13 ospf rouitng

8/11/2019 13 ospf rouitng

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Open standard protocol

Successor of RIP

Classless routing protocol

Uses Shortest Path First (SPF) Algorithm

Updates are sent through Multicast IP address

224.0.0.5

Administrative distance is 110

Metric = Cost =108/Bandwidth in bps (CISCO)

Open Shortest Path First


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Hello packets are sent every 10 seconds

Faster Convergence

Hierarchical design with Multiple Areas

Area 0 is called the backbone area

Router ID

The highest IP address of the active physical interface

of the router is elected as Router ID.

If logical interface is configured, the highest IP

address of the logical interface is elected as Router ID

OSPF (contd..)


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It maintains three tables :

Neighbor Table

Neighbor table contains information about the directly

connected OSPF neighbors forming adjacency.

Database table

Database table contains information about the entire

view of the topology with respect to each router.

Routing information Table

Routing table contains information about the best path

calculated by the shortest path first algorithm in the

database table.

OSPF Tables


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OSPF - Network Diagram

LAN - 192.168.1.0/24 LAN 192.168.2.0/24 LAN - 192.168.3.0/24

AREA 0

E0192.168.1.1/24

E0192.168.2.1/24

E0192.168.3.1/

10.0.0.1/8S0

S110.0.0.2/8

11.0.0.1/8S0

S111.0.0.2/8


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OSPF Packet Types

Hello

DBD (Database Descriptor)

LSR (Link State Request)

LSU (Link State Update)

LSAck (Link State Acknowledge)


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OSPF States

DOWN

Init

2-Way

Ex-Start

Exchange

Loading

Full


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How OSPF Works

10.0.0.1/8SO

10.0.0.2/8

S1

DOWN STATE

I am router ID 192.168.1.1 and I see no one.

INIT STATE Router HYDNeighbors List

192.168.1.1/24, int s1I am router ID 172.16.0.1 and I see 192.168.1.1.

Router CHENeighbors List

172.16.0.0/16, int s0

2-way STATE


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10.0.0.1/8SO

10.0.0.2/8

S1

No, I will start exchange because I have a higher router ID

I will start exchange because I have router ID 172.16.0.1

Ex-Start STATE

Here is a summary of my link-state database

Exchange State

Here is a summary of my link-state database

How OSPF Works


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10.0.0.1/8SO

10.0.0.2/8

S1

Thanks for the Information

Loading State

I need the complete entry for network 172.16.0.0/16

Here is the entry for network 172.16.0.0/16

Thanks for the Information!

Full State

How OSPF Works


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Consumes More Memory and CPU processing

Disadvantages of OSPF


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exityderabad(config-if)#

Hyderabad(config)#

telnet 192.168.1.1

================================

Welcome to Hyderabad Router

================================

User Access Verification

password :

****

****

enable

configure terminal

interface serial 0

ip address 10.0.0.1 255.0.0.0

no shut

clockrate 64000

encapsulation hdlc

Hyderabad>

password :

Hyderabad#

Enter configuration commands, one per line. End with CNTL/Z.

Hyderabad(config)#

Hyderabad(config-if)#




Microsoft Windows 2000 [Version 5.00.2195]

(C) Copyright 1985-2000 Microsoft Corp.

C:\>

Connecting .....

Directly Connected Networks onHYDERABAD Router

192.168.1.0

10.0.0.0


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Hyderabad(config)#

router ospf 1

Hyderabad(config-router)#

Hyderabad(config-router)# network 192.168.1.0 0.0.0.255 area 0


no ip routingyderabad(config)#

Hyderabad(config)#

ip routing

Configuring OSPF

Router(config)# router ospf

Router(config-router)# network area


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show ip routeyderabad#

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

i- IS-IS, L1-IS-IS level-1, L2-IS-IS level-2,*- candidate default

U - per-user static route, o - ODR

Gateway of last resort is not set

C 10.0.0.0/8 is directly connected, Serial0

O 11.0.0.0/8 [110/128] via 10.0.0.2, 00:00:36, Serial0

C 192.168.1.0/24 is directly connected, Ethernet0

O 192.168.2.0/24 [110/74] via 10.0.0.2, 00:00:36, Serial0

O 192.168.3.0/24 [110/138] via 10.0.0.2, 00:00:36, Serial0

Hyderabad#

^

Z

O for OSPF routes110 is nothing but

Administrative Distance

Metric of OSPF

Cost

Hyderabad(config)#

router ospf 1

Hyderabad(config-router)#



no ip routingyderabad(config)#

Hyderabad(config)#

ip routing


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show ip ospf databaseyderabad#

