Netopia R2121 - Manual (Page 105)

IP Setup, SmartIP and Network Address Translation 10-1
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The Netopia R2121 uses Internet Protocol (IP) to communicate both locally and with remote networks. This
chapter shows you how to configure the Router to route IP traffic. You also learn how to configure the Router to
ser ve IP addresses to hosts on your local network.
Netopia’s Smar tIP features IP address ser ving and Network Address Translation. For a detailed discussion of
Network Address Translation, see
Appendix D, “Understanding Netopia NAT Behavior.” This chapter describes
how to use the Network Address Translation feature of Smar tIP.
Note: When you configured your Netopia R2121 using Smar tStar t, Network Address Translation was enabled by
default. You have the option of disabling it, if you wish. This is done through the System Configuration screens
using Console-based Management.
This section covers the following topics:
■ “Network Address Translation features” on page 10-1
■ “Using Network Address Translation” on page 10-3
■ “IP setup” on page 10-6
■ “IP address ser ving” on page 10-16
Network Address Translation allows communication between the LAN connected to the Netopia R2121 and the
Internet using a single IP address, instead of a routed account with separate IP addresses for each computer
on the network.
Network Address Translation also provides increased security by hiding the local IP addresses of the LAN
connected to the Netopia R2121 from the outside world.
With Smar tIP, the setup is simpler, so Internet ser vice providers typically offer dial-up accounts suppor ting
Network Address Translation at a significant cost savings.
Network Address Translation features
■ NAT is selectable on a per connection basis, optionally allowing real addresses to be used for intranet
connections and proxied addresses to be used for Internet connections.
■ The NAT user can use any combination of proxied and unproxied addresses simultaneously on the available
Telco channels. For instance, one unproxied address connection profile can be used to connect to a central
office, while another proxied address connection profile can simultaneously connect the user’s Netopia
R2121 and LAN to the Internet.
■ The single proxy address is acquired at connection time from the answering side. The address can be
assigned by the remote router from either a dynamic pool of addresses or a fixed, static address.
■ Static NAT (Network Address Translation) Security is made simpler and more reliable by only having to
firewall one IP address and by obscuring the internal network structure from the Internet.