NTP Overview

Lab 32: Configuring Static NAT and DLSw ”Part I

Practical Scenario

As automation increases through the network, many users have IP addresses of applications defined in specific user setups. When IP addresses change, it can cause a great deal of labor changing individual scripts and host files on many workstations. In cases such as this, a static mapping of NAT addresses is desirable, to avoid using a different translation address every time the service is required. Static mapping also allows outside networks to make session initiations to the inside network. Keep in mind that this works only if the application does not transport the IP addresses in the data stream.

Lab Exercise

Harms Co., a leading consulting and guide company in northern Wisconsin, is going through an IP address migration. To avoid having to change all the addresses and host tables at once, Harms Co. will use NAT to assist in the migration. The subnet 190.10.1.0/24 previously resided on the Ethernet segment of the green_bay router. Many hosts (not depicted in Figure 15-7 for this lab) have static entries to the hosts on the 190.10.1.0/24 subnet. The new subnet 210.168.1.0/24 will be placed on the Ethernet segment of the green_bay router. NAT will be required to preserve the current host tables of the workstations that reside on the Ethernet segment of the harms_co router. Based on this scenario, the configuration exercises for this lab are as follows :

Figure 15-7. The Harms Co. Network ”Static NAT with DLSw

• Configure the network as depicted in Figure 15-7. Configure the network with EIGRP as the routing protocol. Use an autonomous System ID of 7.

• Configure green_bay so that the router does not circulate the new subnet of 210.168.1.0/24 in EIGRP.

• Configure static translations as follows:

  - 210.168.1.254 translates to 190.10.1.1

  - 210.168.1.250 translates to 190.10.1.2

• Optional: Configure a DLSw peer between the harms_co router and the green_bay router. Use 198.100.1.10 as the local peer on harms_co, and use 210.168.1.254 as the local peer on the green_bay router.

Lab Objectives

• Configure the network as depicted in Figure 15-7. Use EIGRP as the routing protocol, and do not propagate the 210.168.1.0/24 subnet in EIGRP.

• Configure NAT static translations as follows:

  - 210.168.1.254 translates to 190.10.1.1

  - 210.168.1.250 translates to 190.10.1.2

Equipment Needed

• Three Cisco routers. Two routers should be connected through V.35 back-to-back cables or in a similar manner. The third router will connect to another router by an Ethernet segment. Cisco IOS Software Release 11.2 or later is also required.

• Two LAN segments, provided through hubs or switches.

• Two IP workstations will aid in the testing of the NAT configuration.

Physical Layout and Prestaging

• Connect the hubs and serial cables to the routers, as shown in Figure 15-7.

• Connect the two Ethernet hubs to the routers to form two LAN segments, as shown in Figure 15-7.

• Connect and configure two IP-based workstations, as shown in Figure 15-7. This is optional, but it will aid in testing the NAT configuration.