Page 108 - Handout Computer Network.

possible with the millions of hosts on the Internet. All 254 addresses in the sequence of 192.168.10.1
to 192.168.10.254 can be represented by the network address 192.168.10.0.

This allows data to be sent to any one of these hosts just by locating the network address. This means
that routing tables need to contain only one entry of 192.168.10.0 instead of all 254 individual entries.
This is according to the Internet Software Consortium (www.isc.org). For routing to function, this
process of grouping must be used. The following sections describe the router’s use and operations in
performing the key internetworking function of the Open System Interconnection (OSI) reference
model’s network layer, Layer 3️.
In addition, you’ll learn about the difference between routing and routed protocols and how routers
track distance between locations.
Finally, you’ll learn more about distance-vector, link-state, and hybrid routing approaches and how
each resolves common routing problems.

https://www.youtube.com/watch?v=9JXcU6BSqwU&t=30s

5.3 Routing Overview

Routing is an OSI Layer 3 function. It functions as a hierarchical organizational scheme that
allows individual addresses to be grouped and treated as a single unit until the individual address is
needed for final delivery of the data.
Routing is the process of finding the most efficient path from one device to another, the main device
that performs this process is the router.

A router has two key functions:

• To maintain routing tables and make sure other routers know of changes in the network
topology. This function is performed using a routing protocol to communicate network
information to other routers.
• When packets arrive at an interface, the router must use the routing table to determine where
to send the packets. It switches them to the appropriate interface, adds the necessary framing
for the interface, and then transmits the frame. A router is a network layer device that uses
one or more routing metrics to determine the optimal path along which network traffic should
be forwarded.

The routing metric is a value used to determine the route’s desirability. Routing protocols use
various combinations of criteria for determining the routing metric, as shown in Figure 5-2.

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