A Case for Reducing Link Stress in a Multimedia Streaming Service Backbone

Application Layer Multicast, where a group of end hosts peer together to form a multicast overlay network on top of the network underlay is increasingly being used for streaming multimedia content. Current approaches have focused mainly on Quality of Service (QoS) parameters such as latency and bandwidth, ignoring the importance of minimizing underlay link stress. Link stress occurs when a number of overlay links share common links at the network level. Multiple overlay paths may send redundant traffic through the same underlay link, causing unnecessary congestion and unfairly burdening the better links. By distributing traffic over a large number of links rather than putting the burden on a few links, the system would become fairer in terms of resource usage and congestion alleviated. Also, an underlay link failure would affect fewer peers. The problem has been shown to be NP hard in literature, thus in this paper we present a heuristic solution to reduce underlay link stress. Through real traceroute data, we establish that link stress is in fact a problem and then we make use of random search to achieve reduction, of up to 77%, in link stress.