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NAT PAT Configuration Packet Tracer

Today i will discuss how to configure NAT PAT Configuration Packet Tracer simulator. Network address translation (NAT) is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device. [boxads]

There are two different types of NAT:

• NAT
  • Static NAT: The simplest type of NAT provides a one-to-one translation of IP addresses. It is often also referred to as one-to-one NAT. In this type of NAT only the IP addresses, IP header checksum and any higher level checksums that include the IP address need to be changed. The rest of the packet can be left untouched (at least for basic TCP/UDP functionality, some higher level protocols may need further translation). Basic NATs can be used when there is a requirement to interconnect two IP networks with incompatible addressing. With static NAT, translations exist in the NAT translation table as soon as you configure static NAT command(s), and they remain in the translation table until you delete the static NAT command(s).
  • Dynamic NAT: Dynamic NAT has some similarities and differences compared to static NAT. Like static NAT, the NAT router creates a one-to-one mapping between an inside local and inside global address and changes the IP addresses in packets as they exit and enter the inside network. However, the mapping of an inside local address to an inside global address happens dynamically. Dynamic NAT sets up a pool of possible inside global addresses and defines matching criteria to determine which inside local IP addresses should be translated with NAT. The dynamic entry stays in the table as long as traffic flows occasionally. With dynamic NAT, translations do not exist in the NAT table until the router receives traffic that requires translation. Dynamic translations have a timeout period after which they are purged from the translation table.
• PAT
  • Static PAT: Static PAT translations allow a specific UDP or TCP port on a global address to be translated to a specific port on a local address. Static PAT is the same as static NAT, except that it enables you to specify the protocol (TCP or UDP) and port for the real and mapped addresses. Static PAT enables you to identify the same mapped address across many different static statements, provided that the port is different for each statement. You cannot use the same mapped address for multiple static NAT statements. With static PAT, translations exist in the NAT translation table as soon as you configure static PAT command(s), and they remain in the translation table until you delete the static PAT command(s).
  • NAT Overload or PAT: It is common to hide an entire IP address space, usually consisting of private IP addresses, behind a single IP address (or in some cases a small group of IP addresses) in another (usually public) address space. This type of NAT is called PAT in overload. The dynamic entry stays in the table as long as traffic flows occasionally. With PAT in overload, translations do not exist in the NAT table until the router receives traffic that requires translation. Translations have a timeout period after which they are purged from the translation table.

NAT PAT Configuration Packet Tracer Example #1: Static Source NAT

• How to translate the 172.16.0.5 IP address to the 10.16.0.5 ip address.

Define the ip nat inside:
Router(config)#interface fa0/0
Router(config-if)#ip nat inside

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