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Digital Video Transmission
Published in Goff Hill, The Cable and Telecommunications Professionals' Reference, 2012
FIFO is the most common queue-scheduling scheme, where all packets are treated equally by placing them in a single queue; they are serviced in the order in which they arrive at the queue. PQ provides a simple way of supporting differentiated services, where packets are classified and placed into different priority queues. Packets are serviced in order of decreasing priority, provided that the higher-priority queue is empty. FQ was designed to ensure that each flow has fair access to network resources and prevents bursty flows from overconsuming network bandwidth; flows are serviced in a round-robin fashion. WFQ allows a fair distribution of bandwidth by supporting flows with different bandwidth requirements. In WRR, packets are classified according to service class: real-time, interactive, file transfer, and so on, and then serviced using round-robin.
Designing the Switch/Router
Published in James Aweya, Designing Switch/Routers, 2023
When strict priority queuing (also called strict priority scheduling) is used in an architecture, all high-priority packets are forwarded before any lower-priority packets. A device may use scheduling mechanisms such as WFQ to statistically schedule packets into the system. Unlike strict priority queuing, WFQ allows packets from lower priority queues to be scheduled and interleaved with higher priority traffic. WFQ prevents the lower priority traffic from being completely blocked or starved by the higher priority traffic, since each traffic class is guaranteed service for a predefined proportion of the time.
Proactive flow control using adaptive beam forming for smart intra-layer data communication in wireless network on chip
Published in Automatika, 2023
Dinesh Kumar T.R., Karthikeyan A.
The packets are divided into flits, which are smaller pieces. The header flit is the initial flit of a packet, and it contains control information for packet delivery such as the source address, destination address, operation type, packet type, role, priority, and payload size. The path flit is the second flit of the packet, and it provides the path information along with the packet's sequential number in the current transaction between the source and destination. The body flit, also known as the payload, is the third flit of the packet and contains the actual data to be transferred to the destination. The packet format, as shown in Figure 2, is made up of nine fields, including the Source (Sc), which is the communication's initiator. The destination core address is indicated by the letter DC. The type of transaction (read, write, conditional write, broadcast, etc.) is indicated by the operation (Op). The type of information being exchanged (such as data, instructions, or signal types) is indicated by type. The source component's role (e.g. user, root, etc.) is indicated by the role. The priority of traffic is classified by priority. The packet payload, or the number of bytes in the payload, is indicated by size. Payload denotes the actual data information created by the source core, whereas Path denotes the packet's registered path. PF. SDC assigns a proportional weight to each data flow to suit service needs. This is accomplished by setting the priority field in the header file to 0 or 1. Normal or Low Priority (LP) data traffic is coded as 0, while emergency or High Priority (HP) data traffic is coded as 1. Emergency traffic needs superior service. As a result, priority in procuring network resources is usually given to emergency or real-time traffic for rapid and reliable transmission. The most extensively used packet scheduling algorithms are Weighted Fair Queuing (WFQ) [29], Weighted Round Robin (WRR) [30], and Strict Priority (SP) [28]. A tight scheduling discipline with a probabilistic priority (SPP) queuing mechanism is used in the suggested model to cope with the starving problem and make priority discipline adjustable. SPP distinguishes itself from conventional scheduling algorithms by being “simple to develop and configure, effectively utilizing existing bandwidth and requiring very little memory and processing power.” SPP looks at how likely it is that a queue will be served and offers different levels of service based on traffic by giving each queue parameters (high or low priority).