Network nodes forward data. Network nodes may take form in one or more routers, one or more bridges, one or more switches, one or more servers, or any other suitable communications processing device. The data is commonly formatted as packets and forwarded using forwarding tables. A packet is a formatted unit of data that typically contains control information and payload data. Control information may include: information that identifies sources and destinations, such as addresses, error detection codes like checksums, sequencing information, etc. Control information is typically found in packet headers and trailers. Payload data is typically located between the packet headers and trailers.
Forwarding packets involves various processes that, while simple in concept, can be complex. The processes involved in forwarding packets vary, depending on the type of forwarding method used. Multicast is the preferred method of data forwarding for many networks. One reason for this is that multicast is a bandwidth-conserving technology that reduces traffic by simultaneously delivering data to multiple receivers. However, some network environments are not well suited to support multicast. Doing so in such environments often involves discovering and maintaining significant amounts of control, or state, information. Setting up and maintaining this control information has a tendency to become complex and costly in terms of computing resources, and can become a major limiting factor in overall network performance. Another issue with multicast is that due to packet delivery mechanisms used, packets are sometimes forwarded to locations where the packets were not desired. This unnecessary delivery of packets represents an unwelcome burden on network performance. Overcoming this burden by traditional means involves generation and maintenance of even more control information.