ZyXEL Communications P-660H-T1 v3s, User Manual

Page: 100 / 272

Chapter 7 LAN Setup
P-660H-T1v3s User’s Guide
100
Network Address Translation (NAT) feature of the P-660H-T1v3s. 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 P-660H-T1v3s, 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 P-
660H-T1v3s 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 P-
660H-T1v3s 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
Assigned Numbers Authority (IANA) has reserved the following three blocks of IP
addresses specifically for private networks:
• 10.0.0.0 — 10.255.255.255
• 172.16.0.0 — 172.31.255.255
• 192.168.0.0 — 192.168.255.255
You can obtain your IP address from the IANA, from an ISP or it can be assigned
from a private network. If you belong to a small organization and your Internet
access is through an ISP, the ISP can provide you with the Internet addresses for
your local networks. On the other hand, if you are part of a much larger
organization, you should consult your network administrator for the appropriate IP
addresses.
Note: Regardless of your particular situation, do not create an arbitrary IP address;
always follow the guidelines above. For more information on address
assignment, please refer to RFC 1597, “Address Allocation for Private
Internets”
and RFC 1466, “Guidelines for Management of IP Address Space”.