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Gopis
07-31-2009, 09:52 AM
Hi,
anybody explain where actually IP broadcast and MAC broadcast happen?

:confused:
Big Evil
07-31-2009, 10:17 AM
On the OSI or do you mean in a working network?
Gopis
08-01-2009, 03:53 AM
yes, I'm asking in network.
Big Evil
08-01-2009, 01:02 PM
Ok.

A IP broadcast is when traffic is sent to all devises on the network. The broadcast IP would be the highest IP address on that subnet.
Take 192.168.0.0/24 (192.168.0.xxx with subnet mask 255.255.255.0) the broadcast address is 192.168.0.255.

A MAC broadcast address is a special case where all bits of the MAC address are set to '1' (e.g. FF-FF-FF-FF-FF-FF ).

HTH.
Fuzz
08-02-2009, 03:23 AM
A MAC broadcast can occur when the IP address is unknown, like during ARP or DHCP Request. It is also used when the IP address is the subnet broadcast address. It tells the switch to flood the packet out all ports in that vlan.

The broadcast IP address makes all devices on the subnet respond to the packet. Usually if a host receives a packet that is not addresses to it it simply drops the packet. If it receives a broadcast packet it processes the packet normally.