Frequently Asked Questions (FAQ)/Troubleshooting Guide

General Issues

1. My computer frequently crashes when I use Packet Tracer 5.1.
2. The program screen is cluttered with too many windows! I can't see the workspace.
3. What Cisco IOS version do the routers and switches use?
4. Can I learn the necessary information for CCNA certification just by using Packet Tracer 5.1?
5. Does Packet Tracer 5.1 support all of the features found in Cisco devices?
6. When I make an entry into a text field (such as an IP address), how do I know it goes into effect? Is there an "Apply" button?
7. Can I create unlimited devices?
8. I cannot access the tutorial files.
9. Some pictures do not show up in the Help files.
10. May I distribute Packet Tracer 5.1 to my students?
11. Why is Packet Tracer 5.1 running so slowly?
12. Some text in the program is cut off or is not correctly displayed.
13. I have a saved topology from Packet Tracer v3.2 or v4.0. Can I open it with Packet Tracer 5.1?
14. What is the password to edit the included activities with Activity Wizard?
15. When I try to launch Packet Tracer in Ubuntu 6.10, the terminal gives a Fatal Arithemtic error.
16. I have a saved topology from Packet Tracer 5.1. Can I open it with Packet Tracer 4.x?
17. How do I convert PKA files to a PKT file?
18. If I save my file in the default Packet Tracer saves directory in Windows Vista, the save file is found in another directory. However, if I choose another directory, this issue does not occur.
19. When I try to launch Packet Tracer 5.1 in Wine, Packet Tracer 5.1 crashes.
20. On Ubuntu, if I try to create a custom device template, an error message pops up stating "Unable to write to file."
21. How can I save the PKA that I have opened in Activity Wizard to a different file (i.e. Save As)?

Specific Issues

1. In the Physical Workspace, the wiring closet does not display all of the devices I have created in the Logical Workspace.
2. If I turn off the ARP filter in the Event List Filters, does that mean devices won't build ARP tables?
3. Does Packet Tracer 5.1 use the Spanning Tree Protocol?
4. How does loop-breaking process work in Packet Tracer 5.1? Why don't I have the option of viewing packets associated with the loop-breaking process?
5. When I reset the network in Simulation Mode, why do some switch ports show amber link lights and stay that color?
6. Why does the command "clockrate" not work?
7. I created a ping packet in Simulation Mode and ran it. Why do I still see packets (like CDP) running on the network after the ping process is completed?
8. When I issue an extended ping, the parameters I am asked to fill in do not match an extended ping on a real device.
9. Why can't I access sub-interfaces on serial ports?
10. Why can't I test port connectivity with a command such as ping 192.168.1.5:80?
11. Does Packet Tracer 5.1 support VTP?
12. I can't seem to add a secondary address to a port.
13. How does the Auto settings for bandwidth and duplex work on a port?
14. At the end of a simulation (after the last event), I viewed a device table (such as ARP or MAC) and saw that it was blank. Why is this?
15. Sometimes the CLI screen seems to display text incorrectly. For example, when activating an interface, the router prompt appears at the end of the sys log message instead of a new line.
16. When I make the interface a trunk port in a interface sub-panel for the switch (under Config), the VLAN range is set to 1 to 1005 even though the switch does not have that many VLANs set up?
17. When I turn off a router that has its link lights up and then turn it back on, why do the links remain down?
18. When I choose a tool from the Common Tools Bar (such as the Inspect tool), how can I cancel that tool or deselect it?
19. What's the difference between the Reset Simulation button and the Power Cycle Devices button?
20. When I use the Add Simple PDU tool to ping a router, the destination IP address is the Ethernet interface rather than the serial interface. What determines the default destination interface for a ping?
21. When I have a static route and RIP configured on a router, why is it that the static route with an administrative distance of 1 is preferred over RIP routes with an administrative distance of 120?
22. When I configure static NAT on a router and perform a ping, why does the router eventually lose the NAT translations after several successful pings?
23. When I enter an EIGRP network command, such as network 192.168.1.0 255.255.255.0, the result would be network 0.0.0.0 255.255.255.0 instead. However, on a real router, the result is actually network 192.168.1.0.
24. When I try to do an extended ping in the CLI with a source IP address that doesn't belong to the device, it gives me an invalid source error message.
25. In Simulation Mode, when I only have a single Event List Filter enabled, such as UDP, and then click on Capture / Forward, I get the message, "The maximum number of events has been reached..." This is counter-intuitive since no events are shown in the Event List at all.
26. When a router doesn't have a next hop MAC address, it sends an ARP request and will drop the ICMP packet as well. Is this normal behavior?
27. When I save a configuration to the router NVRAM (wr mem or copy run start), the router does not save the configuration when Packet Tracer 5.1 is shut down. This only occurs if you save the topology.
28. When you use the same network/subnet on two different devices, the Cisco IOS CLI reports an error saying that the IP address conflicts with another interface.
29. Which cable do I use to connect an Access Point to other networking devices? Also, why do Packet Tracer 3.2 files with access points connected to other devices no longer work?
30. What is the difference between the activity file (.pka) that I author and the activity file that I give to others?
31. Is it possible to import or open Packet Tracer 3.2 activity files?
32. What is the correct version for EIGRP? I have seen only two versions, v0 and v1. However, in the PDU Information Window, the version reported is version 2.
33. In Simulation Mode, why do some devices/ports sometimes buffer frames and say the ports are sending other frames when there are no frames shown in the Event List?
34. When creating multiple connections between the same two devices (e.g. trunking), the cables connected earlier may be hidden by the new ones. How do I know how many cables are connected?
35. Using the Activity Wizard, how do I lock out the GUI configuration for routers and switches to force the users to use only the CLI?
36. What happens to the IP address of a device when I duplicate the device?
37. What is the limit for the number of wireless hosts and access points in the same coverage area?
38. When I create a template of a device with additional IOS images besides the default IOS image, only the default IOS image of the device appears in the custom device.
