BY DEFAULT, a router will not pass either Broadcast or Multicast. The router has to be configured to do so (IP Helper, for example).
A switch (or bridge, basically the same thing), will flood both types (unless configured to do so).
The difference between a multicast and a broadcast is that a broadcast will be seen by all devices in the broadcast domain, every device that sees the broadcast treats the frame as if it is destined for that machine and passes the frame up the stack. Somewhere up the stack, some process will determine that the packet is or is not of concern to that machine and dispose of it or send it further up the stack. This process wastes processor time if the frame is not of use to the receiving machine.
A multicast is recognized as a specific group address, and unless there is a process looking for that address (or range of multicast addresses), the frames are ignored (or at least ignored much earlier / lower in the stack) ...saving processor time. Also, because a multicast address comes from a specific range of addresses (Class D), they can be managed by switches and routers that are specifically configured to do so. "Management" can be to filter/drop, or to pass the traffic out to ports that have specifically joined a group requesting the traffic ... saving bandwidth on segments that have no participants. Again, by default, routers will block multicast and switches will flood it out to all ports.
We are pleased to announce availability of Beta software for 16.6.3.
16.6.3 will be the second rebuild on the 16.6 release train targeted
towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are
looking for early feedback from customers befor...
Introduction Featured Speakers Luis Espejel is the Telecommunications
Manager of IENova, an Oil & Gas company. Currently he works with Cisco
IOS® and Cisco IOS XE platforms, and NX to some extent. He has also
worked as a Senior Engineer with the Routing P...
In this session you can learn more about Layer 3 multicast and the best
practices to identify possible threats and take security measures. It
provides an overview of basic multicast, the best security practices for
use of this technology, and recommendati...