ZyXEL Communications P-870HW-51a v2 User Manual

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Chapter 6 LAN Setup
P-870HW-51a v2 User’s Guide
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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 
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