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4
ROUTING WITH IP TECHNOLOGY
This chapter gives an overview of IP routing technology, specifically
defining:
What IP routing involves
What elements are necessary for IP routers to effectively transmit packets
How IP routing transmission errors are detected and resolved
Routing with classical IP over ATM
IP Routing and
the OSI Model
An IP router, unlike a bridge, operates at the network layer of the OSI
Reference Model. That is, it routes packets by examining the network layer
address (IP address). Bridges use the data-link layer MAC addresses to make
forwarding decisions. See Figure 4-1.
Figure 4-1 OSI Reference Model and IP Routing
Application Layer
Presentation Layer
Session Layer
Transport Layer
Network Layer
Data-link Layer
Physical Layer
MAC
IP
OSI Reference Model
ARP
RIP
ICMP