Logical multicasting in overlay networks

A method for logical multicasting in overlay networks, the method comprising:

• receiving at a first time, at a first component of a first computing node in an overlay network, from a first virtual machine (VM) operating at the first computing node, a request to receive multicast packets in the overlay network, wherein a multicast data structure for the overlay network is maintained only by a data processing system, and wherein the multicast data structure contains information of each receiver that is configured to receive unicast packets during logical multicasting in the overlay network;
• sending a join request to the data processing system, wherein the join request is usable at the data processing system to add the first VM as a subscriber receiver in a multicast data structure;
• receiving, at the first component, from the first VM, a packet;
• unicasting from the first component to the data processing system, an original unicast packet corresponding to the packet;
• determining at the first component, whether any local VM other than the first VM at the first computing node is configured to receive multicast packets in the overlay network;
• and
• forwarding, responsive to at least one local VM other than the first VM at the first computing node being configured to receive multicast packets in the overlay network, the packet to the at least one local VM.

A computer program product for logical multicasting in overlay networks, the computer program product comprising one or more computer-readable storage media and program instructions stored on at least one of the one or more storage media, the stored program instructions comprising:

• program instructions to receive, at a data processing system, an original unicast packet from a first component in a first computing node in an overlay network, wherein the first component comprises a virtual switch, wherein the received original unicast packet was unicast by the first computing node only to the data processing system, and wherein a multicast data structure for the overlay network is maintained only by the data processing system, the multicast data structure containing information of each receiver that is configured to receive unicast packets during logical multicasting in the overlay network;
• program instructions to select, from a set of subscriber receivers in the multicast data structure, a subset of the subscriber receivers;
• program instructions to unicast a copy of the received original unicast packet to each subscriber receiver in the subset;
• program instructions to configure the first component, to determine whether any local virtual machine (VM) other than a first VM at the first computing node is configured to receive multicast packets in the overlay network, wherein the first VM sends a packet to the first component causing the original unicast packet to be unicast to the data processing system;
• and
• program instructions to forward, responsive to at least one local VM other than the first VM at the first computing node being configured to receive multicast packets in the overlay network, the packet to the at least one local VM.

A computer program product for logical multicasting in overlay networks, the computer program product comprising one or more computer-readable storage media and program instructions stored on at least one of the one or more storage media, the stored program instructions comprising:

• program instructions to receive at a first time, at a first application executing using a processor and a memory in a first component of a first computing node in an overlay network, from a first virtual machine (VM) operating at the first computing node, a request to receive multicast packets in the overlay network, wherein to cause multicasting in the overlay network the first computing node only unicasts to a multicast service cluster data processing system (MSC) and only the MSC maintains a multicast data structure that contains information of each receiver that its configured to receive unicast packets during logical multicasting in the overlay network;
• program instructions to send to the MSC a join request, wherein the join request is usable at the MSC to add the first VM as a subscriber receiver in a multicast data structure;
• receiving, at the first component, from a first VM, a packet;
• unicasting from the first component to the data processing system, an original unicast packet corresponding to the packet;
• determining at the first component, whether any local VM other than the first VM at the first computing node is configured to receive multicast packets in the overlay network;
• and
• forwarding, responsive to at least one local VM other than the first VM at the first computing node being configured to receive multicast packets in the overlay network, the packet to the at least one local VM.

A computer system for logical multicasting in overlay networks, the computer system comprising one or more processors, one or more computer-readable memories, and one or more computer-readable storage media, and program instructions stored on at least one of the one or more storage media for execution by at least one of the one or more processors via at least one of the one or more memories, the stored program instructions comprising:

• program instructions to receive, at a data processing system, an original unicast packet from a first component in a first computing node in an overlay network, wherein the first component comprises a virtual switch, wherein the received original unicast packet was unicast by the first computing node only to the data processing system, and wherein a multicast data structure for the overlay network is maintained only by the data processing system, the multicast data structure containing information of each receiver that is configured to receive unicast packets during logical multicasting in the overlay network;
• program instructions to select, from a set of subscriber receivers in the multicast data structure, a subset of the subscriber receivers;
• program instructions to unicast a copy of the received original unicast packet to each subscriber receiver in the subset;
• program instructions to configure the first component, to determine whether any local virtual machine (VM) other than a first VM at the first computing node is configured to receive multicast packets in the overlay network, wherein the first VM sends a packet to the first component causing the original unicast packet to be unicast to the data processing system;
• and
• program instructions to forward, responsive to at least one local VM other than the first VM at the first computing node being configured to receive multicast packets in the overlay network, the packet to the at least one local VM.