39. Does Realtime mode exactly model actual real world time?
40. Why, when I enable logging and configure devices in the CLI and then save the file, does the save file not save the log?
41. When I send a PDU over devices with multiple links between them, with one of the links shutdown, why does the PDU traverse the shutdown link instead of the active link in Simulation Mode?
42. Why do I get two different average round trip times for the exact same pings in Realtime Mode and Simulation Mode?
43. When I issue the "clear ip route *" command in CLI, it doesn't clear the routing tables.
44. Why can't enable secret passwords be assessed reliably in activities?
45. I can add a WEP key that is out of the hex range for the Linksys router when I shouldn't be able to.
46. In the Event List filter window, why does unchecking HTTP filter have no effect when TCP is checked?
47. Why does the Inspect tool have no effect on the Linksys router?
48. When I telnet into another device, the config tab does not work.
49. Why do static routes with admin distances of 255 show up on the routing table?
50. Packet Tracer 5.1 crashes when I have many instances of Packet Tracer 5.1 opened.
51. How can configurations from Packet Tracer 4.x, Packet Tracer 5.1, and real devices be used in activities to check enable secret and other passwords with service password-encryption on?
52. Why are values in Config tab not changed when I have already changed them in console?
53. Why do HTTP packets still show up when I have the HTTP filter unchecked?
54. Why does Packet Tracer 5.1 generate the same encryption string when the same password is entered more than once?
55. How do I add a graphic image in activity instructions?
56. Why am I able to add and remove content from the activity instructions window when it should be read-only?
57. When I enter "show interface s0/0/0" in the CLI, the IOS output says "show interface s0/0/0" is an ambiguous command.
58. How come I cannot use Variable Manager for scoring with VLAN interface IDs (SVIs)?
59. Is there a way to speed up convergence of the network when I open a file?
60. I cannot make a Multiuser connection between Windows and Linux machines.
61. I can still access the Config tab of a router or switch even if there is an enable secret password in the running configuration.
62. Is there a way to distinguish between outgoing and incoming Multiuser remote network clouds? Also, when I have an incoming Multiuser connection, Packet Tracer creates a Multiuser remote network cloud if the name is incorrect.
63. When I try to set a variable value to Elemental Position in Variable Manager, the value sets itself to zero and cannot be changed to any other position.
64. When I try to copy text from the CLI tab using "Ctrl + C", the output has unorganized text that can be dragged around.
65. How come I am able to enter negative point values for Assessment Items in activities?
66. Can a wireless PC associate to an access point that is from a Multiuser remote network?
67. When I try to create a loop on a switch by connecting a straight-through or cross-over cable to different ports on the same switch, I get a connection error stating that "The cable cannot be connected to that port?"
68. How come when I have multiple wireless profiles in a wireless PC and then delete the wireless router that the wireless PC is currently associated to, the wireless PC does not automatically associate to the other wireless routers that has a profile?
69. In Physical Workspace, sometimes the geoicons do not work correctly. For example, I am able to move the geoicons beyond the "border." Also, the geoicon labels are sometimes detached from the geoicon itself after navigating between locations.
70. How come the output for various commands in the CLI, such as "show ipv6 nat translations," is different from a real router?
71. When I click on Save Settings in the Applications & Gaming section in the Linksys GUI, the last item in focus does not save.
72. How come when I create a complex PDU, the Outgoing Port drop-down list does not contain any interfaces?
73. The Variable Manager Interface in the Activity Wizard Answer Network panel is too narrow.
74. When I have a router with 2 LANs (e.g. 192.168.1.1 and 192.168.2.1), a PC with an IP address in the 192.168.1.0 network can be pinged by a PC in the 192.168.2.0 network even if the PC in the 192.168.1.0 network has the incorrect default gateway (e.g. 192.168.2.1).
75. When I copy and paste the entire "show running-config" output in Global Config Mode, some commands return "% Invalid input detected at '^' marker."
76. When I undo a deleted device/link that was connected to a Multiuser remote network, Packet Tracer crashes.
77. When I delete a link to a Multiuser remote network, the link isn't removed from the Multiuser remote network.

Protocol Modeling Issues

1. For EIGRP, why are new adjacencies being formed after the "no auto" command--this does not happen on real routers?
2. Why does the "no keepalive" command give me an error saying I must set the encapsulation to Frame Relay?
3. On real devices, the link lights would still come up if there is a duplex mismatch between both sides of the Ethernet connection. Why does Packet Tracer not model this behavior?
4. On real switches, if there is a native VLAN mismatch on both sides of the same trunk, CDP and STP would print out error messages. Why does Packet Tracer not model that?
5. I cannot disable STP on switching devices.
6. On a real device, I can ping the loopback address 127.0.0.1, what about in Packet Tracer?
7. On a real router, I can configure an interface with a valid IP address and subnet mask even though it is a supernet, but in Packet Tracer it says that the subnet mask is a "Bad mask."
8. I cannot configure an IP address on a modem interface module, but there is a configuration interface in the Config tab.
9. If there is a DHCP request with two or more DHCP servers, and then a DHCP request fails due to a possible collision when the DHCP servers try to respond simultaneously, there should be lots of traffic but there are no further events after the collision.
10. Why doesn't STP block the ports if the native VLAN mismatches?
11. On a real router, the timer is reset for OSPF and EIGRP routes after a "clear ip route *" command, but not in Packet Tracer 5.1.
12. Why does the Linksys remote management override HTTP port forwarding?
13. The show ip ospf neighbor command shows a priority of 1. Actual 1841 shows priority of 0.
14. Static routes with 255 admin distance should not be added to routing table.
15. Why do wireless ports always buffer the frames before sending?
16. Why are LMI statistics not updated when the link state changes?
17. Why can I only ping one VLAN interface on the switch when there are more than one with the status and line protocol up?
18. Why does OSPF not work over physical serial interface using frame relay?
19. In Simulation Mode, routing tables are updated before the packet arrives in the simulation.
20. On a router with multiple switching modules, there should be individual MAC tables for each switching module. However, "show mac-address table" shows only one MAC table.
