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流量工程和路径规划
通过流量工程和路径规划，确定性网络能够避免网络拥塞，确保数据在网络中的传输路径是优的。流量工程技术通过智能的流量控制和路由选择，确保网络资源的优分配，从而提高网络性能。路径规划则负责寻找短、可靠的数据传输路径。
短路径依然会引起拥塞
如上图，起初基于短路径优先（Shortest Path First, SPF）协议，流量选择短的路径（A-C-E）进行数据传输。然而，当多个流量流都选择相同的路径时，可能会出现拥塞，当这条短路径拥塞时，较长路径 A-B-D-E 可能是更优路线。这就是为什么我们有时需要偏离SPF原则，而采用更为复杂的流量工程策略。通过流量整形、流量监管、路由控制等手段，我们可以优化网络流量的路径选择，避免或减少拥塞，提高网络的可靠性和性能。简单来说，流量工程的目标是确保网络流量能够根据其特性（如优先级、QoS需求等）被合理地分配到不同的路径上，从而避免网络拥塞、提高网络资源利用率。
硬实时通信机制
硬实时通信机制是实现确定性网络中关键数据传输的重要技术，对于一些需要控制时延的应用，确保数据的传输在预定的时间内完成。这需要在网络中实施实时调度机制，以确保实时数据包的及时传输。
时间感知整形器（IEEE 802.1Qbv）是一种用于实现硬实时通信机制的技术，它的主要功能是在以太网帧上标识优先级，并将其指派给基于优先级的VLAN Tag。它通过定义时间表来控制队列流量，每个队列在时间表中都有一个时间段，该时间段定义了队列中数据帧的发送窗口。当数据帧到达队列时，时间感知整形器会根据其优先级和时间表进行调度，以确保关键数据帧在预定的时间内发送。
Traffic engineering and path planning
Through traffic engineering and path planning, deterministic networks can avoid network congestion and ensure that the transmission path of data in the network is optimal. Traffic engineering technology ensures optimal allocation of network resources through intelligent traffic control and routing selection, thereby improving network performance. Path planning is responsible for finding the shortest and most reliable data transmission path.
The shortest path still causes congestion
As shown in the above figure, initially based on the Shortest Path First (SPF) protocol, the traffic selects the shortest path (A-C-E) for data transmission. However, when multiple traffic flows choose the same path, congestion may occur, and when the shortest path is congested, the longer path A-B-D-E may be the better route. That's why sometimes we need to deviate from the SPF principle and adopt more complex traffic engineering strategies. Through methods such as traffic shaping, traffic supervision, and routing control, we can optimize the path selection of network traffic, avoid or reduce congestion, and improve the reliability and performance of the network. Simply put, the goal of traffic engineering is to ensure that network traffic can be reasonably allocated to different paths based on its characteristics (such as priority, QoS requirements, etc.), thereby avoiding network congestion and improving network resource utilization.
Hard real-time communication mechanism
Hard real-time communication mechanism is an important technology for achieving key data transmission in deterministic networks. For some applications that require precise control of latency, it ensures that data transmission is completed within the predetermined time. This requires implementing real-time scheduling mechanisms in the network to ensure timely transmission of real-time data packets.
Time aware shaper (IEEE 802.1Qbv) is a technology used to implement hard real-time communication mechanisms. Its main function is to identify priorities on Ethernet frames and assign them to priority based VLAN Tags. It controls queue traffic by defining a schedule, where each queue has a time period that defines the sending window for data frames in the queue. When a data frame reaches the queue, the time aware shaper schedules it based on its priority and schedule to ensure that key data frames are sent within the predetermined time.
