Configuring EIGRP

1. Configuring EIGRP BSCI Module 2-1 – Introduction to EIGRP

2. Objectives • This module will cover topics which allow students to meet the following objectives: • Describe the key capabilities that distinguish EIGRP from other routing protocols • Identify the four key technologies employed by EIGRP • Describe how EIGRP operates • Describe the five components of the metric used by EIGRP • Calculate the EIGRP metric for a range of pathways between routers • Explain how IGRP routes are integrated into EIGRP routes and vice-versa

3. Purpose of this Lesson Coverage of topics new to the “EIGRP” module of BSCI. • What’s new in this module? • EIGRP metric calculations for pathway ranges between routers.

4. EIGRP Features There are several key differences with EIGRP from other routing protocols which are explored in this module.

5. EIGRP Key Technologies • Neighbor discover/recovery • Reliable Transport Protocol (RTP) • DUAL finite-state machine • Protocol-dependent modules (PDMs)

6. The Diffusing Update Algorithm (DUAL) • How does EIGRP determine which routes are loop-free? • Each of A’s neighbors is reporting reachability to E: • B with a cost of 10 • C with a cost of 10 • D with a cost of 30 • These three costs are called the reported distance (RD); the distance each neighbor is reporting to a given destination

7. 20 through B • 25 through C • 45 through D The Diffusing Update Algorithm (DUAL) • At A, the total cost to reach E is: • The best of these three paths is the path through B, with a cost of 20 • This is the feasible distance (FD) • The route with the best FD is known as the “Successor” • All next best routes are known as “Feasible Successors”

8. The Diffusing Update Algorithm (DUAL) • A uses the FD and the RD to determine which paths are loop-free • The best path (FD) is used as a benchmark; all paths with RDs lower than the FD cannot contain loops • The algorithm may mark some loop-free paths as loops • However, it is guaranteed never to mark a looped path as loop-free

9. The Diffusing Update Algorithm (DUAL) • At A: • The path through B is the best path (FD), at 20 • C can reach E with a cost of 10; 10 (RD) is less than 20 (FD), so this path is loop-free. • D can reach E with a cost of 30; 30 (RD) is not less than 20 (FD), so EIGRP assumes this path is a loop.

10. EIGRP Topology Table

11. Seconds Remaining Before Declaring Neighbor Down How Long Since the Last Time Neighbor Was Discovered How Long It Takes for This Neighbor To Respond To Reliable Packets How Long to Wait Before Retransmitting If No Acknowledgement EIGRP Neighbor Status RTRA#showip eigrp neighbors IP-EIGRP neighbors for process 1 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 2 10.1.1.1 Et0 12 6d16h 20 200 0 233 1 10.1.4.3 Et1 13 2w2d 87 522 0 452 0 10.1.4.2 Et1 10 2w2d 85 510 0 3

12. EIGRP IP Routing Table

13. Example: EIGRP Tables Router C’s tables:

14. EIGRP Packets • Hello: Establish neighbor relationships. • Update: Send routing updates • Query: Ask neighbors about routing information • Reply: Respond to query about routing information • ACK: Acknowledge a reliable packet

15. Initial Route Discovery

16. EIGRP Metric • Same metric components as IGRP: • Bandwidth • Delay • Reliability • Loading • MTU • EIGRP metric is IGRP metric multiplied by 256

17. EIGRP Metric Calculation • By default, EIGRP metric: • Metric = bandwidth (slowest link only) + delay (sum of delays) • Delay = sum of the delays in the path, in tens of microseconds, multiplied by 256. • Bandwidth = [(10^7) / (minimum bandwidth link along the path, in kilobits per second)] * 256 • Formula with default K values (K1 = 1, K2 = 0, K3 = 1, K4 = 0, K5 = 0): • Metric = [K1 * BW + ((K2 * BW) / (256 – load)) + K3 * delay] • If K5 not equal to 0: • Metric = Metric * [K5 / (reliability + K4)]

18. EIGRP Metrics Calculation Example A  B  C  D Least bandwidth 64 kbps Total delay 6,000 A  X  Y  Z  D Least bandwidth 256 kbps Total delay 8,000 • Delay is the sum of all the delays of the links along the paths:Delay = [delay in tens of microseconds] x 256 • BW is the lowest bandwidth of the links along the paths:BW = [10,000,000 / (bandwidth in kbps)] x 256

