User`s guide
Appendix D IP Addresses and Subnetting
User’s Guide
274
Configuring IP Addresses
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. 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. You must also enable Network Address Translation (NAT) on the WiMAX
Modem.
Once you have decided on the network number, pick an IP address for your WiMAX Modem
that is easy to remember (for instance, 192.168.100.1) 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 WiMAX
Modem 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 WiMAX Modem 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 (running only between two branch offices, for example) 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
6 255.255.252.0 (/22) 64 1022
7 255.255.254.0 (/23) 128 510
8 255.255.255.0 (/24) 256 254
9 255.255.255.128 (/25) 512 126
10 255.255.255.192 (/26) 1024 62
11 255.255.255.224 (/27) 2048 30
12 255.255.255.240 (/28) 4096 14
13 255.255.255.248 (/29) 8192 6
14 255.255.255.252 (/30) 16384 2
15 255.255.255.254 (/31) 32768 1
Table 123 16-bit Network Number Subnet Planning (continued)
NO. “BORROWED”
HOST BITS
SUBNET MASK NO. SUBNETS
NO. HOSTS PER
SUBNET