cdp and managing cdp

8/8/2019 Cdp and Managing Cdp

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Lab: USING CISCO DISCOVERY PROTOCOL ANDMANAGING CISCO DEVICES

Lab Summary

Lab Summary

vLab Title 336313 USING CISCO DISCOVERY PROTOCOL AND MANAGING CISCODEVICES

Skills By completing this lab, you will be able to:Use show commands to verify CDP settings.Use a show command to verify which interfaces have CDP enabled.

Use a show command to verify directly connected Cisco devices.Use a show command to verify layer three addressing information of neighboringdevices.Disable CDP on specific interfaces.Disable CDP globally on a router.Copy a configuration stored on a TFTP into a router's running configuration.Copy a configuration stored on a TFTP into a router's startup configuration.Verify CPU utilization using a show command.Enter a debug command to view underlying ICMP messages.Enter a debug command to view underlying routing messages.

Level Of Difficulty BasicCourse ICND1Lab Length 60 minutesCertification CCENTDesired Learner Outcome You will gain the skills required for the practical portion of the CCENT certification and

will be able to configure small Cisco networks.Desired Network Outcome Working through these labs, you will gain hands-on experience and practice in

implementing and operating a simple Cisco network that includes real switches,routers, and remote access technologies.

Dependencies Author Trey McMahonVendor

Network Type Cisco SPV2Technology CiscoReferences Cisco Systems, Interconnecting Cisco Network Devices 1, Cisco Systems,

Inc., Cisco authorized courseware for CCNA certification.James Boney, Cisco IOS In a Nutshell, O'Reilly, A Desktop Quick Reference for IOSon IP Networks

Lab Scenario

Scenario

Quick Start InstructionsAssignmentStoryConditionsNotesDiagram


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Quick Start Instructions

Once a lab has finished initializing, click on the Sample Solution link if one is available. For performance based labs, SampleSolution will not be available. IT IS IMPORTANT TO WAIT UNTIL AFTER INITIALIZATION BEFORE GOING TO THESAMPLE SOLUTION. The reason is that during initialization, you are assigned custom IP addresses that are dynamically

added to your lab instructions. This makes the lab easier to follow than the traditional method of trying to look up pod-specific information in tables. After initialization, the Sample Solution will have the correct information for your gear.

To console into the routers and switches mentioned in the lab steps, click on the network diagram shown on the main page.

Once you have completed a lab, if you have additional time and wish to take it again, go to the Device Controls link and clickon Reload. When the devices are ready, you can start the lab again.

Assignment

Gain skills required for the practical portion of the CCENT certification:Once the lab is finished initializing, click on the Sample Solution link. IT IS IMPORTANT TO WAIT UNTIL AFTERINITIALIZATION BEFORE GOING TO THE SAMPLE SOLUTION. The reason is that during initialization, you are assignedcustom IP addresses that are dynamically added to your lab instructions. This makes the lab easier to follow than thetraditional method of trying to look up pod-specific information in tables. After initialization, the Sample Solution will have thecorrect information for your gear.

To console into the routers and switches mentioned in the lab steps, click on the network diagram shown on the main page.

Once you have completed the lab, if you have additional time and wish to take it again, go to the Device Controls link andclick on Reload. When the devices are ready, you can start the lab again.

Story

N/A

Conditions

The devices in blue on the diagram are the routers and switches that you have control over. The devices in green are coredevices with fixed configurations which play the role of the service provider. All of the devices that you access through vLabare real Cisco routers and switches. Nothing is simulated.

Notes

After taking a vLab for the first time using the Sample Solution, try the Suggested Approach link for a challenge.

You've got a number of tools available on the left bar of the main page to aid you in your lab. Here are brief notes on each.

Summary:lab length, title, book references

Suggested Approach:

contains WHAT to do, but not HOW to do it; use this if you have already completed the lab once and wish to test your

mastery in a second attempt

Sample Solution:

start here when taking the lab for the first time; explanations of the WHY behind your configurations are given when needed;you can also print this out from home to use as a study guide for the CCENT certification

Check Results:since the labs already have built-in verification steps, baseline configurations are found here for reference

Device Controls:


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place a check next to each device; clicking Reload will make the gear ready to take a lab again or to take a new lab; if youbecome disconnected, clicking clearline will allow you to reconnect without losing your configurations

Diagram

Suggested Approach

Suggested Approach

The Suggested Approach steps are provided to test your mastery when taking a vLab for the second time. For your firstattempt, follow the steps listed under Sample Solution.

