It offers insight into why it has proved hard for a Proportional Integral (PI) controller to remain both responsive and stable while controlling `Classic' TCP flows, such as TCP Reno and Cubic. This paper concerns the use of Active Queue Management (AQM) to reduce queuing delay. This document describes the L4S architecture, briefly describing the different components and how the work together to provide the aforementioned enhanced Internet service. At the same time L4S solves the long-recognized problem with the future scalability of TCP throughput. Both parts, sender and network, ensure coexistence with other legacy traffic. Further, the network part is simple to deploy - incrementally with zero-config. By fixing the sending TCP (and other transports) queuing latency becomes so much better than today that operators will want to deploy the network part of L4S to enable new products and services. The insight is that the root cause of queuing delay is in TCP, not in the queue. Even with a high capacity broadband access, the reduced latency of L4S remarkably and consistently improves performance under load for applications such as interactive video, conversational video, voice, Web, gaming, instant messaging, remote desktop and cloud-based apps (even when all being used at once over the same access link). It is becoming widely recognized that adding more access capacity gives diminishing returns, because latency is becoming the critical problem. In extensive testing the new L4S service keeps average queuing delay under a millisecond for all applications even under very heavy load, without sacrificing utilization and it keeps congestion loss to zero. However, the only solution the IETF can offer for ultra-low queuing delay is Diffserv, which only favours a minority of packets at the expense of others. It is becoming common for all (or most) applications being run by a user at any one time to require low latency. This document describes the L4S architecture for the provision of a new service that the Internet could provide to eventually replace best efforts for all traffic: Low Latency, Low Loss, Scalable throughput (L4S). The Research Council of Norway All partners: Develop mechanisms that reduce the latency for time-dependent thin-stream applications without having to change current Internet infrastructure. Locate the sources of increased delay and loss rates for thin streams along the entire path of a data packet. This can be achieved by adding speed to the mix, instead of only thinking about maximising throughput. Thin streams almost invariably come up short against greedy traffic and users are left to cope with the resulting lag. We want a more balanced Internet where thin streams don’t always lose out. Such thin streams cannot compete with greedy traffic for bandwidth. With thin streams only small amounts of data are transmitted at a time and there can be extended periods between data packages. In such cases it is essential to avoid any delay.Īpplications like these often generate what are called thin data streams. The same principle applies for stock market programs when placing orders or requesting share prices, for example, via the trading systems in use the Norwegian Stock Exchange. In real-time gaming against other players online, data is transmitted only when an action such as moving around or shooting at someone is performed. For time-dependant applications such as Internet telephony and online gaming, time lags as short as a few hundred milliseconds can create big problems. The downside is that this can cause latency, or delay, in data transmissions. Up to recently, Internet research has primarily focused on speeding up transmission by increasing bandwidth so that more data can be transferred at a given time. The most common Internet protocol for transmitting data, TCP, works by apportioning available bandwidth among the users present at any given time. The Internet as we know it today has been optimised to transmit large amounts of data or “greedy streams” - the type of transmission involved in downloading large files or watching online TV.
0 Comments
Leave a Reply. |