Client-based dynamic switching of streaming servers for fault-tolerance and load balancing

Abstract

A client-based system for the fault tolerant delivery of real-time or continuous data streams, such as real-time multimedia streams, e.g., live audio and video clips. Multimedia servers are grouped into two or more sets, for example wherein a first set includes one or more primary servers using odd-numbered ports and a second set includes one or more secondary servers using even-numbered ports. The client requests a multimedia stream through a control server or gateway which routes requests to the multimedia servers; and the client receives the stream directly from a selected (primary) server. The client automatically detects load imbalances and/or failures (complete or partial) and dynamically switches to a secondary server in order to continue receiving the real-time multimedia stream with minimal disruption and while maintaining a balanced load across multiple servers in a distributed network environment. The determination can be made based on: the received bit or frame rate (for video); a bit rate or sample rate (for audio); monitoring a delivery rate or for packets arriving out of order: for example using packet numbering mechanisms available in TCP; sequence numbering or time stamp capabilities of RTP (in combination with the User Datagram Protocol (UDP)). In any case, the determination could be based on the rate measurement or monitoring mechanism falling below (or exceeding) some threshold. Alternately, the primary server or the control server could send an explicit distress or switch signal to the client. An explicit signal can be used for example to switch clients in phases with minimal disruption.