CCNAV3.3 303

8/6/2019 CCNAV3.3 303

1/63

1

CCNA Semester 3

Chapter 03Chap

ter 03

EIGRPEIGRP

8/6/2019 CCNAV3.3 303

2/63

2

ObjectivesObjectives

Describe the differences between EIGRP andIGRP

Describe the key concepts, technologies, anddata structures of EIGRP

Understand EIGRP convergence and the basicoperation of the Diffusing Update Algorithm(DUAL)

Perform a basic EIGRP configuration Configure EIGRP route summarization

Describe the processes used by EIGRP to buildand maintain routing tables

Verify EIGRP operations

8/6/2019 CCNAV3.3 303

3/63

3

ObjectivesObjectives

Describe the eight-step process for generaltroubleshooting

Apply a logical process to routingtroubleshooting

Troubleshoot a RIP routing process using showand debug commands

Troubleshoot an IGRP routing process using

show and debug commandsTroubleshoot an EIGRP routing process using

show and debug commands

Troubleshoot an OSPF routing process usingshow and debug commands

8/6/2019 CCNAV3.3 303

4/63

4

Table of ContentTable of Content

1 EIGRP Concepts2 EIGRP Configuration

3 Troubleshooting Routing Protocols

8/6/2019 CCNAV3.3 303

5/63

5

EIGRP CONCEPTSEIGRP CONCEPTS

8/6/2019 CCNAV3.3 303

6/63

6

EIGRP OverviewEIGRP Overview

Cisco released EIGRP in 1994 as a scalable,improved version of its proprietary distancevector routing protocol, IGRP.

Unlike IGRP, which is a classful routing protocol,EIGRP supports CIDR and VLSM.

Hybrid routing protocol

Fast convergence times

Multiple network-layer protocols supported

Reduced bandwidth usage

Easy to configure

8/6/2019 CCNAV3.3 303

7/637

EIGRP and IGRP compatibilityEIGRP and IGRP compatibility

Default: k1 = 1, k2 = 0, k3 = 1, k4 = 0, k5 = 0.

Metric = Bandwidth + Delay

EIGRP scales IGRP's metric by a factor of256.Because EIGRP uses a metric that is 32 bits long(IGRP 24-bit):

Bandwidth for IGRP = (10.000.000 / bandwidth)

Bandwidth for EIGRP = (10.000.000 / bandwidth)*256 Delay for IGRP = (delay/10)

Delay for EIGRP = (delay/10) * 256

k1xBW +k2xBW

256 Load+ k3xDelayMetric =

8/6/2019 CCNAV3.3 303

8/638

EIGRP and IGRP compatibilityEIGRP and IGRP compatibility

192.168.1.0/24

RTC

EIGRP 2446IGRP 2446

172.16.1.0/24

10.1.1.0/24

EIGRP and IGRP automatically redistributeroutes between autonomous systems withsame autonomous system (AS) number.

IGRP has a maximum hop count of 255.

EIGRP has a maximum hop count limit of224.

RTD

RTA

RTB

8/6/2019 CCNAV3.3 303

9/639

Neighbor TableAppleTalkDestination Next Hop

Router

Neighbor TableIPXDestination Next Hop

Router

Neighbor TableIPNext-Hop InterfaceRouter

EIGRP concepts and terminology

8/6/2019 CCNAV3.3 303

10/631


Router


Router


Topology TableAppleTalkDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost

Topology TableIPXDestination 1 Next Router 1/CostDestination 1 Next Router 1/Cost

