1. 1 INTRA- AND INTERDOMAIN ROUTING Routing inside an autonomous system is referred to as intradomain routing. Routing between autonomous systems is referred to as interdomain routing. www.btechebooks4u.blogspot.com

2. 2 Autonomous systems www.btechebooks4u.blogspot.com

3. 3 Figure 14.2 Popular routing protocols www.btechebooks4u.blogspot.com

4. 4 14.2 DISTANCE VECTOR ROUTING In distance vector routing, the least cost route between any two nodes is the route with minimum distance. In this protocol each node maintains a vector (table) of minimum distances to every node The topics discussed in this section include: InitializationSharingUpdating When to Share Two-Node Loop Instability Three-Node Instability www.btechebooks4u.blogspot.com

5. 5 Distance vector routing tables www.btechebooks4u.blogspot.com

6. TCP/IP Protocol Suite 6 Figure 14.4 Initialization of tables in distance vector routing www.btechebooks4u.blogspot.com

7. 7 In distance vector routing, each node shares its routing table with its immediate neighbors periodically and when there is a change. Note: www.btechebooks4u.blogspot.com

8. 8 Figure 14.5 Updating in distance vector routing www.btechebooks4u.blogspot.com

9. 9 Figure 14.6 Two-node instability www.btechebooks4u.blogspot.com

10. 10 Three-node instability www.btechebooks4u.blogspot.com

11. 11 RIP The Routing Information Protocol (RIP) is an intradomain routing protocol used inside an autonomous system. It is a very simple protocol based on distance vector routing. The topics discussed in this section include: RIP Message Format Requests and Responses Timers in RIP RIP Version 2 Encapsulation www.btechebooks4u.blogspot.com

12. 12 Example of a domain using RIP www.btechebooks4u.blogspot.com

13. TCP/IP Protocol Suite 13 Figure 14.9 RIP message format www.btechebooks4u.blogspot.com

14. 14 Figure 14.10 Request messages www.btechebooks4u.blogspot.com

15. TCP/IP Protocol Suite 15 Figure 14.13 RIP version 2 format www.btechebooks4u.blogspot.com

16. TCP/IP Protocol Suite 16 Figure 14.14 Authentication www.btechebooks4u.blogspot.com

17. TCP/IP Protocol Suite 17 RIP uses the services of UDP on well-known port 520. Note: www.btechebooks4u.blogspot.com

18. 18 LINK STATE ROUTING In link state routing, if each node in the domain has the entire topology of the domain, the node can use Dijkstra’s algorithm to build a routing table. The topics discussed in this section include: Building Routing Tables www.btechebooks4u.blogspot.com

19. 19 Concept of link state routing www.btechebooks4u.blogspot.com

20. 20 Figure 14.16 Link state knowledge

21. 21 Figure 14.17 Dijkstra algorithm www.btechebooks4u.blogspot.com

22. 22 Figure 14.18 Example of formation of shortest path tree

23. 23 Table 14.1 Routing table for node A www.btechebooks4u.blogspot.com

24. 24 14.5 OSPF The Open Shortest Path First (OSPF) protocol is an intradomain routing protocol based on link state routing. Its domain is also an autonomous system. The topics discussed in this section include: AreasMetric Types of Links Graphical Representation OSPF Packets Link State Update Packet Other Packets Encapsulation www.btechebooks4u.blogspot.com

25. 25 Areas in an autonomous system www.btechebooks4u.blogspot.com

26. 26 Types of links www.btechebooks4u.blogspot.com

27. TCP/IP Protocol Suite 27 Figure 14.21 Point-to-point link

28. TCP/IP Protocol Suite 28 Figure 14.22 Transient link

29. 29 Figure 14.23 Stub link

30. 30 Figure 14.24 Example of an AS and its graphical representation in OSPF

31. 31 Figure 14.25 Types of OSPF packets www.btechebooks4u.blogspot.com

32. 32 Figure 14.26 OSPF common header www.btechebooks4u.blogspot.com

33. 33 Figure 14.27 Link state update packet

34. 34 Figure 14.28 LSA general header

35. 35 Figure 14.29 Router link www.btechebooks4u.blogspot.com

36. 36 Figure 14.30 Router link LSA

37. 37 Table 14.2 Link types, link identification, and link data

38. TCP/IP Protocol Suite 38 OSPF packets are encapsulated in IP datagrams. Note: www.btechebooks4u.blogspot.com

39. TCP/IP Protocol Suite 39 14.7 BGP Border Gateway Protocol (BGP) is an interdomain routing protocol using path vector routing. It first appeared in 1989 and has gone through four versions. The topics discussed in this section include: Types of Autonomous Systems Path Attributes BGP Sessions External and Internal BGP Types of Packets Packet Format Encapsulation

40. TCP/IP Protocol Suite 40 Figure 14.50 Internal and external BGP sessions www.btechebooks4u.blogspot.com

41. TCP/IP Protocol Suite 41 Figure 14.51 Types of BGP messages

42. TCP/IP Protocol Suite 42 Figure 14.52 BGP packet header

43. TCP/IP Protocol Suite 43 Figure 14.53 Open message www.btechebooks4u.blogspot.com

44. TCP/IP Protocol Suite 44 Figure 14.54 Update message

45. TCP/IP Protocol Suite 45 BGP supports classless addressing and CIDR. Note: www.btechebooks4u.blogspot.com

46. TCP/IP Protocol Suite 46 Figure 14.55 Keepalive message www.btechebooks4u.blogspot.com

47. TCP/IP Protocol Suite 47 Figure 14.56 Notification message

48. TCP/IP Protocol Suite 48 Table 14.3 Error codes

49. TCP/IP Protocol Suite 49 BGP uses the services of TCP on port 179. Note: www.btechebooks4u.blogspot.com