B-10
TM4400013
REV.
D
B-8
IP Addresses, Netmask etc
An IP address is a 32-bit value, divided into four octets of eight bits each. The standard representation is four
decimal numbers (in the range of 0..255), divided by dots.
Example: 192.2.1.123
This is called decimal-dot notation.
The IP address is divided in two parts: a network and a host part. To support different needs, three “network
classes“ have been defined. Depending on the network class, the last one, two or last three bytes define the
host, while the remaining part defines the network. In the following text, ‘x’ stands for the host part of the IP
address:
IP address 1.x.x.x to 127.x.x.x
Only 127 different networks of this class exist. These have a very large number of potential connected devices
(up to 16777216)
Example: 10.0.0.1, (network 10, host 0.0.1)
IP address 128.0.x.x to 191.255.xxx.xxx
These networks are used for large company networks. Every network can consist of up to 65534 devices.
Example: 172.1.3.2 (network 172.1, host 3.2)
IP address 192.0.0.xxx to 223.255.255.xxx
These network addresses are most common. Most small company networks are class C networks. These
networks can consist of a maximum number of 254 hosts.
Example: 192.7.1.9 (network 192.7.1, host 9)
The remaining addresses 224.x.x.x - 239.x.x.x are defined as “Class D“ and are used as a multicast address.
Note: No addresses are allowed with the four highest-order bits set to 1-1-1-1. (240.x.x.x. - 254.x.x.x)These
addresses, called "class E", are reserved.
The host address with all host bits set to "0" is used to address the network as a whole (for example in routing
entries).
The address with the host part bits all set to “1“ is the broadcast address, meaning “for every stations“.
Network and Broadcast addresses must not be used as a host address (e.g. 192.168.0.0 identifies the entire
network, 192.168.0.255 identifies the broadcast address).
