Edge Service Caching for Service Function Chains

In Multi-access Edge Computing, services are hosted at the edge of the network to reduce latency and congestion. Services comprise Network Functions which provide security and optimize the network, and signalling and data processing functions. Services are chained to constitute Service Function Chains (SFCs). For latency critical applications or when the cloud is inaccessible, we posit that all the services of an SFC must be cached at the edge. Since services may be common across SFCs and require resources, the set of services to evict when the cache is full must be chosen such that as many SFCs as possible have all their services cached. We call this the SFC Cache Replacement Problem (SFC-CRP) and argue that measuring the service hit rate is insufficient. For the first time, we define the problem, quantity how to measure whether all the services of an SFC are cached at the edge and formulate it as an optimization problem. We implement the solution and demonstrate its effectiveness over a simple LRU heuristic by evaluations using datasets which we have derived from real (Alibaba) cluster traces.