Siemens SINAUT MD741-1 System Manual page 140

Glossary
CIDR
140
Classless Inter-Domain Routing
IP netmasks and CIDR are notations for grouping a number of IP
addresses into an address space. Thus a range of contiguous
addresses is treated as a network.
The CIDR method reduces, for example the routing tables stored in
routers by means of a postfix in the IP address. This postfix can be
used to designate a network together with its subnetworks. This
method is described in RFC 1518.
In order to specify a range of IP addresses to the SINAUT MD741-1, or
when configuring the firewall, it may be necessary to specify the
address space in the CIDR notation. The following table shows the IP
netmask on the left-hand side, and to the far right the corresponding
CIDR notation.
IP netmask binary
255.255.255.255 11111111 11111111 11111111 11111111 32
255.255.255.254 11111111 11111111 11111111 11111110 31
255.255.255.252 11111111 11111111 11111111 11111100 30
255.255.255.248 11111111 11111111 11111111 11111000 29
255.255.255.240 11111111 11111111 11111111 11110000 28
255.255.255.224 11111111 11111111 11111111 11100000 27
255.255.255.192 11111111 11111111 11111111 11000000 26
255.255.255.128 11111111 11111111 11111111 10000000 25
255.255.255.0 11111111 11111111 11111111 00000000 24
255.255.254.0 11111111 11111111 11111110 00000000 23
255.255.252.0 11111111 11111111 11111100 00000000 22
255.255.248.0 11111111 11111111 11111000 00000000 21
255.255.240.0 11111111 11111111 11110000 00000000 20
255.255.224.0 11111111 11111111 11100000 00000000 19
255.255.192.0 11111111 11111111 11000000 00000000 18
255.255.128.0 11111111 11111111 10000000 00000000 17
255.255.0.0 11111111 11111111 00000000 00000000 16
255.254.0.0 11111111 11111110 00000000 00000000 15
255.252.0.0 11111111 11111100 00000000 00000000 14
255.248.0.0 11111111 11111000 00000000 00000000 13
255.240.0.0 11111111 11110000 00000000 00000000 12
255.224.0.0 11111111 11100000 00000000 00000000 11
255.192.0.0 11111111 11000000 00000000 00000000 10
255.128.0.0 11111111 10000000 00000000 00000000 9
255.0.0.0 11111111 00000000 00000000 00000000 8
254.0.0.0 11111110 00000000 00000000 00000000 7
252.0.0.0 11111100 00000000 00000000 00000000 6
248.0.0.0 11111000 00000000 00000000 00000000 5
240.0.0.0 11110000 00000000 00000000 00000000 4
224.0.0.0 11100000 00000000 00000000 00000000 3
192.0.0.0 11000000 00000000 00000000 00000000 2
128.0.0.0 10000000 00000000 00000000 00000000 1
0.0.0.0 00000000 00000000 00000000 00000000 0
Example: 192.168.1.0 / 255.255.255.0 corresponds to CIDR:
192.168.1.0/24
CIDR
SINAUT MD741-1
C79000-G8976-C236-05