Cidr Notation; Selecting An Ip Address - CTI Janus 2500C-J Series Installation And Operation Manual

This can be accomplished by using the Windows calculator Programmer view. Using this example, you would enter
the value of the third octet (40), click on the "and" button, enter the Subnet Mask (240), and then click on the "="
button. The result, in this case, is 32. Thus, the Network Address is 127.18.32.0.

CIDR Notation

CIDR notation (Classless Inter-Domain Routing) is an alternate method of representing a subnet mask. It is simply a
count of the number of network bits (bits that are set to 1) in the subnet mask. It provides a more concise way to
represent the subnet mask. The CIDR number is typically preceded by a slash "/" and follows the IP address. For
example, an IP address of 131.10.55.70 with a subnet mask of 255.0.0.0 (which has 8 network bits) would be
represented as 131.10.55.70 /8. The following table can be used to convert between subnet mask and CIDR.
CIDR Dotted Decimal
/1 128.0.0.0
/2 192.0.0.0
/3 224.0.0.0
/4 240.0.0.0
/5 248.0.0.0
/6 252.0.0.0
/7 254.0.0.0
/8 255.0.0.0
/9 255.128.0.0
/10 255.192.0.0
/11 255.224.0.0
/12 255.240.0.0
/13 255.248.0.0
/14 255.252.0.0
/15 255.254.0.0
/16 255.255.0.0

Selecting an IP Address

The Janus Controller typically requires a fixed IP Address. If you are connecting to an existing network, you should
obtain an unused static IP Address and Subnet Mask from the network administrator.
If you are establishing your own IP Addresses, you should select IP Addresses from a block of 'private" addresses
established by the Internet Assigned Numbers Authority (IANA). The private address blocks are:
•
10.0.0.0 through 10.255.255.255 (Class A)
•
172.16.0.0 through 172.31.255.255 (Class B)
•
192.168.0.0 through 192.168.255.255 (Class C)
These addresses will not be forwarded by the Internet backbone routers; therefore, you are free to use any
address in this group as long as it does not conflict with the usage by your local organization.
72
CIDR Dotted Decimal
/17 255.255.128.0
/18 255.255.192.0
/19 255.255.224.0
/20 255.255.240.0
/21 255.255.248.0
/22 255.255.252.0
/23 255.255.254.0
/24 255.255.255.0
/25 255.255.255.128
/26 255.255.255.192
/27 255.255.255.224
/28 255.255.255.240
/29 255.255.255.248
/30 255.255.255.252
/31 255.255.255.254
/32 255.255.255.255
CTI Janus Programmable Automation Controller IOG