2. 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 =10 8 /Bandwidth in bps (CISCO) Open Shortest Path First

3. 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..)

4. 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

5. OSPF - Network Diagram LAN - 192.168.1.0/24LAN – 192.168.2.0/24LAN - 192.168.3.0/24 AREA 0 E0 192.168.1.1/24 E0 192.168.2.1/24 E0 192.168.3.1/24 10.0.0.1/8 S0 S1 10.0.0.2/8 11.0.0.1/8 S0 S1 11.0.0.2/8

6. OSPF Packet Types Hello DBD (Database Descriptor) LSR (Link State Request) LSU (Link State Update) LSAck (Link State Acknowledge)

7. OSPF States DOWN Init 2-Way Ex-Start Exchange Loading Full

8. How OSPF Works 10.0.0.1/8 SO 10.0.0.2/8 S1 DOWN STATE I am router ID 192.168.1.1 and I see no one. INIT STATE Router HYD Neighbors List 192.168.1.1/24, int s1 I am router ID 172.16.0.1 and I see 192.168.1.1. Router CHE Neighbors List 172.16.0.0/16, int s0 2-way STATE

9. 10.0.0.1/8 SO 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

10. 10.0.0.1/8 SO 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

11. Consumes More Memory and CPU processing Disadvantages of OSPF

13. exit Hyderabad(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 on HYDERABAD Router 192.168.1.0 10.0.0.0 Directly Connected Networks on HYDERABAD Router 192.168.1.0 10.0.0.0

14. Hyderabad(config)# router ospf 1 Hyderabad(config-router)# network 192.168.1.0 0.0.0.255 area 0 network 10.0.0.0 0.255.255.255 area 0 no ip routing Hyderabad(config)# ip routing Configuring OSPF Router(config)# router ospf Router(config-router)# network area Configuring OSPF Router(config)# router ospf Router(config-router)# network area

15. show ip route Hyderabad# 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 routes 110 is nothing but Administrative Distance Metric of OSPF Cost Metric of OSPF Cost Hyderabad(config)# router ospf 1 Hyderabad(config-router)# network 192.168.1.0 0.0.0.255 area 0 Hyderabad(config-router)#network 10.0.0.0 0.255.255.255 area 0 no ip routingHyderabad(config)# ip routing

16. show ip ospf database Hyderabad# 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#

17. Chennai(config-if)# ================================ Welcome to Chennai Router ================================ User Access Verification password : **** **** enable configure terminal ip address 10.0.0.2 255.0.0.0 no shut encapsulation hdlc interface serial 0 Chennai> password : Chennai# Enter configuration commands, one per line. End with CNTL/Z. Chennai(config)# Chennai(config-if)# Microsoft Windows 2000 [Version 5.00.2195] (C) Copyright 1985-2000 Microsoft Corp. 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 on CHENNAI Router 192.168.2.0 10.0.0.0 11.0.0.0 Directly Connected Networks on CHENNAI Router 192.168.2.0 10.0.0.0 11.0.0.0

18. Chennai(config)# router ospf 2 Chennai(config-router)# network 192.168.2.0 0.0.0.255 area 0 network 10.0.0.0 0.255.255.255 area 0 no ip routing Chennai(config)# ip routing network 11.0.0.0 0.255.255.255 area 0 Chennai(config-router)# Configuring OSPF Router(config)# router ospf Router(config-router)# network area Configuring OSPF Router(config)# router ospf Router(config-router)# network area

19. show ip route Chennai# 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, Serial1 C 11.0.0.0/8 is directly connected, Serial0 O 192.168.1.0/24 [110/74] via 10.0.0.1, 00:01:33, Serial1 C 192.168.2.0/24 is directly connected, Ethernet0 O 192.168.3.0/24 [110/74] via 11.0.0.2, 00:01:33, Serial0 Chennai# ^ Z O – for OSPF routes 110 is nothing but Administrative Distance Metric of OSPF Cost Metric of OSPF Cost Chennai(config)# router ospf 2 Chennai(config-router)# network 192.168.2.0 0.0.0.255 area 0 Chennai(config-router)#network 10.0.0.0 0.255.255.255 area 0 no ip routingChennai(config)# ip routing network 11.0.0.0 0.255.255.255 area 0 Chennai(config-router)#

20. show ip ospf database Chennai# OSPF Router with ID (192.168.2.1) (Process ID 2) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link 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 # show ip ospf neighbor Neighbor ID Pri State Dead Time Address 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#

21. exit Banglore(config-if)# Banglore(config)# ================================ Welcome to Banglore Router ================================ User Access Verification password : **** **** enable configure terminal ip address 11.0.0.2 255.0.0.0 no shut clockrate 64000 encapsulation hdlc Banglore> password : Banglore# Enter configuration commands, one per line. End with CNTL/Z. Banglore(config)# Banglore(config-if)# Microsoft Windows 2000 [Version 5.00.2195] (C) Copyright 1985-2000 Microsoft Corp. C:\> Connecting..... telnet 192.168.3.1 interface serial 1 Directly Connected Networks on Banglore Router 192.168.3.0 11.0.0.0 Directly Connected Networks on Banglore Router 192.168.3.0 11.0.0.0

22. Banglore(config)# router ospf 1 Banglore(config-router)# network 192.168.3.0 0.0.0.255 area 0 no ip routing Banglore(config)# ip routing network 11.0.0.0 0.255.255.255 area 0 Configuring OSPF Router(config)# router ospf Router(config-router)# network area Configuring OSPF Router(config)# router ospf Router(config-router)# network area

23. show ip route Banglore# 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 O 10.0.0.0/8 [110/128] via 11.0.0.1, 00:02:09, Serial1 C 11.0.0.0/8 is directly connected, 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 C 192.168.3.0/24 is directly connected, Ethernet0 Banglore# ^ Z O – for OSPF routes 110 is nothing but Administrative Distance Metric of OSPF Cost Metric of OSPF Cost Banglore(config)# router ospf 1 Banglore(config-router)# network 192.168.3.0 0.0.0.255 area 0 Banglore(config-router)# no ip routingBanglore(config)# ip routing network 11.0.0.0 0.255.255.255 area 0

24. show ip ospf database Banglore# OSPF Router with ID (192.168.3.1) (Process ID 1) Router Link States (Area 0) Link ID ADV Router Age Seq# Checksum Link 192.168.1.1 192.168.1.1 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# show ip ospf neighbor Neighbor ID Pri State Dead Time Address 192.168.2.1 1 FULL/ - 00:00:37 11.0.0.1 Banglore#

25. ping 192.168.3.10 Hyderabad# 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 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.10, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms Hyderabad# !!!!!

26. ping 192.168.1.10 Chennai# Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.10, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms Chennai# !!!!! ping 192.168.3.10 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 Chennai# !!!!!

27. ping 192.168.1.10 Banglore# Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.1.10, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms Banglore# !!!!! ping 192.168.2.10 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.10, timeout is 2 seconds: Success rate is 100 percent (5/5), round-trip min/avg/max = 40/43/44 ms Banglore# !!!!!