USING CISCO DISCOVERY PROTOCOL AND MANAGING CISCO DEVICES

1) Console into R2. Enable interface s1/0.

2) Console into R1. Enable interfaces s1/1 and s1/2.

3) On R1, verify that Cisco Discovery Protocol is enabled and that CDP packets are being sent every 60 seconds using ashow command.

4) On R1, enter a show command that lists all of the interfaces currently running CDP.

5) Enter a show command that lists R1s directly connected Cisco neighboring devices.

6) Enter a show command on R1 that will list the IP address configured on R2.

7) Enter a show command on R1 that will list the IP addresses for all directly attached Cisco devices.

8) Disable CDP on R1s s1/2 interface.

9) Enter a command on R1 that shows counters for CDP packets sent and received.

10) Enter a command on R1 that disables CDP entirely.

11) Enter a command on R1 that shows the current configuration register setting.

12) On R1, verify which files are located in flash.

13) Enable RIPv2 on R1. Disable auto-summarization and advertise networks 10.0.0.0 and 172.41.0.0.

14) From R1, ping: 100.100.100.100


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15) On R1, copy the file: lab14-r1 into the running configuration of R1. The TFTP server address is: 100.100.100.100

16) On R1, exit out of the router and then return to privileged mode.

17) On R1, copy the file: lab14-r1 into the startup configuration of R1. The TFTP server address is: 100.100.100.100

18) Enter a show command to view R1s startup configuration stored in NVRAM.

19) On R1, enter a show command to display information about the routers CPU utilization.

20) On R1, enter the undebug all command.

21) On R1, enter a show command to verify that no debugs are currently running.

22) On R1, enter a debug command to view ICMP messages being exchanged as they occur.

23) Since you do not see any output from the debug, enter a show command to verify that a debug is running on R1.

24) From R1, ping: 100.100.100.100

25) From R1, enable debugging for the RIP routing process.

26) Using a show command, verify that ICMP and RIP debugs are concurrently running on R1.

27) On R1, disable both debugs with a single command.

28) You have finished the lab.

Sample Solution

Sample Solution

Task Index

Task 1 USING CISCO DISCOVERY PROTOCOL AND MANAGING CISCO DEVICES

Task 1

USING CISCO DISCOVERY PROTOCOL AND MANAGING CISCO DEVICES

Step 1 : Console into R2. Enable interface s1/0.Action:

r2> enabler2# config t

r2(config)# interface s1/0r2(config-if)# no shut

r2(config-if)#

Result:


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Anytime you see a device blinking, it is a reminder to console into a new device.

Step 2 : Console into R1. Enable interfaces s1/1 and s1/2.Action:

r1> enabler1# config t

r1(config)# interface s1/1r1(config-if)# no shutr1(config-if)# interface s1/2r1(config-if)# no shut

r1(config-if)#

Result:

Anytime you see a device blinking, it is a reminder to console into a new device.

Step 3 : On R1, verify that Cisco Discovery Protocol is enabled and that CDP packets are being sent every 60 seconds using show command.Action:

r1(config-if)# endr1# show cdp

r1#

Result:

Explanation:The show cdp command displays global CDP settings. CDP can be enabled or disabled globally. If it is enabled globally, it then can bdisabled on a per interface basis. CDP allows for the discovery of directly connected Cisco devices.

Step 4 : On R1, enter a show command that lists all of the interfaces currently running CDP.Action:

r1# show cdp interface

r1#

Result:

Explanation:The show cdp interface command shows every interface on the Cisco device that has CDP enabled. If CDP is disabled on particular

interface, it drops from the list. Shutting down an interface, however, does not exclude it from the list.

Step 5 : Enter a show command that lists R1s directly connected Cisco neighboring devices.Action:

r1# show cdp neighbors

r1#

Result:

You should see sw1 and r2. The device in the core network has CDP disabled, so it will not appear in the list. The Local Interface is thinterface on R1 that it uses to reach the neighboring device. The Port ID is the remote interface on the neighboring device.

Explanation:

In order for a device to appear on the list the connection to it must have the status of up/up. The first up refers to the physical layer, lay


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1, and the second up refers to the data link layer, layer 2. CDP runs at layer 2.

