Prestige 645M-A1 ADSL Bridge
3-2
Internet Access
3.3 IP Address and Subnet Mask
Similar to the way houses on a street share a common street name, the machines on a LAN also 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 (ignoring the trailing zero).
The Internet Assigned Number Authority (IANA) has 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 3 numbers specify the network number while the last number identifies an
individual computer on that network.
The subnet mask specifies the network number portion of an IP address. Your Prestige 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 Prestige unless you are instructed to.
3.3.1 Private IP Addresses
Every machine on the Internet must have a unique address. If your networks are isolated from the Internet, e.g.,
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 have it assigned by 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.