.1.1.  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 of the group output ParallelOut's instances.
   If the parallel type is of type split (1), the packet will be split
   into same size chunks except the last which MAY be smaller, with the
   max size being defined by the ChunkSize component.  All chunks will
   be sent out in a round-robin fashion through the group output



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   ParallelOut's instances.  Each packet or chunk will be accompanied by
   the following metadata set as a struct :

   o  ParallelType - The paralleltype split or flood.

   o  Parallel ID - generated by the splitter LFB to identify that
      chunks or packets belong to the same parallel work.

   o  Parallel Num - 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 parallel id.

5.1.2.  Components

   This LFB has only two components specified.  The first is the
   ParallelType, an uint32 that defines how the packet will be processed
   by the Splitter LFB.  The second is the ChunkSize, an uint32 that
   specifies the maximum size of a chunk when a packet is split into
   multiple same size chunks.

5.1.3.  Capabilities

   This LFB has only one capability specified, the MinMaxChunkSize a
   struct of a uint32 to specify the minimum chunk size and a uint32 to
   specify the maximum chunk size.

5.1.4.  Events

   This LFB has no events specified.

5.2.  Merger

   A merger LFB receives multiple packets or multiple chunks of the same
   packet and merge them into one merged packet.

5.2.1.  Data Handling

   The Merger LFB receives either a packet or a chunk via the group
   input ParallelIn, along with the ParallelType metadata to identify
   whether what was received was a packet or a chunk, the Correlator,
   the ParallelNum and the ParallelPartsCount.

   In case that an LFB has dropped a packet or a chunk within a parallel
   path the merger LFB MAY receive only the metadata or both metadata
   and packet or chunk through the InvalidIn group input port.  It



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   SHOULD receive a metadata specifying the error code.  Current defined
   metadata's in the Base LFB Library [RFC6956] are the ExceptionID and
   the ValidateErrorID.  The Merger LFB MAY store the parallel metadata
   along with the exception metadata as a string in the optional
   InvalideMetadataSets as a means for the CE to debug errors in the
   parallel path.

   If the MergeWaitType is set to false the Merger LFB will initiate the
   merge process upon receiving the first packet.  If false it will wait
   for all packet in the Correlator to arrive.

   If one packet or chunk has been received through the InvalidIn port
   then the merging procedure will be operate as configured by the
   InvalidAction component.  If the InvalidAction component has been set
   to 0 then if one packet or chunk is not valid all will dropped, else
   the process will initiate.  Once the merging process has been
   finished the resulting packet will be sent via the singleton output
   port PacketOutput.

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

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

   3.  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.

   4.  InvalidAllCounter - a uint 32 that counts the number of merges
       where all packets/chunks entered the merger LFB through the
       InvalidIn input port.





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   5.  InvalidIDCounters - a struct of two arrays.  Each array has a
       uint32 per row.  Each array counts 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.

   6.  InvalideMetadataSets - an array of strings.  An optional
       component that stores metadata sets along with the error id as a
       string.  This could provide a debug information to the CE
       regarding errors in the parallel paths.

5.2.3.  Capabilities

   This LFB has no capabilities specified.

5.2.4.  Events

   This LFB specifies only two event.  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.

6.  XML for Parallel LFB library

   <?xml version="1.0" encoding="UTF-8"?>
   <LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="urn:ietf:params:xml:ns:forces:lfbmodel:1.0"
      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



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                        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>
      </dataTypeDefs>
      <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>Correlator</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="18">



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            <name>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>PacketIn</name>
                  <synopsis>An input port expecting any kind of frame
                  </synopsis>
                  <expectation>
                     <frameExpected>
                        <ref>Arbitrary</ref>
                     </frameExpected>
                  </expectation>
               </inputPort>
            </inputPorts>
            <outputPorts>
               <outputPort group="true">
                  <name>ParallelOut</name>
                  <synopsis>An parallel output port that sends the same
                     packet to all output instances or chunks of the same
                     packet different chunk on each instance.</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 same size chunks</synopsis>
                  <typeRef>uint32</typeRef>
               </component>
            </components>



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            <capabilities>
               <capability componentID="31">
                  <name>MinMaxChunkSize</name>
                  <synopsis>The minimum and maximum size of a chunk
                     capable of splitted by this LFB</synopsis>
                  <struct>
                     <component componentID="1">
                        <name>MinChunkSize</name>
                        <synopsis>Minimum chunk size</synopsis>
                        <optional/>
                        <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="19">
            <name>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>ParallelIn</name>
                  <synopsis>An 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 will be sent to this
                     output port in the Merger LFB</synopsis>
                  <expectation>



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                     <frameExpected>
                        <ref>Arbitrary</ref>
                        <ref>Chunk</ref>
                     </frameExpected>
                     <metadataExpected>
                        <one-of>
                           <ref>ExceptionID</ref>
                           <ref>ValidateErrorID</ref>
                        </one-of>
                     </metadataExpected>
                  </expectation>
               </inputPort>
            </inputPorts>
            <outputPorts>
               <outputPort>
                  <name>PacketOutput</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



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                     packets or chunks to be received prior to sending
                     out a response</synopsis>
                  <typeRef>boolean</typeRef>
               </component>
               <component componentID="3" 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="4" access="read-reset">
                  <name>InvalidAllCounter</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="5" access="read-reset">
                  <name>InvalidIDCounters</name>
                  <synopsis>Counts 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>
               <component componentID="6" access="read-reset">
                  <name>InvalideMetadataSets</name>
                  <synopsis>Buffers metadata sets along with the error id
                     as a string.</synopsis>
                  <optional/>
                  <array>
                     <typeRef>string</typeRef>
                  </array>



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               </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></eventGreaterThan>
                  <eventReports>
                     <eventReport>
                        <eventField>InvalidMergesCounter</eventField>
                     </eventReport>
                  </eventReports>
               </event>
               <event eventID="2">
                  <name>ManyAllInvalids</name>
                  <synopsis>An event that specifies if there are too many
                     invalids</synopsis>
                  <eventTarget>
                     <eventField>InvalidCounter</eventField>
                  </eventTarget>
                  <eventGreaterThan></eventGreaterThan>
                  <eventReports>
                     <eventReport>
                        <eventField>InvalidAllCounter</eventField>
                     </eventReport>
                  </eventReports>
               </event>
            </events>
         </LFBClassDef>
      </LFBClassDefs>
   </LFBLibrary>

                      Figure 4: Parallel LFB library

7.  Acknowledgements

   The authors would like to thank Jamal Hadi Salim and Dave Hood for
   comments and discussions that made this document better.









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8.  IANA Considerations

8.1.  LFB Class Names and LFB Class Identifiers

   LFB classes defined by this document belong to LFBs defined by
   Standards Track RFCs.  According to IANA, the registration procedure
   is Standards Action for the range 0 to 65535 and First Come First
   Served with any publicly available specification for over 65535.
   This specification includes the following LFB class names and LFB
   class identifiers:

   +--------------+----------+---------+-------------------+-----------+
   |  LFB Class   |   LFB    |   LFB   |    Description    | Reference |
   |  Identifier  |  Class   | Version |                   |           |
   |              |   Name   |         |                   |           |
   +--------------+----------+---------+-------------------+-----------+
   |      18      | Splitter |   1.0   |   A splitter LFB  |    This   |
   |              |          |         |  will either send |  document |
   |              |          |         |  the same packet  |           |
   |              |          |         |  or chunks of one |           |
   |              |          |         |     packet to     |           |
   |              |          |         |   multiple LFBs.  |           |
   |              |          |         |                   |           |
   |      19      |  Merger  |   1.0   |    A merger LFB   |    This   |
   |              |          |         | receives multiple |  document |
   |              |          |         |     packets or    |           |
   |              |          |         |  multiple chunks  |           |
   |              |          |         |    of the same    |           |
   |              |          |         |  packet and merge |           |
   |              |          |         |   them into one.  |           |
   +--------------+----------+---------+-------------------+-----------+

     Logical Functional Block (LFB) Class Names and Class Identifiers

8.2.  Metadata ID

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

           +------------+---------------------+---------------+
           |   Value    |         Name        |   Definition  |
           +------------+---------------------+---------------+
           | 0x00000010 | ParallelMetadataSet | This document |
           +------------+---------------------+---------------+

                Metadata ID assigned by this specification





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9.  Security Considerations

10.  References

10.1.  Normative References

   [I-D.ietf-forces-model-extension]
              Haleplidis, E., "ForCES Model Extension", draft-ietf-
              forces-model-extension-00 (work in progress), September
              2013.

   [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.

   [RFC5812]  Halpern, J. and J. Hadi Salim, "Forwarding and Control
              Element Separation (ForCES) Forwarding Element Model", RFC
              5812, March 2010.

   [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.

10.2.  Informative References

   [Cilc]     MIT, "Cilk language", ,
              <http://supertech.csail.mit.edu/cilk/>.

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

Authors' Addresses

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

   Email: ehalep@ece.upatras.gr









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   Joel Halpern
   Ericsson
   P.O. Box 6049
   Leesburg  20178
   VA

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











































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