Ip Routing And The Osi Model - 3Com LANPLEX 2500 EXTENDEDPLEX®2500 EXTENDED User Manual

4
IP Routing and
the OSI Model
R
OUTING WITH
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
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.
OSI Reference Model
Application Layer
Presentation Layer
Session Layer
Transport Layer
IP
Network Layer
ARP
MAC
Data-link Layer
Physical Layer
Figure 4-1 OSI Reference Model and IP Routing
IP T
ECHNOLOGY
RIP
ICMP