December 2000 20 - 1
Chapter 20
Network Address Translation
You can configure a Foundry Layer 3 Switch to perform standard Network Address Translation (NAT). NAT
enables private IP networks that use nonregistered IP addresses to connect to the Internet. Configure NAT on the
Foundry device at the border of an inside network and an outside network (such as the Internet). NAT translates
the internal local addresses to globally unique IP addresses before sending packets to the outside network. NAT
also allows a more graceful renumbering strategy for organizations that are changing service providers or
voluntarily renumbering into Classless Interdomain Routing (CIDR) blocks.
Use NAT to translate your private (inside) IP addresses into globally unique (outside) IP addresses when
communicating outside of your network.
NOTE: This feature is supported on all chassis Layer 3 Switches with Management II modules or higher and on
the IP-only NetIron Stackable Layer 3 Switch.
NOTE: The maximum number of global IP addresses you can configure depends on how much memory the
Layer 3 Switch has and whether you enable the Port Address Translation feature. Regardless of the amount of
memory, you cannot configure more than 256 global IP addresses.
NOTE: NAT support is available for traffic originated by hosts on the private network. You cannot configure NAT
to translate global addresses into private addresses for traffic generated by global addresses.
A Foundry device configured for NAT must have an interface to the private network and an interface to a public
network (for example, the Internet). In a typical environment, NAT is configured on the Foundry device between
the private network and the Internet. When you configure a Foundry device for NAT, the device does not advertise
the private networks to the Internet. However, the device can advertise route information received from the
Internet to the private networks.
Figure 20.1 shows a basic example of a network using NAT on a Foundry device. In this example, a BigIron 8000
Layer 3 Switch is using NAT to translate traffic originated from the hosts on the 10.10.10.x/24 sub-net into public
addresses from the address pool.
To Next Page
Loading...
Need help?
General
