Reconfiguration of ´data connectivity trees´ in large dynamic networks

An infrastructure network often maintains nodes that participate in the distribution of video and/or content from a server to clients. To support these application sessions, the infrastructure network needs to maintain logical connectivity between the server and client entities, realized through transport-level path segments that interconnect one or more intermediate nodes. The connectivity can be viewed as an acyclic graph, i.e., a tree whose vertices include the nodes containing the client and server entities with edges set up over the intervening path segments. The paper deals with reconfiguration algorithms to handle the addition or removal of a vertex due to application-level actions like a client joining the distribution session or a server leaving. Dynamic network changes may also trigger the reconfiguration of a distribution path at the session level. With reconfiguration activities occurring asynchronously at the connectivity management level, coordination among these activities is required so that the reconfigured distribution path maintains the tree-structure (i.e., the connectivity graph remains acyclic). The paper provides an algorithmic framework that employs loosely synchronized time-stamp ordering to coordinate between multiple reconfiguration activities. Policy functions that prescribe constraints on the tree setups (e.g. minimum cost trees) can augment our algorithms to suit specific application domains. The usefulness of our framework in distribution path setups under resource constraints is also described. The framework is evaluated using discrete-event simulation.