Enhanced IGRP (EIGRP)

dargspurNetworking and Communications

Oct 27, 2013 (3 years and 1 month ago)

51 views

1

Enhanced IGRP (EIGRP)

2

Agenda


EIGRP Features and


Operation


Using EIGRP to Support


Large Networks


Verifying EIGRP

3

EIGRP Features and Operation

4

EIGRP Features and Operation


Protocol
-
dependent modules


Efficient neighbor discovery


Communication via Reliable Transport Protocol (RTP)


Best path selection via Diffusing Update Algorithm
(DUAL)

5

Protocol
-
Dependent Modules


Provides routing support for multiple Network layer
protocol:


IP


IPX


AppleTalk

6

Neighbor Discovery


Three condition that must be met for
neighborship establishment:


Hello or ACK received


AS number match


Identical metrics (K values)


EIGRP advertise its entire routing table when it
discover a new neighbor.


Only changes to the routing table are
propagated from then on.

7

Reliable Transport Protocol (RTP)


Proprietary protocol.


Uses multicast and unicast.


Multicast address 224.0.0.10.


For each multicast it sends out, it maintains a list of the
neighbors who have replied.


If EIGRP doesn’t get a reply from a neighbor, it will
switch to using unicasts to resend the same data.


After 16 unicast attempts


neighbor is declared dead.

8

Diffusing Update Algorithm (DUAL)


Backup route determination if one is available.


Support of Variable
-
Length Subnet Masks (VLSMs).


Dynamic route recoveries.


Sending out queries for an alternate route if no route
can be found.


9

EIGRP’s Terms


Feasible distance


the best metric along all path
to a remote network.


Reported distance


the metric of a remote
network, as reported by a neighbor.


Feasible successor


backup route


rd < fd

10

Using EIGRP to Support
Large Networks

11

Multiple AS


Only routers that have the same AS (autonomous
system) numbers share routes.


Support multiple distinct AS


use redistribution.


Internal EIGRP route


administrative distance 90.


External EIGRP route


administrative distance 170.

12

A Discontiguous Network

13

EIGRP Auto Summarization

14

Route Discovery and Maintenance


Neighborship table


Topology table


Route table

15

EIGRP Metrics


Bandwidth


Delay


Load


Reliability

16

Verifying EIGRP

17

EIGRP Troubleshooting
Commands


show ip route




shows the entire routing table


show ip route eigrp




shows only EIGRP entries in the routing table


show ip eigrp neighbors




shows all EIGRP neighbors


show ip eigrp topology




shows entries in the EIGRP topology table