Quality of Service (QoS)

Abstract

Network QoS refers to the mechanisms employed by routers and switches along the traffic path to manage throughput, loss, latency, reordering, and jitter of the traffic. Today, the Internet and many other TCP/IP networks only support the so-called best effort characteristic for traffic, which is insufficient to support the requirements of many current and, in the opinion of the authors, even more futuristic applications including real-time signalling and control, critical reliability, and application requiring any form of guarantees. While TCP/IP has seen a range of architectural options to support better than best effort service characteristic, these are often either limited in scalability, challenging to operationalize, or inflexible.

This chapter gives an overview of the current best practices of existing QoS mechanisms for TCP/IP networks, discusses gaps, and describes their applicability to different scopes of networks, such as the Internet, Home, Access-Provider, and Mobile Networks. It then suggests a longer-term evolution of the network scopes and discusses how to apply QoS in them. It then introduces a set of future QoS concepts including experience based and high-precision QoS. To enable such future QoS concepts, a future “toolkit” of architectural concepts is required in future networks, including programmability of QoS, virtualization of QoS, flexible network packet header functionality, instrumentation, and monetization.