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Instructor & Todd Lammle

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Sybex CCNA 640-802 Chapter 7: EIGRP and OSPF Instructor & Todd Lammle * Enhanced Interior Gateway Routing Protocol (EIGRP) is a proprietary Cisco protocol that runs ... – PowerPoint PPT presentation

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Title: Instructor & Todd Lammle


1
Sybex CCNA 640-802 Chapter 7 EIGRP and OSPF
  • Instructor Todd Lammle

2
Chapter 7 Objectives
  • Enhanced IGRP
  • EIGRP tables
  • Configuring EIGRP
  • Verifying EIGRP
  • Open Shortest Path First
  • Configuring OSPF
  • Verifying OSPF
  • Configuring OSPF with wildcards

2
3
What Is Enhanced IGRP (EIGRP)?
IP RoutingProtocols
IP RoutingProtocols
AppleTalk Routing Protocol
EnhancedIGRP
AppleTalk Routing Protocol
IPX RoutingProtocols
IPX RoutingProtocols
  • Enhanced IGRP supports
  • Rapid convergence
  • Reduced bandwidth usage
  • Multiple network-layer support
  • Uses Diffused Update Algorithm (DUAL) to select
    loop-free routes and enable fast convergence
  • Up to six unequal paths to a remote network (4 by
    default)

4
Comparing EIGRP and IGRP
  • Similar metric
  • Same load balancing
  • Improved convergence time
  • Reduced network overhead
  • Maximum hop count of 255 (100 default)
  • EIGRP can differentiate between internal and
    external routes

5
EIGRP for IP
  • No updates. Route updates sent only when a change
    occurs multicast on 224.0.0.10
  • Hello messages sent to neighbors every 5 seconds
    (60 seconds in most WANs)

hello
6
EIGRP Terminology
Neighbor TableIP Next Hop Interface
Router
Note A feasible successor is a backup route and
stored in the Topology table
7
EIGRP Tables
  • The neighbor table and topology table are held in
    ram and are maintained through the use of hello
    and update packets.

hello
To see all feasible successor routes known to a
router, use the show ip eigrp topology command
8
Successor routes
  • Successor route is used by EIGRP to forward
    traffic to a destination
  • A successor routes may be backed up by a feasible
    successor route
  • Successor routes are stored in both the topology
    table and the routing table

9
Choosing Routes
IP
IP
A
B
19.2
AppleTalk
AppleTalk
T1
T1
IPX
IPX
T1
C
D
  • EIGRP uses a composite metric to pick the best
    path bandwidth and delay of the line
  • EIGRP can load balance across six unequal cost
    paths to a remote network (4 by default)

10
Configuring EIGRP for IP
AS10
C
A
B
172.16.10.0
10.110.1.0
192.168.0.0
192.168.0.0
Router(config)router eigrp 10Router(config-route
r)network 10.0.0.0Router(config-router)network
172.16.0.0
Enable EIGRP Assign networks
If you use the same AS number for EIGRP as IGRP,
EIGRP will automatically redistribute IGRP into
EIGRP
11
Redistribution
  • Redistribution is translating one type of routing
    protocol into another.

EIGRP
IGRP
Router B
Router D
Router A
Router C
IGRP and EIGRP translate automatically, as long
as they are both using the same AS number
12
Route Path
  • Assuming all default parameters, which route will
    RIP (v1 and v2) take, and which route will EIGRP
    take?

T1
T1
56K
10BaseT
100BaseT
100BaseT
13
Verifying Enhanced IGRP Operation
show ip eigrp neighbors
Router
  • Displays the neighbors discovered by IP Enhanced
    IGRP
  • Displays the IP Enhanced IGRP topology table
  • Displays current Enhanced IGRP entries in the
    routing table
  • Displays the parameters and current state of the
    active routing protocol process
  • Displays the number of IP Enhanced IGRP packets
    sent and received

show ip eigrp topology
Router
show ip route eigrp
Router
show ip protocols
Router
show ip eigrp traffic
Router
14
Show IP Route
P1R1sh ip route output cut Gateway of last
resort is not set D 192.168.30.0/24 90/2172
via 192.168.20.2,000436, Serial0/0 C
192.168.10.0/24 is directly connected,
FastEthernet0/0 D 192.168.40.0/24 90/2681
via 192.168.20.2,000436, Serial0/0 C
192.168.20.0/24 is directly connected,
Serial0/0 D 192.168.50.0/24 90/2707 via
192.168.20.2,000435, Serial0/0 P1R1
  • -D is for DUAL
  • -90/2172 is the administrative distance and
    cost of the route. The cost of the route is a
    composite metric comprised from the bandwidth and
    delay of the line

15
Introducing OSPF
  • Open standard
  • Shortest path first (SPF) algorithm
  • Link-state routing protocol (vs. distance vector)
  • Can be used to route between ASs

