We investigate the problem of maintaining a topology with small degree as well as small diameter in a dynamic distributed system such that the system always stays connected and processes that wish to leave the system can do so quickly. Perpetual system connectivity is necessary to solve many important problems in dynamic distributed systems, including atomic broadcast and stable property detection, that need strict (deterministic) guarantees about system connectivity to be solvable. To our knowledge, in all existing topology maintenance algorithms that provide perpetual system connectivity, either (1) the topology has large worst-case degree and/or diameter or (2) a process may experience high worst-case delay when leaving the system. In this paper, we present a spanning tree maintenance algorithm that satisfies the following desirable properties. First, the spanning tree has small maximum degree of O(1) and small maximum diameter of O(log N), where N denotes the maximum size of the s...