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DTUS065 rev A.7 – June 27, 2014
V.1.1.2
IP Networks
IP is the part of the TCP/IP stack that manages computer addresses and
routing. Each network interface is seen by the IP as a separate LAN. Each
LAN must have an IP address, something like “192.168.1.2”, to enable it to
be used by IP. Within one computer, the IP protocol makes use of “IP
network interfaces” to access the various LANs. An IP interface is thus the
piece of software that drives one network hardware interface.
The set of all the LANs that can communicate together by means of routers
is an “internetwork”; the Internet itself is an example of such concept.
Routers themselves are nothing more than a computer equipped with several
network connections and used specifically to route packets.
Here is the path followed by a data packet routed through 2 routers. The
source and destination IP address never changes during the transit, contrary
to the MAC addresses which change at each routing point.
Computer 1
Application
IP routing
IP interface
Data flow for routed packets
Transport
layer
Computer 2
Application
IP routing
IP interface
Transport
layer
Router 1
IP routing
IP i/f
IP i/f
Router 2
IP routing
IP i/f
IP i/f
Configuration and monitoring tools
IP routing
IP interface
e.g.
Ethernet1
IP interface
e.g.
Wi-Fi client
IP interface
e.g.software bridge
Network
interface
e.g.
Ethernet2
Network
interface
e.g.Wi-Fi
access point
Network
interface
e.g.
Ethernet3
IP address 3
IP address 1
IP address 2
IP stack with network interface and software bridge