Information Technology Reference
In-Depth Information
Study Guide
Introduction to Distance Vector Routing Protocols
One way to characterize routing protocols is by the type of routing algorithm they use to build and
maintain their routing table. By doing this, routing protocols can be differentiated as a distance vector,
link-state, or path vector routing protocol. In the following sections, you will review the basic con-
cepts of distance vector routing protocols.
Distance Vector Protocols Concepts Exercise
Distance vector routing protocols include RIP, IGRP, and EIGRP. The following are some key charac-
teristics of these protocols. Fill in the blanks to provide the missing words or phrases.
RIP
Routing Information Protocol
(RIP) was originally specified in RFC
1058
. It has the following key
characteristics:
Hop count
is used as the metric for path selection.
■
If the metric for a network is greater than
15
, RIP cannot supply a route to that network.
■
Routing updates are broadcast or multicast every
30
seconds, by default.
■
IGRP
Interior Gateway Routing Protocol
(IGRP) is a proprietary protocol developed by Cisco. IGRP has the
following key design characteristics:
Bandwidth
,
delay
,
load
, and
reliability
are used to create a composite metric.
■
Routing updates are broadcast every
90
seconds, by default.
■
IGRP is the predecessor of
EIGRP
and is now obsolete.
■
EIGRP
Enhanced
IGRP (EIGRP) is a Cisco-proprietary distance vector routing protocol. EIGRP has these
key characteristics:
It can perform
unequal
-cost load balancing.
■
It uses
Diffusing Update Algorithm
(DUAL) to calculate the shortest path.
■
There are no periodic updates as with RIP and IGRP. Routing updates are sent only when there
is a
change
in the topology.
■
Meaning of Distance Vector
Briefly explain what is meant by the term
distance vector
.
Routes are advertised as vectors of distance and direction. Distance is defined in terms of a metric,
and direction is simply the next-hop router or exit interface.
