Multicasting, the transmission of a packet to a group of hosts, is an important service for improving the efficiency and robustness of distributed systems and applications. Although multicast capability is available and widely used in local area networks, when those LANs are interconnected by store-and-forward routers, the multicast service is usually not offered across the resulting internetwork. To address this limitation, we specify extensions to two common internetwork routing algorithms-distance-vector routing and link-state routing-to support low-delay datagram multicasting beyond a single LAN. We also describe modifications to the single-spanning-tree routing algorithm commonly used by link-layer bridges, to reduce the costs of multicasting in large extended LANs. Finally, we discuss how the use of multicast scope control and hierarchical multicast routing allows the multicast service to scale up to large internetworks.

We present a protocol for maintaining multiple paths to each destination in a network of processes. For each destination, each process in the network maintains a set of neighbors which are used as next-hops to reach the destination. This set is known as the successor set. Collectively, the successor sets from all processes in the network with respect to a given destination form a spanning, directed, and acyclic graph, whose only sink is the given destination. The protocol we present has two interesting properties. First, the graph is maintained acyclic at all times, even though the successor set is dynamic. Second, the protocol tolerates all types of transient faults, even those which may not be detected. Therefore, if the protocol is started from an arbitrary initial state, it will converge to a normal operating state in which a spanning, directed, and acyclic graph is obtained and subsequently maintained.

This note describes some theoretically-possible failure modes for TCP connections and discusses possible remedies. In particular, one very simple fix is identified.

This memo is a policy statement on the implementation of the Exterior Gateway Protocol in the Internet. This is an official policy statement of ICCB and DARPA