Fairness Measures or metrics are often used in computer networks and network engineering to determine whether users/applications are receiving a "fair share" of system resources. There are several mathematical and conceptual definitions of "fair" commonly used. These include

TCP Fairness

When creating Congestion Control mechanisms for new network transmission protocols or Peer to peer applications one major research goal is to ensure they interact well with TCP. TCP fairness simply states that the new protocol receives no larger share of the network than a comparable TCP flow. This is important as TCP is the dominant transport protocol on the Internet, and if new protocols acquire "unfair" capacity they tend to cause problems such as Congestion Collapse. For example, this was the case with the very first versions of Real's streaming protocol: it was based on UDP and was widely blocked at organizational firewalls until a TCP-based version was developed. This article needs to be cleaned up to conform to a higher standard of quality. ... A peer-to-peer (or P2P) computer network is a network that relies on the computing power and bandwidth of the participants in the network rather than concentrating it in a relatively low number of servers. ... The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite. ... The User Datagram Protocol (UDP) is one of the core protocols of the Internet protocol suite. ...

Jain's Fairness Metric

Used to determine, given a set of values, how fair they are. It is based on the following equation below with a range of 0 (totally unfair) to 1 (totally fair). This has the desirable features that it is minimized when one flow receives all the system capacity, and mazimized when all flows receive the same capacity. It captures the problems of single flows receving poor allocations, but is not unduly sensitive to outliers in a distribution. This equation was originally published in 1984 by R. Jain, D.M. Chiu and W. Hawe as "A Quantitative Measure of Fairness and Discrimination for Resource Allocation in Shared Systems"

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Max-Min Fairness

States that small flows receive what they demand, and larger flows equally share excess capacity. Conceptually, bandwidth is allocated equally to all flows until one is satisfied; then bandwidth is equally allocated among the remainder, and so on until all flows are satisfied or bandwidth is exhausted. Computationally this can be done efficiently by determining the bottleneck flow (via, e.g. depth-first search or a Network Flow algorithm) allocating its requirements, and recursively solving for the remainder of the graph. In graph theory, a network flow is an assignment of flow to the edges of a directed graph (called a flow network in this case) where each edge has a capacity, such that the amount of flow along an edge does not exceed its capacity. ...

There are also other, less commonly used measures.