Step 6 : Enter a show command on R1 that will list the IP address configured on R2.Action:

r1# show cdp entry r2r1#

Result:The name r2 is case-sensitive. You could see that r2 was lower-case when you previously entered the show cdp neighbors commanEntering show cdp entry R2 would be invalid.

Explanation:You should see that the address listed for r2 is 10.4.0.2, the router is a Cisco 2811, and the IOS version running on the neighboring rois 12.4

Step 7 : Enter a show command on R1 that will list the IP addresses for all directly attached Cisco devices. Action:

r1# show cdp neighbor detail

r1#

Result:This command and the show cdp entry command lists the layer 3 networking addresses configured on the neighboring devices. This

includes more than just IP. For instance, if r2 had an IPX address or an AppleTalk address, it would be found under the Entry addressheading instead.

Explanation:If this output looks familiar it is because it is exactly the same information that you saw with the show cdp entry r2 command. The ondifference is that the show cdp neighbors detail command lists the information for all devices instead of just one.

Step 8 : Disable CDP on R1s s1/2 interface.Action:

r1# config tr1(config)# interface s1/2r1(config-if)# no cdp enable

r1(config-if)#

Result:

In this scenario, interface s1/2 is the network connection to the service provider.

Explanation:

CDP allows you to potentially diagram an entire topology. It tells you exactly what each interface connects to and the IP address of theremote device, but it only can see as far as what is directly connected. With the remote IP address, however, you can then telnet to thadevice and enter the show commands again to discover what it is directly connected to. The downside to this is that hackers can also u

this information. Therefore, it is safer to disable CDP on the interfaces that connect your network to the outside world. If interface s1/2were the connection to the service provider, theres no good reason for broadcasting CDP information out that interface.

Step 9 : Enter a command on R1 that shows counters for CDP packets sent and received.Action:

r1(config-if)# end

r1# show cdp traffic


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r1#

Result:

Explanation:This command shows the total number of CDP messages sent and received, along with other statistical information such as CDPmessage failures and the cause of those failures.

Step 10 : Enter a command on R1 that disables CDP entirely.Action:

r1# config t

r1(config)# no cdp runr1(config)#

Result:The CDP commands demonstrated in this lab can be entered on Cisco switches as well.

Explanation:

Some administrators increase their security even higher by disabling CDP altogether. The downside to this is that they lose a valuable

troubleshooting tool.

Step 11 : Enter a command on R1 that shows the current configuration register setting. Action:

r1(config)# endr1# show versionr1#

Result:

The configuration register is listed at the bottom of the output.

Explanation:

By default, the configuration register is set to 0x2102. The 0x indicates that it is a number in hexadecimal. The configuration register isbits long. Each number that you see after 0x represents 4 bits. Depending on whether or not particular bits are turned on or off, it canchange the behavior of the router. For instance, if this router supported RxBoot, the mini-IOS used for recovery, it could be accessed ilast number were set to 1 instead of 2.

Step 12 : On R1, verify which files are located in flash.Action:

r1# show flash

r1#

Result:

A number of support files may be found in flash. The most important file found in flash is the IOS image. It will typically end in the .bin

extension, indicating it is a Cisco IOS binary file. It is possible to have multiple IOS images stored in flash, each with different versionnumbers or feature sets.

Explanation:

The first .bin file found in flash will be loaded as the IOS image. If multiple IOS images exist, you can use a boot system command tochoose the image that will be loaded.

Step 13 : Enable RIPv2 on R1. Disable auto-summarization and advertise networks 10.0.0.0 and 172.41.0.0. Action:


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r1# config tr1(config)# router ripr1(config-router)# version 2r1(config-router)# network 10.0.0.0

r1(config-router)# network 172.41.0.0r1(config-router)# no auto-summaryr1(config-router)#

Result:

Explanation:

Enabling RIP will allow R1 to receive a route to the 100.0.0.0 network, which is necessary for upcoming steps.

Step 14 : From R1, ping: 100.100.100.100Action:

r1(config-router)# endr1#ping 100.100.100.100

r1#

Result:Your pings should be successful.

Explanation:100.100.100.100 is another TFTP server. Instead of sharing IOS files, it is sharing configuration files.