Topology TableIPDestination 1


8/6/2019 CCNAV3.3 303

11/631



Topology TableIPDestination 1

Routing TableAppleTalkDestination 1 Next Router XDestination 1 Next Router X

Routing TableIPXDestination 1 Next Router XDestination 1 Next Router X

Routing TableIPDestination 1


Router


Router



8/6/2019 CCNAV3.3 303

12/631



Topology TableIPDestination 1 Successor



Routing TableIPDestination 1 Successor


Router


Router



8/6/2019 CCNAV3.3 303

13/631



Topology TableIPDestination 1 SuccessorDestination 1 Feasible Successor



Routing TableIPDestination 1 Successor


Router


Router


EIGRP concepts and terminologyEIGRP concepts and terminology

8/6/2019 CCNAV3.3 303

14/631

Network Z

EIGRP Successors and Feasible successor

RTA

RTB

I have a routeto Z, with ametric of 5

RTB is successor to NetZ

8/6/2019 CCNAV3.3 303

15/631

Network Z


RTA

RTB

RTC

I have aroute to Z,

with a metricof 5


RTB is successor to NetZRTB is successor to NetZ

8/6/2019 CCNAV3.3 303

16/631

Network Z


RTA

RTX

RTB

RTC

RTY

I have aroute to Z,

with a metricof 5



RTB is successor to NetZRTB is successor to NetZRTX is feasiblesuccessor to Net Z

8/6/2019 CCNAV3.3 303

17/631

EIGRP designEIGRP design

EIGRP's advantages over simple distance-vector protocols :

Rapid convergence (because of useDiffusing Update Algorithm - DUAL)

Efficient use of bandwidth

Partial, bounded (incremental) updates

Minimal consumption of bandwidth when

the network is stable with small hellopackets

Support for VLSM and CIDR

Multiple network-layer support and

Independence from routed protocols

8/6/2019 CCNAV3.3 303

18/631

EIGRP technologiesEIGRP technologies

Many new technologies are improvement inoperating efficiency, speed of convergence,or functionality relative to others routing

protocols.

Four categories:

Neighbor discovery and recovery

Reliable Transport Protocol (RTP)

DUAL finite-state machine algorithm

Protocol-dependent modules (PDM)

8/6/2019 CCNAV3.3 303

19/631

Neighbor discovery and recoveryNeighbor discovery and recovery

EIGRP routers establish adjacencies with neighborrouters by using small hello packets

On IP networks, EIGRP routers send hellos to themulticast IP address 224.0.0.10

RTA#show ip eigrp neighbors

IP-EIGRP neighbors for process 400

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 172.68.2.2 To0 13 02:15:30 8 200 0 9

0 172.68.16.2 Se1 10 02:38:29 29 200 0 6

13 02:15:30

10 02:38:29

Bandwidth Example link Default hellointerval

Default hold times

T1 or less Multipoint framerelay, ISDN

60 seconds 180 seconds

Greater than T1 Ethernet, T1 5 seconds 15 seconds

8/6/2019 CCNAV3.3 303

20/632

Neighbor discovery and recoveryNeighbor discovery and recovery

By forming adjacencies, EIGRP routers do:

Dynamically learn of new routes that jointheir network

Identify routers that become eitherunreachable or inoperable

Rediscover routers that had previouslybeen unreachable

8/6/2019 CCNAV3.3 303

21/63

2

I am router A, who is on the link?Hello

A B

1

Initial Route DiscoveryInitial Route Discovery

Here is my complete routing information. Update2

Thanks for theinformation!

Ack3Topology

Table

4

Here is my complete route information.Update5

Converged

Thanks for the information! 6

8/6/2019 CCNAV3.3 303

22/63

2

Reliable Transport Protocol (RTP)Reliable Transport Protocol (RTP)

EIGRP uses RTP as its own proprietary transport-layer protocol, that can guarantee ordereddelivery of routing information to all neighbors.

EIGRP can call on RTP to provide reliable orunreliable service as the situation warrants.

Reliable delivery of other routing information canactually speed convergence, because EIGRP

routers are not waiting for a timer to expirebefore they retransmit.

With RTP, EIGRP can multicast and unicast todifferent peers simultaneously, which allows for

maximum efficiency.

