Specifications

A - 10 RSLinx – Training Guide
Network.Network.Node.Node
To determine the valid number of Network Addresses, recall that a
Class B network has a first octet with the leading bit pattern 10. This
leaves only 14-bits available, from the first two octets, for Network
Addresses. Converting this binary number to decimal gives a total of
16,384 possible Network Addresses. Thus, the only valid Class B
Network Addresses available will always have a first octet that begins
with a decimal number between 128-191 decimal. This means that any
TCP/IP address that begins with a number between 128 and 191 is a
Class B Network.
To determine the valid number of Node Addresses, use the remaining
two octets for addressing the hosts. Converting this 16-bit binary
number to decimal gives a total of 65,536 possible Node Addresses. A
Node Address of all zeros and all ones is invalid. Thus, this leaves a
total of 65,534 possible Node Addresses available for a Standard
Class B Network.
In a Standard Class C network, the first three octets are reserved for
the Network Address, while the last octet is reserved for the Node
Addresses. The Class C format is:
Network.Network.Network.Node
To determine the valid number of Network Addresses, recall that a
Class C network has a first octet with the leading bit pattern 110. This
leaves only 21-bits available, from the first three octets, for Network
Addresses. Converting this binary number to decimal gives a total of
2,097,152 possible Network Addresses. Thus, the only valid Class C
Network Addresses available will always have a first octet that begins
with a decimal number between 192-223 decimal. This means that any
TCP/IP address that begins with a number between 192 and 223 is a
Class C Network.
To determine the valid number of Node Addresses, use the last octet
for addressing the hosts. Converting this 8-bit binary number to
decimal gives a total of 256 possible Node Addresses. A Node
Address of all zeros and all ones is invalid. Thus, this leaves a total of
254 possible Node Addresses available for a Standard Class C
Network.