Step 15 : On R1, copy the file: lab14-r1 into the running configuration of R1. The TFTP server address is: 100.100.100.100 Action:

r1# copy tftp runAddress or name of remote host []? 100.100.100.100Source filename []? lab14-r1

Destination filename [running-config]? (PRESS ENTER)

r1#

Result:The copy should be successful.

Explanation:

When a configuration is copied into the running configuration, the new configuration is merged with the existing configuration. To betteunderstand this, go to the next step.

Step 16 : On R1, exit out of the router and then return to privileged mode.

Action:

r1# exit (PRESS ENTER TWICE)

r1> enable

r1#

Result:


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If you are successful, you should see a new banner message appear. The syntax of the copy command is to first specify from wherethis case tftp) and then specify to where (in this case the running-config). Saving a configuration follows the same logic, but in reversesave the running-config to a TFTP server, you would enter: copy run tftp But again notice, it is still in the format offrom where - towhere. In this lab, the TFTP server is set to read only, so it is not allowing you to save configs. However, the key thing here is to

understand the syntax to make it happen.

Explanation:To emphasize the concept of a merge, the configuration file you pulled from the TFTP server only contained one configuration changebanner. Nothing else was specified. For instance, a hostname was not found in the configuration file. When the two merged, the hostnthat was already in the running config stayed intact. However, the banner configuration was new, so it was simply added to the existingconfiguration. Nothing was removed.

Step 17 : On R1, copy the file: lab14-r1 into the startup configuration of R1. The TFTP server address is: 100.100.100.100 Action:

r1# copy tftp startAddress or name of remote host []? 100.100.100.100Source filename []? lab14-r1Destination filename [startup-config]? (PRESS ENTER)

r1#

Result:The copy should be successful.

Explanation:

When a configuration is copied into the startup configuration the new configuration overwrites the existing one. To see how this is diffefrom a merge, proceed to the next step.

Step 18 : Enter a show command to view R1s startup configuration stored in NVRAM. Action:

r1# show start

r1#

Result:

Explanation:

Here you see the entire file that was stored on the TFTP server. It did not merge with the startup-config; it overwrote the startup-configcompletely. If you reloaded your router at this point, it would boot up with the hostname Router instead of r1, none of the interfaces wohave IP addresses, and all would be shutdown. It would look exactly like a default configuration except for the fact that this banner woualso be present.

Step 19 : On R1, enter a show command to display information about the routers CPU utilization. Action:

r1# show processesr1#

Result:Type the letter q to end the output.

Explanation:Here you will see a lot of output, but one of the most helpful statistics is listed in the first line. You can see a snapshot of current CPUutilization, based on the last 5 seconds. Also provided is the average utilization over the last minute and over the last 5 minutes. Theaverage is shown as a percentage.


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Step 20 : On R1, enter the undebug all command.Action:

r1# undebug all

r1#

Result:

The undebug all command ends any active debug processes.

Step 21 : On R1, enter a show command to verify that no debugs are currently running. Action:

r1# show debuggingr1#

Result:

You should find that no debugs are running currently.

Explanation:

One cause of high CPU utilization is an active debug running. The processes that normally take place under the hood, so to speak, arereported as they occur. As an analogy, say you were extremely busy at work. A manager approaches you with a trainee and says thatneed to verbally report to the trainee every thought process as it enters your mind, while you get your work done. This could slow youdown so much that nothing gets done. The CPU on a Cisco device can be affected the same way when debugs are running. Thereforeis important to use them sparingly on a production network.

Step 22 : On R1, enter a debug command to view ICMP messages being exchanged as they occur. Action:

r1# debug ip icmp

r1#

Result:

Pings are an example of ICMP messages.

Step 23 : Since you do not see any output from the debug, enter a show command to verify that a debug is running on R1.Action:

r1# show debugging

r1#

Result:

You should see that ICMP packet debugging has been turned on.

Step 24 : From R1, ping: 100.100.100.100Action:

r1#ping 100.100.100.100

r1#

Result:


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Explanation:

Without the debug, you would simply see exclamation marks indicating that the ping was successful. However, with the debug enabledyou are able to see the details of the underlying process.

Step 25 : From R1, enable debugging for the RIP routing process.Action:

r1# debug ip rip

r1#

Result:

Explanation:

Wait a few minutes to observe some RIP routing protocol updates being sent and received.