8/6/2019 CCNAV3.3 303

23/63

2

Reliable Transport Protocol (RTP)Reliable Transport Protocol (RTP)

EIGRP reliable packets are packets thatrequires explicit acknowledgement:

Update: Send routing updates

Query: Ask neighbors about routinginformation

Reply: Response to query about routinginformation

EIGRP unreliable packets are packets that donot require explicit acknowledgement:

Hello: Establish neighbor relationships

ACK: Acknowledgement of a reliable packet

8/6/2019 CCNAV3.3 303

24/63

2

Diffusing Update Algorithm (DUAL) is EIGRP'sroute-calculation engine.

Finite-state machine

Tracks all routes advertised by neighbors

Select loop-free path using a successor andremember any feasible successors

If successor lost, use feasible successor

If no feasible successor, query neighborsand recomputed new successor

DUAL finite-state machine algorithmDUAL finite-state machine algorithm

8/6/2019 CCNAV3.3 303

25/63

2

DUAL DUAL Discovery routeDiscovery route

A B

CRouter B information

Neighbor TableIP

Router C information

Router B information

Topology TableIP

Router C information

Successor (primaryroute)

Feasible successor

Routing TableIP

Successor (primary route)

DUAL?

8/6/2019 CCNAV3.3 303

26/63

2

EIGRP Successor

8/6/2019 CCNAV3.3 303

27/63

2

EIGRP Feasible Successor

8/6/2019 CCNAV3.3 303

28/63

2

Feasible Successor Route

8/6/2019 CCNAV3.3 303

29/63

2

No EIGRP Feasible Successor

8/6/2019 CCNAV3.3 303

30/63

3

DUAL Example (Start)

8/6/2019 CCNAV3.3 303

31/63

3

DUAL Example: Link Goes Down

8/6/2019 CCNAV3.3 303

32/63

3

DUAL Example: D Sends Queries

8/6/2019 CCNAV3.3 303

33/63

3

DUAL Example: E Sends Queries

8/6/2019 CCNAV3.3 303

34/63

3

DUAL Example: C Replies

8/6/2019 CCNAV3.3 303

35/63

3

DUAL Example: E Replies

8/6/2019 CCNAV3.3 303

36/63

3

DUAL Example: Convergence

8/6/2019 CCNAV3.3 303

37/63

3

Protocol-dependent modules (PDM)Protocol-dependent modules (PDM)

Support for routed protocols, such as IP, IPX, andAppleTalk, is included in EIGRP through PDMs.

Easily adapt to new or revised routed protocols, suchas IPv6, by adding protocol-dependent modules.

Each PDM is responsible for all functions related to its

specific routed protocol. The IP-EIGRP module isresponsible for the following:

Sending and receiving EIGRP packets that bear IPdata

Notifying DUAL of new IP routing information that isreceived

Maintaining the results of DUAL routing decisions inthe IP routing table

Redistributing routing information that was learnedby other IP-capable routing protocols

Router

8/6/2019 CCNAV3.3 303

38/63

3

XX

RepliesReplies

Router

A

Router

B

Router

CRouter

D

QueriesQueries

XX

XX

XX

XX

s In some cases, it can take too long for the query to be answered.

s When this happens, the router that issued the query gives up and resets its

neighbor relationship with the router that didnt answer.

s The most basic situation where this occurs is when it simply takes too long

for a query to reach the other end of the network and a reply to travel back.

Stuck in Active (SIA)Stuck in Active (SIA)

8/6/2019 CCNAV3.3 303

39/63

3

Typically, SIAs results when a router cannotanswer a query because:

the router is too busy to answer the query(generally high cpu utilization)

the router cannot allocate the memory to processthe query or build the reply packet

the circuit between the two routers is not good

(packet loss) unidirectional links (a link on which traffic can

only flow in one direction due to a failure)

Stuck in Active (SIA)Stuck in Active (SIA)

