packet, the router fills in the GIADDR field of the packet with the IP address of the router for that segment. This address will then be the gateway address for the DHCP client, when it gets the IP address. The DHCP server receives the discover packet. The server uses the GIADDR field to index into the list of address pools, to find one which has the gateway address set to the value in GIADDR. This pool is then used to supply the client with its IP address. Lab Activity Lab Exercise: Configuring DHCP Relay In this lab, a router will be configured for Dynamic Host Configuration Protocol (DHCP). Lab Activity e-Lab Activity: Configuring DHCP Relay In this lab, the student will configure a router for DHCP, add the ability for workstations to remotely obtain DHCP addresses and dynamically assign addresses to the attached hosts. Web Links Configuring DHCP Relay, DHCP Server, and PAT http://www.cisco.com/univercd/cc/td/ doc/product/ ccess/acs_fix/750/ cfgguide/700cgdhc.htm

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Content Summary An understanding of the following key points should have been achieved:

• Private addresses are for private, internal use and should never be routed by a public Internet router.
• NAT alters the IP header of a packet so that the destination address, the source address, or both addresses are replaced with different addresses.
• PAT uses unique source port numbers on the inside global IP address to distinguish between translations.
• NAT translations can occur dynamically or statically and can be used for a variety of uses.
• NAT and PAT may be configured for static translation, dynamic translation, and overloading.
• The process for verifying NAT and PAT configuration include the clear and show commands.
• The debug ip nat command is used for troubleshooting NAT and PAT configuration.
• NAT has advantages and disadvantages.
• DHCP works in a client/server mode, enabling clients to obtain IP configurations from a DHCP server.
• BOOTP is the predecessor of DHCP and shares some operational characteristics with DHCP, but BOOTP is not dynamic.
• A DHCP server manages pools of IP addresses and associated parameters. Each pool is dedicated to an individual logical IP subnet.
• The DHCP client configuration process has four steps.
• Usually, a DCHP server is configured to assign more than IP addresses.
• The show ip dhcp binding command is used to verify DHCP operation.
• The debug ip dhcp server events command is used for troubleshooting DHCP.
• When a DHCP server and a client are not on the same segment and are separated by a router, the ip helper-address command is used to relay broadcast requests.