Cisco Catalyst 6500 Series User Manual

9-3
Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide
OL-6392-01
Chapter 9 Configuring Network Address Translation
NAT Overview
Figure 9-1 shows a typical NAT scenario, with a private network on the inside. When the inside host
sends a packet to a web server, the local source address of the packet is changed to a routable global
address. When the server responds, it sends the response to the global address, and the FWSM receives
the packet. The FWSM then translates the global address to the local address before sending it on to
the host.
Figure 9-1 NAT Example
See the following commands for this example:
FWSM/contexta(config)# nat (inside) 1 10.1.2.0 255.255.255.0
FWSM/contexta(config)# global (outside) 1 209.165.201.1-209.165.201.15
NAT Types
You can implement address translation as dynamic NAT, Port Address Translation (PAT), static NAT, or
static PAT or as a mix of these types. You can also bypass NAT. See the following sections for
information about each type:
• Dynamic NAT, page 9-3
• PAT, page 9-4
• Static NAT, page 9-5
• Static PAT, page 9-5
• Bypassing NAT, page 9-7
Dynamic NAT
Dynamic NAT translates a group of local addresses to a pool of global addresses that are routable on the
destination network. The global pool can include fewer addresses than the local group. When a local host
accesses the destination network, the FWSM assigns it an IP address from the global pool. Because the
Web Server
www.cisco.com
FWSM
Outside
Inside
209.165.201.2
10.1.2.1
10.1.2.27
104669
Source Addr Translation
209.165.201.1010.1.2.27
Originating
Packet
Dest Addr Translation
209.165.201.10 10.1.2.27
Responding
Packet

Cisco Catalyst 6500 Series Specifications

General

Brand	Cisco
Model	Catalyst 6500 Series
Category	Switch
Language	English