Page 106 - Handout Computer Network.

CHAPTER 5
ROUTING FUNDAMENTALS AND SUBNETS

5.1 Introduction

This chapter covers topics related to the Internet Protocol (IP). IP is the fundamental protocol
used in the Internet. Topics discussed include how IP is delivered, how the header is modified at Layer
3 devices, and the actual layout of the IP packet. You will learn the difference between routing and
routed protocols and how routers track distance between locations. This chapter introduces the
distance-vector, link-state, and hybrid routing approaches and how each resolve common routing
problems and Subnet address concepts.

https://www.youtube.com/watch?v=aHwAm8GYbn8

5.2 Routed, Routable, and Routing Protocols

A protocol is a standards-based set of rules that determines how computers communicate
with each other across networks. A protocol also serves as the common denominator or medium by
which different applications, hosts, or systems communicate. When computers communicate with
one another, they exchange data messages. To accept and act on these messages, computers must
have definitions of how a message is defined and what it means. Examples of messages include
establishing a connection to a remote machine, sending or receiving e-mail, and transferring files and
data.
A protocol describes:

• The format that a message must take

• The way in which computers must exchange a message within the context of a particular
activity, such as sending messages across networks Because of the similarity of a
routed/routable protocol versus a routing protocol, confusion over these terms often exists.
The following provides some clarification:

• Routed protocol—Any network protocol that provides enough information in its network layer
address to allow a packet to be forwarded from one host to another host based on the
addressing scheme. Routed protocols define the field formats within a packet. Packets are
generally conveyed from end system to end system. A routed protocol uses the routing table
to forward packets.
Examples of routed or routable protocols are shown in the routing table in Figure 5-1.

They include the following:

— Internet Protocol (IP)

124