Network latency impact on performance of software deployed across multiple clouds

In cloud computing, an "edge cloud" may be introduced close to some of the end users, to give faster service for very demanding applications. The transactions that require heavy processing capacity and longer processing times are seen as more suitable to be carried out at the "core" cloud. Parts in the core and edge may then have to communicate, introducing associated network latencies. An application should be deployed across edge and core with the aim to reduce the overall effect of network latencies, in order to meet end user response time goals. In this paper, we use a Layered Queueing Network performance model to explore the impact of network latency and some possible deployment choices on the responsiveness of an application called HCAT (Home Care Aides Technology). The evaluations show that the use of the edge cloud may cause performance degradation, rather than gain, for some kinds of applications.