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Method and apparatus for implementing reliable multicast in overlay network

IP.com Disclosure Number: IPCOM000240871D
Publication Date: 2015-Mar-09

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure will provide a method to achieve reliable multicast in overlay network. It includes 2 new parts: 1. Virtual switch aggregate the ACK/NACK from receivers to solve ack-implosion problem. The receivers in a local region send their ACK/NACK to the corresponding virtual switch. The virtual switches send aggregated ACK/NACK to the sender indicating which packets they have received and which packets they have not received. 2. Introduce a new multicast service which locates near the receivers, it has the capability of caching multicast packet. The virtual switch detects packets lost, and interacts with Multicast service to achieve efficient retransmission. 3. Multicast service can provide different cache scalability based on tenant requirement.

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Method and apparatus for implementing reliable multicast in overlay network

Network virtualization is an emerging data center and cloud computing trend which aims to virtualize a network as seen by end stations in a way that greatly simplifies network provisioning in multi-tenant environments, as well as traditional environments. Overlay networks run as independent virtual networks on top of a physical network infrastructure.

IP Multicast is a popular technical used to help conserve bandwidth in the data center and reduce the load on servers. Overlay multicast is a term about IP multicast running in overlay network.

Reliable multicast aims to provide sequenced, lossless delivery of bulk data from one sender to a group of receivers. Sender ensures reliable delivery by selectively retransmitting lost packets in response to the retransmission request of the receivers. Each receiver sends its status acknowledgement (ACK) / negative acknowledgement (NACK) to the sender.

If each receiver sends its status (ACK/NACK) to the sender, it results in the throttling of the sender which is the well-known ack-implosion problem. In addition, if some receivers are located far away from the sender and the sender retransmits lost packets to these distant receivers, the end-to-end delay is significantly increased, and throughput is considerably reduced.

In order to alleviate the ACK implosion problem, in a hierarchical tree-based scheme, the designated receivers (DR)

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to be chosen based on approximate location of the receivers. However, because the overlay multicast forwarding does not discriminate between receivers that are all one hop away, selecting the DR is difficult and it will lead to inefficient transmission. Besides this, in overlay network environment, if the DR migrates, it cannot service other receivers well.

The traditional DRs are not suitable for the overlay network and we need a new method to solve the ack-implosion problem and achieve reliable multicast.

The following Figure 1 illustrates multi-level hierarchy Multicast tree

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Figure1 illustrates multi-level hierarchy Multicast tree.

The following Figure 2 illustrates one-hop Multicast tree

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Figure2 illustrates one-hop Multicast tree.

This disclosure will provide a method to achieve reliable multicast in overlay network. It includes:

1. Virtual switch aggregate the ACK/NACK from receivers to solve ack-implosion problem. The receivers in a local

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region send their ACK/NACK to the corresponding virtual switch. The virtual switches send aggregated ACK/NACK to the sender indicating which packets they have received and which packets they have not received.

2. Introduce a new multicast service which locates near the receivers, it has the capability of caching multicast packet. The virtual switch detects packets lost, and interacts with Multicast service to achieve efficient retransmission.

3. Multicast service can provide differen...