Network Hub

The predecessor to the network switch.

A network hub only works at the Physical layer. It forwards all incoming traffic to all nodes connected to it's network segment using the broadcast address ff:ff:ff:ff:ff:ff. All the nodes are configured to ignore received packet frames that don't have their MAC address as the destination.

Network Bridge

If two network segments were connected by a hub, both of them would forward to all connected nodes in their network segment, including each other. This creates a LOT of unnecessary traffic, and network bridges are were used to combat this. They isolate each hub to it's own collision domain.

Network bridges operate at the Datalink layer, and they use packet filtering based on MAC addresses when connecting network hubs together. They keep a database that tracks what ports are associated with what MAC addresses, constantly flushing out old data to stay up-to-date.

If a packet is received that has a destination address not stored in the bridges address table, it panics and forwards the packet to all the nodes in it's segment, acting like a hub.

#XI