ZyXEL Communications VMG1312-B Series User Manual page 326

Appendix B IP Addresses and Subnetting
Configuring IP Addresses
Where you obt ain your net work num ber depends on your part icular sit uat ion. I f t he I SP or your
net work adm inist rat or assigns you a block of regist ered I P addresses, follow t heir inst ruct ions in
select ing t he I P addresses and t he subnet m ask.
I f t he I SP did not explicit ly give you an I P net work num ber, t hen m ost likely you have a single user
account and t he I SP will assign you a dynam ic I P address when t he connect ion is est ablished. I f t his
is t he case, it is recom m ended t hat you select a net work num ber from 192.168.0.0 t o
192.168.255.0. The I nt ernet Assigned Num ber Aut horit y ( I ANA) reserved t his block of addresses
specifically for privat e use; please do not use any ot her num ber unless you are t old ot herwise. You
m ust also enable Net work Address Translat ion ( NAT) on t he Device.
Once you have decided on t he net work num ber, pick an I P address for your Device t hat is easy t o
rem em ber ( for inst ance, 192.168.1.1) but m ake sure t hat no ot her device on your net work is using
t hat I P address.
The subnet m ask specifies t he net work num ber port ion of an I P address. Your Device will com put e
t he subnet m ask aut om at ically based on t he I P address t hat you ent ered. You don't need t o change
t he subnet m ask com put ed by t he Device unless you are inst ruct ed t o do ot herwise.
Private IP Addresses
Every m achine on t he I nt ernet m ust have a unique address. I f your net works are isolat ed from t he
I nt ernet ( running only bet ween t wo branch offices, for exam ple) you can assign any I P addresses t o
t he host s wit hout problem s. However, t he I nt ernet Assigned Num bers Aut horit y ( I ANA) has
reserved t he following t hree blocks of I P addresses specifically for privat e net works:
• 10.0.0.0
• 172.16.0.0
• 192.168.0.0 — 192.168.255.255
You can obt ain your I P address from t he I ANA, from an I SP , or it can be assigned from a privat e
net work. I f you belong t o a sm all organizat ion and your I nt ernet access is t hrough an I SP , t he I SP
can provide you wit h t he I nt ernet addresses for your local net works. On t he ot her hand, if you are
part of a m uch larger organizat ion, you should consult your net work adm inist rat or for t he
appropriat e I P addresses.
Regardless of your part icular sit uat ion, do not creat e an arbit rary I P address; always follow t he
guidelines above. For m ore inform at ion on address assignm ent , please refer t o RFC 1597, Address
Allocat ion for Privat e I nt ernet s and RFC 1466, Guidelines for Managem ent of I P Address Space.
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— 10.255.255.255
— 172.31.255.255
VMG1312-B Series User's Guide