Routing protocols

1. Routing protocols Chapter 12 Intro to Routing & Switching

2. objectives • Upon completion of this chapter, you should be able to: • Read a routing table • Configure a static route • Compare & contrast distance vector and link state routing protocols • Describe & configure RIPv1 & v2 • Describe & configure EIGRP • Describe & configure OSPF

3. 12.1 routing

4. 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

5. 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

6. The Routing Table

7. Reading The routing table

8. activity • Routing Table Homework

9. 12.2 Static routes

10. Static route • You telling the router: • “To get to this network, go this way!” • Used so routers do less “thinking” or when there’s only one way out of a network • Stub networks or small networks • Same as default route config, but replacing quad zero with destination network address

11. 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?

12. activity • Handout: Create static routes • Complete the PT lab together • Configure default and static routes

13. 12.3 Dynamic routes:distance vector routing protocols

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occur • Bad cables, interfaces go down, better route learned • Best route to a network in table • Removes routes when no longer valid • When all routers agree on topology= converged • Two routers can exchange these tables as long as they use the same protocol

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

16. Distance Vector Routing update metric • Directly connected network has an administrative distance 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

17. activity • 6.1.2.4 • Activity for Routing Table • Do together on SmartBoard • Create a Diagram from Routing Tables • On paper • In groups of 2, create a topology based on Routing Table

18. 12.4 rip:distance vector routing protocol

19. rip • 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

20. RIP • RIPv1 • Doesn’t send subnet mask in updates • Classfulsubnetting • RIPv2 • Classless (VLSM) subnetting • Supports authentication • Otherwise, same as v1

21. RIP

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

23. Verifying RIP • Ping • Show ip route • Show ipprotocols • Debug ip rip

24. Show ip protocols output

25. Disadvantages of RIP • Increased traffic every 30 seconds • Max hop count of 15 • Further away is unreachable • Only considers hops, not speed • Possible routing loops

26. activities • Configure RIP • In groups of 2, using the handout • PT Lab Configure & Verify RIP • Use our in class PT lab to configure RIP & verify it. • RIP Homework

27. Review- 5q • What routing protocol uses hops for its metric and understands classless routing? • RIPv2 • What is the AD of RIP? • 120 • What’s the purpose of entering your router’s network numbers when configuring RIP? • To tell it what networks to advertise in updates • A directly connected network has an AD of… • 0 • A static route has an AD of… • 1

28. 12.5 eigrp:enhanced dvrouting protocol

29. EIGRP • Enhanced Interior Gateway Routing Protocol • Cisco proprietary DV (mix LS & DV) • AD of 90 • Many metrics (bandwidth, delay, load, reliability) • Up to 255 hops • Routing Table, Neighbor Table, Topology Table • Updates on start of router & only when a change happens • VLSM Support

30. Configure eigrp • R1(config)#router eigrp 100 • R1(config-router)#network 192.168.1.193 • Autonomous System # • Must be the same on all routers in the network

31. Configure eigrp

32. 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 best 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

33. Verify eigrp • Show ip route • Show ipeigrp neighbors

34. Review- 4q • How do you configure EIGRP? • Router eigrp as • When viewing the routing table, what letter indicates an EIGRP route? • D • What 4 metrics are used for EIGRP? • Bandwidth, load, delay, reliability • What algorithm calculates the best path for EIGRP? • DUAL

35. activity • EIGRP Configuration Lab

36. test • Static route • RIP • EIGRP

37. 12.6 ospf:link staterouting protocol

38. Link state routing

39. Link state routing

40. Link State Routing review • Knows all routes in your network • Sends out LSA • Makes a Topological database • With info from LSAs • Uses the SPF algorithm • 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 • Adds best path to routing table

41. What is ospf? • Most popular interior routing protocol • Multi-vendor • Unlike Cisco’s EIGRP • Link-state • Knows map of whole network • Routing updates ONLY when change occurs

42. All about ospf • Uses SPF algorithm • Sends updates only when the topology changes • Does not send periodic updates of the entire routing table • AD of 110 • Metric is cost (bandwidth) • Fast convergence, no loops • Supports VLSM/classless addressing • Provides route authentication • Multi-vendor (unlike EIGRP)

43. Ospf databases • Neighbor table • List of neighbor routers • Unique to each router • Topology table • Represents the whole network • All routers have same one • Routing Table • Routes

44. The router id • Tells neighbors who they are • Is an IP address as follows: • Highest IP address on a loopback interface (virtual bc it never goes down) • No loopback= highest IP of active interfaces • Or assigned manually

45. Hello packets • Used to establish & maintain adjacency • Helps elect Designated Router & BDR • Sent every 10 seconds to 224.0.0.5 • Dead after 40 seconds • To form adjacency: • Hello, dead interval & area # must match

46. A problem?

47. Dr/bdr election • One DR/BDR per multi-access area (switch) • All routers will form a full neighbor adjacency with the DR • Link updates sent to DR/BDR • Then forwards to other routers • Reduces LSA flood/traffic • Chosen by Priority # • Highest is DR, next highest is BDR • Tie breaker is highest Router ID • Default on router is 1; 0 means NEVER!

48. How ospf works

49. Ospf areas • OSPF works with the concepts of areas • Keeps the map of network smaller if you break it up into areas • By default you will always have a single area • Normally this is area 0 • You can have multiple areas • They all connect to area 0 (the backbone) • See picture…

50. Review- 4q • Area 0 is also known as what? • Backbone area • If multiple areas are used, where must they all connect to? • Area 0 • What do you know about link state protocols? • Know whole topology, calculates shortest path, updates when change happens • To maintain connectivity to neighbors, what do OSPF routers send? • Hello packets