Fundamentals of Networking

1. Fundamentals of Networking Discovery 2, Chapter 6 Routing

2. Objectives • Describe the purpose and function of dynamic routing. • Configure RIPv2 dynamic routing. • Describe the use of exterior routing protocols across the Internet. • Enable BGP on a customer router.

3. Basics • Routers can be used to break network smaller • Subnet • To go from router to router • Routing table • Finds route to other networks • Statically set • Dynamically learned

4. The Routing Table • Router looks at destination IP & SM • ANDing the destination IP & SM • Result is a network # • Looks in table for the match & forwards it out that interface • No match= default route, if set • Routing Table has list of networks & paths

5. The Routing Table

6. Static Routes

7. Configuring the Static Route • ip route destination_networksubnet_masknext hop ip or outgoing int • R1(config) #ip route 192.168.16.0255.255.255.0192.168.15.1 What would be the static route on R2 to reach the ladies’ network? PT 6.1.1.5

8. Dynamic Routes Distance Vector

9. Dynamic Routing Protocols • Maintain tables when changes occur • Bad cables, interfaces go down, better route learned • Best route to a network in table • Removes routes when no longer valid • When all routers agree on topology= converged • Two routers can exchange these tables as long as they use the same protocol

10. Distance Vector Routing • Passes updates every so often to connected neighbors • Distance & Direction • Metric (hops, speed, reliability, etc)

11. Distance Vector Routing & Lab • Interface that leads to the connected network has a distance (metric) of 0 • Neighbors update each other & add on how far away it is Star is 2 away Star is 1 away Star is 0 away Star is 2 away

12. Practice • 6.1.2.4 • Activity for Routing Table • 6.1.2.5 Lab • Create a topology based on Routing Table

13. RIP: Distance Vector

14. RIP- Routing Information Protocol • DV • Metric is Hops • Only15 Max; 16 is unreachable (D) • Updates every 30 seconds by default • Sends entire routing table (D) • If change, update sent immediately (triggered) • Slow to converge whole network (D) • Administrative Distance is 120

15. RIP • RIPv1 • Doesn’t send subnet mask in updates • Classfull subnetting • RIPv2 • Classless subnetting

16. RIP

17. EIGRP: Distance Vector

18. EIGRP • Enhanced Interior Gateway Routing Protocol • Cisco proprietary DV (mix LS & DV) • AD of 90 • Many metrics (bandwidth, delay, load, reliability) • Up to 224 hops • Routing Table, Neighbor Table, Topology Table • Updates on start of router & only when a change happens • VLSM Support

19. EIGRP Tables • Neighbor Table • Has info about neighbor direct connect routers • Topology Table • Built from advertisements of its neighbors • Contains ALL routes advertised by neighbor routers • DUAL calculates the shortest path to a destination and installs it into the routing table • Is able to find the best alternate path quickly when a network change occurs • If no alternate route exists it asks its neighbors to find a new path to the destination

20. Dynamic Routes Link State

21. Link State Routing • Knows routes further away • LSA • Topological database • Info from LSAs • SPF • Each change causes new calc & database update • Map of network from point of view of the router • Info in tree is used to build the routing table

22. OSPF • AD of 110 • Metric is cost • Uses SPF • Sends updates only when the topology changes • Does not send periodic updates of the entire routing table • Fast convergence • Supports VLSM • Provides route authentication

23. Which to Use??????

24. DV vs. Link State

25. Summary of Routing Protocols

26. Routing • May be multiple routes to same path • Use AD (metrics) to pick best path • Lowest AD is best

27. Configuring RIP

28. Configure RIP • Router(config)#router rip • Router (config-router)#version 2 • Router(config-router)#network network-number

29. Verifying RIP • PT 6.1.5.3 • Lab 6.1.5.4 • Ping • Show ip route • Show ipprotocols • Debug ip rip

30. Show ip protocols output

31. Show ip route output Administrative Distance/metric; lower AD to a network=more trustworthy route

32. Problems with RIP

33. Exterior Routing Protocols

34. Autonomous Systems • A set of networks under one administration • An ISP & its customers • Has one routing policy in the AS • Each has unique AS# • Large businesses register their own AS

35. Activity

36. Routing Between AS • IGP runs within your network & between your routers • RIP, EIGRP, OSPF • EGP runs between different AS • Most common is BGP • Runs on border gateway routers • The router at the end of an AS • Finds the best path between AS

37. AS- Link

38. Routing Across Internet

39. Help from the ISP • Keep the Internet connection available • ISP provides backup routes & routers • ISP advertises routes to other AS • If route fails, sends an update with a backup route

40. ISP Handling of Traffic- Link • Local traffic • Stays within the AS • Transit traffic • Outside of AS to go in/through AS • Like detouring traffic from Rt.55 onto Tanyard Rd. • Could cause overflow of traffic • Can’t handle that much • AS may or may not allow this traffic

41. Configure the Border Gateway • Static Route to ISP • If router participates in the AS, configure BGP Lab 6.2.5 on PT

42. Review- 13 Questions

43. Fundamentals of Networking Discovery 2, Chapter 6 Routing