Internet Engineering Task Force E. Haleplidis Internet-Draft University of Patras Intended status: Informational J. Halpern Expires: April 12, 2013 Ericsson October 9, 2012 ForCES Model Extension draft-haleplidis-forces-packet-parallelization-00 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 April 12, 2013. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the Haleplidis & Halpern Expires April 12, 2013 [Page 1] Internet-Draft ForCES Model Extension October 2012 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 . . . . . . . . . . . . . . . . . 3 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Packet Parallelization . . . . . . . . . . . . . . . . . . . . 6 4. Parallel Base Types . . . . . . . . . . . . . . . . . . . . . 12 4.1. Frame Types . . . . . . . . . . . . . . . . . . . . . . . 12 4.2. Data Types . . . . . . . . . . . . . . . . . . . . . . . . 12 4.3. MetaData Types . . . . . . . . . . . . . . . . . . . . . . 12 5. Parallel LFBs . . . . . . . . . . . . . . . . . . . . . . . . 14 5.1. Splitter . . . . . . . . . . . . . . . . . . . . . . . . . 14 5.1.1. Data Handling . . . . . . . . . . . . . . . . . . . . 14 5.1.2. Components . . . . . . . . . . . . . . . . . . . . . . 14 5.1.3. Capabilities . . . . . . . . . . . . . . . . . . . . . 14 5.1.4. Events . . . . . . . . . . . . . . . . . . . . . . . . 15 5.2. Merger . . . . . . . . . . . . . . . . . . . . . . . . . . 15 5.2.1. Data Handling . . . . . . . . . . . . . . . . . . . . 15 5.2.2. Components . . . . . . . . . . . . . . . . . . . . . . 15 5.2.3. Capabilities . . . . . . . . . . . . . . . . . . . . . 16 5.2.4. Events . . . . . . . . . . . . . . . . . . . . . . . . 16 6. XML for Parallel LFB library . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 23 9. Security Considerations . . . . . . . . . . . . . . . . . . . 24 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25 10.1. Normative References . . . . . . . . . . . . . . . . . . . 25 10.2. Informative References . . . . . . . . . . . . . . . . . . 25 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 26 Haleplidis & Halpern Expires April 12, 2013 [Page 2] Internet-Draft ForCES Model Extension October 2012 1. Terminology and Conventions 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 Haleplidis & Halpern Expires April 12, 2013 [Page 3] Internet-Draft ForCES Model Extension October 2012 this list for completeness because the ForCES formal model uses XML. 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. Haleplidis & Halpern Expires April 12, 2013 [Page 4] Internet-Draft ForCES Model Extension October 2012 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 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. Haleplidis & Halpern Expires April 12, 2013 [Page 5] Internet-Draft ForCES Model Extension October 2012 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. 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. 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. This modelling framework however allows for more complex parallel datapath topologies as can be seen in Figure 3 which shows one of the parallel paths to be further splitted into a new parallel section. Haleplidis & Halpern Expires April 12, 2013 [Page 6] Internet-Draft ForCES Model Extension October 2012 +-------+ +------>| LFB |-------+ +----------+ | +-------+ | +----------+ | |---+ +------>| | | | +-------+ | | --->| Splitter |---------->| LFB |-------------->| Merger |---> | LFB | +-------+ | LFB | | |---+ +------>| | +----------+ | +-------+ | +----------+ +------>| LFB |-------+ +-------+ Figure 1: Simple split parallel processing +------------+ | Classifier | +---->| LFB |-----+ +----------+ | +------------+ | +----------+ | |----+ +---->| | | | +------------+ | | --->| Splitter | | Meter | | Merger |---> | LFB |--------->| LFB |---------->| LFB | | | +------------+ | | | |---+ +---->| | +----------+ | +------------+ | +----------+ +----->| IPv4 TTL |-----+ | Decrement | | LFB | +------------+ Figure 2: Simple flood parallel processing Haleplidis & Halpern Expires April 12, 2013 [Page 7] Internet-Draft ForCES Model Extension October 2012 +-------+ +-->| LFB |--+ +----------+ | +-------+ | +----------+ | |--+ +-->| | | | +-------+ | | +--->| Splitter |----->| LFB |----->| Merger |---+ | | LFB | +-------+ | LFB | | | | |--+ +-->| | | | +----------+ | +-------+ | +----------+ | | +-->| LFB |--+ | | +-------+ | | | +------------------------------+ | | | +-------+ | +------------+ +------>| LFB |--+ | +----------+ | +-------+ | +----------+ | |---+ +-->| | | | +-------+ | | --->| Splitter |---------->| LFB |-------------->| Merger |---> | LFB | +-------+ | LFB | | |---+ +------>| | +----------+ | +-------+ | +----------+ +------>| LFB |-------+ +-------+ Figure 3: Complex parallel processing 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 accesible 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 FEObjectLFB must be able to specify for the LFB to 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. Haleplidis & Halpern Expires April 12, 2013 [Page 8] Internet-Draft ForCES Model Extension October 2012 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. ParallelLFBType Table entry for parallel LFBs LFBName The name of an LFB Class string LFBClassID The id of the LFB Class uint32 LFBVersion The version of the LFB Class used by this FE string LFBParallelOccurenceLimit The upper limit of instances of the same parallel LFBs of this class uint32 AllowedParallelAfters List of LFB Classes that this parallel LFB class can follow in a parallel pipeline uint32 Haleplidis & Halpern Expires April 12, 2013 [Page 9] Internet-Draft ForCES Model Extension October 2012 AllowedParallelBefores List of LFB Classes that this LFB class can follow in a parallel pipeline uint32 AllowedParallel List of LFB Classes that this LFB class be run in parallel with uint32 ParallelLFBs List of all supported parallel LFBs ParallelLFBType Figure 4: 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 are defined: 1. ParallelType - Flood or split 2. ParallelID - Identifies packets or chunks on the same parallel work 3. ParallelNum - Number of packet or chunk for specific parallelID. Haleplidis & Halpern Expires April 12, 2013 [Page 10] Internet-Draft ForCES Model Extension October 2012 4. ParralelPartsCount - Total number of packets or chunks for specific parallelID. 5. Valid - Whether a packet or chunk is valid. This metadata is produced from the Splitter LFB and is passed without being consumed by the LFBs in the parallel datapath. In case that in a parallel path there is an additional Splitter LFB therefore parallelizing even more that path, a new set of metadata MUST be produced for that specific path and the first set of metadata MUST be tunneled through without being consumed or changed until reaching the corresponding Merger LFB where it will be sent out again in the previous parallel path. 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 on the path to be received by the Merger LFB 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. Haleplidis & Halpern Expires April 12, 2013 [Page 11] Internet-Draft ForCES Model Extension October 2012 4. Parallel Base Types 4.1. Frame Types One frame type has been defined in this library. +---------------+---------------------------------------------------+ | Frame Type | Synopsis | | Name | | +---------------+---------------------------------------------------+ | Chunk | A chunk is a frame that is part of an original | | | larger frame | +---------------+---------------------------------------------------+ Parallel Frame Types 4.2. Data Types No data types have been defined in this library. 4.3. MetaData Types The following metadata are defined in the OpenFlow type library: +--------------------+---------+----+-------------------------------+ | Metadata Name | Type | ID | Synopsis | +--------------------+---------+----+-------------------------------+ | ParallelType | uchar | 32 | The type of parallelization | | | | | this packet will go through. | | | | | 0 for flood, 1 for split. | | | | | | | ParallelID | uint32 | 33 | An identification number to | | | | | specify that packets or | | | | | chunks belong to the same | | | | | parallel work. | | | | | | | ParallelNum | uint32 | 34 | Defines the number of the | | | | | specific packet or chunk of | | | | | the specific parallel ID. | | | | | | | ParallelPartsCount | uint32 | 35 | Defines the total number of | | | | | packets or chunks for the | | | | | specific parallel ID. | | | | | | | Valid | boolean | 36 | Marks whether the chunk or a | | | | | parallel processed packet as | | | | | valid or not. | +--------------------+---------+----+-------------------------------+ Haleplidis & Halpern Expires April 12, 2013 [Page 12] Internet-Draft ForCES Model Extension October 2012 Metadata Structure for Merging Haleplidis & Halpern Expires April 12, 2013 [Page 13] Internet-Draft ForCES Model Extension October 2012 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, along with the ParallelType metadata to identify how the packet will be treated. If the parallel type is of type flood, the same packet will be sent through all of the group output ParallelOut's instances. If the parallel type is of type split, the packet will be split into same size chunks, the size being defined by the ChunkSize component, and each chunk will be sent through one of the group output ParallelOut's instances. Each packet or chunk will be accompanied by the following metadata: 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. o Valid - with a default value of true. The merger LFB must know if a packet or a chunk must be set invalid by an LFB in one part of the parallel pipeline. 