Hirschmann RS20 User Manual page 31

Entering the IP Parameters
Since 1993, RFC 1519 has been using Classless Inter-Domain Routing
(CIDR) to provide a solution. CIDR overcomes these class boundaries and
supports classless address ranges.
With CIDR, you enter the number of bits that designate the IP address range.
You represent the IP address range in binary form and count the mask bits
that designate the netmask. The netmask indicates the number of bits that
are identical to the network part for the IP addresses in a given address
range. Example:
IP address, decimal
149.218.112.1
149.218.112.127
CIDR notation: 149.218.112.0/25
The combination of a number of class C address ranges is known as
"supernetting". This enables you to subdivide class B address ranges to a
very fine degree.
UM BasicConfig L2E
Release 8.0 05/2013
Network mask,
decimal
255.255.255.128
Mask bits
2.1 IP Parameter Basics
IP address, binary
10010101 11011010 01110000 00000001
10010101 11011010 01110000 01111111
25 mask bits
31