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TOPIC: Broadcast blocking

Broadcast blocking 10 years 7 months ago #13021

  • eli2983
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Hi ,

I was told that there is a way to block a port of a switch if it recieves many broadcasts. does anyone know a command of a cisco switch that enables it?

thanks :)
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Re: Broadcast blocking 10 years 7 months ago #13033

  • havohej
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hi.

Broadcast operation is a normal behavior of any network, the arps request an replysmust work in every network and it is brodacast traffic.
I know two commands, to prevents the switch ports from being flooded by unknown unicast traffic, when the switch does not have an entry of an uknown mac destion it floods to all ports, but to stop flooding to some ports, you can use the command:

switch(config-if)#switchport block unicast

so it protects the device connected to the port from receiving the unknonw unicast flooded to all the switch ports.

Also if you want to stop a device connected to a switchport from receiving multicast traffic you can use the interface command:

switch(config-if)#switchport block multicast.

It only prevents multicast traffic from entering the inetrface, but it still forwards normal traffic to the device connected to the interface.
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