Layer 3
Router is a marketing term for a Layer 3 switch, typically a router optimized for Ethernet interfaces. Like other switches, it connects devices to single ports for microsegmentation. The ports normally operate in full duplex.Switches, even primarily Layer 2 switches, can be aware of Layer 3 multicast and increase efficiency by delivering the traffic of a multicast group only to ports where the attached device has signaled that it wants to listen to that group. In a switch not aware of multicasting and broadcasting, frames are also forwarded on all ports of each broadcast domain, but in the case of IP multicast this causes inefficient use of bandwidth. To work around this problem some switches implement IGMP snooping.