ZyXEL Communications Prestige 642 - Manual (Page 119)

Prestige 642 ADSL Internet Access Router
3-2 Internet Access
3.3 TCP/IP Parameters
3.3.1 IP Address and Subnet Mask
Similar to the houses on a street that share a common street name, the machines on a LAN share one
common network number, also.
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) and you must enable the Single User Account feature of the Prestige. 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 3 numbers specify the network number while the last number identifies an individual workstation 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 do otherwise.
3.3.2 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 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.
3.3.3 RIP Setup
RIP (Routing Information Protocol) allows a router to exchange routing information with other routers. The
RIP Direction
field controls the sending and receiving of RIP packets. When set to both, the Prestige will