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Clicking the Create New Connection button opens the WAN Wizard for further configuration. Figure 5-19 shows the wizard welcome window. Click Next to continue.

Figure 5-19 WAN Wizard

If the ISP uses PPP over Ethernet (PPPoE), click the check box, and then click Next. These options are shown in Figure 5-20.

Figure 5-20 PPPOE Configuration

Click the Dynamic (DHCP Client) radio button and enter the hostname as shown in Figure 5-21.

Figure 5-21 DHCP Configuration

Check the Port Address Translation check box and choose the inside interface in the drop-down list as shown in Figure 5-22.

Figure 5-22 PAT Configuration

When you are finished, the wizard provides a summary of the configuration, as shown in Figure 5-23.

Figure 5-23 Configuration Summary

Figure 5-23 Configuration Summary

Verifying the DHCP Client Configuration

You can use the Interfaces and Connections window in SDM to verify that the DHCP client is obtaining an address from the DHCP server. This is shown in Figure 5-24.

Figure 5-24 Configuration Verification

Figure 5-24 Configuration Verification

NOTE The client IP address might not display in the window immediately, and you might need to refresh the window.

Verifying the NAT and PAT Configuration

You can verify the NAT and PAT configuration with the command show ip nat translation. Its output follows:

RouterX# show ip nat translations

Pro Inside global Inside local Outside local Outside global

Table 5-2 shows the commands that you can use in EXEC mode to display and manage translation information.

Table 5-2 Useful NAT Management Commands



show ip nat translations

Displays active translations

clear ip nat translation *

Clears all dynamic address translation entries from the NAT translation table

After you have configured NAT, verify that it operates as expected. You can do this by using the show and clear commands.

By default, dynamic address translations time out from the NAT and PAT translation tables at some time after a period of nonuse. When port translation is not configured, translation entries time out after 24 hours unless you reconfigure them with the ip nat translation command. You can clear the entries before the timeout by using the clear command listed in the Table 5-2.

Alternatively, you can use the show run command and look for NAT, ACL, interface, or pool commands with the required values.

Summary of Enabling the Internet Connection

This topic summarizes the key points that were discussed in this section.

■ Packet-switched networks send data packets over different routes of a shared public network owned by a carrier to reach the same destination. The route that the packets take to reach the destination site, however, varies.

■ DSL comes in several varieties, including ADSL, SDSL, HDSL, IDSL, and CDSL. DSL has both advantages (speed, always on, and so on) and disadvantages (availability).

■ The global Internet grew from a U.S. Department of Defense plan to build a command-and-control network in the 1960s to its present state as the largest WAN on earth, with multiple ways to access it and multiple communication, research, and commercial uses.

■ An interface can get its IP address from a DHCP server.

■ NAT enables private IP internetworks that use nonregistered IP addresses to connect to the Internet.

■ You can translate your own IP addresses into globally unique IP addresses when you are communicating outside of your network.

■ Overloading is a form of dynamic NAT that maps multiple unregistered IP addresses to a single registered IP address (many-to-one) by using different ports, known also as PAT.

■ After NAT is configured, the clear and show commands can be used to verify that it operates as expected.

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