21. Why is the command "ip ospf network" not available in the loopback interface mode?
22. The round trip times for pings in Multiuser networks are very long.
23. When I issue the command "debug ppp negotiate" before enabling PPP encapsulation, debug messages do not show.
24. On a real switch, when I create a VLAN and then assign a name to the VLAN, VTP revision number increases by 1. In Packet Tracer, the VTP revision number increases by 2.

General Issues

| Question/Problem | Answer/Solution
1 | My computer frequently crashes when I use Packet Tracer 5.1. | You need to update your video card drivers, especially if your computer has an ATI video card. If you are using an IBM laptop issued by Cisco, you can use Windows Update or this link to IBM support. If you are using a computer built by another company please check their web site for updates or if you know you have an ATI video card, go to http://ati.amd.com/products/index.html to find an updated driver. You may also need to clear some disk space. If there is insufficient free space on your hard drive while the program is running, it may crash.
2 | The program screen is cluttered with too many windows! I can't see the workspace. | You can undock sub-windows by double-clicking on the title bar and move them away from the workspace area. You can also prevent sub-windows from docking by holding down Ctrl while moving them.
3 | What Cisco IOS version do the routers and switches support? | Packet Tracer 5.1 uses simplified models Cisco IOS, using real Cisco IOS images as references. The Cisco 1841 router supports Cisco IOS version 12.3(14)T7, 12.4(12), and 12.4(15)T1. The Cisco 2600 series routers support Cisco IOS version 12.2(28), 12.4(8), and 12.4(15)T1. The Cisco 2811 router supports Cisco IOS version 12.3(14)T7, 12.4(8), and 12.4(15)T1. The Router-PT router supports Cisco IOS version 12.2(8). The Cisco Catalyst 2950 series switches supports Cisco IOS version 12.1(22)EA4 and 12.1(22)EA8. The Cisco Catalyst 2960-24TT switch supports Cisco IOS version 12.2(25)FX and 12.2(25)SEE1. The Switch-PT switch supports Cisco IOS Version 12.1(22)EA4. The Cisco Catalyst 3560-24PS switch supports Cisco IOS version 12.2(37)SE1.
4 | Can I learn the necessary information for CCNA certification just by using Packet Tracer 5.1? | No. Packet Tracer 5.1 is a tool to supplement the CCNA curriculum. Students can learn basic to intermediate router and switch configuration and see how packets are processed by networking devices as they traverse the network.
5 | Does Packet Tracer 5.1 support all of the features found in Cisco devices? | No. The program supports a small subset of the features from Cisco devices. Please see the "Router IOS" or "Switch IOS" help pages. Packet Tracer 5.1 uses simplified models of networking protocols and Cisco IOS; you should always compare your results to those obtained from real equipment.
6 | When I make an entry into a text field (such as an IP address), how do I know it goes into effect? Is there an "Apply" button? | Text field inputs are updated and applied as soon as they lose focus (e.g., when you click somewhere else on the screen). There are no "Apply" buttons.
7 | Can I create unlimited devices? | No. The number of devices is limited by the amount of free memory on your computer.
8 | I cannot access the tutorial files. | Pop-up blockers can stop the tutorial files from running. Make sure you have these disabled when trying to view the tutorials.
9 | Some pictures do not show up in the Help files. | The "pictures" are actually Macromedia Flash content (.swf) files. If you have recently installed the Windows XP SP2 update, or if Internet Explorer does not show Flash files by default, you can change your Internet settings to solve this problem. From the Internet Explorer toolbar, select Tools > Internet Options. Click the Advanced tab, and scroll down to the section on "Security," then check the box for "Allow active content to run in files on My Computer." You will also need to install the Flash plug-in if it is not already installed.
10 | May I distribute Packet Tracer 5.1 to my students? | Yes. Please distribute Packet Tracer to currently enrolled Cisco Networking Academy Program students. If the distribution method is through a website, ensure that the website is password protected. Refer to the "Copyrights" page for more information.
11 | Why is Packet Tracer 5.1 running so slowly? | Does your system meet the minimum requirements? The minimum requirements, listed in the help documentation, allow for the basic use of Packet Tracer 5.1 in creating small- to medium-size networks. It is recommended that you use a faster machine with more memory to create large networks. You can turn off the Sound and Animation options to increase performance.
12 | Some text in the program is cut off or is not correctly displayed. | Packet Tracer 5.1 by default requires that your system supports the Verdana font to display text correctly. Alternatively, you may change the fonts for dialogs, workspace/Activity Wizard, and the general interface in Preferences under the Font tab.
13 | I have a saved topology from Packet Tracer v3.2 or v4.x. Can I open it with Packet Tracer 5.1? | Yes. Packet Tracer 5.1 offers limited backward-compatibility with Packet Tracer 3.2. When you open Packet Tracer 3.2 files with Packet Tracer 5.1, the only elements imported are the network topology (which includes devices and their links) and configuration files (running and startup config). Nothing else is loaded. Files from older versions (Packet Tracer 3.1) are not officially supported. Files from Packet Tracer 4.x are supported.
14 | What is the password to edit the included activities with Activity Wizard? | Instructors may obtain the password from the Packet Tracer forums on the Academy Connection website.
15 | When I try to launch Packet Tracer in Ubuntu 6.10, the terminal gives a Fatal Arithemtic error. | Ubuntu 6.10 is not supported.
16 | I have a saved topology from Packet Tracer 5.1. Can I open it with Packet Tracer 4.x? | No. Forward compatibility of save files is not fully supported. An "Invalid File" message may appear if you have a save file from Packet Tracer 5.1and then try to open it in Packet Tracer 4.x.
17 | How do I convert PKA files to a PKT file? | There are actually multiple "PKT" files inside an activity file. To "convert" from a PKA to a PKT file: 1. Open the PKA 2. Go to Activity Wizard. If you are interested in the Answer Network, go to the Answer Network section and click on "Export Answer Network to File" and save it as a PKT. If you are interested in the Initial Network, go to the Initial Network section and click on "Export Initial Network to File" and save it as a PKT.
