Telematics Chapter 6: Network Layer - Freie Universität Berlin

Network Address Translation (NAT)
● Problem: IP addresses are scarce,
thus not every node gets an public
IP address
● Approach: Special IP addresses
that must no be used in the global
public Internet, but can be used in
an Intranet
● Each internal computer in the
Intranet needs an own IP address
to communicate with the others.
● For this purpose, “private” address
blocks are reserved
● 10.0.0.0 – 10.255.255.255
● 172.16.0.0 – 172.31.255.255
● 192.168.0.0 – 192.168.255.255
● When using addresses of those
ranges,
the internal computers can
communicate with each other
Internet
Public Internet with
global IP addresses
Univ.-Prof. Dr.-Ing. Jochen H. Schiller ▪ cst.mi.fu-berlin.de ▪ Telematics ▪ Chapter 6: Network Layer
• Device with global public IP
address and private IP address
• Translates private to public
addresses
• Intranet with private IP
addresses
• Each node in the
Intranet has a unique
IP address
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