ZyXEL Communications P-660HW-DX, User Manual

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Chapter 6 LAN Setup
P-660HW-Dx User’s Guide
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6.3.1 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.
6.3.1.1 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.
"
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.