WAGO 750-370 Manual page 148

148 • Fieldbus Communication
ETHERNET
Attention
Never set all bits to equal 0 or 1 in one byte (byte = 0 or 255). These are
reserved for special functions and may not be allocated. Therefore, the address
10.0.10.10 may not be used due to the 0 in the second byte.
If a network is to be directly connected to the Internet, only registered,
internationally unique IP addresses allocated by a central registration service
may be used. These are available from InterNIC (International Network
Information Center).
Attention
Direct connection to the Internet should only be performed by an authorized
network administrator and is therefore not described in this manual.
Subnets
To allow routing within large networks a convention was introduced in the
specification RFC 950. Part of the Internet address, the subscriber ID is
divided up again into a subnetwork number and the station number of the
node. With the aid of the network number it is possible to branch into internal
subnetworks within the partial network, but the entire network is physically
connected together. The size and position of the subnetwork ID are not
defined; however, the size is dependent upon the number of subnets to be
addressed and the number of subscribers per subnet.
1
1 0
Fig. 4-10: Class B address with Field for Subnet ID
Subnet mask
A subnet mask was introduced to encode the subnets in the Internet. This
involves a bit mask, which is used to mask out or select specific bits of the IP
address. The mask defines the subscriber ID bits used for subnet coding,
which denote the ID of the subscriber. The entire IP address range
theoretically lies between 0.0.0.0 and 255.255.255.255. Each 0 and 255 from
the IP address range are reserved for the subnet mask.
8 16
Net-ID Subnet-ID
24 32
Host-ID
WAGO-I/O-SYSTEM 750
PROFINET IO