Multicast routing method satisfying quality of service constraints, software and devices

摘要

A multicast routing method satisfying quality of service constraints, devices and software are disclosed. A route requester may initiate establishment of a multicast route on a network to a multicast source node. Routing request messages are broadcast by a node receiving the request to adjacent nodes. Upon arrival of a request message at each node, QoS constraints are tested to ensure that a multicast path satisfying the QoS constraints may include this node. If so, resources at the node are tentatively reserved, and the request message is propagated to adjacent nodes. If not, a message is propagated in the reverse direction, releasing all tentative reserved resources at downstream nodes until a node through which another path to the multicast source has been routed or is tentatively reserved (i.e. a branch node) is encountered along the path. The process is repeated at each node, as routing messages are propagated in multiple directions away from the requester. Equivalent routing requests at any node may be merged. Similarly, in the event a route through a node to the multicast source already exists, a routing request may merge a requested route with an existing route, downstream (i.e. toward the multicast source) of the node, thereby attaching to an existing branch within the multicast routing tree. Once a routing message arrives at the source or at a node that merges an existing route to the source, this source or merge node confirms routing by dispatching a confirmation message to the requesting node, along the tentatively reserved route.