Subnet Mask; Dhcp - NEC UX5000 Hardware Manual

Chapter 5 - LAN Connection
With a Global IP Address, connected equipment can be accessed through the internet, so each address must
be unique. To avoid a conflict, the addresses are controlled by ARIN (American Registry for Internet Numbers).
To obtain a Global IP Address, contact ARIN or apply with your local ISP (internet service provider).
The first one to three groups of numbers (depending on the subnet mask) identify the network on which your
computer is located. The remaining group(s) of numbers identify your computer on that network.
5.1.3

Subnet Mask

As the IP Address includes information to identify both the network and the final destination, the Subnet Mask
is used to set apart the network and destination information.
The default subnet masks are:
In the above table, you'll see that the Subnet Mask is made up of four groups of numbers. When a group
contains the number '255', this is telling the router to ignore or mask that group of numbers in the IP address
as it is defining the network location of the final destination. So, for example, if the IP Address were:
172.16.0.10 and the Subnet Mask used was Class B (255.255.0.0), the first two groups of numbers (172.16)
would be ignored once they reached the proper network location. The next two groups (0.10) would be the
final destination within the LAN to which the connection is to be made.
5.1.4

DHCP

DHCP (Dynamic Host Configuration Protocol) is a protocol which assigns a dynamic IP Address. Network
control may be easier with DHCP as there is no need to assign and program individual IP Addresses for the
LAN equipment. To use a dynamic IP Address, a DHCP server must be provided. The UX5000 system
provides the ability to use DHCP.
When equipment which is connected to the LAN (the DHCP client) is requesting an IP Address, it searches the
DHCP server. When the request for an address is recognized, the DHCP server assigns an IP Address,
Subnet definition, and the IP Address of the router, etc., based upon the system programming.
Note that the CCPU must always have a static IP address. This address is set in Program 10-12-01 : CCPU
Network Setup - IP Address (default: 192.168.0.10).
5 - 2
Class Default Subnet Mask
A
B
C
255.0.0.0
255.255.0.0
255.255.255.0
Chapter 5