Table 75: Example: Class B Address With Field For Subnet Ids; Table 76: Subnet Mask For Class A Network; Table 77: Subnet Mask For Class B Network; Table 78: Subnet Mask For Class C Network - WAGO -I/O-SYSTEM 750 Manual

212 Fieldbus Communication

Table 75: Example: Class B Address with Field for Subnet IDs

1
1 0
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.
The standard masks depending upon the respective network class are as follows:
• Class A Subnet mask:

Table 76: Subnet Mask for Class A Network

255
• Class B Subnet mask:

Table 77: Subnet Mask for Class B Network

255
• Class C Subnet mask:

Table 78: Subnet Mask for Class C Network

255
Depending on the subnet division the subnet masks may, however, contain other
values beyond 0 and 255, such as 255.255.255.128 or 255.255.255.248.
Your network administrator allocates the subnet mask number to you.
Together with the IP address, this number determines which network your PC
and your node belongs to.
The recipient node, which is located on a subnet, initially calculates the correct
network number from its own IP address and subnet mask. Only then the node
checks the node number and, if it corresponds, delivers the entire packet frame.

Table 79: Example for an IP Address from a Class B Network

IP address
Subnet mask
Net ID
Subnet ID
Host ID
Manual
1.5.0
750-882 Media Redundancy ETHERNET Controller
8
... Network ID
.0
.255
.255
172.16.233.200
255.255.255.128
172.16.0.0
0.0.233.128
0.0.0.72
16 24
Subnet ID
.0
.0
.255
'10101100 00010000 11101001 11001000'
'11111111 11111111 11111111 10000000'
'10101100 00010000 00000000 00000000'
'00000000 00000000 11101001 10000000'
'00000000 00000000 00000000 01001000'
WAGO-I/O-SYSTEM 750
32
Host ID
.0
.0
.0