QOS-Enabled Networks

2G Second Generation 3GPP Third-Generation Partnership Project ACK Acknowledgment AF Assured – forwarding APN Access Point Name AUC Authentication Center BA behavior aggregate BE best-effort BHT Busy Hour Traffic Bps bits per second BSC Base Station Controller BSR Broadband Service Router BTS Base Transceiver Station BU business CDMA Code Division Multiple Access CEIR Central Equipment […]

The QOS World

Quality of Service (QoS) has always been in a world of its own, but as the technology has been refined and has evolved in recent years, QOS usage has increased to the point where it is now considered a necessary part of network design and operation. As with most technologies, large-scale deployments have led to […]

The QOS Tools Part 1

As with any technology, as QOS matures and evolves, new developments always occur and features are always being added. However, before diving deeply into the specifics and all possible variations and evolutions of each QOS tool, the first step is to understand the basic structure of each tool. This topic presents a high-level view of […]

The QOS Tools Part 2

Queue A queue contains two sub-blocks: a buffer and a dropper. The buffer is where packets are stored while awaiting transmission. It works in a FIFO (first in, first out) fashion, which means that the order in which packets enter the buffer is the same in which they leave. No overtaking occurs inside the buffer. […]

The QOS Tools Part 3

Delay and Jitter Insertion Two QOS tools can insert delay, the shaper and a combination of queuing and scheduling. Because the value of inserted delay is not constant, both tools can also introduce jitter. The shaper can sustain excess traffic at the expense of delaying it. This means that there is a trade-off between how […]

Challenges (QOS-Enabled Networks) Part 1

In the previous topic, we discussed the QOS toolkit that is available as part of a QOS deployment on a router. We now move on, leaving behind the perspective of an isolated router and considering a network-wide QOS deployment. Such deployments always have peculiarities depending on the business requirements, which make each single one unique. […]

Challenges (QOS-Enabled Networks) Part 2

Inherent Delay Factors When traffic crosses a network from source to destination, the total amount of delay inserted at each hop can be categorized in smaller factors that contribute to the overall delay value. There are two groups of contributors to delay. The first group encompasses the QOS tools that insert delay due to their […]

Challenges (QOS-Enabled Networks) Part 3

Trust Borders When traffic arrives at a router, in terms of QOS, the router can trust it or not. The term trust can be seen from two different perspectives. The first is whether the information present in the packets is valid input for the classifier deciding the class of service to which the packets belong. […]

Traffic Types (QOS-Enabled Networks) Part 1

Different types of traffic have different sensitivities to delay,jitter, and packet loss: there is no "one size fits all" recipe. Thus, the focus of this topic is not to describe every single possible type of traffic but rather focus on three specific subjects: the Transport Control Protocol (TCP) protocol, real-time traffic, and the evolution of […]

Traffic Types (QOS-Enabled Networks) Part 2

TCP Congestion Mechanism The current TCP implementations in most operating systems are very much influenced by two legacy TCP implementations called Tahoe and Reno. Their essential algorithms and specifications originate with UNIX BSD versions 4.3 and 4.4, and no doubt some eventful hiking trip. The enhancements added by Tahoe and Reno focused on the TCP […]