BASICS OF SWITCH

1) Switch is an Intelligent Device

If a switch receives a frame on a port it reads the destination MAC address and forward to appropriate port only and not to other ports.

2) When Switch receives a frame on a port it will open Layer 2 Information read source MAC   of and make the entry of the mac address in its MAC table against the port on which it was received.

Switch takes forwarding decision on basis of MAC address and MAC address is Layer 2 address.
Hence Switch is a "Layer 2" device.

For Quick reference and fast forwarding the MAC address table should be precise and updated with the correct MAC address entries.

So the MAC address table should be controlled and Stale entries have to be deleted.

Any entry not referred / used for a stipulated time is consider as Stale.

Switch would remove stale entry from MAC table and the stipulated time can be from 5 to 30 mins depending upon the switch.

Cisco Switch

3) Switch is also called as "Multiport Bridge"

Normally Bridge would have only 16 ports where as switch have multiple ports.

Switch & Bridge are similar devices but use to different mediums.

Bridge -----> Thick , thin wire
Switch -----> Twisted Pair / Fiber.

4) If a switch receives a " Broadcast Frame " on a port it will create multiple copies of the frame and forwards it to all other ports.

Switch don't broadcast but forwards the broadcast received on a port to all other ports.

If a sender and receiver are on the same ports switch blocks / discards the frame.

If sender and receiver are on the different ports , Switch will bridge the information to relevant port only.

Switch segments the network whereas HUB extends the  network.

If a receiver is not known switch forwards the information to all the ports.

5) Switch allows simultaneous communication between  multiple communicating pairs connected on different ports.

Every port of a switch has its own dedicated Bandwidth .

6) Every port of a switch is member of a separate collision domain.

Switch is a multiple collision domain.

Every port of a switch is member of same broadcast domain.

Switch is a single broadcast domain device .

Thanks for Reading !!!!