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<pre>Internet Engineering Task Force (IETF) E. Haleplidis
Request for Comments: 7409 University of Patras
Category: Experimental J. Halpern
ISSN: 2070-1721 Ericsson
November 2014
<span class="h1">Forwarding and Control Element Separation (ForCES)</span>
<span class="h1">Packet Parallelization</span>
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 (<a href="./rfc5812">RFC 5812</a>) and controlled via
the ForCES protocol (<a href="./rfc5810">RFC 5810</a>).
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 <a href="./rfc5741#section-2">Section 2 of RFC 5741</a>.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
<a href="http://www.rfc-editor.org/info/rfc7409">http://www.rfc-editor.org/info/rfc7409</a>.
<span class="grey">Haleplidis & Halpern Experimental [Page 1]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-2" ></span>
<span class="grey"><a href="./rfc7409">RFC 7409</a> ForCES Packet Parallelization November 2014</span>
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to <a href="https://www.rfc-editor.org/bcp/bcp78">BCP 78</a> and the IETF Trust's Legal
Provisions Relating to IETF Documents
(<a href="http://trustee.ietf.org/license-info">http://trustee.ietf.org/license-info</a>) 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.
<span class="grey">Haleplidis & Halpern Experimental [Page 2]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-3" ></span>
<span class="grey"><a href="./rfc7409">RFC 7409</a> ForCES Packet Parallelization November 2014</span>
Table of Contents
<a href="#section-1">1</a>. Introduction . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-1.1">1.1</a>. Requirements Language . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-1.2">1.2</a>. Definitions . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-4">4</a>
<a href="#section-2">2</a>. Packet Parallelization . . . . . . . . . . . . . . . . . . . <a href="#page-5">5</a>
<a href="#section-2.1">2.1</a>. CoreParallelization LFB . . . . . . . . . . . . . . . . . <a href="#page-7">7</a>
<a href="#section-2.2">2.2</a>. Parallelization Metadata . . . . . . . . . . . . . . . . <a href="#page-10">10</a>
<a href="#section-3">3</a>. Parallel Base Types . . . . . . . . . . . . . . . . . . . . . <a href="#page-11">11</a>
<a href="#section-3.1">3.1</a>. Frame Types . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-11">11</a>
<a href="#section-3.2">3.2</a>. Data Types . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-11">11</a>
<a href="#section-3.3">3.3</a>. Metadata Types . . . . . . . . . . . . . . . . . . . . . <a href="#page-12">12</a>
<a href="#section-4">4</a>. Parallel LFBs . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-12">12</a>
<a href="#section-4.1">4.1</a>. Splitter . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-12">12</a>
<a href="#section-4.1.1">4.1.1</a>. Data Handling . . . . . . . . . . . . . . . . . . . . <a href="#page-13">13</a>
<a href="#section-4.1.2">4.1.2</a>. Components . . . . . . . . . . . . . . . . . . . . . <a href="#page-13">13</a>
<a href="#section-4.1.3">4.1.3</a>. Capabilities . . . . . . . . . . . . . . . . . . . . <a href="#page-13">13</a>
<a href="#section-4.1.4">4.1.4</a>. Events . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-13">13</a>
<a href="#section-4.2">4.2</a>. Merger . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-14">14</a>
<a href="#section-4.2.1">4.2.1</a>. Data Handling . . . . . . . . . . . . . . . . . . . . <a href="#page-14">14</a>
<a href="#section-4.2.2">4.2.2</a>. Components . . . . . . . . . . . . . . . . . . . . . <a href="#page-15">15</a>
<a href="#section-4.2.3">4.2.3</a>. Capabilities . . . . . . . . . . . . . . . . . . . . <a href="#page-15">15</a>
<a href="#section-4.2.4">4.2.4</a>. Events . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-16">16</a>
<a href="#section-4.3">4.3</a>. CoreParallelization . . . . . . . . . . . . . . . . . . . <a href="#page-16">16</a>
<a href="#section-4.3.1">4.3.1</a>. Data Handling . . . . . . . . . . . . . . . . . . . . <a href="#page-16">16</a>
<a href="#section-4.3.2">4.3.2</a>. Components . . . . . . . . . . . . . . . . . . . . . <a href="#page-16">16</a>
<a href="#section-4.3.3">4.3.3</a>. Capabilities . . . . . . . . . . . . . . . . . . . . <a href="#page-16">16</a>
<a href="#section-4.3.4">4.3.4</a>. Events . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-17">17</a>
<a href="#section-5">5</a>. XML for Parallel LFB Library . . . . . . . . . . . . . . . . <a href="#page-17">17</a>
<a href="#section-6">6</a>. IANA Considerations . . . . . . . . . . . . . . . . . . . . . <a href="#page-25">25</a>
<a href="#section-6.1">6.1</a>. LFB Class Names and LFB Class Identifiers . . . . . . . . <a href="#page-25">25</a>
<a href="#section-6.2">6.2</a>. Metadata ID . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-26">26</a>
<a href="#section-7">7</a>. Security Considerations . . . . . . . . . . . . . . . . . . . <a href="#page-26">26</a>
<a href="#section-8">8</a>. References . . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-26">26</a>
<a href="#section-8.1">8.1</a>. Normative References . . . . . . . . . . . . . . . . . . <a href="#page-26">26</a>
<a href="#section-8.2">8.2</a>. Informative References . . . . . . . . . . . . . . . . . <a href="#page-27">27</a>
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-27">27</a>
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . <a href="#page-27">27</a>
<span class="grey">Haleplidis & Halpern Experimental [Page 3]</span></pre>
<hr class='noprint'/><!--NewPage--><pre class='newpage'><span id="page-4" ></span>
<span class="grey"><a href="./rfc7409">RFC 7409</a> ForCES Packet Parallelization November 2014</span>
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Introduction</span>
A lot of network devices can process packets in a parallel manner.
