Distributed constrained tree formation for deterministic multicast

A method, comprising:

• receiving, at a node in a network, a path lookup request flooded into the network from a multicast listener device to search for nodes on a multicast tree, wherein the path look up request includes one or more constraints;
• determining, by the node, if the node is on the multicast tree;
• in response to determining, by the node, that the node is on the multicast tree:
• determining, by the node, a total path latency from a source of the multicast tree to the multicast listener device via the node;
• in response to determining that the total path latency is less than or equal to a maximum allowable path latency:
• determining, by the node, a unicast routing cost from the candidate node to the multicast listener device;
• and
• returning, by the node, a path lookup response to the multicast listener node only when the total path latency is less than or equal to a maximum allowable path latency, the path lookup response indicating to the multicast listener that the node is a candidate node for a join point on the multicast tree, wherein the path lookup response indicates the unicast routing cost,
• wherein the path lookup response causes the multicast listener device to select a particular node of one or more candidate nodes as a join point for the multicast tree based on the associated unicast routing cost to the multicast listener device from among the one or more candidate nodes;
• joining, by the node, the multicast listener to the multicast listener tree when the node has the lowest unicast routing cost from among those nodes that responded as having total path latencies of less than or equal to a maximum allowable path latency.

An apparatus, comprising:

• one or more network interfaces to communicate within a network as a multicast listener device;
• a processor coupled to the network interfaces and adapted to execute one or more processes;
• and
• a memory configured to store a process executable by the processor, the process when executed operable to:
• flood a path lookup request into the network to search for nodes on a multicast tree;
• receive one or more path lookup responses from one or more candidate nodes on the multicast tree, wherein each of the one or more path lookup responses indicates a unicast routing cost from a respective candidate node to the multicast listener device, and wherein only nodes where the total path latency is less than the maximum allowable path latency respond to the path lookup request as the one or more candidate nodes;
• select a particular node of the one or more candidate nodes that responded to the path look up request, wherein the particular node is a join point for the multicast tree and is selected based on the particular node having a lowest associated unicast routing cost to the multicast listener device from among the one or more candidate nodes;
• and
• join the multicast tree at the selected join point to build a multicast tree, wherein the join point is the particular node where the total path latency is less than the maximum allowable path latency while also having the lowest associated unicast routing cost of the one or more candidate nodes.

An apparatus, comprising:

• one or more network interfaces to communicate within a network;
• a processor coupled to the network interfaces and adapted to execute one or more processes;
• and
• a memory configured to store a process executable by the processor, the process when executed operable to:
• receive a path lookup request flooded into the network from a multicast listener device to search for nodes on a multicast tree, wherein the path look up request includes one or more constraints;
• determine if the apparatus is a node on the multicast tree;
• and
• in response to determining that the node is on the multicast tree:
• determine a total path latency from a source of the multicast tree to the multicast listener device via the node;
• determine a unicast routing cost from the candidate node to the multicast listener device in response to the total path latency being less than or equal to a maximum allowable path latency;
• return a path lookup response to the multicast listener node only when the total path latency is less than or equal to a maximum allowable path latency, the path lookup response indicating to the multicast listener that the node is a candidate node for a join point on the multicast tree, wherein the path lookup response includes the unicast routing cost,
• wherein the path lookup response causes the multicast listener device to select a particular node of one or more candidate nodes as a join point for the multicast tree based on the associated unicast routing cost to the multicast listener device from among the one or more candidate nodes;
• and
• join the multicast listener to the multicast listener tree when the node has the lowest unicast routing cost from among those nodes that responded as having total path latencies of less than or equal to a maximum allowable path latency.