I’ve been getting questions about switches in GNS3 so decided to write this article explaining which switching protocols you can or cannot use in GNS3. First of all, it’s impossible to run switches in GNS3! That being said the option that we do have is using the NM-16SW switching module in a router which gives us some capabilities. Now you are probably wondering ‘which capabilities’ so let’s have a look what we can do. You might have noticed that in the newer versions of GNS3 there’s a Etherswitch Router.
This is a Cisco 3725 with the NM-16SW module so only the icon is different. Now let’s see what “switching” options we have. Vlan interfaces: You can create vlan interfaces which can be used as the default gateway for clients. For example interface vlan 10 with IP address 10.10.10.10 and interface vlan 20 with IP address 20.20.20.20. This is the same as you would do on any L3 switch like the 3550 or 3560. Trunking: Trunking is looking good, the only encapsulation type is 802.1Q which is fine (no ISL). But you are able to setup a trunk connection just fine.
There is no dynamic auto or dynamic desirable mode so now way to lab this. Vlan Trunking Protocol (VTP): VTP is working just like on a switch, you can configure the VTP domain, mode like server / client / transparent, pruning and passwords. Etherchannel: If you want to learn etherchannel you are better off with some real switches, you can enable it but there’s no Lacp or Pagp support.
Spanning-Tree: You can learn the basics of spanning-tree, see which ports are in blocking and forwarding mode but don’t expect any fancy stuff. To be honest you are better of with real switches to study spanning-tree if you ask me. Switched Port Analyzer: Should be possible but to be honest I didn’t fully test it yet. The commands are there so I believe it should work just fine.
I would just like to ask what is the latest IOS version of 3550 switch? Also how will I know that the version is an EMI version? Sign In or Register. Does upgrading/downloading the IOS from cisco website free? Jeanathan Posts. So you must pay when you download cisco IOS on cisco website? Is that correct?
Storm Control: Storm control is there and seems to be just fine. Quality of Service (QOS): The switch commands for Qos are there like “mls qos” and you can configure the mls qos maps. This looks cool to me! So what do I think of it? To be honest I like it a bit better after researching all the commands and what the options are.
If you want to play with vlans or vlan interfaces there’s nothing wrong using the NM16-SW module. Trunking is fine, you can do everything that you want as long as you don’t care about ISL. VTP is the same thing as on a real switch so no need for real hardware here. Etherchannel I don’t like since there’s no Lacp or Pagp support, the same for spanning-treeyou lack a lot of commands and there’s no way to switch to other modes like MST which you can do on a real switch. SPAN is excellent and I also like Storm Control and the Quality of Service commands. So what should you do? Get real switches or use GNS3?
If you have no budget and are studying for CCNA, just use GNS3. If you do have some money to spend get 2 or 3 Cisco 2950’s and you will have more fun. If you are studying for CCNP SWITCH just get yourself a 3550 and a 2950 or something. It’s not too expensive and using a real switch is better.
For the CCIEdo yourself a favor and invest in 2x 3560 and 2x 3550 and connect them to a breakout switch or get quad-nics. You’ll be spending a LOT of time studying and it’s better to spend your time at switches than the NM16-SW module. If you want to know all the options for the NM16-SW module check out this article on the Cisco website: Next time i’ll be writing an article how to connect your real physical switches to your GNS3 topology. So what do you think?
Is there anything i’m missing? Please share your opinion in the comments!
. Boot the switch into SWITCH ROM mode. Initialize the flash file system. OPTIONAL – Format the flash file system if needed.
(This will remove your startup configuration). Set the baud rate to 115200 to increase xmodem transfer speed and decrease time required to restore the IOS Image.
Copy the Cisco IOS Image via xModem to Flash:. Set the boot parameter to the new image name located in Flash:. Unset the baud so that it defaults back to 9600. Boot the switch and verify that the switch boots properly. Lab Instruction Recovering the Cisco IOS Image on a fix configuration Cisco Catalyst Series Switch is quite a bit different and more of an “old school” way of doing an IOS image recovery. Unfortunately fixed configuration switches require the use of xModem to restore a corrupt or missing IOS images unlike the Cisco 4500 and Cisco 6500 Series supervisor engines which use compact flash cards Step 1.
Boot your switch into switch ROM mode. This typically involves holding down the STAT button on the front of the switch when plugging in the power.
You can check out the required procedure by clicking Once you’ve booted your switch into Switch ROM mode you’ll be see the following dispatch; Boot Sector Filesystem (bs) installed, fsid: 2 Base ethernet MAC Address: 00:14:f2:d2:41:80 Xmodem file system is available. The password-recovery mechanism is enabled. The system has been interrupted prior to initializing the flash filesystem. The following commands will initialize the flash filesystem, and finish loading the operating system software: flashinit boot switch: Step 2.
Once you’ve booted into Switch ROM mode you’ll need to initialize the flash file system by executing the flashinit command as shown below; switch: flashinit Initializing Flash. Flashfs0: 1 files, 1 directories flashfs0: 0 orphaned files, 0 orphaned directories flashfs0: Total bytes: 15998976 flashfs0: Bytes used: 12474880 flashfs0: Bytes available: 3524096 flashfs0: flashfs fsck took 10 seconds.done Initializing Flash. Switch: Step 3 – OPTIONAL – If your image is corrupted you can format your flash file system by executing the format flash: command as shown below however this will delete your start-up configuration!!!
Switch: format flash: Are you sure you want to format 'flash:' (all data will be lost) (y/n)?y flashfs0: 0 files, 1 directories flashfs0: 0 orphaned files, 0 orphaned directories flashfs0: Total bytes: 7741440 flashfs0: Bytes used: 1024 flashfs0: Bytes available: 7740416 flashfs0: flashfs fsck took 12 seconds. Filesystem 'flash:' formatted Switch: Step 4. To speed up the xModem file transfer speed you’ll need to set the console line BAUD rate to 115200 by executing the set BAUD 115200. If you do this you’ll need to disconnect your console session and change the serial line speed from 9600 to 115200. However if you do not set the BAUD to 115200 your file transfer can take up to 3 hours. Switch: set BAUD 115200 每 Step 5.
Once setting the BAUD rate and reconnecting to the console line of your Cisco switch you’re ready to copy the IOS image via xModem to the switch’s flash memory by executing the copy xmodem: flash:filename.bin and starting the xModem file transfer from the terminal emulator client as shown below; switch: copy xmodem: flash:c3560-ipservicesk9-mz.122-53.SE.bin Begin the Xmodem or Xmodem-1K transfer now. CCC Starting xmodem transfer.
Press Ctrl+C to cancel. Transferring c3560-ipservicesk9-mz.122-53.SE.bin. 100% 12181 KB 6 KB/s 00:31:56 0 Errors. File 'xmodem:' successfully copied to 'flash:c3560-ipservicesk9-mz.122-53.SE.bin' switch. Once the IOS image is copied into flash you’ll need to update the BOOT parameter by executing the set BOOT flash:filename.bin command as shown below; switch: set BOOT flash:c3560-ipservicesk9-mz.122-53.SE.bin Step 7. Once the boot parameter has been set you can now set the BAUD rate back to the default 9600bps by executing the command unset BAUD.
Note that when doing this you’ll need to disconnect your current console connection and change the baud speed on your terminal emulator from 115200 back to 9600. Switch: unset BAUD 每 Step 8 is the last step which is to boot the switch and verify that the switch successfully boots the IOS image placed into flash from xMODEM.