16
OSPF Hierarchical Routing
  • Consists of areas and autonomous systems
  • Minimizes routing update traffic
  • Supports VLSM
  • Unlimited hop count

17
Link State Vs. Distance Vector
  • Link State
  • Provides common view of entire topology
  • Calculates shortest path
  • Utilizes event-triggered updates
  • Can be used to route between ASs
  • Distance Vector
  • Exchanges routing tables with neighbors
  • Utilizes frequent periodic updates

18
Types of OSPF Routers
Area 1
Area 2
Backbone Area 0
ABR and BackboneRouter
Backbone/InternalRouters
InternalRouters
InternalRouters
ASBR andBackbone Router
ABR and BackboneRouter
  • External AS

19
Configuring Single Area OSPF
Router(config)router ospf process-id
Defines OSPF as the IP routing protocol Note The
process ID is locally significant and is needed
to identify a unique instance of an OSPF database
Router(config-router)network address mask area
area-id
Assigns networks to a specific OSPF area
20
OSPF Example
21
Verifying the OSPF Configuration
Routershow ip protocols
Verifies that OSPF is configured
Routershow ip route
Displays all the routes learned by the router
Routershow ip ospf interface
Displays area-ID and adjacency information
Routershow ip ospf neighbor
Displays OSPF-neighbor information on a
per-interface basis
22
OSFP Neighbors
  • OSPF uses hello packets to create adjacencies and
    maintain connectivity with neighbor routers
  • OSPF uses the multicast address 224.0.0.5

Hello? 224.0.0.5
  • Hello packets provides dynamic neighbor discovery
  • Hello Packets maintains neighbor relationships
  • Hello packets and LSAs from other routers help
    build and maintain the topological database

23
OSPF Terminology
  • Neighbor
  • Adjacency

Neighbors
ABR
DR
Adjacencies
Non-DR
Cost6
BDR
24
Router ID (RID)
  • Each router in OSPF needs to be uniquely
    identified to properly arrange them in the
    Neighbor tables.

25
Electing the DR and BDR
Multicast Hellos are sent and compared Router
with Highest Priority is Elected as DR Router
with 2nd Highest Priority is Elected as BDR
  • OSPF sends Hellos which elect DRs and BDRs
  • Router form adjacencies with DRs and BDRs in a
    multi-access environment

26
Configuring Loopback Interfaces
  • Router ID (RID)
  • Number by which the router is known to OSPF
  • Default The highest IP address on an active
    interface at the moment of OSPF process startup
  • Can be overridden by a loopback interface
    Highest IP address of any active loopback
    interface also called a logical interface

27
Interface Priorities
  • What is the default OSPF interface priority?
  • Router show ip ospf interface ethernet0/0
  • Ethernet0 is up, line protocol is up
  • Internet Address 192.168.1.137/29, Area 4
  • Process ID 19, Router ID 192.168.1.137, Network
    Type BROADCAST,
  • Cost 10 Transmit Delay is 1 sec, State DR,
    Priority 1
  • Designated Router (ID) 192.168.1.137, Interface
    address 192.168.1.137
  • No backup designated router on this network
  • Timer intervals configured, Hello 10, Dead 40,
    Wait 40, Retransmit 5
  • Hello due in 000006
  • Index 2/2, flood queue length 0
  • Next 0x0(0)/0x0(0)
  • Last flood scan length is 0, maximum is 0
  • Last flood scan time is 0 msec, maximum is 0 msec
  • Neighbor Count is 0, Adjacent neighbor count is 0
  • Suppress hello for 0 neighbor(s)

28
Ensuring your DR
  • What options can you configure that will ensure
    that R2 will be the DR of the LAN segment?

29
Configuring Wildcards
  • If you want to advertise a partial octet
    (subnet), you need to use wildcards.
  • 0.0.0.0 means all octets match exactly
  • 0.0.0.255 means that the first three match
    exactly, but the last octet can be any value
  • After that, you must remember your block sizes.

30
Wildcard
  • The wildcard address is always one less than the
    block size.
  • 192.168.10.8/30 0.0.0.3
  • 192.168.10.48/28 0.0.0.15
  • 192.168.10.96/27 0.0.0.31
  • 192.168.10.128/26 0.0.0.63

31
Wildcard Configuration of the Lab_B Router
  • Lab_C
  • E0 192.168.50.1/24
  • S1 172.16.10.9/30
  • Lab_B
  • E0 192.168.40.1/24
  • S0 192.168.10.10/30
  • S1 192.168.10.6/30
  • Lab_A
  • E0 192.168.30.1/24
  • S0 172.16.10.5/30

32
Summary
  • Go through all the written and review questions
  • Go over the answers with the class

32
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