19. EIGRP Metrics Are Backward-Compatible with IGRP

20. Summary • EIGRP capabilities include fast convergence and support for VLSM, partial updates, and multiple network layer protocols. • EIGRP key technologies are: neighbor discovery/recovery, RTP, DUAL finite-state machine, and protocol-dependent modules. • EIGRP uses three tables: neighbor table, topology table, and routing table. The routing table contains the best route to each destination, called the successor route. A feasible successor route is a backup route to a destination; it is kept in the topology table. • EIGRP uses the same metric components as IGRP: delay, bandwidth, reliability, load, and MTU. • By default, EIGRP metric = bandwidth (slowest link) + delay (sum of delays).  • EIGRP metrics are backward-compatible with IGRP; the EIGRP-equivalent metric is the IGRP metric multiplied by 256.

21. Self Check • What is a reported distance? • What is a feasible distance? • EIGRP uses three tables: name the three tables: __________, ____________, _____________. Which of the tables contains the best route or successor route to each destination? • EIGRP uses what metrics? __________, _________, _________, __________, ___________

22. Resources • http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009405c.shtml • http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml

23. Q and A

25. Configuring EIGRP BSCI Module 2-2 – Implementing and Verifying EIGRP

26. Objectives • Upon completing this lesson, you will be able to describe how to implement EIGRP routing. This ability includes being able to meet these objectives: • Describe the commands used in a basic EIGRP configuration task • Explain how to configure a router to use wildcard masks to select the interfaces and networks that will participate in EIGRP routing • Configure the gateway of last resort or default route • Verify that the router recognizes EIGRP neighbors and routes • Verify EIGRP operations

27. Purpose of this Lesson Coverage of topics new to the “EIGRP” module of BSCI. • What’s new in this module? • Describe the commands used in a basic EIGRP configuration task • Explain how to configure a router to use wildcard masks to select the interfaces and networks that will participate in EIGRP routing • Configure the gateway of last resort or default route.

28. Configuring EIGRP Router(config)# router eigrp autonomous-system-number • Defines EIGRP as the IP routing protocol. • All routers in the internetwork that must exchange EIGRP routing updates must have the same autonomous system number. Router(config-router)# network network-number [wildcard-mask] • Identifies attached networks participating in EIGRP. • The wildcard-mask is an inverse mask used to determine how to interpret the address. The mask has wildcard bits, where 0 is a match and 1 is “don’t care.”

29. Configuring EIGRP (Cont.) Router(config-if)# bandwidth kilobits • Defines the interface’s bandwidth for the purposes of sending routing update traffic.

30. Configuring EIGRP for IP Network 192.168.1.0 is not configured on router A,because it is not directly connected to router A.

31. Configuring EIGRP with IP (cont.) What’s wrong with this? Classful configuration example: routerA(config)#router eigrp 109 routerA(config-router)#network 10.1.0.0 routerA(config-router)#network 10.4.0.0 routerA(config-router)#network 172.16.7.0 routerA(config-router)#network 172.16.2.0 Classless configuration example: routerA(config)#router eigrp 109 routerA(config-router)#network 10.1.0.0 0.0.255.255 routerA(config-router)#network 10.4.0.0 0.0.255.255 routerA(config-router)#network 172.16.2.0 0.0.0.255 routerA(config-router)#network 172.16.7.0 0.0.0.255

32. Using the Wildcard Mask in EIGRP

33. Using and Configuring the ip default-network command for EIGRP

34. Example R1 EIGRP Configuration

35. R2 EIGRP Configuration <output omitted> interface FastEthernet0/0 ip address 172.17.2.2 255.255.255.0 <output omitted> interface Serial0/0/1 bandwidth 64 ip address 192.168.1.102 255.255.255.224 <output omitted> router eigrp 100 network 172.17.2.0 0.0.0.255 network 192.168.1.0

36. EIGRP Manual Summarization • Automatic summarization of routes at the major classful boundary is a characteristic of distance vector operations. • With EIGRP you can disable automatic summarization and create one or more summary routes within the network on any bit boundary as long as a more specific route exists in the routing table. • When a more specific route no longer exists the summary route is removed from the routing table.

37. EIGRP Summarization • In the routing table, summary routes are automatically assigned to interface null0 to prevent routing loops. • This is also true for manual summarization • If the summarizing router receives a packet for a destination that is included in the summary route but is unknown by the router, the router will send it to the null interface – drops the packet. • For manual summarization to be effective, blocks of contiguous addresses (subnets) must come together at a common router so that the router can advertise a single summary route.

