(also mrouter, multicast router port)
Multicast router definition
A multicast router (mrouter) is a network device that is responsible for forwarding multicast traffic. It sends IGMP (Internet Group Management Protocol) queries to ask which devices are interested in receiving the traffic and then forwards the traffic only to those devices, using UDP to send the queries to a multicast group. If the multicast router doesn’t get an answer to its queries, it won’t send data. On the other hand, if it does, it sends the multicast data to the appropriate receivers. A multicast router handles the two types of signaling packets – multicast and unicast.
Multicast router protocols
- Dense-mode routing. Dense-mode routing forwards multicast traffic on all interfaces. It only stops forwarding if a downstream router requests so. The neighboring routers of the ones directly connected to the multicast router forward the data further to their neighbors.
- Sparse-mode routing. Sparse-mode routing only forwards multicast traffic on interfaces if a downstream router requests it. If there are no requests, it does not forward any multicast traffic. Sparse-mode routing uses a non-flooding model to forward traffic from the source to the multicast receiver.
Multicast router advantages
- Comes with lower bandwidth requirements.
- Offers a smooth migration path.
- Provides more efficient network bandwidth use.
- Improves scalability and performance.
- Allows the use of a single source node for numerous streams, making fault tolerance simpler.
- Enables different applications to run simultaneously.