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Fundamentals of Networking Discovery 2, Chapter 6 Routing.

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Presentation on theme: "Fundamentals of Networking Discovery 2, Chapter 6 Routing."— Presentation transcript:

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


7 Configuring the Static Route ip route destination_network subnet_mask next hop ip or outgoing int R1(config) #ip route What would be the static route on R2 to reach the ladies’ network? PT


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occur ▫ Bad cables, interfaces go down, better route learned ▫ Best route to a network in table ▫ Removes routes when no longer valid When all routers agree on topology= converged Two routers can exchange these tables as long as they use the same protocol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 0 away Star is 1 away Star is 2 away

12 Practice ▫ Activity for Routing Table Lab ▫ Create a topology based on Routing Table


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


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


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 ProtocolDV or LSADMetricFeatures RIP v1DV120Hops 15 hops max RIP v2DV120Hops 15 max; VLSM EIGRP DV- Hybrid 90 Bandwidth, Load, Delay, Reliability Cisco’s; VLSM OSPFLS110Cost Multi- vendor; VLSM

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


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

29 Verifying RIP Ping Show ip route Show ip protocols Debug ip rip PT Lab

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


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- LinkLink

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- LinkLink 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

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