Summary: Membership Algorithms for Multicast
Yair Amir, Danny Dolev ? , Shlomo Kramer, Dalia Malki
The Hebrew University of Jerusalem, Israel
Abstract. We introduce a membership protocol that maintains the set
of currently connected machines in an asynchronous and dynamic envi
ronment. The protocol handles both failures and joining of machines. It
operates within a multicast communication subsystem.
It is well known that solving the membership problem in an asynchronous
environment when faults may be present is impossible. In order to cir
cumvent this difficulty, our approach rarely extracts from the member
ship live (but not active) machines unjustfully. The benefit is that our
procotol always terminates within a finite time. In addition, if a machine
is inadvertently taken out of the membership, it can rejoin it right away
using the membership protocol.
Despite the asynchrony, configuration changes are logically synchronized
with all the regular messages in the system, and appear virtually syn
chronous to the application layer.
The protocol presented here supports partitions and merges. When parti
tions and merging occur, the protocol provides the application with exact