
C.ETHERNET-RELATED TERMINOLOGY APPENDIX B-63354EN/04
- 386 -386
Leading Octet
Value
Network Address
Part
Host Address
Part
Class A 0 to 127
xxx.xxx.xxx.xxx xxx.xxx.xxx.xxx
Class B 128 to 191
xxx.xxx.xxx.xxx xxx.xxx.xxx.xxx
Class C 192 to 223
xxx.xxx.xxx.xxx xxx.xxx.xxx.xxx
Hatched parts indicate the sections corresponding to the respective
addresses.
Generally, Class C is used if a single network does not support 255 or
more communications devices.
In a single network, the IP addresses of communications devices
connected to that network all share the same network address, and each
have unique values as their host address.
Network addresses and host addresses expressed as either all 0's or all
255's are not allowed.
IP addresses are managed in an integrated manner internationally. For
this reason, to use an IP address, an official IP address must be acquired
from an international organization.
However, note that if the network used by the user is a closed local
network at the user site (a network built only inside the company that is
not connected to an outside network), appropriate address can be set as
the IP address under the user's management and responsibility. In the
case of a local network, an IP address whose network address is one
Class A address "10", 16 Class B addresses "172.16" to "172.31", or
256 Class C addresses "192.168.0" to "192.168.255" can be used
without being officially registered. So, we recommend using IP
addresses having these network addresses when the IP addresses are
used within a local network.
Subnet mask (MASK address)
This is the address that constitutes the mask value for identifying the
network address in the above IP address.
Specify "255.0.0.0" in the case of a Class A network.
Specify "255.255.0.0" in the case of a Class B network.
Specify "255.255.255.0" in the case of a Class C network.
MAC address (Ethernet address)
This address is assigned to the Ethernet control card of each
communications device, and is used for identifying each control device
at the MAC layer (Media Access Control layer, the lowest layer of the
data link layer). A unique address acquired from an international
organization is assigned as the MAC address to the manufacturer of the
Ethernet control card.