1. Class Agenda 10/17/15 Learning Objectives Unit 5: Presentation and Discussions Chapter 15-16: IP Troubleshooting and EIGRP Midterm Exams will be held the next Class. Lab Activities will be done in class. Assignments will be given in class. Break Times. 10 Minutes break in every 1 Hour. Note: Submit all Assignment and labs due today.

2. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: Unit 5: Slide 2 Unit 5 IP Troubleshooting and EIGRP Chapters 15 & 16 NT2640.U5.PS1

3. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: Unit 5: Slide 3 Objectives In this unit, students will demonstrate an: Understanding of the Host Networking Utilities Understanding of Host IP Routing Troubleshooting including Common Troubleshooting Commands Understanding of Router IP Routing Troubleshooting including Common Troubleshooting Commands Understanding of EIGRP including Neighbor Discovery and Establishment, Topology Exchange and Route Selection Processes Understanding of EIGRP Convergence Understanding of EIGRP Configuration and Verification Steps

4. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: Unit 5: Slide 4 IP Troubleshooting Chapter 15 NT2640-U5-PS1 Chapter 1 4

5. Troubleshooting IP Routing To troubleshoot a network, you need to know several pieces of information. You need to know how IP addressing works, how IP subnetting works, as well as IP routing, RIP-2, and many related protocols, like ARP and Ethernet. In other words, you need to know how all the network components work by themselves, and how they relate to each other. Before you can troubleshoot any networking problem, you need to know something about how networking protocols work. By this point, you should know a lot about IP addressing, IP routing, IP subnetting, RIP-2, and several related protocols and functions. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 5

6. IP Troubleshooting Tips and Tools Avoiding Reserved IP Addresses:  One of the first things to check when examining a networking problem is whether the IP addresses are reserved and should not be used as unicast IP addresses. These reserved addresses can be categorized into one of three groups:  Addresses that are always reserved  Two addresses that are reserved in each subnet  Addresses in two special subnets of each classful network, namely the zero subnet and broadcast subnet. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 6

7. The first category of reserved addresses includes two Class A networks that are always reserved, plus all Class D (multicast) and Class E (experimental) IP addresses. You can easily recognize these IP addresses based on the value of their first octet, as follows: 0 (because network 0.0.0.0 is always reserved) 127 (because network 127.0.0.0 is always reserved ) 224–239 (all Class D multicast IP addresses) 240–255 (all Class E experimental IP addresses) © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 7

8. The second category of reserved IP addresses includes the two reserved addresses inside each subnet. When subnetting, each subnet reserves two numbers—the smallest and largest numbers in the subnet—otherwise known as: The subnet number The subnet’s broadcast address © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 8

9. The third category of reserved IP addresses may or may not apply to a particular internetwork or question. For a given classful network, depending on several factors, the following two subnets may not be allowed to be used: The zero subnet The broadcast subnet © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 9

10. Summary of IP Addressing Tips Generally speaking, keep the following tips and facts in mind when you approach questions that include details about IP addresses:  1. Check the mask used on each device in the same LAN; if different, then the devices cannot have the same view of the range of addresses in the subnet.  2. On point-to-point WAN links, check the IP addresses and masks on both ends of the link, and confirm that the two IP addresses are in the same subnet.  3. When checking to confirm that hosts are in the same subnet, do not just examine the subnet number. Also check the subnet mask, and the implied range of IP addresses.  4. Be ready to use the commands to quickly find the IP addresses, masks, and subnet numbers. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 10

11. Host Networking Commands Routing: If the packet’s destination is on the same subnet, send the packet directly; if not, send the packet to the default gateway. Address assignment: Before sending any packets, the host may use DHCP client services to learn its IP address, mask, default gateway, and DNS IP addresses. The host could also be statically configured with these same details. Name resolution: When the user directly or indirectly references a host name, the host typically uses DNS name resolution requests to ask a DNS to identify that host’s IP address unless the host already has that information in its name cache. IP-to-MAC resolution: The host uses ARP requests to find the other host’s MAC address, or the default gateway’s IP address, unless the information is already in the host’s ARP cache. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 11

