Latency requirements determines the degree of user satisfaction about the web service. Software development practices shall consider the end-to-end latency as one of user-oriented characteristics during the entire life-cycle of an application. Latency budget defines latency target and non-functional requirements for distributed systems.
TCP/IP do not utilizes a full bandwidth when connection is established. It gradually increases a data flow. Effect of TCP/IP slow start and its latency becomes visible for applications while mobile network is used.
The radio access networks are slow and applications needs to optimise number of round trips.
Distributed systems involve various technologies and communication principles that bring overhead and latencies. The root cause of latencies varies from physical properties of the network to the quality of software components. The post discussed sources of latencies from the prism of infrastructure, protocol and application.
The network infrastructure involves various technologies, interfaces and protocols along the communication path. It is conveniently partitioned into domains: Internet, Data Center and Internet Service Provider. The post gives an introduction to high-level IP network architecture and its impact on communication latencies.