“Characteristics of Destination Address Locality in Computer Networks: A Compar-
ison of Caching Schemes,” R. Jain, Computer Networks and ISDN, vol. 18, pp. 243–254, 1989/1990.

This paper is probably the first to think about locality in network traffic. At that time, most of the networks were built on pure proprietary architectures, however, some of the conclusions are still applicable today. However, as the analysis was performed on non IP networks, we'll not discuss the experimental part in this summary.