1 © 2003, Cisco Systems, Inc. All rights reserved. CCNA 4 v3.0 Module 1 Scaling IP Addresses

222 © 2003, Cisco Systems, Inc. All rights reserved. Objectives Scaling networks with Network Address Translation and Port Address Translation Dynamic Host Configuration Protocol

333 © 2003, Cisco Systems, Inc. All rights reserved. Private Addressing

444 © 2003, Cisco Systems, Inc. All rights reserved. NAT A NAT-enabled device typically operates at the border of a stub network.

555 © 2003, Cisco Systems, Inc. All rights reserved. NAT Terms Inside Local Addresses – An IP address assigned to a host inside a network. This address is likely to be a RFC 1918 private address. Inside Global Address – A legitimate IP address assigned by the NIC or service provider that represents one or more inside local IP address to the outside world. Outside Local Address - The IP address of an outside host as it known to the hosts in the inside network. Outside Global Address - The IP address assigned to a host on the outside network. The owner of the host assigns this address.

666 © 2003, Cisco Systems, Inc. All rights reserved. NAT Features Static NAT is designed to allow one-to-one mapping of local and global addresses. Dynamic NAT is designed to map a private IP address to a public address.

777 © 2003, Cisco Systems, Inc. All rights reserved. PAT Features PAT uses unique source port numbers on the inside global IP address to distinguish between translations.

888 © 2003, Cisco Systems, Inc. All rights reserved. NAT Benefits Eliminates re-assigning each host a new IP address when changing to a new ISP Eliminates the need to re-address all hosts that require external access, saving time and money Conserves addresses through application port-level multiplexing Protects network security

999 © 2003, Cisco Systems, Inc. All rights reserved. Configuring NAT and PAT

10 © 2003, Cisco Systems, Inc. All rights reserved. Configuring NAT

11 © 2003, Cisco Systems, Inc. All rights reserved. Configuring PAT

12 © 2003, Cisco Systems, Inc. All rights reserved. Verifying NAT and PAT Configuration

13 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting NAT and PAT

14 © 2003, Cisco Systems, Inc. All rights reserved. Issues With NAT

15 © 2003, Cisco Systems, Inc. All rights reserved. DHCP DHCP works by providing a process for a server to allocate the IP information to clients. Clients lease the information from the server for an administratively defined period.

16 © 2003, Cisco Systems, Inc. All rights reserved. BOOTP and DHCP Differences DHCP defines mechanisms through which clients can be assigned an IP address for a finite lease period. This lease period allows for re-assignment of the IP address to another client later, or for the client to get another assignment, if the client moves to another subnet. Clients may also renew leases and keep the same IP address. DHCP provides the mechanism for a client to gather other IP configuration parameters, such as WINS and domain name.

17 © 2003, Cisco Systems, Inc. All rights reserved. Major DHCP Features Automatic Allocation Manual Allocation Dynamic Allocation

18 © 2003, Cisco Systems, Inc. All rights reserved. DHCP Operation

19 © 2003, Cisco Systems, Inc. All rights reserved. The Order of DHCP Messages Transmitting

20 © 2003, Cisco Systems, Inc. All rights reserved. Configuring DHCP

21 © 2003, Cisco Systems, Inc. All rights reserved. Configuring DHCP While Excluding IP

22 © 2003, Cisco Systems, Inc. All rights reserved. Verifying DHCP

23 © 2003, Cisco Systems, Inc. All rights reserved. Troubleshooting DHCP

24 © 2003, Cisco Systems, Inc. All rights reserved. DHCP Relay