Adaptive Software Defined Multicast

Internet Service Providers (ISPs) need to cope with a growing amount of over-the-top (OTT) traffic, often without a share in the high revenues of the content providers. To achieve an efficient global delivery of content, today content providers usually employ content delivery networks (CDNs) located at the edge of ISP networks from where content is delivered to end users via IP unicast. Many OTT services could benefit from a better support within the ISP's network, e.g. by packet duplication to deliver OTT video streams. While traditional solutions like IP multicast did not prevail, SDN-based alternatives have started to gain attention recently. In contrast to traditional approaches, SDN enables ISPs to support network services in a more manageable and flexible manner. However, the approaches proposed so far are quite rigid and keep state at every network device, independent of the multicast group size. To alleviate this problem, this paper proposes a new approach termed ASDM enabling ISPs to dynamically adjust the tradeoff between bandwidth and state for any multicast service. It is shown that, given ISP-defined bandwidth and state cost functions, the optimal parameter for ASDM can be derived and applied for a transparent multicast-to-unicast conversion achieving the desired characteristics. The proposed approach results in up to 30% bandwidth reduction compared to unicast while using only a seventh of the network state compared to traditional multicast.