1. © 2002, Cisco Systems, Inc. All rights reserved. 1 Routing Overview

2. To route, a router needs to do the following: Know the destination address Identify the sources it can learn from Discover possible routes Select the best route Maintain and verify routing information What Is Routing?

3. Routers must learn destinations that are not directly connected. What Is Routing? (Cont.)

4. Static Route –Uses a route that a network administrator enters into the router manually Dynamic Route –Uses a route that a network routing protocol adjusts automatically for topology or traffic changes Identifying Static and Dynamic Routes

5. Static Routes Configure unidirectional static routes to and from a stub network to allow communications to occur.

6. –Defines a path to an IP destination network or subnet or host Router(config)#ip route network [mask] {address | interface}[distance] [permanent] Static Route Configuration

7. Static Route Example This is a unidirectional route. You must have a route configured in the opposite direction.

8. Default Routes This route allows the stub network to reach all known networks beyond router A.

9. Verifying the Static Route Configuration router#show ip route Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area 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 Gateway of last resort is 0.0.0.0 to network 0.0.0.0 10.0.0.0/8 is subnetted, 1 subnets C 10.1.1.0 is directly connected, Serial0 S* 0.0.0.0/0 is directly connected, Serial0

10. Routing protocols are used between routers to determine paths and maintain routing tables. Once the path is determined, a router can route a routed protocol (IP). What Is a Routing Protocol?

11. An autonomous system is a collection of networks under a common administrative domain. IGPs operate within an autonomous system. EGPs connect different autonomous systems. Autonomous Systems: Interior or Exterior Routing Protocols

12. Classes of Routing Protocols

13. © 2002, Cisco Systems, Inc. All rights reserved. 13 Distance Vector Routing

14. Routers pass periodic copies of routing table to neighbor routers and accumulate distance vectors. Distance Vector Routing Protocols

15. Updates proceed step-by-step from router to router. Maintaining Routing Information

16. 16 RIP

17. Metric

18. Is a value that assign to each path Use to calculate with path is the best path to remote destination network Different in routing protocol The route with the lowest metric is the best route

19. Hop Count is metric in RIP Routing

20. –Maximum is 6 paths (default = 4) –Hop-count metric selects the path –Routes update every 30 seconds RIP Overview

21. RIP Table

22. Load Balancing with RIP By default, on a Cisco router, if multiple equal-cost paths exist up to six entries are placed into the forwarding database and the routers load balance between them.

23. –Defines an IP routing protocol Router(config)#router protocol [keyword] Mandatory configuration command for each IP routing process Identifies the physically connected network that routing updates are forwarded to Router(config-router)#network network-number Dynamic Routing Configuration

24. –Starts the RIP routing process Router(config)#router rip Router(config-router)#network network-number Selects participating attached networks Requires a major classful network number RIP Configuration

25. RIP Configuration Example

26. Verifying the RIP Configuration

27. Displaying the IP Routing Table

28. debug ip rip Command

29. Summary –RIP is a distance vector routing protocol that uses hop count as the metric for route selection and broadcasts routing updates every 30 seconds. –To enable a dynamic routing protocol, you will select the routing protocol and then assign IP network numbers. –The router rip command specifies RIP as the routing protocol. The network command identifies a participating attached network. –The show ip commands display information about routing protocols and the routing table. –Use the debug ip rip command to display information on RIP routing transactions.

30. Router RIP Example

31. S0 : 192.168.1.1 S1 : 192.168.3.1 F0/0 : 192.168.2.1 S0 : 192.168.3.2 S1 : 192.168.4.1 S0 : 192.168.4.2 S0 : 192.168.9.2 S0 : 192.168.7.2 S1 : 192.168.7.1 S1 : 192.168.9.1 S1 : 192.168.1.2 F0/0 : 192.168.10.1 F0/0 : 192.168.5.1F0/0 : 192.168.6.1F0/0 : 192.168.8.1

32. Configure RIP 1.Assign ip to interface 2.Configure RIP Routing 3.Ping 4.Trace route 5.Show routing table

33. Verifying the RIP Configuration

34. Displaying the IP Routing Table

35. debug ip rip Command

36. Key Elements of RIP –Hop count is the metric for path selection. –Maximum hop count of 15 – 16 hops is considered infinity –By default, routing updates are broadcast every 30 seconds. –Capable of load balancing

37. 37 IGRP Interior gateway routing protocol))

38. This is helpful in larger networks and solves the problem of 15 hops being the maximum possible in a RIP network

39. Complex Metrics MTU

40. Bandwidth 1 23 4

41. Delay of line amount of time necessary to move a packet transmition from source to destination. 1 mb/s 2 mb/s

42. Reliability 2 mb/s

43. Load 1 mb/s 2 mb/s

44. MTU MTU : Maximum Transmission Unit -The Maximum Packet size, in byte, that a particular interface can handle. - The default MTU value on Ethernet interface is 1500 byte.

45. IGRP metric calculation By default IGRP chooses a route based on Bandwidth and delay Metric = bandwidth + delay

46. –Maximum 6 paths (default = 4) –Within metric variance –Next-hop router closer to destination IGRP Unequal Multiple Paths

47. Configuring IGRP Router(config-router)#network network-number Selects participating attached networks Router(config)#router igrp autonomous-system Defines IGRP as the IP routing protocol

48. Verifying the IGRP Configuration

49. debug ip igrp transaction Command

50. debug ip igrp events Command RouterA#debug ip igrp events IGRP event debugging is on RouterA# 00:23:44: IGRP: sending update to 255.255.255.255 via Ethernet0 (172.16.1.1) 00:23:44: IGRP: Update contains 0 interior, 2 system, and 0 exterior routes. 00:23:44: IGRP: Total routes in update: 2 00:23:44: IGRP: sending update to 255.255.255.255 via Serial2 (10.1.1.1) 00:23:45: IGRP: Update contains 0 interior, 1 system, and 0 exterior routes. 00:23:45: IGRP: Total routes in update: 1 00:23:48: IGRP: received update from 10.1.1.2 on Serial2 00:23:48: IGRP: Update contains 1 interior, 1 system, and 0 exterior routes. 00:23:48: IGRP: Total routes in update: 2

51. Displaying the IP Routing Table

52. Updating Routing Information Example

53. Updating Routing Information Example (Cont.)

56. Router IGRP Example

57. S0 : 192.168.1.1 S1 : 192.168.3.1 F0/0 : 192.168.2.1 S0 : 192.168.3.2 S1 : 192.168.4.1 S0 : 192.168.4.2 S0 : 192.168.9.2 S0 : 192.168.7.2 S1 : 192.168.7.1 S1 : 192.168.9.1 S1 : 192.168.1.2 F0/0 : 192.168.10.1 F0/0 : 192.168.5.1F0/0 : 192.168.6.1F0/0 : 192.168.8.1

58. Configure IGRP 1.Assign ip to interface 2.Configure RIP Routing 3.Ping 4.Trace route 5.Show routing table