18 | If I save my file in the default Packet Tracer saves directory in Windows Vista, the save file is found in another directory. However, if I choose another directory, this issue does not occur. | This appears to be how Windows Vista handles saving items in the Program Files directory.
19 | When I try to launch Packet Tracer 5.1 in Wine, Packet Tracer 5.1 crashes. | Wine is not supported. Please use the Linux version of Packet Tracer 5.1 instead.
20 | On Ubuntu, if I try to create a custom device template, an error message pops up stating "Unable to write to file." | If Packet Tracer is installed as root, then you need to run as root in order to write to templates folder in the Packet Tracer directory.
21 | How can I save the PKA that I have opened in Activity Wizard to a different file (i.e. Save As)? | While in Activity Wizard, go to File -> Save As in the main Packet Tracer window and then save the PKA to a different file.

Specific Issues

| Question/Problem | Answer/Solution
1 | In the Physical Workspace, the wiring closet does not display all of the devices I have created in the Logical Workspace. | A wiring closet can have a maximum of three tables or racks. When closets become full, additional ones will be created automatically to accommodate more devices. When multiple closets are created they are one on top of the other, so you must move the first one to see the second and the third, etc..
2 | If I turn off the ARP filter in the Event List Filters, does that mean devices won't build ARP tables? | No. The filters are for display purposes only and do not affect the actual function of the network. The packets are in the network but are not visible. Note that while users new to networking may not want to display ARP packets, many behaviors involving Ethernet (such as the first ping across a router being dropped while ARP is occurring) are not fully explainable without reference to ARP.
3 | Does Packet Tracer 5.1 use the Spanning Tree Protocol? | Yes. Packet Tracer 5.1 models Per Vlan Spanning Tree Protocol to break possible switching loops. When first loading files with switches, or routers with switchports, the Spanning Tree Protocol will go through the different states on the ports before putting them in forwarding state, indicated by an amber light. If this causes an annoying delaying, toggling between Realtime and Simulation mode 3 or 4 times will decrease the delay caused by the transition of states.
4 | How does loop-breaking process work in Packet Tracer 5.1? Why don't I have the option of viewing packets associated with the loop-breaking process? | Layer 2 loop-breaking is done in STP. This is a notable change from Packet Tracer 4.0. You can view these packets in Simulation Mode. Layer 1 loop-breaking is still done in a Packet Tracer proprietary protocol and converges immediately.
5 | When I reset the network in Simulation Mode, why do some switch ports show amber link lights and stay that color? | The amber link light indicates that the switch port is not in STP forwarding state. STP takes over 30 seconds to put a port into forwarding state if there are no loops. A port may be put in blocking mode and stay in amber color if the port is in a loop.
6 | Why does the command clockrate not work? | The term "clockrate" is not a documented Cisco IOS command. Use clock rate instead.
7 | I created a ping packet in Simulation Mode and ran it. Why do I still see packets/frames (like CDP) running on the network after the ping process is completed? | Routers and switches send out CDP frames every 60 seconds regardless of what packets you created yourself. If you do not want to see the CDP events, uncheck the CDP filter in the Event List Filters. You can also disable CDP on the Cisco devices by using the Cisco IOS CLI. There are other protocols that periodically send out packets/frames without any configurations, including STP and DTP.
8 | When I issue an extended ping, the parameters I am asked to fill in do not match an extended ping on a real device. | Some parameters, such as the following, are not supported: Extended commands [n]: Sweep range of sizes [n]:
9 | Why can't I access sub-interfaces on serial ports? | Packet Tracer 5.1 support serial sub-interfaces for frame relay encapsulation only. HDLC and PPP serial sub-interfaces are not supported in this version. In order to create a serial sub-interface, the physical interface must be configure to use frame relay encapsulation first. Then, in creating a serial sub-interface, the type (point-to-point or multipoint) must be defined.
10 | Why can't I test port connectivity with a command such as ping 192.168.1.5:80? | Packet Tracer 5.1 does not support this specific ping feature.
11 | Does Packet Tracer 5.1 support VTP? | Packet Tracer 5.1 supports several commands relating to VTP domain, mode, password, and version.
12 | I can't seem to add a secondary address to a port. | Packet Tracer 5.1 does not support the ip address secondary command.
13 | How does the Auto settings for bandwidth and duplex work on a port? | The Auto setting enables auto-negotiation on the port of the device. When two ports are connected and both have auto-negotiation on, the best connection settings will be determined automatically and the link will be functional. The link will also be functional if one port has auto-negotiation on and the other is set at Half Duplex. However, if the other port is set at Full Duplex, the link will not be functional.
14 | At the end of a simulation (after the last event), I viewed a device table (such as ARP or MAC) and saw that it was blank. Why is this? | Did you press the Capture / Forward button after the last event occurred? The ARP table clears after the end of the animation because after the last packet, the only timers left are ARP entry timeout timers. Because the Capture / Forward button advances in time to the next event (but there are no more future packets), the ARP entry timeout timer will expire. Thus, the ARP table becomes empty. This is similarly true for MAC tables.
15 | Sometimes the CLI screen seems to display text incorrectly. For example, when activating an interface, the router prompt appears at the end of the sys log message instead of a new line. | There is a no line break after the interface status messages because that is how it is displayed on real devices. However, note that the Packet Tracer 5.1 status messages are displayed immediately after the event occurs. Real devices may have a delay of about 1 second.
16 | When I make the interface a trunk port in a interface sub-panel for the switch (under Config), the VLAN range is set to 1 to 1005 even though the switch does not have that many VLANs set up? | In Packet Tracer 5.1 as well as on real equipment, the switch allows all VLANs (1 to 1005) on a trunk port by default, even if the VLAN does not actually exist on the switch. From the drop-down menu, you can view the VLANs that do exist and block (uncheck) them from the trunk. However, you cannot block VLANs that do not exist. This action does not affect the switch functionality. It is simply a way to display VLANs (or a range of VLANs) that the trunk supports.
