  MultiPath TCP (MPTCP) is a promising protocol which brings new light to the
TCP/IP protocol stack ossification problem by means of an impactful innovation
of the transport layer. A MPTCP connection consists of a set of one or more
subflows, where each subflow offers an alternative path to reach a target
remote end-system. However, simply applying the standard TCP congestion control
on each subflow would give an unfair resource sharing. Various subflows of a
connection would dispute bottleneck links with regular single-path TCP
connections, leading them to starvation conditions. To deal with this concern,
a multipath congestion control algorithm adjusts the sending operation of all
subflows in a coupled fashion in order to achieve various objectives, e.g.,
friendliness, responsiveness, throughput improvement, and congestion balance.
In this report, we describe the four coupled congestion control algorithms
deployed in the MPTCP Linux kernel implementation, namely: LIA, OLIA, BALIA,
and wVegas. We provide a concise material with technical details of each
algorithm, while summarizing all of them together from a single notation.
