NEC Aspire S Manual page 204

Section 6: LAN Connection
IP Address
Equipment/devices used in the Aspire LAN setup must have an IP address assignment. An IP address assigns
a unique address for each device. There are two types of IP addresses: Private and Global. A Private IP
Address is not accessible through the internet - a Global IP Address can be accessed through the internet.
With a Private IP Address, with equipment that does not access the internet directly, addresses can be
assigned to the equipment within Class A, B or C by assigning a number within the class's range of numbers.
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 Num-
bers). 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.
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 con-
tains 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.
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 Aspire S system pro-
vides 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 CPU must always have a static IP address. This address is set in Program 10-12-01 : NTCPU
Network Setup - IP Address (default: 172.16.0.10).
6-2 ◆ Section 6: LAN Connection
Class Allowed IP Address
A 10.0.0.0 ---10.22.255.255
B 172.16.0.0 --- 172.31.255.255
C 192.168.0.0 --- 192.168.255.255
Class
A
B
C
Recommended Environment
Default Subnet Mask
255.0.0.0
255.255.0.0
255.255.255.0
Large Scale Network
Mid Scale Network
Small Scale Network
Aspire S Hardware Manual