Netmask - Hirschmann RS20 User Manual

Entering the IP Parameters
0 Net ID - 7 bits
I 0 Net ID - 14 bits
I I 0 Net ID - 21 bits
I I I 0 Multicast Group ID - 28 bits
I I I I reserved for future use - 28 b its
Figure 6: Bit representation of the IP address
All IP addresses belong to class A when their first bit is a zero, i.e. the first
decimal number is less than 128.
The IP address belongs to class B if the first bit is a one and the second bit
is a zero, i.e. the first decimal number is between 128 and 191.
The IP address belongs to class C if the first two bits are a one, i.e. the first
decimal number is higher than 191.
Assigning the host address (host ID) is the responsibility of the network
operator. He alone is responsible for the uniqueness of the IP addresses he
assigns.
2.1.2

Netmask

Routers and gateways subdivide large networks into subnetworks. The
netmask assigns the IP addresses of the individual devices to a particular
subnetwork.
The division into subnetworks with the aid of the netmask is performed in
much the same way as the division of the network addresses (net id) into
classes A to C.
26
Host ID - 24 bits
Class A
Host ID - 16 bits
Class B
Host ID - 8 bit s
Class C
Class D
Class E
2.1 IP Parameter Basics
UM BasicConfig L2E
Release 8.0 05/2013