38. Configuring Summary Routes • Summary routes are manually configured at the interface. if)# ip summary-address eigrp [as number] [network] [subnet mask] • Remember, these are summary addresses that your router is summarizing • Summary addresses also cut down on the number of eigrp queries.

39. Verifying EIGRP: show ip eigrp neighbors R1#show ip eigrp neighbors IP-EIGRP neighbors for process 100 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 5 R1#

40. Verifying EIGRP: show ip route eigrp R1#show ip route eigrp D 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:07:01, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:05:13, Null0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks D 192.168.1.0/24 is a summary, 00:05:13, Null0 R1#show ip route <output omitted> Gateway of last resort is not set D 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:06:55, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:05:07, Null0 C 172.16.1.0/24 is directly connected, FastEthernet0/0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks C 192.168.1.96/27 is directly connected, Serial0/0/1 D 192.168.1.0/24 is a summary, 00:05:07, Null0

41. Verifying EIGRP: show ip protocols R1#show ip protocols Routing Protocol is "eigrp 100" Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 EIGRP maximum hopcount 100 EIGRP maximum metric variance 1 Redistributing: eigrp 100 EIGRP NSF-aware route hold timer is 240s <output omitted> Maximum path: 4 Routing for Networks: 172.16.1.0/24 192.168.1.0 Routing Information Sources: Gateway Distance Last Update (this router) 90 00:09:38 Gateway Distance Last Update 192.168.1.102 90 00:09:40 Distance: internal 90 external 170

42. Verifying EIGRP: show ip eigrp interfaces R1#show ip eigrp interfaces IP-EIGRP interfaces for process 100 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Fa0/0 0 0/0 0 0/10 0 0 Se0/0/1 1 0/0 10 10/380 424 0

43. Verifying EIGRP: show ip eigrp topology R1#show ip eigrp topology IP-EIGRP Topology Table for AS(100)/ID(192.168.1.101) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 192.168.1.96/27, 1 successors, FD is 40512000 via Connected, Serial0/0/1 P 192.168.1.0/24, 1 successors, FD is 40512000 via Summary (40512000/0), Null0 P 172.16.0.0/16, 1 successors, FD is 28160 via Summary (28160/0), Null0 P 172.16.1.0/24, 1 successors, FD is 28160 via Connected, FastEthernet0/0 P 172.17.0.0/16, 1 successors, FD is 40514560 via 192.168.1.102 (40514560/28160), Serial0/0/1

44. Verifying EIGRP: show ip eigrp traffic R1#show ip eigrp traffic IP-EIGRP Traffic Statistics for AS 100 Hellos sent/received: 429/192 Updates sent/received: 4/4 Queries sent/received: 1/0 Replies sent/received: 0/1 Acks sent/received: 4/3 Input queue high water mark 1, 0 drops SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0 Hello Process ID: 113 PDM Process ID: 73

45. Summary • The configuration commands for basic EIGRP include: • router eigrp autonomous-system • network network-number [wildcard-mask] • bandwidth kilobits • The optional wildcard-mask parameter in the network command is an inverse mask used to determine how to interpret the network-number. A wildcard bit of 0 is a match and of 1 is “don’t care”. • Create and advertise a default route in an EIGRP autonomous system with the ip default-network network-number command.

46. Summary (cont.) • Use the show ip eigrp neighbors command to verify that the router recognizes its neighbors. Use the show ip route eigrp command to verify that the router recognizes routes from its neighbors. • Use the show ip protocols, show ip eigrp interfaces, show ip eigrp neighbors, show ip eigrp topology, and show ip eigrp traffic commands to verify EIGRP operations. • .

47. Activity • Create a simple network using EIGRP as your routing protocol. These steps were discussed at the beginning of this module. • Verify your connections by running the show commands discussed in the module: • show ip protocols, show ip eigrp interfaces, show ip eigrp neighbors, show ip eigrp topology, and show ip eigrp traffic • Reflection: Are your routes displayed correctly in the routing table and identified as both directly connected or EIGRP?

48. Self Check • Which show command verifies the router can recognize its neighbors? • Show ip route eigrp has what function? • What command establishes EIGRP as the routing protocol? • Identify the command to create and advertise a default route in an EIGRP autonomous system.

49. Resources • http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008009405c.shtml • http://www.cisco.com/en/US/products/sw/iosswrel/ps1828/products_command_reference_chapter09186a00800ca5a9.html • http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f07.shtml • .

50. Q and A