如果您使用自动化的工作与连接生产操作的网络和系统的网络有任何关系，那么您现在已经听到了关于时间敏感的网络（TSN）的赔率。但是，使用支持TSN的设备刚刚获得可用，赔率也很好，您尚未成为TSN的专家或其应用。
With so much information on TSN available, it can be difficult to know where to start. But if you're looking to begin with a good grounding in the basics, a solid option is the new “Time Sensitive Networking for Dummies” book from Belden/Hirschmann. Published in the well-known “… for Dummies” style, this book is a short (43 pages), easy read. I say “easy” because it avoids getting too far down into the technical weeds, but it doesn’t scrimp on the details either.
It also assumes you have a basic understanding of networking, i.e., how switched Ethernet networks function. If you’re not up to speed on that yet, the book offers suggestions for further reading.
周围的一个重要问题提出早期book by its authors, Oliver Kleineberg and Axel Schneider of Hirschmann (a Belden brand supplier of industrial networking technology), is the shifting structure of industrial automation networks in light of the move towards greater digitalization and the Industrial Internet of Things/Industry 4.0. This shift I’m referring to is a move from the well-known automation pyramid structure to an automation pillar structure.(您可以在2017年IOT解决方案世界大会上与Kleineberg进行的采访中了解更多有关此内容。）
The core idea behind this shift is that, in the automation pillar structure, the controller level of the automation pyramid disappears—with some control functions moving to the field as distributed control units (for fast, reliable reactions in applications such as safety), while others move to the management level as centralized control units. These central control units are virtual programmable logic controllers (PLCs) hosted in a local automation cloud where they interact directly with production processes through the connectivity layer that, with the help of TSN, provides high-speed, low latency performance while also carrying background traffic in a way that will not impact time-critical traffic.
Beyond its explanation of the evolving industrial network structure and more specific aspects of TSN, the book covers a number of issues. Some of the more prominent topics addressed include device buying tips, how faults are handled with TSN, the flexibility of TSN network architectures, and security.
在购买支持TSN的设备时，该书建议买家仔细查看设备的时间级别同步。随着较低质量同步的同步更好，随着较低的质量同步将需要留下误差的网络设计，从而降低TSN性能。
作者指出，这在交换机和终端设备中特别关键，因为以太网不存在额外的紧急车道 - 只有所有数据流量流过的电缆。因此，网络上的流量的不同优先级必须能够在不同时间访问电缆，以便“时间关键流量在发送的确切时间内经历完全空的以太网电缆。”这本书如何描述这种情况：交换机同时为高优先级帧打开传输门，以确保高优先级流量沿途不间断。同时，终端设备需要知道当传输门在开关中打开，以便它们可以相应地传输高优先级帧。
As for how TSN handles faults, the authors point out that seamless redundancy maintains continuous operation on a TSN network in the event of a fault, such as with functional safety requirements. According to the book, TSN can use High-Availability Seamless Redundancy (HSR), Parallel Redundancy Protocol (PRP), or IEEE 802.1CB-2017 (part of the TSN standard that operates similarly to HSR and PRP) to provide proper handling of faults. Using any of the methods, “whenever a mission-critical frame is sent, it’s duplicated and routed over at least two redundant paths. When the duplicate frames arrive at their destination, one is accepted and the other is dropped,” say the authors.
意识到网络需求可能会随着时间的推移而变化，提交人解释了原因，通过TSN，不需要从一开始就明确地定居在集中或分散的架构上。您可以组合模型。例如，集中式TSN可以很好地在网络的一部分上工作，而分散的TSN可能会更好地工作。这两个模型的TSN可以根据需要在网络中组合。另一种选择是通过组合集中式和分散模型的部分来创建混合模型。在这种混合模式中，最终设备只需要支持一个配置协议。混合模式的额外福利是用户仍将具有整个网络的集中视图。
Like anything dealing with Ethernet, cybersecurity is a big concern of users looking into TSN. The book notes that cybersecurity mechanisms are not included in TSN because security is “outside the scope of basic Ethernet.” The authors add that the time synchronization aspects of TSN present a new attack surface that was not present before with basic Ethernet. In addition, a concern with resolving TSN cybersecurity issues is that many network security mechanisms can introduce additional latency and jitter into the network, which can be unacceptable for TSN. Despite there being no quick and easy fix to TSN cybersecurity, there are methods available to deal with these issues. The two methods detailed in the book are segmenting traffic with zones and conduits, and filtering and policing traffic by stream.
If you’re looking to learn more about the basics of TSN, the book can be downloaded for free at:www.belden.com/resources/knowledge/ebooks/time-sensitive-networking-for-dummies-lp
