4-3
Private and Global Addresses
4-3-1
Private and Global Addresses
There are two kinds of IP addresses, private and global.
Global address These are IP addresses that connect directly to the Internet. Allocated by applica-
tion to NIC, each address is unique in the world, and as many as 4.3 billion can be
allocated worldwide.
Private address These are IP addresses for Intranet (LAN) use. Direct connection to the Internet is
not possible. Frames that include private IP addresses are restricted by the router
from being sent outside the LAN.
Generally, as shown below, global addresses in the intranet are allocated only to IP routers (such as
broadband routers) interfaced with the Internet. All other nodes in the intranet, which includes the built-
in EtherNet/ IP port, are allocated private addresses.
Firewall
Ethernet (EtherNet/IP)
Controller
Controller
Ethernet (EtherNet/IP)
Controller
Priva
te address
Personal computer
(e.g., Sysmac Studio)
Private addressPrivate address
Private address
Global address
IP router
Cannot connect to Internet
Cannot connect to Internet
Global address
Private address
Private address
IP router
Firewall
Personal computer
(e.g., Sysmac Studio)
(required)
Intranet
Internet
Intranet
4 Determining IP Addresses
4-12
NJ/NX-series CPU Unit Built-in EtherNet/IP Port User’s Manual (W506)
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