17 | When I turn off a router that has its link lights up and then turn it back on, why do the links remain down? | By default, router ports are in a "shutdown" state unless the no shutdown command has been issued. When a router is turned off and then on, it reads the startup-config file for configuration information. If the router contains no saved startup configuration that included the no shutdown command on a port, that port will not come up automatically.
18 | When I choose a tool from the Common Tools Bar (such as the Inspect tool), how can I cancel that tool or deselect it? | Press the Esc key or click on another tool in the Common Tools Bar.
19 | What's the difference between the Reset Simulation button and the Power Cycle Devices button? | The Power Cycle Devices button does everything the Reset Simulation button does in addition to power-cycling devices that are powered on. Reset Simulation impacts the display and animation of already captured packets but not change the actual state of the networking devices.
20 | When I use the Add Simple PDU tool to ping a router, the destination IP address is the Ethernet interface rather than the serial interface. What determines the default destination interface for a ping? | The Add Simple PDU tool is a quick way to create PDUs. The source device does not specify a source interface. It uses the outgoing interface as the source interface. The destination IP address is chosen to be the first interface with a set IP address on the destination device. The order of the interfaces is the same order as displayed in the show running-config and show interfaces commands. To specify the destination address manually, use either the CLI or the Add Complex PDU tool. Both of these allow for configuration of the outgoing interface and destination IP address of the source device.
21 | When I have a static route and RIP configured on a router, why is it that the static route with an administrative distance of 1 is preferred over RIP routes with an administrative distance of 120? | Packet Tracer 5.1 is modeled from real routers, in which a static route with a smaller administrative distance is preferred over RIP routes. Instead of using the default administrative distance of 1 for the static routes, you can try using an administrative distance larger than 120 so that RIP routes would be installed in the routing table when they are available and static routes would be installed if RIP routes are not there.
22 | When I configure static NAT on a router and perform a ping, why does the router eventually lose the NAT translations after several successful pings? | The ICMP NAT entries timeout in 1 minute. So, if 1 minute has passed either in Realtime or Simulation Mode, the NAT entries generated by ICMP packets would be removed from the NAT table.
23 | When I enter an EIGRP network command, such as network 192.168.1.0 255.255.255.0, the result should be network 0.0.0.0 255.255.255.0 instead. However, on a real router, the result is actually network 192.168.1.0. | The network command for EIGRP should accept a wildcard mask for the second argument, as stated in the help command network 192.168.1.0 ?. So, the command network 192.168.1.0 0.0.0.255 means the network 192.168.1.0/8. However, this command is inconsistent with the help command in which network 192.168.1.0 255.255.255.0 also means the network 192.168.1.0/8. Packet Tracer 5.1 implements the command like a real router.
24 | When I try to do an extended ping in the CLI with a source IP address that doesn't belong to the device, it gives me an invalid source error message. | This is how extended ping works. You can only specify an IP address on the device as the source address. Otherwise, it gives an error.
25 | In Simulation Mode, when I only have a single Event List Filter enabled, such as UDP, and then click on Capture / Forward, I get the message, "The maximum number of events has been reached..." This is counter-intuitive since no events are shown in the Event List at all. | The Event List Filters are not connected to how events are captured. Even if nothing is checked to display, Packet Tracer 5.1 still captures everything. So, after capturing 500 events, Packet Tracer 5.1 will show that message. However, the last part of the message says that the user can adjust the Event List Filters to see previous events.
26 | When a router doesn't have a next hop MAC address, it sends an ARP request and will drop the ICMP packet as well. Is this normal behavior? | Yes. When a router does not have the next hop MAC address, it will send an ARP request, but will also drop the packet. It does not buffer the packet and wait for the ARP reply to come back because that could cause considerable performance decreases if there are a lot of pending ARP entries.
27 | When I save a configuration to the router NVRAM (wr mem or copy run start), the router does not save the configuration when Packet Tracer 5.1 is shut down. This only occurs if you save the topology. | Yes. Saving the configuration to NVRAM only saves to the current file. You have to save the topology as a .pkt file to preserve your work between different Packet Tracer 5.1 sessions.
28 | When you use the same network/subnet on two different devices, the Cisco IOS CLI reports an error saying that the IP address conflicts with another interface. | Packet Tracer 5.1 allows for using the same network/subnet on different devices. However, Packet Tracer 5.1 does not allow the same IP address on different devices. Real devices do not check for this and have no practical way of checking. The Packet Tracer 5.1 computational model requires this check because some features require devices to have unique IP addresses.
29 | Which cable do I use to connect an Access Point to other networking devices? Also, why do Packet Tracer 3.2 files with access points connected to other devices no longer work? | Access points connect to hubs and switches with a straight-through cable. Meanwhile, a crossover cable is needed to connect an access point to routers and end devices. In Packet Tracer 3.2, the implementation was in reverse order. Since Packet Tracer 5.1 corrects this model, connections between access points and other devices in Packet Tracer 3.2 files will not work if loaded in Packet Tracer 5.1. You will have to reestablish the connection again with the proper cable.
30 | What is the difference between the activity file (.pka) that I author and the activity file that I give to others? | The activity file created with Activity Wizard contains both the authoring information and the activity itself. If you do not want others to view or change the contents of your activity, you may password protect the activity in Activity Wizard. Just like a regular Packet Tracer 5.1 network file (.pkt), the progress of activity files can be saved at any time. To have a fresh activity for redistribution, be sure to reset the activity in the instructions box, then save the activity.
31 | Is it possible to import or open Packet Tracer 3.2 activity files? | The short answer is "No." However, Packet Tracer 5.1 can import Packet Tracer 3.2 network files (.pkt), with some limitations. You may export the answer and initial networks from Packet Tracer 3.2, then import then into Packet Tracer 5.1 using Activity Wizard. Though there are fewer restrictions, some limitations also apply to the use of PT 4.0 activity files. It is best to re-author activities in PT 5.1, though existing work from 4.0 can be imported and adjusted.
