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This chapter is from the book

Foundation Summary

The "Foundation Summary" section of each chapter lists the most important facts from the chapter. Although this section does not list every fact from the chapter that will be on your CCDA exam, a well-prepared CCDA candidate should at a minimum know all the details in each "Foundation Summary" before going to take the exam.

This chapter covered the following topics that you will need to master for the CCDA exam:

  • RIPv1—The first version of RIP

  • RIPv2—The enhancements in Version 2 of RIP to support network designs

  • IGRP—The Cisco proprietary routing protocol IGRP

  • EIGRP—The enhanced version of IGRP and its uses in network design

Some reviews listings and/or tables that appear in this summary were copied directly from within the chapter to emphasize their significance for exam preparation.

Table 12-5 compares the routing protocols covered in this chapter.

Table 12-4 Routing Protocols Comparison

 

Routing Protocol

 

 

 

 

RIPv1

RIPv2

IGRP

EIGRP

Distance Vector

Yes

Yes

Yes

Hybrid

VLSMs

No

Yes

No

Yes

Authentication

No

Yes

No

Yes

Update Timer (sec)

30

30

90

n/a

Invalid Timer (sec)

180

180

270

n/a

Flush Timer (sec)

240

240

630

n/a

Holddown Timer (sec)

180

180

280

n/a

Protocol/port

UDP 520

UDP 520

IP 9

IP 88

Admin Distance

120

120

100

90


RIPv1 Summary

The characteristics of RIPv1 follow:

  • Distance-vector protocol.

  • Uses UDP port 520.

  • Classful protocol (no support for VLSMs or CIDR).

  • Metric is router hop count.

  • Maximum hop count is 15; unreachable routes have a metric of 16.

  • Periodic route updates broadcast (255.255.255.255) every 30 seconds.

  • 25 routes per RIP message.

  • Implements split horizon with poison reverse.

  • Implements triggered updates.

  • No support for authentication.

  • Administrative distance for RIP is 120.

  • Used in small, flat networks or at the edge of larger networks.

RIPv2 Summary

The characteristics of RIPv2 follow:

  • Distance-vector protocol.

  • Uses UDP port 520.

  • Classless protocol (support for CIDR).

  • Supports VLSMs.

  • Metric is router hop count.

  • Maximum hop count is 15; infinite (unreachable) routes have a metric of 16.

  • Periodic route updates sent every 30 seconds to multicast address 224.0.0.9.

  • 25 routes per RIP message (24 if authentication is used).

  • Supports authentication.

  • Implements split horizon with poison reverse.

  • Implements triggered updates.

  • Subnet mask included in route entry.

  • Administrative distance for RIPv2 is 120.

  • Used in small, flat networks or at the edge of larger networks.

IGRP Summary

The characteristics of IGRP follow:

  • Distance-vector protocol.

  • Uses IP protocol 9.

  • Classful protocol (no support for CIDR).

  • No support for VLSMs.

  • Composite metric of bandwidth and delay.

  • You can factor load and reliability into the metric.

  • Route updates broadcast every 90 seconds.

  • 104 routes per IGRP message.

  • No support for authentication.

  • Implements split horizon with poison reverse.

  • Implements triggered updates.

  • By default, equal-cost load balancing. Unequal-cost load balancing with the variance command.

  • Administrative distance is 100.

  • Previously used in large networks; now replaced by EIGRP.

EIGRP Summary

The characteristics of EIGRP follow:

  • Hybrid routing protocol (distance vector that has link-state protocol characteristics).

  • Uses IP protocol 88.

  • Classless protocol (supports VLSMs).

  • Default composite metric of bandwidth and delay.

  • You can factor load and reliability into the metric.

  • Sends route updates to multicast address 224.0.0.10.

  • Sends partial route updates only when there are changes.

  • Support for authentication.

  • Uses DUAL for loop prevention.

  • By default, equal-cost load balancing. Unequal-cost load balancing with the variance command.

  • Administrative distance is 90 for EIGRP internal routes, 170 for EIGRP external routes, and 5 for EIGRP summary routes.

  • Potential routing protocol for the core of a network; used in large networks.

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