The Forwarding and Control Element Separation (ForCES) model
[<a href="./rfc5812" title=""Forwarding and Control Element Separation (ForCES) Forwarding Element Model"">RFC5812</a>] 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 [<a href="#ref-Cilk" title=""The Cilk Project"">Cilk</a>]. 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 <a href="#section-1.2">Section 1.2</a> 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.
<span class="h3"><a class="selflink" id="section-1.1" href="#section-1.1">1.1</a>. Requirements Language</span>
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 [<a href="./rfc2119" title=""Key words for use in RFCs to Indicate Requirement Levels"">RFC2119</a>].
<span class="h3"><a class="selflink" id="section-1.2" href="#section-1.2">1.2</a>. Definitions</span>
This document follows the terminology defined by the ForCES model in
[<a href="./rfc5812" title=""Forwarding and Control Element Separation (ForCES) Forwarding Element Model"">RFC5812</a>]. 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.
<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Packet Parallelization</span>
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.
<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>. CoreParallelization LFB</span>
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 [<a href="./rfc5810" title=""Forwarding and Control Element Separation (ForCES) Protocol Specification"">RFC5810</a>]
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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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<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>. Parallelization Metadata</span>
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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<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Parallel Base Types</span>
<span class="h3"><a class="selflink" id="section-3.1" href="#section-3.1">3.1</a>. Frame Types</span>
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
<span class="h3"><a class="selflink" id="section-3.2" href="#section-3.2">3.2</a>. Data Types</span>
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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<span class="h3"><a class="selflink" id="section-3.3" href="#section-3.3">3.3</a>. Metadata Types</span>
The following metadata structure with ID 16, using the ForCES model
extension [<a href="./rfc7408" title=""Forwarding and Control Element Separation (ForCES) Model Extension"">RFC7408</a>], 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
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Parallel LFBs</span>
<span class="h3"><a class="selflink" id="section-4.1" href="#section-4.1">4.1</a>. Splitter</span>
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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<span class="h4"><a class="selflink" id="section-4.1.1" href="#section-4.1.1">4.1.1</a>. Data Handling</span>
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.
<span class="h4"><a class="selflink" id="section-4.1.2" href="#section-4.1.2">4.1.2</a>. Components</span>
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.
<span class="h4"><a class="selflink" id="section-4.1.3" href="#section-4.1.3">4.1.3</a>. Capabilities</span>
This LFB has only one capability specified; the MinMaxChunkSize is a
struct of two uint32s to specify the minimum and maximum chunk size.
<span class="h4"><a class="selflink" id="section-4.1.4" href="#section-4.1.4">4.1.4</a>. Events</span>
This LFB has no events specified.
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<span class="h3"><a class="selflink" id="section-4.2" href="#section-4.2">4.2</a>. Merger</span>
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
<span class="h4"><a class="selflink" id="section-4.2.1" href="#section-4.2.1">4.2.1</a>. Data Handling</span>
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 [<a href="./rfc6956" title=""Forwarding and Control Element Separation (ForCES) Logical Function Block (LFB) Library"">RFC6956</a>] 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.
<span class="h4"><a class="selflink" id="section-4.2.2" href="#section-4.2.2">4.2.2</a>. Components</span>
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.
<span class="h4"><a class="selflink" id="section-4.2.3" href="#section-4.2.3">4.2.3</a>. Capabilities</span>
This LFB has no capabilities specified.