32 | What is the correct version for EIGRP? I have seen only two versions, v0 and v1. However, in the PDU Information Window, the version reported is version 2. | The version field in the EIGRP packet indicates the EIGRP version of the sender. There is only one version of EIGRP. However, from the packet captures from routers, the version number is always 2. This is a constant. Packet Tracer 5.1 is modeling as it would be captured from a real network.
33 | In Simulation Mode, why do some devices/ports sometimes buffer frames and say the ports are sending other frames when there are no frames shown in the Event List? | There are some types of frames that Packet Tracer 5.1 does not display to the user, such as keepalives on the serial links. When these frames are being sent, the device will buffer the other frames that are waiting.
34 | When creating multiple connections between the same two devices (e.g. trunking), the cables connected earlier may be hidden by the new ones. How do I know how many cables are connected? | Packet Tracer 5.1 will display several distinct cables in parallel. However, there is a limit. A workaround is to use another device, such as a repeater for Ethernet connections, to emphasize the visual distinction of a particular link.
35 | Using the Activity Wizard, how do I lock out the GUI configuration for routers and switches to force the users to use only the CLI? | Attach a console cable from the PC to the switch or router. In the Initial Network section of the Activity Wizard, lock "Configuration" for the switch or the router. Now, users must console into the switch or router from the terminal of the PC to configure them.
36 | What happens to the IP address of a device when I duplicate the device? | When you duplicate a device with an IP address assigned to any of its interfaces, the IP addressing will be cleared on the duplicate device.
37 | What is the limit for the number of wireless hosts and access points in the same coverage area? | The limit is 10 wireless hosts with 3 access points in the same coverage area. Beyond that limit, wireless connections become unpredictable. This is similar to real equipment except Packet Tracer 5.1 has a lower limit.
38 | When I create a template of a device with additional IOS images besides the default IOS image, only the default IOS image of the device appears in the custom device. | The template devices store the hardware information only, including the device model and what modules are installed on them. The workaround to this issue is to copy and paste the device. The duplicated device will have the same IOS images as the original device.
39 | Is Realtime mode exactly in sync with real world time? | No. Realtime mode in Packet Tracer runs at a different rate than real world time. It may run slower as more devices and protocols are added to the network. The speed of the computer running Packet Tracer also affects the Realtime mode.
40 | Why, when I enable logging and configure devices in the CLI and then save the file, does the save file not save the log? | The command log is not saved with the save file and is session based. Alternatively, you may export the log under the Interface tab in Preferences.
41 | When I send a PDU over devices with multiple links between them, with one of the links shutdown, why does the PDU traverse the shutdown link instead of the active link in Simulation Mode? | This is a result of an animation error. The PDU takes the center path between the two devices instead of the center path between the two endpoints of the links. A possible workaround is to use hubs or repeaters to connect some of the links.
42 | Why do I get two different average round trip times for the exact same pings in Realtime Mode and Simulation Mode? | In Realtime Mode, time is always running regardless of the events occurring in the network. In Simulation Mode, time is event driven, under your control. The time in Realtime Mode may be affect by the speed of the computer Packet Tracer is running on and the number of devices and protocols running in Packet Tracer. For more information, please view the "Time Management Between Realtime and Simulation Mode" section in the Simulation Mode: Special Notes page.
43 | When I issue the "clear ip route *" command in CLI, it doesn't clear the routing tables. | The "clear ip route *" command just clears the routing table. For some protocols like EIGRP and OSPF, the routes are added back to the routing table immediately if there are no changes. For RIP, the routes are added back when receiving the next updates from its neighbors. However, in Realtime mode, it may happen before "show ip route" is issued again. You can see its effects easier in Simulation Mode.
44 | Why can't enable secret passwords be assessed reliably in activities? | The issue is that each time an enable secret password is generated, the encrypted string may be different even for the same cleartext password. As a result, when activities are graded, the assessment item for enable secret passwords is incorrect since the two password strings may not be the same even if it is the same password. If you wish to create activities involving passwords, use the enable password command instead, but without issuing the service password-encryption command.
45 | I can add a WEP key that is out of the hex range for the Linksys router when I shouldn't be able to. | This is an error that occurs in both the Config and GUI tabs since out of hex range WEP keys should be invalid.
46 | In the Event List filter window, why does unchecking HTTP filter have no effect when TCP is checked? | HTTP packets are also TCP packets, so they are not filtered out.
47 | Why does the Inspect tool have no effect on the Linksys router? | The Linksys device tables are not available.
48 | When I telnet into another device, the config tab does not work. | This is an error. The workaround is to exit from the telnet session before resuming configuration with the Config tab.
49 | Why do static routes with admin distances of 255 show up on the routing table? | This is an error. Static routes with admin distances of 255 means Unreachable and should not show up on the routing table.
50 | Packet Tracer crashes when I have many instances of Packet Tracer opened. | We recommend using one instance of Packet Tracer at a time. Although Packet Tracer does not impose a limitation on how many instances may be running at the same time, system resources (RAM, disk swap, or GDI objects) may affect the actual number of simultaneous instances.
51 | How can configurations from Packet Tracer 4.x, Packet Tracer 5.1, and real devices be used in activities to check enable secret and other passwords with service password-encryption on? | Packet Tracer 5.1 generates password encryptions only once, with only one seed. If the same password is entered more than once, Packet Tracer only generates one encryption string. In order for passwords generated from outside of Packet Tracer 5.1 to work in activity checking, you must re-enter the passwords again after importing.
52 | Why are values in Config tab not changed when I have already changed them in console? | Packet Tracer 5.1 does not keep opened dialogs in sync when changes are made from a different dialog. To see the updated values, please close the opened dialog and open it again.
53 | Why do HTTP packets still show up when I have the HTTP filter unchecked? | If the HTTP filter is unchecked, but the TCP filter is checked, HTTP packets would still show up, because HTTP packets are TCP packets. This is the same behavior for other packets that are encapsulated within TCP or UDP. If you want control over the types of packets you want to see, use ACL Filters.