8/6/2019 CCNAV3.3 303

40/63

4

CONFIGURING EIGRPCONFIGURING EIGRP

8/6/2019 CCNAV3.3 303

41/63

4

For IP networksFor IP networks

1.router(config)# router eigrpautonomous-system-number

AS much match all router inside AS

1.router(config-router)# networknetwork-number

Network number only for connected network

1.router(config-if)# bandwidthkilobits

Serial interface link use (if not Router take default)

router(config-if)# eigrp log-neighbor-changes

Enables the logging of neighbor adjacency changes

8/6/2019 CCNAV3.3 303

42/63

4

For IP networksFor IP networks

8/6/2019 CCNAV3.3 303

43/63

4

EIGRP summarization EIGRP summarization AutomaticAutomatic

8/6/2019 CCNAV3.3 303

44/63

4

Manual summarization

Configurable on a per-interface basis in anyrouter within network

When summarization is configured on aninterface, the router immediate creates a routepointing to null zero

Loop prevention mechanism

When the last specific route of the summarygoes away, the summary is deleted

The minimum metric of the specific routes is

used as the metric of the summary route

EIGRP SummarizationEIGRP SummarizationManualManual

8/6/2019 CCNAV3.3 303

45/63

4

(config-router)#

no auto-summary

Turns off autosummarization for theEIGRP process

(config-if)#

ip summary-address eigrp

Creates a summary address to be generated

by this interface

EIGRP SummarizationEIGRP SummarizationManualManual

8/6/2019 CCNAV3.3 303

46/63

4

Summarizing EIGRP routes Summarizing EIGRP routes ManualManual

TC(config)#router eigrp 2446TC(config-router)#no auto-summaryTC(config-router)#exitTC(config)#interface serial0

TC(config-if)#ip summary-address eigrp 2446 2.1.0.0 255.255.

TC(config)#router eigrp 2446TC(config-router)#no auto-summaryTC(config-router)#exitTC(config)#interface serial0

TC(config-if)#ip summary-address eigrp 2446 2.1.0.0 255.255.

8/6/2019 CCNAV3.3 303

47/63

4

Verify EIGRP withVerify EIGRP withShowShowcommandcommand

Command Description

Show ip eigrp neighbors[int type] [details]

Display EIGRP neighbor table

Show ip eigrp interfaces

[int type] [as-number]

[details]

Displays EIGRP statistics and status information

Show ip eigrp topology [as-

number][ [ip-add] mask ]

Display the EIGRP topology table, use the show ipeigrp topology EXEC command. Also used todetermine DUAL states & debug possible DUALproblems.

Show ip eigrp topology

[active | pending | zero-successor]

Depending on keywork is used. Display all routes in

the topology table that are either active, pending orwithout successor

Show ip eigrp all-links Display all routes not just FC in EIGRP topology

Show ip eigrp traffic [as-

number]

Display the number of EIGRP packets send and

received.

8/6/2019 CCNAV3.3 303

48/63

4

Verify EIGRP withVerify EIGRP withDebugDebugcommandcommand

Command Description

Debug eigrp fsm This command helps you observe EIGRP FS activutyand to determine whether route updates are beinginstalled and deleted by the routing process

debug eigrp packet Displays all types of EIGRP packets, both sent andreceived

debug eigrp neighbor Displays the EIGRP neighbor interaction

debug ip eigrp route Displays advertisements and changes EIGRP makes tothe routing table

debug ip eigrp summary Displays a brief report of the EIGRP routing activity

show ip eigrp events Displays the different categories of EIGRP activity,including route calculations

8/6/2019 CCNAV3.3 303

49/63

4

TROUBLESHOOTINGTROUBLESHOOTINGROUTING PROTOCOLSROUTING PROTOCOLS

8/6/2019 CCNAV3.3 303

50/63

5

Routing protocol troubleshooting processRouting protocol troubleshooting process

8/6/2019 CCNAV3.3 303

51/63

5

Routing protocol troubleshooting process (cont.)Routing protocol troubleshooting process (cont.)

8/6/2019 CCNAV3.3 303

52/63

5

Troubleshooting Tools and UtilitiesTroubleshooting Tools and Utilities

8/6/2019 CCNAV3.3 303

53/63

5

Troubleshooting RIP configurationTroubleshooting RIP configuration

If the RIP routes are not being advertised, checkthe following:

Layer 1 or Layer 2 connectivity issues exist.

VLSM subnetting is configured. VLSMsubnetting cannot be used with RIP v1.

Mismatched RIP v1 and RIP v2 routingconfigurations exist.

Network statements are missing or incorrectlyassigned.

The outgoing interface is down.

The advertised network interface is down.

8/6/2019 CCNAV3.3 303

54/63

5

UseUse show ip protocolsshow ip protocols commandcommand

8/6/2019 CCNAV3.3 303

55/63

5

UseUse debug ip ripdebug ip rip commandcommand

3d08h: RIP: bad version 128 from 160.89.80.43

8/6/2019 CCNAV3.3 303

56/63

5

Troubleshooting IGRP configurationTroubleshooting IGRP configuration

If IGRP does not appear to be workingcorrectly, check the following:

Layer 1 or Layer 2 connectivity issuesexist.

Autonomous system numbers on IGRProuters are mismatched.

Network statements are missing or

incorrectly assigned.The outgoing interface is down.

The advertised network interface isdown.

8/6/2019 CCNAV3.3 303

57/63

5

Troubleshooting IGRP configuration (cont.)Troubleshooting IGRP configuration (cont.)

To view IGRP debugging information, use thefollowing commands:

debug ip igrp transactions [host ip

address] to view IGRP transactioninformation

debug ip igrp events [host ipaddress] to view routing updateinformation

To turn off debugging, use the no debug ipigrp command.

8/6/2019 CCNAV3.3 303

58/63

5

Troubleshooting EIGRP configurationTroubleshooting EIGRP configuration

Some possible reasons why EIGRP may not beworking correctly are:

Layer 1 or Layer 2 connectivity issues exist.

Autonomous system numbers on EIGRP routers

are mismatched. The link may be congested or down.

The outgoing interface is down.

The advertised network interface is down. Auto-summarization is enabled on routers with

discontiguous subnets.

Use no auto-summary to disable automatic

network summarization.

8/6/2019 CCNAV3.3 303

59/63

5

UseUse show ip eigrp neighborsshow ip eigrp neighbors commandcommand

One of the most common reasons for amissing neighbor is a failure on the actuallink. Another possible cause of missingneighbors is an expired holddown timer.

RTA#show ip eigrp neighbors

IP-EIGRP neighbors for process 400

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

1 172.68.2.2 To0 13 02:15:30 8 200 0 9

0 172.68.16.2 Se1 10 02:38:29 29 200 0 613

10

should normallybe a value

between 10 and

15.

8/6/2019 CCNAV3.3 303

60/63

6

Troubleshooting OSPF configurationTroubleshooting OSPF configuration

The majority of problems encountered with OSPFrelate to the formation of adjacencies and thesynchronization of the link-state databases.

The show ip ospf neighbor command is useful

for troubleshooting adjacency formation. Use the debug ip ospf events privileged EXEC

command to display the following informationabout OSPF-related events:

Adjacencies Flooding information

Designated router selection

Shortest path first (SPF) calculation

8/6/2019 CCNAV3.3 303

61/63

8/6/2019 CCNAV3.3 303

62/63

6

SummarySummary

Cisco released EIGRP in 1994 as a scalable,

improved version of its proprietary distancevector routing protocol, IGRP.

EIGRP improves the convergence properties and

the operating efficiency significantly over IGRP. EIGRP includes may new technologies. These

technologies fall into one of the following fourecategories:

Neighbor discovery and recovery

Reliable Transport Protocol

DUAL finite-state machine algorithm

Protocol-dependent modules

8/6/2019 CCNAV3.3 303

63/63

Q&AQ&A

Documents

CCNAV3.3 303