OSPF Router with ID (192.168.1.1) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link

192.168.1.1 192.168.1.1 790 0x80000003 0x897B 3

192.168.2.1 192.168.2.1 234 0x80000005 0x542 5

192.168.3.1 192.168.3.1 232 0x80000003 0xD328 3

Hyderabad#

show ip ospf neighbor

Neighbor ID Pri State Dead Time Address

192.168.2.1 1 FULL/ - 00:00:36 10.0.0.2

Hyderabad#


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Chennai(config-if)#

Chennai(config-if)#

================================

Welcome to Chennai Router

================================


password :

****

****

enable

configure terminal

ip address 10.0.0.2 255.0.0.0

no shut

encapsulation hdlc

interface serial 0

Chennai>

password :

Chennai#


Chennai(config)#

Chennai(config-if)#

Chennai(config-if)#

Chennai(config-if)#

Chennai(config-if)#



C:\>

Connecting .....

Chennai(config-if)#

telnet 192.168.2.1

interface serial 1

ip address 11.0.0.1 255.0.0.0

no shut

encapsulation hdlc

Directly Connected Networks onCHENNAI Router

192.168.2.0

10.0.0.0

11.0.0.0


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Chennai(config)#

router ospf 2

Chennai(config-router)#

Chennai(config-router)# network 192.168.2.0 0.0.0.255 area 0


no ip routinghennai(config)#

Chennai(config)#

ip routing

network 11.0.0.0 0.255.255.255 area 0


Configuring OSPF




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show ip routehennai#










O 192.168.1.0/24 [110/74] via 10.0.0.1, 00:01:33, Serial1


O 192.168.3.0/24 [110/74] via 11.0.0.2, 00:01:33, Serial0

Chennai#

^

Z



Metric of OSPF

Cost

Chennai(config)#

router ospf 2




no ip routinghennai(config)#

Chennai(config)#

ip routing

network 11.0.0.0 0.255.255.255 area 0



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show ip ospf databasehennai#




192.168.1.1 192.168.1.1 1253 0x80000003 0x897B 3

192.168.2.1 192.168.2.1 695 0x80000005 0x542 5

192.168.3.1 192.168.3.1 693 0x80000003 0xD328 3

Chennai#



192.168.3.1 1 FULL/ - 00:00:35 11.0.0.2

192.168.1.1 1 FULL/ - 00:00:32 10.0.0.1

Chennai#


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exitanglore(config-if)#

Banglore(config)#

================================

Welcome to Banglore Router

================================


password :

****

****

enable

configure terminal

ip address 11.0.0.2 255.0.0.0

no shut

clockrate 64000

encapsulation hdlc

Banglore>

password :

Banglore#


Banglore(config)#

Banglore(config-if)#






C:\>

Connecting .....

telnet 192.168.3.1

interface serial 1

Directly Connected Networks onBanglore Router

192.168.3.0

11.0.0.0


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Banglore(config)#

router ospf 1

Banglore(config-router)#

Banglore(config-router)# network 192.168.3.0 0.0.0.255 area 0


no ip routinganglore(config)#

Banglore(config)#

ip routing

network 11.0.0.0 0.255.255.255 area 0

Configuring OSPF




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show ip routeanglore#








O 10.0.0.0/8 [110/128] via 11.0.0.1, 00:02:09, Serial1


O 192.168.1.0/24 [110/138] via 11.0.0.1, 00:02:09, Serial1

O 192.168.2.0/24 [110/74] via 11.0.0.1, 00:02:09, Serial1


Banglore#

^

Z



Metric of OSPF

Cost

Banglore(config)#

router ospf 1


Banglore(config-router)# network 192.168.3.0 0.0.0.255 area 0


no ip routinganglore(config)#

Banglore(config)#

ip routing

network 11.0.0.0 0.255.255.255 area 0


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show ip ospf databaseanglore#




192.168.1.1 192.168.1.1 1506 0x80000003 0x897B 3

192.168.2.1 192.168.2.1 948 0x80000005 0x542 5

192.168.3.1 192.168.3.1 944 0x80000003 0xD328 3

Banglore#



192.168.2.1 1 FULL/ - 00:00:37 11.0.0.1

Banglore#


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ping 192.168.3.10yderabad#

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.168.3.10, timeout is 2 seconds:

Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms

Hyderabad#ping 192.168.2.10




Hyderabad#


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ping 192.168.1.10hennai#




Chennai# ping 192.168.3.10




Chennai#


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ping 192.168.1.10anglore#




Banglore#ping 192.168.2.10




Banglore#

13 ospf rouitng

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