54 | Why does Packet Tracer 5.1 generate the same encryption string when the same password is entered more than once? | On real devices, each time a password is entered, the seed changes, and it would generate a different encryption string. Even if the same password is entered twice, the encryption string would be different. In order for activity checking to work, we must always generate the same encryption string so that the user's password and the Answer Network password generate the same encryption string.
55 | How do I add a graphic image of a topology in the activity instructions? | Use <img> tags to add images in the activity instructions.
56 | Why am I able to add and remove content from the activity instructions window when it should be read-only? | You have to lock Edit Instructions in the Locking Items tree to make the instructions content read-only.
57 | When I enter "show interface s0/0/0" in the CLI, the IOS output says "show interface s0/0/0" is an ambiguous command. | In the IOS, interfaces have higher priority for matches. The workaround is to enter "show interface se0/0/0" instead.
58 | How come I cannot use Variable Manager for scoring with VLAN interface IDs (SVIs)? | Variables cannot be used to check for nodes that depend on names, such as device names, port names, dhcp pool names, etc.
59 | Is there a way to speed up convergence of the network when I open a file? | You can speed up convergence of the network by switching to Simulation Mode and then switching back to Realtime mode. Do this as many times as required (depends on the network).
60 | I cannot make a Multiuser connection between Windows and Linux machines. | Make sure to disable all firewalls on both the Windows and Linux machines (procedure will vary depending on the firewall). If the machines are behind NAT (e.g. a SOHO router), be sure to forward the appropriate ports (i.e. 38000 by default) as well.
61 | I can still access the Config tab of a router or switch even if there is an enable secret password in the running configuration. | You can use Activity Wizard to lock Use Config Tab or you can hide the Config tab in Preferences if needed.
62 | Is there a way to distinguish between outgoing and incoming Multiuser remote network clouds? Also, when I have an incoming Multiuser connection, Packet Tracer creates a Multiuser remote network cloud if the name is incorrect. | You can mouseover a Multiuser remote network cloud to show who the other side is connected to. Also, changing the Multiuser remote network cloud's name does not reflect on the other side.
63 | When I try to set a variable value to Elemental Position in Variable Manager, the value sets itself to zero and cannot be changed to any other position. | When you set a value for a variable, you must press Enter on the keyboard to change the value.
64 | When I try to copy text from the CLI tab using "Ctrl + C", the output has unorganized text that can be dragged around. | There is no way to prevent this in the interface since Packet Tracer 4.0. A workaround is to use the Copy button in the CLI tab.
65 | How come I am able to enter negative point values for Assessment Items in activities? | Negative point values in Assessment Items has several useful benefits. For example, if you ask a student to configure a network using RIP and they use static routes to trick the connectivity tests, you can give them negative points for configuring static routes instead of RIP. Also, negative point values varies the point system which allows different types of game related activities.
66 | Can a wireless PC associate to an access point that is from a Multiuser remote network? | No. Wireless requires the devices to be within physical range of each other. Multiuser nodes are in different wiring closets.
67 | When I try to create a loop on a switch by connecting a straight-through or cross-over cable to different ports on the same switch, I get a connection error stating that "The cable cannot be connected to that port?" | A workaround is to use a hub or repeater to create a loop between the two ports on the same switch.
68 | How come when I have multiple wireless profiles in a wireless PC and then delete the wireless router that the wireless PC is currently associated to, the wireless PC does not automatically associate to the other wireless routers that has a profile? | In Packet Tracer 5.1, there is no way to choose multiple wireless profiles in the Config tab.
69 | In Physical Workspace, sometimes the geoicons do not work correctly. For example, I am able to move the geoicons beyond the "border." Also, the geoicon labels are sometimes detached from the geoicon itself after navigating between locations. | These are some known issues with the Physical Workspace in Packet Tracer 5.1. It will be fixed in a later version.
70 | How come the output for various commands in Packet Tracer 5.1, such as "show ipv6 nat translations," is different from a real router? | This is due to differing versions of IOS images. Please see General Issue #3 for a list of IOS images that Packet Tracer 5.1 supports.
71 | When I click on Save Settings in the Applications & Gaming section in the Linksys GUI, the last item in focus does not save. | The workaround is to click on another item to change the focus before clicking on Save Settings.
72 | How come when I create a complex PDU, the Outgoing Port drop-down list does not contain any ports? | To select an Outgoing Port manually, the source port needs to be configured properly. That is, the source port needs to be up and it must be configured with an IP address.
73 | The Variable Manager Interface in the Activity Wizard Answer Network panel is too narrow. | The workaround is to use the table splitters to adjust the size.
74 | When I have a router with 2 LANs (e.g. 192.168.1.1 and 192.168.2.1), a PC with an IP address in the 192.168.1.0 network can be pinged by a PC in the 192.168.2.0 network even if the PC in the 192.168.1.0 network has the incorrect default gateway (e.g. 192.168.2.1). | This is how it is works on a real router.
75 | When I copy and paste the entire "show running-config" output in Global Config Mode, some commands return "% Invalid input detected at '^' marker." | Some commands are not supported, but shows in the "show running-config" output.
76 | When I undo a deleted device/link that was connected to a Multiuser remote network, Packet Tracer crashes. | This is a bug. Packet Tracer crashes when undoing any deleted devices/links connected to Multiuser remote network. Avoid undo right after deleting devices/links that are connected to Multiuser remote networks.
77 | When I delete a link to a Multiuser remote network, the link isn't removed from the Multiuser remote network. | This is a bug. Deleting links to Multiuser remote networks do not remove them from the Multiuser remote network. Avoid creating and deleting too many new links.

Protocol Modeling Issues

| Question/Problem | Answer/Solution
1 | For EIGRP, why are new adjacencies being formed after the "no auto" command--this does not happen on real routers? | To accurately implement the "no auto" command, when it is issued, the router needs to calculate which directly connected and learned routes are advertised to which neighbors as summary routes. The router needs to tell those neighbors those routes are down now and advertise the new non-summarized routes. The Packet Tracer 5.1 model simply resets the neighbor adjacencies and consequently removes all previous routes and has to relearn them. This process does not simulate the real process of convergence but shares the same results after the convergence.