12. Microsoft Windows XP Network Command Reference CommandFunction ipconfig /allDisplays detailed IP configuration information for all interfaces, including IP address, mask, default gateway, and DNS IP addresses ipconfig /releaseReleases any DHCP-leased IP addresses ipconfig /renewAcquires an IP address and related information using DHCP nslookup nameSends a DNS request for the listed name arp –aLists the host’s ARP cache ipconfig /displaydnsLists the host’s name cache ipconfig /flushdnsRemoves all DNS-found name cache entries arp -dFlushes (empties) the host’s ARP cache netstat -rnDisplays a host’s routing table © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 12

13. Configuring Static IP Addresses on Windows XP © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 13

14. Troubleshooting Commands The most popular troubleshooting command on a router or switch is the ping command. Basically, the ping command sends a packet to another host, and the receiving host sends back a packet to the original host, testing to see if packets can be routed between the two hosts. Three additional Cisco IOS commands that can be useful when troubleshooting routing problems, namely the show ip arp, traceroute, and telnet commands. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 14

15. show ip arp Command Sample show ip arp Command Output R1#show ip arp Protocol Address Age Hardware Addr Type Interface Internet 172.16.1.1 8 0013.197b.2f58 ARPA FastEthernet0/0 Internet 172.16.1.253 - 0013.197b.5004 ARPA FastEthernet0/0 Internet 172.16.2.253 - 0013.197b.5005 ARPA FastEthernet0/1 © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 15

16. The “traceroute” Command The Cisco IOS traceroute command, like the Cisco IOS ping command, tests the route between a router and another host or router. However, the traceroute command also identifies the IP addresses of the routers in the route. Internetwork Used in traceroute Example © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 16

17. Telnet and Suspend Many engineers troubleshoot network problems sitting at their desks. To get access to a router or switch, the engineer just needs to use Telnet or SSH on their desktop PC to connect to each router or switch, oftentimes opening multiple Telnet or SSH windows to connect to multiple devices. As an alternative, the engineer could connect to one router or switch using a Telnet or SSH client on their desktop computer, and then use the telnet or ssh Cisco IOS EXEC commands to connect to other routers and switches. These commands acts as a Telnet or SSH client, respectively, so that you can easily connect to other devices when troubleshooting. When finished, the user could just use the exit command to disconnect the Telnet or SSH session. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 17

18. Scenario 3: Incomplete Network Diagram © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 18

19. Show Commands The show users command lists all users logged into the router on which the command is used. This command lists all sessions, including users at the console, and those connecting using both Telnet and SSH. The show ssh command lists the same kind of information, but only for users that connected using SSH. Note that these commands differ from the show sessions command, which lists suspended Telnet/SSH sessions from the local router to other devices. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 19

20. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: : Unit 1: Slide 20 Check Point 1.List two reserved addresses 2.Describe the mechanics of the traceroute utility 3.Describe a basic IP troubleshooting process 4.Describe what information is displayed with the MS Windows “ipconfig /all” utility 5.What protocols resolves IP address to MAC addresses?

21. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: : Unit 1: Slide 21 Break 10 Min.

22. Chapter 16 EIGRP NT2640-U5-PS2 © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: Unit 5: Slide 22

23. Open Short Path First (OSPF) OSPF is an interior gateway routing protocol OSPF propagates link-state advertisements rather than routing table updates. Because only LSAs are exchanged instead of the entire routing tables, OSPF networks converge more quickly than RIP networks. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 23

24. OSPF OSPF uses a link-state algorithm to build and calculate the shortest path to all known destinations. The advantages of OSPF: OSPF link-state database is updated instantly rather than gradually as stale information is timed out © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 24

