31 Days Before Your CCNA Exam

Day 5 301Configuring Static NATStatic NAT is a one-to-one mapping between an inside address and an outside address. Static NATallows connections initiated by external devices to inside devices. For instance, you might want tomap an inside global address to a specific inside local address that is assigned to your web server.The steps and syntax to configure static NAT are as follows:Step 1Configure the static translation of an inside local address to an inside global address:Router(config)#ip nat inside source static local-ip global-ipStep 2Specify the inside interface:Router(config)#interface type numberRouter(config-if)#ip nat insideStep 3Specify the outside interface:Router(config)#interface type numberRouter(config-if)#ip nat outsideFigure 5-4 shows a sample static NAT topology.Figure 5-4Static NAT TopologyInside NetworkS0/0/010.1.1.2R2S0/1/0209.165.200.225InternetServer192.168.10.254209.165.201.30Example 5-1 shows the static NAT configuration.Example 5-1Static NAT ConfigurationR2(config)#ip nat inside source static 192.168.10.254 209.165.200.254R2(config)#interface serial0/0/0R2(config-if)#ip nat insideR2(config-if)#interface serial 0/1/0R2(config-if)#ip nat outsideThis configuration statically maps the inside IP address of 192.168.10.254 to the outside addressof 209.165.10.254. This allows outside hosts to access the internal web server using the public IPaddress 209.165.10.254.Configuring Dynamic NATDynamic NAT maps private IP addresses to public addresses drawn from a NAT pool. The stepsand syntax to configure dynamic NAT are as follows: