lesson 1 - introduction to eigrp

8/3/2019 Lesson 1 - Introduction to EIGRP

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2006 Cisco Systems, Inc. All rights reserved. Cisco ConfidentialBSCI 2 - 1 1

Configuring EIGRP

BSCI Modulo 2-1 Introduccin a EIGRP


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Objetivos

This module will cover topics which allow students tomeet the following objectives:

Describir las capacidades claves que distinguen EIGRP de losotros protocolos de enrutamiento

Identificar las cuatro tecnologas clave empleadas por EIGRPDescribir cmo funciona EIGRP

Describir los cinco componentes de la mtrica utilizados porEIGRP

Calcular la mtrica EIGRP para una gama de rutas entre

enrutadores

Explicar cmo rutas IGRP son integrados en rutas EIGRP yviceversa


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Purpose of this Lesson

Coverage of topics new to the EIGRP module of BSCI.

Qu es lo nuevo en este mdulo?

EIGRP metric calculations for pathway ranges between routers.


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EIGRP caracteristicas

Hay varias diferencias claves entre EIGRP y otrosprotocolos de enrutamiento que se estudiaron en elCCNA.


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EIGRP Key Technologies

Neighbor discover/recovery

Reliable Transport Protocol (RTP)

DUAL finite-state machine

Protocol-dependent modules (PDMs)


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The Diffusing Update Algorithm (DUAL)

Cmo EIGRP determinaqu rutas son libres debucle?

Cada uno de los vecinos deA indica la posibilidad deacceso a E

B con un costo de 10

C con un costo de 10

D con un costo de 30

Estos tres costos sonllamados reporteddistance (RD);


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En A, el costo total paraalcanzar E es:

20 a travs de B

25 a travs de C

45 a travs de D

El mejor de estas tresrutas es a travs de B.

Este es la feasibledistance (FD)


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A uses the FD and the RDto determine which pathsare loop-free

The best path (FD) is usedas a benchmark; all pathswith RDs lower than the FDcannot contain loops

The algorithm may mark

some loop-free paths asloops

However, it is guaranteednever to mark a looped pathas loop-free


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At A:

The path through B is thebest path (FD), at 20

C can reach E with a costof 10; 10 (RD) is less than20 (FD), so this path isloop-free.

D can reach E with a

cost of 30; 30 (RD) isnot less than 20 (FD),so EIGRP assumesthis path is a loop.


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EIGRP Topology Table


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RTRA#show ip eigrp neighbors

IP-EIGRP neighbors for process 1

H Address Interface Hold Uptime SRTT RTO Q Seq

(sec) (ms) Cnt Num

2 10.1.1.1 Et0 12 6d16h 20 200 0 233

1 10.1.4.3 Et1 13 2w2d 87 522 0 4520 10.1.4.2 Et1 10 2w2d 85 510 0 3

Seconds Remaining Before Declaring Neighbor Down

How Long Since theLast Time Neighbor Was Discovered

How Long It Takes for This Neighbor To Respond To Reliable Packets

How Long to Wait Before Retransmitting If No Acknowledgement

EIGRP Neighbor Status


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EIGRP IP Routing Table


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Example: EIGRP TablesRouter Cs tables:


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EIGRP Packets

Hello: Establish neighbor relationships.

Update: Send routing updates

Query: Ask neighbors about routing information

Reply: Respond to query about routing information

ACK: Acknowledge a reliable packet


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Initial Route Discovery


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EIGRP Metric

Same metric components as IGRP:

Bandwidth

Delay

Reliability

Loading

MTU

EIGRP metric is IGRP metric multiplied by 256


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EIGRP Metric Calculation

By default, EIGRP metric:

Metric = bandwidth (slowest link) + delay (sum of delays)

Delay = sum of the delays in the path, in tens ofmicroseconds, multiplied by 256.

Bandwidth = [10 / (minimum bandwidth link along thepath, in kilobits per second)] * 256

Formula with default K values (K1 = 1, K2 = 0, K3 = 1,K4 = 0, K5 = 0):

Metric = [K1 * BW + ((K2 * BW) / (256 load)) + K3 * delay]

If K5 not equal to 0:

Metric = Metric * [K5 / (reliability + K4)]


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EIGRP Metrics Calculation Example

A B C D Least bandwidth 64 kbps Total delay 6,000

A X Y Z D Least bandwidth 256 kbps Total delay 8,000

Delay is the sum of all the delays of the links along the paths:Delay = [delay in tens of microseconds] x 256

BW is the lowest bandwidth of the links along the paths:BW = [10,000,000 / (bandwidth in kbps)] x 256


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EIGRP Metrics Are Backward-Compatible

with IGRP


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Summary

EIGRP capabilities include fast convergence and support forVLSM, partial updates, and multiple network layer protocols.

EIGRP key technologies are: neighbor discovery/recovery, RTP,DUAL finite-state machine, and protocol-dependent modules.

EIGRP uses three tables: neighbor table, topology table, androuting table. The routing table contains the best route to eachdestination, called the successor route. A feasible successor routeis a backup route to a destination; it is kept in the topology table.

EIGRP uses the same metric components as IGRP: delay,

bandwidth, reliability, load, and MTU. By default, EIGRP metric = bandwidth (slowest link) + delay (sum

of delays).

EIGRP metrics are backward-compatible with IGRP; the EIGRP-equivalent metric is the IGRP metric multiplied by 256.


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Self Check

What is a reported distance?

What is a feasible distance?

EIGRP uses three tables: name the three tables: __________,____________, _____________. Which of the tables contains the

best route or successor route to each destination?

EIGRP uses what metrics? __________, _________, _________,__________, ___________


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Resources

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009405c.shtml

http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml


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Q and A


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lesson 1 - introduction to eigrp

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