- Freecom Router User Manual

Class E

Class E addresses are for experimental use.

For each unique value of the network portion of the address, the base address

of the range (host address of all zeros) is known as the network address and is

not usually assigned to a host. Also, the top address of the range (host address

of all ones) is not assigned, but is used as the broadcast address for simultane-

ously sending a packet to all hosts with the same network address.

Netmask

The partitioning scheme separating the different address classes can be ex-

pressed by a netmask associated with the IP address. A netmask is a 32-bit

quantity that, when logically combined (using an AND operator) with an IP

address, yields the network address. For instance, the netmasks for Class A, B,

and C addresses are 255.0.0.0, 255.255.0.0, and 255.255.255.0, respectively.

For example, the address 192.168.170.237 is a Class C IP address whose network

portion is 192.168.170. When combined (using an AND operator) with the Class

C netmask, as shown here, only the network portion of the address remains:

11000000 10101000 10101010 11101101 (192.168.170.237)

combined with:

11111111 11111111 11111111 00000000 (255.255.255.0)

Equals:

11000000 10101000 10101010 00000000 (192.168.170.0)

As a shorter alternative to dotted-decimal notation, the netmask may also be

expressed in terms of the number of ones from the left. This number is appended

to the IP address, following a backward slash ( / ), as "/n." In the example, the

address could be written as 192.168.170.237/24, indicating that the netmask is

24 ones followed by 8 zeros.

Appendix