Often referred to as an mrouter, a multicast router that is configured to recognize signaling that is received in either multicast or unicast packets. Based on the type of packet identified, multicast routers then determine the routing or distribution of the data that is needed to forward the multicast or unicast packets to their intended destination. By employing a series of algorithms as part of the identification process, mrouters quickly initiate sending orders to the appropriate switches within the network and execute the delivery of the data packet.
The multicast router works side by side with unicast routers as part of a larger network that is generally referred to as the Multicast Internet or Backbone. Along the structure of this Backbone, various multicast routers will reside along with the unicast routers. In order to achieve rapport with the unicast routers, the mrouters will make use of the ability to disguise the data packets so they appear to be configured into a unicast model. In this manner, one multicast router will pass on the data packet to the next multicast router in the process, using a unicast router as a conduit for the transmission. The next multicast router will recognize the disguised data as truly being a multicast packet and then determine if disguising the packet is necessary to continue, or if the packet is at a point that is can continue in the original multicast format.
Currently, there are two different protocols used by multicast routers. The first is known as dense mode routing. When the network is composed on a large number of end users and there is a considerable amount of available bandwidth, the multicast router will employ dense mode routing. However, if the network contains relative few end users and operates with a smaller amount of available bandwidth, then the multicast router will employ the second protocol, known as sparse mode routing. The router will choose the routing method based on current conditions, which means that if a network adds bandwidth and new users, there is no need to replace any existing routers.
