Broadcasting implies a destination MAC of (by convention) all ones.
Flooding (like what happens when a switch doesn't have the destination MAC in the forwarding table) means that the un-altered frame is transmitted out all ports (except the port from which the frame arrived).
Broadcast: all-ones destination MAC, transmitted out all connected ports (because the destination address matches all hosts)
Flooding: all-port transmission of the unaltered frame. No change in the destination MAC.
Generaly, routers only send broadcasts for their own use, such as arp, just like any node on a network. However, the router may support "directed broadcasts" also called "subnet broadcasts"
Lets say I am on network 10.1.1.0/24 and can reach network 10.1.2.0/24 accross one or more routers. I can send to the IP address 10.1.2.255. This would be the IP broadcast address for the 10.1.2.0/24 network. When the router for that network receives the IP directed-broadcast packet, it will forward it out that network using layer 2 broadcast so that all nodes on that net will receive it.
This behavior can be turned on and of with the "ip directed-broadcast" IOS command in interface config mode.
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...