25. EIGRP EIGRP is an enhanced version of IGRP developed by Cisco. Unlike IGRP and RIP, EIGRP does not send out periodic route updates. EIGRP updates are sent out only when the network topology changes. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 25

26. EIGRP Key capabilities that distinguish EIGRP from other routing protocols include: fast convergence, support for variable-length subnet mask, support for partial updates, and support for multiple network layer protocols. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 26

27. EIGRP Concepts and Operation Like OSPF, EIGRP follows three general steps to be able to add routes to the IP routing table:  Neighbor discovery: EIGRP routers send Hello messages to discover potential neighboring EIGRP routers and perform basic parameter checks to determine which routers should become neighbors.  Topology exchange: Neighbors exchange full topology updates when the neighbor relationship comes up, and then only partial updates as needed based on changes to the network topology. Choosing routes: Each router analyzes its respective EIGRP topology tables, choosing the lowest-metric route to reach each subnet. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 27

28. EIGRP Neighbors An EIGRP neighbor is another EIGRP-speaking router, connected to a common subnet, with which the router is willing to exchange EIGRP topology information. EIGRP uses EIGRP Hello messages, sent to multicast IP address 224.0.0.10, to dynamically discover potential neighbors. A router learns of potential neighbors by receiving a Hello. Routers perform some basic checking of each potential neighbor before that router becomes an EIGRP neighbor. A potential neighbor is a router from which an EIGRP Hello has been received. Then the router checks the following settings to determine if the router should be allowed to be a neighbor: © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 28

29. Exchanging EIGRP Topology Information EIGRP uses EIGRP Update messages to send topology information to neighbors. Update messages can be sent to multicast IP address 224.0.0.10 if the sending router needs to update multiple routers on the same subnet; otherwise, the updates are sent to the unicast IP address of the particular neighbor.  (Hello messages are always sent to the 224.0.0.10 multicast address.) Unlike OSPF, there is no concept of a Designated Router (DR) or Backup Designated Router (BDR), but the use of multicast packets on LANs allows EIGRP to exchange routing information with all neighbors on the LAN efficiently. The update messages are sent using Reliable Transport Protocol (RTP). The significance of RTP is that, like OSPF, EIGRP resends routing updates that are lost in transit. By using RTP, EIGRP can better avoid loops. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 29

30. EIGRP Summary and Comparisons with OSPF EIGRP is a popular IGP for many reasons. It works well, converging quickly while avoiding loops as a side effect of its underlying balanced hybrid/advanced distance vector algorithms. It does not require a lot of configuration or a lot of planning, even when scaling to support larger internetworks. EIGRP also has another advantage that is not as important today as in years past: the support of Novell’s IPX and Apple’s AppleTalk Layer 3 protocols. Routers can run EIGRP to learn IP routes, IPX routes, and AppleTalk routes, with the same wonderful performance features. However, like many other Layer 3 protocols, IP has mostly usurped IPX and AppleTalk, making support for these Layer 3 protocols a minor advantage. © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 30

31. EIGRP as compared to OSPF Table 16-1 EIGRP Features Compared to OSPF FeatureEIGRPOSPF Converges quicklyYes Built-in loop preventionYes Sends partial routing updates, advertising only new or changed information Yes Classless; therefore, supports manual summarization and VLSMYes Allows manual summarization at any routerYesNo Sends routing information using IP multicast on LANsYes FeatureEIGRPOSPF Uses the concept of a designated router on a LANNoYes Flexible network design with no need to create areasYesNo Supports both equal-metric and unequal-metric load balancingYesNo Robust metric based on bandwidth and delayYesNo Can advertise IP, IPX, and AppleTalk routesYesNo Public standardNoYes © 2011 ITT Educational Services Inc. NT-2640 Wan Technologies: Unit 5: Slide 31

32. © 2011 ITT Educational Services Inc. NT-2640 Advanced Networking: : Unit 1: Slide 32 Break 10 Min.