2 | Why does the "no keepalive" command give me an error in some situations? | Packet Tracer 5.1 only supports "no keepalive" on serial links.
3 | On real devices, the link lights would still come up if there is a duplex mismatch between both sides of the Ethernet connection. Why does Packet Tracer not model this behavior? | On real devices, the link lights would come up in the case of duplex mismatch, but the error rate on the ports would go up because of mismatch. However, Packet Tracer does not model the statistics on the ports, and there is no other way to show that having mismatch duplex is a problem. So, Packet Tracer makes the link not come up to indicate the problem.
4 | On real switches, if there is a native VLAN mismatch on both sides of the same trunk, CDP and STP would print out error messages. Why does Packet Tracer not model that? | In Packet Tracer 5.1, CDP prints out an error message, but STP does not.
5 | I cannot disable STP on switching devices. | This is a modeling decision in Packet Tracer since disabling STP may cause loops that can generate broadcast storms in the network. This can severely impact the performance of Packet Tracer.
6 | On a real device, I can ping the loopback address 127.0.0.1, what about in Packet Tracer? | Packet Tracer 5.1 now supports pinging loopback addresses on PCs, but not on routers and switches.
7 | On a real router, I can configure an interface with a valid IP address and subnet mask even though it is a supernet (e.g., 172.24.11.1 255.254.0.0), but in Packet Tracer it says that the subnet mask is a "Bad mask." | This is a modeling limitation in Packet Tracer. Packet Tracer 5.1 does not support supernets. The workaround is to use 255.255.0.0 for the subnet mask for the example given.
8 | I cannot configure an IP address on a modem interface module on the router, but there is a configuration interface in the Config tab. | Packet Tracer 5.1 has a simplified model of modem interfaces and does not model all modem operations accurately.
9 | If there is a DHCP request with two or more DHCP servers, and then a DHCP request fails due to a possible collision when the DHCP servers try to respond simultaneously, there should be lots of traffic but there are no further events after the collision. | Packet Tracer 5.1 has a simplified model of layer 1 collisions. Once a frame is sent out on an interface, and if a collision happens before the frame reaches the destination, the source device would not retransmit.
10 | Why doesn't STP block the ports if the native VLAN mismatches? | STP in this version of Packet Tracer does not implement this feature. However, CDP detects the error and prints out an error message. This modeling limitation is fixed in Packet Tracer 5.1.
11 | On a real router, the timer is reset for OSPF and EIGRP routes after a "clear ip route *" command, but not in Packet Tracer 5.1. | This is a modeling limitation of Packet Tracer 5.1.
12 | Why does the Linksys remote management override HTTP port forwarding? | The problem is that the Linksys router uses port 80 for remote management. On a real Linksys router, it uses port 80 on the LAN side and port 8080 on the Internet port. The current implementation of Packet Tracer 5.1 determines whether or not to allow remote management by using an ACL on the Internet port that blocks all traffic to port 80. The workaround is to enable remote management on the Linksys router. This allows traffic to port 80 into the device. NAT then translates to the IP address on the destination device and then sends it out to the destination device.
13 | The show ip ospf neighbor command shows a priority of 1. Actual 1841 shows priority of 0. | The OSPF priority depends on the IOS version. On version 12.2, it shows 1. On version 12.3 and later, it shows 0 even if the priority is manually changed to 100. This may be a bug in the IOS and would not be modeled in this version of Packet Tracer.
14 | Static routes with 255 admin distance should not be added to routing table. | This is a bug in Packet Tracer and was discovered late in the testing process. It will be fixed in a future version of Packet Tracer.
15 | Why do wireless ports always buffer the frames before sending? | This is because the wireless port is doing CSMA/CA and sends a Request To Send (RTS) before sending any data frame. It then has to receive a Clear To Send (CTS) from the destination device before sending the data frame. Packet Tracer 5.1 is not showing the wireless management frames, so it would show the data frames being buffered without seeing any other frames.
16 | Why are LMI statistics not updated when the link state changes? | Packet Tracer 5.1 does not use an accurate model of LMI. As a result, static outputs are shown for show LMI commands.
17 | Why can I only ping one VLAN interface on the switch when there are more than one with the status and line protocol up? | The 2950 switch allows only one active VLAN interface up at a time. However, the 2960 switch and the ISR routers allow multiple. To bridge the gap between the more -used 2960 switch, ISR routers and our modeling, we allow multiple VLAN interfaces to be up at the same time. However, to minimize the risk of changing some major components at testing stage, we do not allow multiple VLAN interfaces to have layer 3 functionality.
18 | Why does OSPF not work over physical serial interface using frame relay? | OSPF over NBMA networks is not currently supported in this version. This includes physical serial interfaces and multipoint sub-interfaces. However, it works on point-to-point sub-interfaces.
19 | In Simulation Mode, routing tables are updated before the packet arrives in the simulation. | This is a modeling limitation of Packet Tracer 5.1.
20 | On a router with multiple switching modules, there should be individual MAC tables for each switching module. However, "show mac-address table" shows only one MAC table. | This is a modeling limitation of Packet Tracer 5.1.
21 | Why is the command "ip ospf network" not available in the loopback interface mode? | This command is only available on Serial interfaces to allow OSPF to work over Frame Relay.
22 | The round trip times for pings in Multiuser networks are very long. | This is a modeling limitation of Packet Tracer 5.1. The delay can also be caused by the propagation of real TCP packets.
23 | When I issue the command "debug ppp negotiate" before enabling PPP encapsulation, debug messages do not show. | This is a bug in Packet Tracer and was discovered late in the testing process. It will be fixed in a future version of Packet Tracer.
24 | On a real switch, when I create a VLAN and then assign a name to the VLAN, VTP revision number increases by 1. In Packet Tracer, the VTP revision number increases by 2. | This is a modeling limitation of Packet Tracer 5.1.