Switch User Manual

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