Enterasys Networks X-PeditionTM manual Inside Outside, Static NAT within Interface

Configuring NAT Examples

	Figure 5-15 Static NAT within Interface
Inside	Outside

		Request						After Translation
		SA: 10.1.1.1						DA: 164.17.2.1
		DA: 172.20.2.1						SA: 201.2.2.1
	10.1.1.1
		Internal				External
		interface				interface
				XSR
								F2
							After Translation
10.1.1.2							DA: 172.20.2.1
								SA: 201.2.2.1
				NAT Table
			Inside local		Inside global
	Request		IP Address		IP Address
SA: 10.1.1.2			10.1.1.1			203.2.2.1
DA: 164.17.2.1			10.1.1.2			201.2.2.1

164.17.2.2

Internet

Reply DA: 203.2.2.1 SA: 172.20.2.1 172.20.2.1

As shown in Figure 5-15, packets from the PC at 10.1.1.1 are statically NATted to the PC at

203.2.2.1but through neither of the pools. This occurs because static NAT takes precedence over other NAT forms. Also, this static NAT would be used only when packets from PC 10.1.1.1 exit the F2 interface. On any other interface the translation would not occur, unless the same mapping is configured. Static NAT within an interface procedes as follows:

1.The user at 10.1.1.1 opens a connection to host 172.20.2.1.

2.When the XSR receives the first packet from 10.1.1.1, the static NAT table for the interface is checked and a mapping found. That mapping is used to translate the source IP address to 203.2.2.1.

3.The packet goes out as being transmitted from 203.2.2.1 to destination 172.20.2.1.

4.When a reply packet is received by the XSR, static mappings are again checked resulting in the translation of the destination IP address from 203.2.2.1 to 10.1.1.1.

Enter the following commands to configure static NAT at interface F2:

XSR(config)#access-list 101 permit ip any 172.20.0.0 0.0.255.255

+Configures the ACL for the destination on the 172.20.0.0 network

XSR(config)#access-list 102 permit ip any 164.17.0.0 0.0.255.255

+Configures the ACL for the destination on the 164.17.0.0 network

XSR(config)#ip local pool NatPool 200.2.2.0/24

XSR(ip-local-pool)#exit

XSR(config)#ip local pool NatPool1 201.2.2.0/24

XSR(ip-local-pool)#exit

+Create two IP local pools with the specified inside global IP addresses

XSR(config)#ip nat pool NatPool

XSR(config)#ip nat pool NatPool1

+Assigns the above pools to NAT

XSR(config)#interface F2

XSR(config-if<F2>)#ip nat source list 101 pool NatPool

XSR(config-if<F2>)#ip nat source list 102 pool NatPool1

XSR User’s Guide 5-43