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<span class="h4"><a class="selflink" id="section-4.2.4" href="#section-4.2.4">4.2.4</a>. Events</span>
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
<span class="h3"><a class="selflink" id="section-4.3" href="#section-4.3">4.3</a>. CoreParallelization</span>
A core LFB that specifies that the FE supports parallelization
instead of updating the FEObject LFB
<span class="h4"><a class="selflink" id="section-4.3.1" href="#section-4.3.1">4.3.1</a>. Data Handling</span>
The CoreParallelization does not handle data.
<span class="h4"><a class="selflink" id="section-4.3.2" href="#section-4.3.2">4.3.2</a>. Components</span>
This LFB has no components specified.
<span class="h4"><a class="selflink" id="section-4.3.3" href="#section-4.3.3">4.3.3</a>. Capabilities</span>
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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<span class="h4"><a class="selflink" id="section-4.3.4" href="#section-4.3.4">4.3.4</a>. Events</span>
This LFB specifies no events.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. XML for Parallel LFB Library</span>
<?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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<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. IANA Considerations</span>
<span class="h3"><a class="selflink" id="section-6.1" href="#section-6.1">6.1</a>. LFB Class Names and LFB Class Identifiers</span>
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 <<a href="http://www.iana.org/assignments/forces">http://www.iana.org/assignments/forces</a>> 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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<span class="h3"><a class="selflink" id="section-6.2" href="#section-6.2">6.2</a>. Metadata ID</span>
The Metadata ID namespace is 32-bits long. Values assigned by this
specification are:
+------------+---------------------+-----------+
| Value | Name | Reference |
+------------+---------------------+-----------+
| 0x00000010 | ParallelMetadataSet | <a href="./rfc7409">RFC 7409</a> |
+------------+---------------------+-----------+
Metadata ID Assigned by this Specification
<span class="h2"><a class="selflink" id="section-7" href="#section-7">7</a>. Security Considerations</span>
This document does not alter either the ForCES model [<a href="./rfc5812" title=""Forwarding and Control Element Separation (ForCES) Forwarding Element Model"">RFC5812</a>] or the
ForCES protocol [<a href="./rfc5810" title=""Forwarding and Control Element Separation (ForCES) Protocol Specification"">RFC5810</a>]. 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.
<span class="h2"><a class="selflink" id="section-8" href="#section-8">8</a>. References</span>
<span class="h3"><a class="selflink" id="section-8.1" href="#section-8.1">8.1</a>. Normative References</span>
[<a id="ref-RFC2119">RFC2119</a>] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", <a href="https://www.rfc-editor.org/bcp/bcp14">BCP 14</a>, <a href="./rfc2119">RFC 2119</a>, March 1997,
<<a href="http://www.rfc-editor.org/info/rfc2119">http://www.rfc-editor.org/info/rfc2119</a>>.
[<a id="ref-RFC5810">RFC5810</a>] 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", <a href="./rfc5810">RFC 5810</a>, March 2010,
<<a href="http://www.rfc-editor.org/info/rfc5810">http://www.rfc-editor.org/info/rfc5810</a>>.
[<a id="ref-RFC5812">RFC5812</a>] Halpern, J. and J. Hadi Salim, "Forwarding and Control
Element Separation (ForCES) Forwarding Element Model", <a href="./rfc5812">RFC</a>
<a href="./rfc5812">5812</a>, March 2010,
<<a href="http://www.rfc-editor.org/info/rfc5812">http://www.rfc-editor.org/info/rfc5812</a>>.
[<a id="ref-RFC6956">RFC6956</a>] Wang, W., Haleplidis, E., Ogawa, K., Li, C., and J.
Halpern, "Forwarding and Control Element Separation
(ForCES) Logical Function Block (LFB) Library", <a href="./rfc6956">RFC 6956</a>,
June 2013, <<a href="http://www.rfc-editor.org/info/rfc6956">http://www.rfc-editor.org/info/rfc6956</a>>.
<span class="grey">Haleplidis & Halpern Experimental [Page 26]</span></pre>
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[<a id="ref-RFC7408">RFC7408</a>] Haleplidis, E., "Forwarding and Control Element Separation
(ForCES) Model Extension", <a href="./rfc7408">RFC 7408</a>, November 2014,
<<a href="http://www.rfc-editor.org/info/rfc7408">http://www.rfc-editor.org/info/rfc7408</a>>.
<span class="h3"><a class="selflink" id="section-8.2" href="#section-8.2">8.2</a>. Informative References</span>
[<a id="ref-Cilk">Cilk</a>] Massachusetts Institute of Technology, "The Cilk Project",
<<a href="http://supertech.csail.mit.edu/cilk/">http://supertech.csail.mit.edu/cilk/</a>>.
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
Haleplidis & Halpern Experimental [Page 27]
</pre>
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