HIERARCHICAL VECTOR CLOCK

A hierarchial vector clock (HVC) providing a logical time system to a collection of distributed systems. HVC is not restricted to any fixed number of hierarchy levels and scals naturally when the number of levels increases. Unlike constant-size clocks, its storage and processing requirements grow gracefully at approximately a logarithmic rate with the number of distributed sites within the distributed system. HVC is well suited for modern, message-passing distributed systems which make use of highly hierarchical communication networks.