The Router and GossipServer processes have overlapping functionality: both of them allows a member to fetch initial membership information. In addition the Router provides routing functionality. The reason for not merging the functionalities is that some (probably most) applications only need gossiping, but not routing functionality. Therefore they will use the lightweight GossipServer, without having to use Router whose routing functionality would not be used. As a matter of fact both processes used to be merged in earlier versions of JavaGroups.