5.1.2. Components This LFB has only one component specified the ChunkSize, an uint32 that specifies the 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. Haleplidis & Halpern Expires April 12, 2013 [Page 14] Internet-Draft ForCES Model Extension October 2012 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, 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 ParallelID, the ParallelNum the ParallelPartsCount and the Valid metadata. In case that an LFB has dropped a packet or a chunk within a parallale path only the metadata is received. If the MergeWaitType is set to false the Merger LFB will initiate the merge process. If false it will wait for all packet in the ParallelID to arrive. Before the merging process begins, the Merger LFB will check for the valid flags in each of the packets or chunks. 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 5.2.2. Components This LFB has three 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. InvalidCounter - a uint32 that counts the number of invalid merges Haleplidis & Halpern Expires April 12, 2013 [Page 15] Internet-Draft ForCES Model Extension October 2012 5.2.3. Capabilities This LFB has no capabilities specified. 5.2.4. Events This LFB specifies only one event. It detects whether the invalidcounter has exceeded a specific value. The error report will send the invalid counter value. Haleplidis & Halpern Expires April 12, 2013 [Page 16] Internet-Draft ForCES Model Extension October 2012 6. XML for Parallel LFB library Chunk A chunk is a frame that is part of an original larger frame ParallelType The type of parallelization this packet will go through 32 uchar Flood The packet should be sent as a whole to multiple recipients Split The packet should be split into multiple chunks and sent to recipients ParallelID An identification number to specify that packets or chunks belong to the same parallel work. 33 uint32 ParallelNum Defines the number of the specific packet or chunk Haleplidis & Halpern Expires April 12, 2013 [Page 17] Internet-Draft ForCES Model Extension October 2012 of the specific parallel ID. 34 uint32 ParallelPartsCount Defines the total number of packets or chunks for the specific parallel ID. 35 uint32 Valid Marks whether the chunk or a parallel processed packet as valid or not. 36 boolean Splitter 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 1.0 Input An input port expecting any kind of frame Arbitrary ParallelType ParallelOut An parallel output port that sends the same packet to all output instances or chunks of the same packet different chunk on each instance. Haleplidis & Halpern Expires April 12, 2013 [Page 18] Internet-Draft ForCES Model Extension October 2012 Arbitrary Chunk ParallelType ParallelID ParallelNum ParallelPartsCount Valid ChunkSize The size of a chunk when a packet is split into multiple same size chunks uint32 MinMaxChunkSize The minimum and maximum size of a chunk capable of splitted by this LFB MinChunkSize Minimum chunk size uint32 MaxChunkSize Maximum chunk size uint32 Merger A merger LFB receives multiple packets or multiple chunks of the same packet and merge them into one merged Haleplidis & Halpern Expires April 12, 2013 [Page 19] Internet-Draft ForCES Model Extension October 2012 packet 1.0 ParallelIn An parallel input port that accepts packets or chunks from all output instances Arbitrary Chunk Null ParallelType ParallelID ParallelNum ParallelPartsCount Valid PacketOutput An output port expecting any kind of frame Arbitrary InvalidAction What the Merge LFB will do if an invalid chunk or packet is received uchar DropAll Drop all packets or chunks Haleplidis & Halpern Expires April 12, 2013 [Page 20] Internet-Draft ForCES Model Extension October 2012 Continue Continue with the merge MergeWaitType Whether the Merge LFB will wait for all packets or chunks to be received prior to sending out a response boolean InvalidCounter Counts the number of invalid merges uint32 ManyInvalids An event that specifies if there are too many invalids InvalidCounter 50 InvalidCounter Figure 5: Parallel LFB library Haleplidis & Halpern Expires April 12, 2013 [Page 21] Internet-Draft ForCES Model Extension October 2012 7. Acknowledgements The authors would like to thank Jamal Hadi Salim for discussions that made this document better. Haleplidis & Halpern Expires April 12, 2013 [Page 22] Internet-Draft ForCES Model Extension October 2012 8. IANA Considerations This memo includes no request to IANA. Haleplidis & Halpern Expires April 12, 2013 [Page 23] Internet-Draft ForCES Model Extension October 2012 9. Security Considerations Haleplidis & Halpern Expires April 12, 2013 [Page 24] Internet-Draft ForCES Model Extension October 2012 10. References 10.1. Normative References [I-D.haleplidis-forces-openflow-lib] Haleplidis, E., Cherkaoui, O., Hares, S., and W. Wang, "Forwarding and Control Element Separation (ForCES) OpenFlow Model Library", draft-haleplidis-forces-openflow-lib-01 (work in progress), July 2012. [OpenFlowSpec1.1] http://www.OpenFlow.org/, "The OpenFlow 1.1 Specification.", . [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. 10.2. Informative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. Haleplidis & Halpern Expires April 12, 2013 [Page 25] Internet-Draft ForCES Model Extension October 2012 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, 20178 VA Phone: +1 703 371 3043 Email: joel.halpern@ericsson.com Haleplidis & Halpern Expires April 12, 2013 [Page 26]