ZyXEL Communications P-870HN-51B - V1.0 Manual page 98

Chapter 6 LAN Setup
IP Pool Setup
The ZyXEL Device is pre-configured with a pool of IP addresses for the DHCP
clients (DHCP Pool). See the product specifications in the appendices. Do not
assign static IP addresses from the DHCP pool to your LAN computers.
LAN TCP/IP
The ZyXEL Device has built-in DHCP server capability that assigns IP addresses
and DNS servers to systems that support DHCP client capability.
IP Address and Subnet Mask
Similar to the way houses on a street share a common street name, so too do
computers on a LAN share one common network number.
Where you obtain your network number depends on your particular situation. If
the ISP or your network administrator assigns you a block of registered IP
addresses, follow their instructions in selecting the IP addresses and the subnet
mask.
If the ISP did not explicitly give you an IP network number, then most likely you
have a single user account and the ISP will assign you a dynamic IP address when
the connection is established. If this is the case, it is recommended that you select
a network number from 192.168.0.0 to 192.168.255.0 and you must enable the
Network Address Translation (NAT) feature of the ZyXEL Device. The Internet
Assigned Number Authority (IANA) reserved this block of addresses specifically for
private use; please do not use any other number unless you are told otherwise.
Let's say you select 192.168.1.0 as the network number; which covers 254
individual addresses, from 192.168.1.1 to 192.168.1.254 (zero and 255 are
reserved). In other words, the first three numbers specify the network number
while the last number identifies an individual computer on that network.
Once you have decided on the network number, pick an IP address that is easy to
remember, for instance, 192.168.1.1, for your ZyXEL Device, but make sure that
no other device on your network is using that IP address.
The subnet mask specifies the network number portion of an IP address. Your
ZyXEL Device will compute the subnet mask automatically based on the IP
address that you entered. You don't need to change the subnet mask computed by
the ZyXEL Device unless you are instructed to do otherwise.
Private IP Addresses
Every machine on the Internet must have a unique address. If your networks are
isolated from the Internet, for example, only between your two branch offices, you
can assign any IP addresses to the hosts without problems. However, the Internet
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P-870HN-51b User's Guide