Switches

This device is typically found in computer networks and filters and forwards packets of data in LAN segments. Switches operate at the data link layer and the network layer of the OSI reference model and can support all packet protocols. Simple networks don't require switches, a LAN may be organised by a bus arrangement that each destination may inspect each message and reads any message with its address. In an Ethernet local area network a switch can determine the MAC address in each message frame which output to port forward it to and out of.

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