3Com 2500 manual Routing with IP Technology, IP Routing, OSI Model

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	An IP router, unlike a bridge, operates at the network layer of the OSI
the OSI Model	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
Network Layer	IP
	ARP
Data-link Layer	MAC
Physical Layer

RIP

ICMP

Figure 4-1 OSI Reference Model and IP Routing