Broadcast Address Definition

A Broadcast Address is a special address used to broadcast data to all devices in the network. The format determines for each protocol (communication protocol).

A packet or frame transmitted by specifying a broadcast address delivers to all other nodes in the network. It is not transferred to another network via a relay device such as a router. The use of an unconfigured terminal just connected to the network for a special purpose, such as searching for a server that teaches setting information.

In the MAC address used in Ethernet, etc., “FF: FF: FF: FF: FF: FF,” all bits of which are 1, is a [broadcast address], and the frame reaches all nodes in the same segment.

Types

There are two types of [broadcast addresses] used at this time: limited broadcast and directed broadcast.

Limited Broadcast Address (all one broadcast address)

It is an IP address with all bits set to 1. That is, the IP address “255.255.255.255” is the limited [broadcast address].
When data is broadcasted to this address, the data is transmitted to all computers connected to the network segment (in the case of Ethernet, one Ethernet segment). It is not sent to other segments connected via the router. It can only send computers on the local network segment.

Directed Broadcast Address

This is an address in which it leaves the network address part as it is, and it only sets the host address part to all 1.

For example, if there is a network address of “192.168.1.0/255.255.255.0” (this is the same as 192.168.1.0/24), this host address part (lower 8 bits) is all 1 Then, the IP address “192.168.1.255” becomes the directed [broadcast address].

When broadcasting to this address, all computers with the network address “192.168.1.0/255.255.255.0” become communication targets. It is known because it sends to a specific network address (directly). In general, the use of this broadcast seems to be more often.

All 0 Broadcast Address
The use of this old-style [broadcast address] is no longer. A limited [broadcast address] or a directed [broadcast address] uses 0 instead of (binary) 1 and corresponds to addresses such as 0.0.0.0 or 172.16.1.0/255.255.255.0. Currently, it exists only for compatibility and is never used.