Step 26 : Using a show command, verify that ICMP and RIP debugs are concurrently running on R1.Action:

r1# show debugging

r1#

Result:

You should find both the ICMP and RIP debugs listed.

Step 27 : On R1, disable both debugs with a single command.Action:

r1# undebug all

r1#

Result:The status messages from RIP should cease.

Explanation:If you entered the show debugging command at this point, entries would no longer be listed.

Step 28 : You have finished the lab.Action:You can take this lab again if time permits.

Result:

To take this lab a second time, you first need to reset the devices back to the baseline configurations that were present at the beginninthe lab. This can be done by clicking on the Device Controls link on the left bar, selecting all devices, and clicking the Reload button.

Once the devices are all marked green, you can begin the lab. This process takes several minutes.

You can also test your mastery of the material when you take the lab for the second time. Instead of using the Sample Solution link w

walks you through each step, you can use the Suggested Approach link. This provides the same steps, but without the walkthrough.

Check Results


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Check Results

This vLab was designed with verification commands and detailed explanations already built in to give you a deeperunderstanding of the technologies.

The routers and switches begin the lab with baseline configurations in place to allow you the feature of taking any lab in anyorder. The configurations for each device are listed below for reference.

hostname r1

!

no ip domain lookup

!

interface FastEthernet0/0

description CONNECTION TO SW1

ip address 10.4.1.1 255.255.255.0

!


shutdown

!interface Serial1/0

shutdown

!

interface Serial1/1

description CONNECTION TO R2

ip address 10.4.0.1 255.255.255.0

shutdown

!

interface Serial1/2

description CONNECTION TO FRAME SWITCH

ip address 172.41.4.1 255.255.255.0

encapsulation frame-relay

frame-relay map ip 172.41.4.5 44 broadcastno frame-relay inverse-arp

shutdown

!

interface Serial1/3

shutdown

!

line con 0

exec-timeout 30 0

logging synchronous

line aux 0

line vty 0 4

logging synchronous

login

!end

hostname r2

!

no ip domain lookup


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!


shutdown

!


shutdown

!

interface Serial1/0


ip address 10.4.0.2 255.255.255.0

clock rate 64000

shutdown

!

interface Serial1/1

shutdown

!

interface Serial1/2

description CONNECTION TO FRAME SWITCH

ip address 172.41.4.2 255.255.255.0

encapsulation frame-relay

frame-relay map ip 172.41.4.5 94 broadcastno frame-relay inverse-arp

shutdown

!

interface Serial1/3

shutdown

!

line con 0

exec-timeout 30 0

logging synchronous

line aux 0

line vty 0 4

logging synchronous

login

!

end

hostname sw1

!

spanning-tree mode pvst

spanning-tree extend system-id

!


description CONNECTION TO CORESWC

switchport mode dynamic desirable

shutdown

!



switchport mode access

!




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!



!



!



!



!



!



!


switchport mode dynamic desirable!


description CONNECTION TO CORESWA


shutdown

!


description CONNECTION TO CORESWB


shutdown

!



!



!



!



!



!

interface FastEthernet0/18switchport mode dynamic desirable

!



!



!



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!



!



!



!

interface GigabitEthernet0/1


!



!

interface Vlan1

ip address 10.4.1.2 255.255.255.0

!

ip default-gateway 10.4.1.1!

line con 0

exec-timeout 30 0

logging synchronous

line vty 0 4

login

line vty 5 15

login

!

end

hostname CoreSwC

!

no ip domain-lookup

vtp domain ICND

vtp mode transparent

!

spanning-tree mode rapid-pvst

spanning-tree extend system-id

spanning-tree vlan 1 priority 28672

!

vlan 41

!

interface FastEthernet0/1description CONNECTION TO SW1

switchport trunk encapsulation dot1q

switchport mode trunk

switchport nonegotiate

!



!


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!



!



!



!



!



!



!interface FastEthernet0/10


!



!


description CONNECTION TO CORESWB

switchport trunk encapsulation dot1q

switchport mode trunk

switchport nonegotiate

!



!



!



!



!



!interface FastEthernet0/18


!



!



!


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!



!



!



!



!



!

interface Vlan1

ip address 10.4.1.8 255.255.255.0

!ip default-gateway 10.4.1.1

!

line con 0

exec-timeout 30 0

logging synchronous

line vty 0 4

login

line vty 5 15

login

!

end

cdp and managing cdp

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