Network Working Group Y. Zha Internet Draft Y. Jiang Intended status: Informational Huawei Technologies Expires: January 2017 L. Geng China Mobile July 8, 2016 Deterministic Networking Flow Information Model draft-zha-detnet-flow-info-model-00 Abstract Deterministic Networking (DetNet) provides end-to-end absolute delay and loss guarantee to serve real-time applications. DetNet is focused on a general approach that use techniques such as 1) data plane resources reservation for DetNet flows; 2) providing fixed path for DetNet flows; 3)sequentializng, replicating, and eliminating duplicate packets transmission [I-D.finn-detnet- architecture] to guarantee the worst case delay of DetNet flow while allow sharing among best effort traffic. Data flow information model is important to the DetNet work that it defines information be used by flow establishment and control protocols. This document describes and DetNet flow information model that represents the flow identifier, traffic description information so that can make resource reservation and provide differentiate service. 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), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." 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Table of Contents 1. Introduction .................................................2 2. Conventions used in this document ............................3 3. DetNet Flow Information Model ................................3 3.1. Flow Identifier .........................................4 3.2. Flow Traffic Description ................................5 3.3. Flow Statistics .........................................7 4. Use of Flow Information Model ................................7 4.1. Data plane configuration ................................7 5. Security Considerations ......................................9 6. IANA Considerations ..........................................9 7. Acknowledgments .............................................9 8. References ...................................................9 8.1. Normative References ....................................9 8.2. Informative References ..................................9 1. Introduction Deterministic service with both assured delay and data loss is promising to service providers. Due to lack of deterministic service provisioning mechanism there is no guarantee when deploying a time critical service [RFC3393]. Deterministic Networking (DetNet) tries to provide a solution to this issue with limited scope that the data flows are constrained with some maximum data rate properties. DetNet delivers assured end-to-end latency and packet loss by dedicating network resources to DetNet Zha Expires January 8, 2016 [Page 2] Internet-Draft DetNet Flow Info Model July 2016 flows while unused reserved resource are still open to best effort traffic. In order to reserve proper amount of network resource to serve the DetNet flow, the DetNet flow first needs to be described with such parameters that can be understood by the network. Secondly, current flow description and resource reservation are mainly focused on bandwidth which is basically a statistical concept during a relative long observation interval. And also, there are different type of use cases those requires deterministic networking services [I-D.ietf-detnet-use-cases]. Data plane techniques such as queuing, shaping, scheduling and preemption are configured in a standard way to guarantee deterministic forwarding behavior in the network device. The controller or control plane takes the description of the DetNet flow and then translates into data plane level configuration to serve the flow. This is the key of DetNet as to define how to describe DetNet flow and how to reserve network resource for it. The flow description should be focused on traffic characteristics of real time service with parameters that could be converted to device level configurations. An information model defines concepts in a uniform way, enabling formal mapping processes to be developed to the information model to a set of data models. This simplifies the process of constructing software to automate the policy management process. It also simplifies the language generation process, though that is beyond the scope of this document. This document describes an information model for representing DetNet flow with comment concept and parameters of a DetNet service that can be mapped into device level configurations. 2. Conventions used in this document 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]. In this document, these words will appear with that interpretation only when in ALL CAPS. Lower case uses of these words are not to be interpreted as carrying [RFC2119] significance. 