Internet transport: A more performant, more robust, more reliable TCP

TCP (Transmission Control Protocol) is the reference connection-oriented transport protocol in the TCP/IP suite. TCP is the cornerstone of exchanges linked to web site consultation in particular, and occupies an almost hegemonic position in terms of the typology of traffic carried on the Internet. This position has remained unchanged for the past three decades, despite the standardization of a number of alternative proposals designed to promote transport modes better suited to the needs of certain applications, for example by simplifying the connection establishment procedure at the transport layer, or by improving the robustness of connections against denial-of-service attacks. However, the alternative proposals presented in Section 1 of this article never met with the success we had hoped for, not only because their impact on operating systems (OS) such as Windows was technically and commercially prohibitive, but also because they failed to convince the community of application developers of the need to design new sockets capable of exploiting the resources of these new transport-layer protocol stacks.

However, the basic TCP protocol specification published in 1981 has evolved over time as the Internet has developed. These functional evolutions of the TCP protocol are designed to meet a wide variety of needs, such as :

• an overall improvement in the performance of the TCP protocol machinery. This improvement is multi-faceted, and is aimed in particular at optimizing the time taken to establish a TCP connection by taking advantage of the first exchanges characteristic of the "3-way handshake" (3WHS) negotiation procedure to send and receive the first useful data;

• the prospects of being able to exploit all the network resources available to multi-terminal interfaces are promising. Indeed, the ability to establish a TCP connection over several paths increases the bandwidth associated with the connection. This capability also improves the availability of the connectivity service;

• the need to make TCP connections more impervious to denial-of-service attacks ;

• the need to adapt TCP protocol machinery to the global evolution of networks, some of whose resources are now virtualized and hosted in cloud infrastructures. This need is also protean: it can be expressed in terms of dynamic management of virtual machine mobility when they migrate from one data center to another. It can also illustrate the emergence of engineering choices based on the introduction of TCP connection aggregation functions in the network. Such functions enable users to benefit from optimized use of network resources without imposing the slightest constraint on the terminals at the origin...