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Why will a switch never learn a broadcast address?

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Question added by Sajjad Ali , Personal Assistant , Population welfare
Date Posted: 2016/03/21
Syed Javed
by Syed Javed , it consultant , Infosys

Broadcast address ffff.ffff.ffff can never be a host's Mac address so that's why switch will never learn that in its table.

Sajid Ibrahim
by Sajid Ibrahim , Network Engineer , Insight school of Engineering and Management

Switch is working under layer 2. So it will not use any broadcast instead of that it will use mac address.

Md. Farhad Hossain
by Md. Farhad Hossain , IT Officer , Regency Garments Ltd.

a broadcast address is not a source address, it's only a destination.

Switches learns the MAC addresses of its hosts to update MAC Database (CAM Table). MAC Addresses with all the F's on are broadcast addresses which broadcast into 1 broadcast domain and will be learn by each host in same broadcast domain. Broadcast addresses are used to find the destination host connected to switch because switch don't have the MAC Address of destination host. e.g., Host A sends frame to Host B but switch don't have MAC address of Host B so switch will broadcast to each host except Source port from where it received the frame. Host B will reply that broadcast and all other hosts will discard that frame. I hope you are cleared now that why & how switch broadcast?

mahmoud hany
by mahmoud hany , IT Engineer , Al Shalawi Holding Company

Switch work in layer 2(Data link layer) ,  and work with mac address 

 

but broadcast is an ip  and it in layer 3 (Network layer)

ARSHAD GAFOOR
by ARSHAD GAFOOR , Network Implementation Engineer , Wipro

A broadcast address ffff.ffff.ffff.ffff is meant for all as destinations. And it is not a host MAC address. So the switch will always a MAC table for the connected hosts not the broadcast address.

Deleted user
by Deleted user

Switches learn address from the source of the frame

Gautham R G
by Gautham R G , Network Engineer , Mohan's Networking Institute

Switch will learn only source mac address, and broadcast will never be in source mac

Mohammed Imtiaz Ali Ahsan
by Mohammed Imtiaz Ali Ahsan , IT Resident Engineer , DXC Technology - P&G Account

A broadcast address will never be the source address of a frame

nandan singh
by nandan singh , Network Admin , Networkers Home Pvt Ltd

because ffff.ffff.ffff is a broadcast address .means go and find out this address (it is a instruction for switch) but eventually this address we can not assign to any device , switch is not able to find out this address so thats the only reason ,switch never learn this address.

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