3. DetNet Flow Information Model According to current charter, DetNet information model is to identify the information needed for flow establishment and control Zha Expires January 8, 2016 [Page 3] Internet-Draft DetNet Flow Info Model July 2016 and be used by reservation protocols and data plane configuration. The work will be independent from the protocol(s) used to control the flows. The DetNet information model presented in this document defines some common concept of DetNet flows with information that can be used for flow identification, flow monitoring, performance management, reservation protocol, and data plane configuration. For example, deterministic properties of controlled latency, low packet loss, low packet delay variation, and high reliability. More information can be added in the future. And each part of the information model can be used individually by different network function or network entities. The DetNet information model only defines what kind of information is needed and how it could be used. Data repository, data definition language, query language, implementation language, and protocol should not be defined here. More specifically, the information model can be used by a data model for different scenarios. As defined in [RFC3198], data model is "A mapping of the contents of an information model into a form that is specific to a particular type of data store or repository." In this document, DetNet information model contains three sets of information, flow identifier information, flow metering statistics, and traffic description. More information will be added in the future version to make DetNet fully functional. 3.1. Flow Identifier Flow identifier is the first step of flow description as DetNet requires differentiate service so it needs to be identified by the data plane. The DetNet service is described at flow level so each flow could have unique flow identifier. +--------+ | DetNet | --------+ +---------+ | Sender |----\ /--- |||||---| | +--------+ \ +-----------+ / --------+ |Trans- | \ | DetNet |/ DetNet Queue |mission | ---| Classifier|\ |Selection|--- +-----------+ / +-----------+ \ --------+ | | |Best Effort| / \--- ||| ||||---| | | Sender |-/ --------+ +---------+ +-----------+ Best Effort Queue Figure 1. DetNet flow being classified Zha Expires January 8, 2016 [Page 4] Internet-Draft DetNet Flow Info Model July 2016 As shown in figure 1, network reserves dedicate resource for DetNet flows which will be identified first to use the resource. So a DetNet flow model should first contain information for flow identification. As shown in table 1, the information model has stream identifier and service type information for flow identification. +--------------+--------------+ | Name | Elements | +--------------+--------------+ |Stream | MAC Address | |Identifier +--------------+ | | StreamID | +--------------+--------------+ |ServiceType | | +--------------+--------------+ 3.2. Flow Traffic Description The information model should contain traffic description information to define the traffic profile from the source. Detnet flow defines the source guarantee that is the promise of source that the maximum amount traffic it can send. It is a kind of contract between the source and network who serve the flow. If the source is sending overload or different type of traffic, the overload or traffic does not match the predefined traffic profile will be not guaranteed. So the DetNet is that the source tells the network I will send the traffic like this, and the network will reserve the resource for the flow based on its traffic characteristics as defined in the model. Unlike previous flow model or traffic profile which is mainly based on bandwidth of service, DetNet flow should be more accurate and at lower level for deterministic forwarding. For DetNet service provisioning which is focused on absolute worst case delay, the network needs to know not only the number of packets the flow will be sending but also when or during what period of time the source will be sending what amount of packets. Based on the architecture draft, there are two kinds of flows, synchronous one and asynchronous one. The information model of the DetNet flow with traffic description information is shown as below. Zha Expires January 8, 2016 [Page 5] Internet-Draft DetNet Flow Info Model July 2016 +--------------+--------------+--------------+ | Name | Elements | Elements | +--------------+--------------+--------------+ |Priority | | | |--------------+--------------+--------------+ |MTU | | | +--------------+--------------+--------------+ |Bandwidth | | | +--------------+--------------+--------------+ |BurstList- | | | |Periodic | | | +--------------+--------------+--------------+ |PeriodValue | | | +--------------+--------------+--------------+ |BurstList- | | | |Length | | | |--------------+--------------+--------------+ | |BurstListID | | | +--------------+--------------+ | |BurstLegnth | | | +--------------+--------------+ | | |BurstID | | | +--------------+ |BurstList | |MaxFrames | | | +--------------+ | |Burst |MaxFrameSize | | | +--------------+ | | |StartTime | | | +--------------+ | | |EndTime | +--------------+--------------+--------------+ The basic idea is that the flow consists of a list of bursts. The Burst is a set of packets with burst duration. The burst is close related to service traffic pattern and also it is dependent on the data plane technique. There are two basic requirements for traffic information definition, first it can be used to describe service; second the parameter defined here can be mapped to data plane configuration. Zha Expires January 8, 2016 [Page 6] Internet-Draft DetNet Flow Info Model July 2016 3.3. Flow Statistics As a matter of fact, there is no mechanism to provide flow delay and loss parameter, which is also important for DetNet service. Keeping the knowledge of flow-based delay and loss information is also crucial for OAM and fault management. The detail of flow metering statistic information in the information model will be proposed in next version. +--------------+--------------+ | Name | Elements | +--------------+--------------+ |MaxDelay | | |--------------+--------------+ |MaxPacketLoss | | +--------------+--------------+ 4. Use of Flow Information Model As defined in current charter, DetNet flow information model is used for flow establishment and control and can also be used by reservation protocols and YANG data models. 4.1. Data plane configuration This section proposes a way to map information model parameters into network configuration. As defined in current charter, the DetNet data plane should be TSN compatible. Take TSN TAS (Time Aware Shaper) for example, the information defined in the flow model can be mapped to data plane parameter to configure TSN time aware shaper that provides a deterministic forwarding behavior for the flow. As defined in previous section, information model contains traffic description of DetNet flow that can be used to configure data plane. In this section, take TSN time aware shaper as an example for data plane technique, mapping of data flow parameter to TAS configuration is presented. The basic idea is that, the controller or network control plane takes data flow traffic description as the request and compute the associated time interval and control list of the TAS gate control function. Data flow model contains timing information of the DetNet flow as it arrives at T1 and ends at T2, which can be Zha Expires January 8, 2016 [Page 7] Internet-Draft DetNet Flow Info Model July 2016 mapped into control list of TAS to reserve an open gate for the DetNet flow for time period T1 to T2. As shown in figure 2, a DetNet flow with data traffic between T1 and T2 send the request to controller or control plane, and then the control plane uses the information to configure the TAS based on current status of TAS. Finally, the TAS function being configured with control list update for open gate transmission for this flow during T1 and T2. As a result, ideally, the flow will be transmitted immediately using the dedicated open gate time slot with absolute delay and loss guarantee. T1 T2 DetNet data flow +---------------+ /___________\ Traffic description |Data flow model| \ / +---------------+ ||||||||||||| | | | | \ / +---------------+ | Control Plane | +---------------+ / \ | | \ / +-----------------------------+ Control List | Time Aware Shaper | T0 CCCCCCCO | | T1 OCCCCCCC | --------+ +----+ +---------+| T2 CCCCCCCO | |||||-|Gate|-| || . | --------+ +----+ | || . |DetNet Queue |Trans- || . | . |mission || Tn CCCCCCCC | . |Selection|| | . | || | --------+ +----+ | || | |||||-|Gate|-| || | --------+ +----+ +---------+| |Best Effort | |Queue | +-----------------------------+ Figure 2. Mapping of Flow Model into TAS Configuration Zha Expires January 8, 2016 [Page 8] Internet-Draft DetNet Flow Info Model July 2016 5. Security Considerations TBD 6. IANA Considerations This document has no actions for IANA. 7. Acknowledgments This document has benefited from reviews, suggestions, comments and proposed text provided by the following members, listed in alphabetical order: Jinchun Xu and Hengjun Zhu. 8. References 8.1. Normative References [RFC2119] S. Bradner, "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3393] C. Demichelis, "IP Packet Delay Variation Metric for IP Performance Metrics (IPPM) ", RFC 3393, November 2002. 8.2. Informative References [I-D.finn-detnet-problem-statement] Finn, N. and P. Thubert, "Deterministic Networking Problem Statement", draft-finn-detnet-problem-statement-01 (work in progress), October 2014. [I-D.finn-detnet-architecture] Finn, N., Thubert, P., and M. Teener, "Deterministic Networking Architecture", draft-finn-detnet-architecture-01 (work in progress), March 2015. Zha Expires January 8, 2016 [Page 9] Internet-Draft DetNet Flow Info Model July 2016 Authors' Addresses Yiyong Zha Huawei Technologies Email: zhayiyong@huawei.com Yuanlong Jiang Huawei Technologies Email: jiangyuanlong@huawei.com Liang Geng China Mobile Email: gengliang@chinamobile.com Zha Expires January 8, 2016 [Page 10]