IP Network Address Translation (NAT)

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Presentation Description

Brief overview of IPv4 network address translation using various translation techniques is provided. Static NAT, dynamic NAT, and Overloading NAT explained. Configuration example provided using Cisco IOS.

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Cisco™ CCNA : NAT Copyright © 2000 - 2017 SimulationExams.com Version 3.0 CCNA Network Simulator CCNA Exam Simulator CCENT Exam Simulator CCNA ICND2 Exam Simulator CCNP Route Exam Simulator Disclaimer: Simulationexams.com is NOT associated or affiliated with Cisco Systems ® . All Simulation Exams practice tests exam cram notes and/or material are neither sponsored by nor endorsed by Cisco ® Systems. CCNA ® CCENT ® ICND2 ® are registered trade marks of Cisco ® Systems and duly acknowledged. Overloading A special case of dynamic NAT that maps multiple unregistered IP addresses to a single registered globally unique IP address by using different port numbers. Dynamic NAT with overloading is also known also as PAT Port Address Translation. Static NAT Maps an unregistered IP address to registered IP globally unique addresses on one-to-one basis. The command ip nat inside source static local ip global ip configures address translation for static NAT. Configuring NAT When configuring NAT NAT should be enabled on at least one inside and one outside interface. 1. The command for enabling NAT on inside interface is: R1config-ifip nat inside 2. The command for enabling NAT on the outside interface is: R1config-ifip nat outside Remember to enter into appropriate configuration modes before entering the commands. Usually the inside NAT will be configured on an Ethernet interface whereas the outside NAT is configured on a serial interface. Address Classification Inside Local : An actual address assigned to an inside host Inside Global : An inside address seen from the outside Outside Global : An actual address assigned to an outside host Outside Local : An outside address seen from the inside NAT Pool : A pool of IP addresses to be used as inside global or outside local addresses in translations Defining an IP NAT Pool 1. Defining an IP NAT pool for the inside network using the command: ip nat pool pool-name start-ip end-ip netmask net-mask | prefix-length prefix-length type- rotary Ex: ip nat pool pool1 200.200.200.3 200.200.200.4 netmask 255.255.255.0 Note that type-rotary is optional command. It indicates that the IP address range in the address pool identifies hosts among which TCP load is distributed. 2. Mapping the access-list to the IP NAT pool by using the command: ip nat inside source list access-list-number pool pool-name Ex: ip nat inside source list 1 pool pool1 Dynamic NAT Maps an unregistered IP address to a registered globally unique IP address from a group of registered globally unique IP addresses. The command ip nat inside source list access-list-number pool name is used to map the access-list to the IP NAT pool during the configuration of Dynamic NAT. Overlapping This occurs when your internal IP addresses belong to global IP address range that belong to another network. SimulationExams.com

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