The request reply family of group routing protocols

We present a family of group routing protocols for a network of processes. The task of these protocols is to route data messages to each member of a process group. To this end, a tree of processes is constructed in the network, ensuring that each group member is included in the tree. No processing or storage overhead is required for processes not included in the tree. The overhead of processes in the tree consists solely of the periodic exchange of request/reply messages with their parent. To choose the processes that constitute the tree, we take advantage of the existing unicast routing protocol in the network. In addition, our family of group routing protocols distinguishes itself from other group routing protocols in three ways. First, the protocols are proven correct. Second, the protocols preserve the integrity of the group tree as it adapts to changes in the unicast routing tables, even in the presence of temporary unicast routing loops. Third, data messages are propagated along the entire group tree, even while the tree adapts to changes in the unicast routing tables.