Subnet Mask - NEC Aspila EX Hardware Manual

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Section 6: LAN Connection
IP Address
Equipment/devices used in the Aspila EX 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 Glo-
bal. 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.
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 Sub-
net 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.
DHCP
DHCP (Dynamic Host Configuration Protocol) is a protocol which assigns a dynamic IP Address. Net-
work 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 Aspila EX 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 program-
ming.
Note that the NTCPU 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
Chuyên phân phối tổng đài NEC
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
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Large Scale Network
Mid Scale Network
Small Scale Network
Aspila EX Hardware