Quality of service in the context of Traffic flow (computer networking)

A chart (sometimes known as a graph) is a graphical representation for data visualization, in which "the data is represented by symbols, such as bars in a bar chart, lines in a line chart, or slices in a pie chart". A chart can represent tabular numeric data, functions or some kinds of quality structure and provides different info.

The term "chart" as a graphical representation of data has multiple meanings:

Rail transport in Germany is provided predominantly by Deutsche Bahn (DB, lit. 'German Railway'). As of 2021, the railway network in Germany (DB only) had a length of 33,399 km (20,753 mi), of which 20,540 km (12,760 mi) were electrified and 18,556 km (11,530 mi) were double track. About 1,658 km (1,030 mi) are high-speed railway lines. Germany has the 6th longest railway network in the world, and the largest in Europe after Russia.

Germany was ranked 4th among national European rail systems in the 2017 European Railway Performance Index assessing intensity of use, quality of service and safety. It had a very good rating for intensity of use, by both passengers and freight, and good ratings for quality of service and safety. It also captured relatively high value in return for public investment with cost to performance ratios that outperform the average ratio for all European countries.

Transition refers to a computer science paradigm in the context of communication systems which describes the change of communication mechanisms, i.e., functions of a communication system, in particular, service and protocol components. In a transition, communication mechanisms within a system are replaced by functionally comparable mechanisms with the aim to ensure the highest possible quality, e.g., as captured by the quality of service.

Transitions enable communication systems to adapt to changing conditions during runtime. This change in conditions can, for example, be a rapid increase in the load on a certain service that may be caused, e.g., by large gatherings of people with mobile devices. A transition often impacts multiple mechanisms at different communication layers of a layered architecture.

Network congestion in computer networking and queueing theory is the reduced quality of service that occurs when a network node or link is carrying or processing more load than its capacity. Typical effects include queueing delay, packet loss or the blocking of new connections. A consequence of congestion is that an incremental increase in offered load leads either only to a small increase or even a decrease in network throughput.

Network protocols that use aggressive retransmissions to compensate for packet loss due to congestion can increase congestion, even after the initial load has been reduced to a level that would not normally have induced network congestion. Such networks exhibit two stable states under the same level of load. The stable state with low throughput is known as congestive collapse.