Broadcast, Unicast, Multicast ve ARP Structure

In order for users to communicate with each other and access the internet through the switches, some protocols must be provided beforehand. When the user first turns on his computer, he sends a broadcast to the switch to which he is connected.

The broadcast contains the Mac address of the computer. Starting from the switch to which it is connected, the broadcast reaches every point in the local network. When it encounters Router, Firewall, Switch or Server, this broadcast is responded according to the configuration.

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This packet, known as Reply, reaches the source user who broadcast the broadcast. According to the reply, the user can be included in the Vlan, get IP from DHCP or get authorization from the server. From the moment the reply packet reaches the user computer, if a positive reply is received, mutual Unicast and Multicast broadcasting starts.

This is the basic working logic of switches and one of the most important features that distinguishes them from multiplexer hubs. The broadcast packet can come from the source PC or from the switch at certain intervals. Switches also communicate with each other with this method. In order to get IP from MAC address, broadcast is always broadcast before unicast.

Broadcast packets broadcast by PCs and switches cannot go out of the router. They can only exist to provide communication in the local network. Only unicast and multicast packets can go outside the router. Worm type viruses are known to spread in the local network with broadcast logic.

ARP (Address Resolution Protocol ): It is a protocol that communicates network elements and users with each other according to their Mac addresses with Broadcast, Unicast and Multicast packets and performs the Address Resolution process, whose short name is ARP.