Tuesday, 23 December 2014

Some Things I've learnt about GNS3

I am in no way an expert on GNS3, just a trainee   below are a few things i have learnt lately. I thought it might be a good idea to produce something like this. If everyone replied to it and added a few tips of their own it could be turned into a CLN GNS3 tips and tricks document.


GNS3 Web Sites
http://www.gns3.net GNS3’s primary Web site
http://wiki.gns3.net GNS3’s Wiki site
http://www.ipflow.utc.fr/index.php/Cisco_7200_Simulator Dynamips – the actual emulator

http://www.ipflow.utc.fr/blog/ Dynamips blog
http://dyna-gen.sourceforge.net/ Dynagen
http://www.ipflow.utc.fr/bts/ Dynamips/Dynagen bug tracking
http://7200emu.hacki.at Hacki’s forum
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1. GNS3 has less chance of crashing if the bin files are unzipped.

2. Currently images for 2600 routers must be uncompressed to work with Dynamips.

3. To dramatically reduce the load on your processor, right click on the router and choose idle, after a few moments it will give you a list to choose from.
Choose the one with a * against it, if you don't see a * in the choice run it again.

4. If you don't need any special routers then use the same type on the whole lab, this will use far less processing power and memory.

5. To print out the diagram of your network click file then export, you can export all or just what is visible.

6. To move your router/routers/links etc click the left mouse button and draw around what you want to move, you can then move everything that is inside that shape.

7. I find that if you move around the interface identities they eventually go back to their original position. I don't move them anymore as it looks a bit
messy when that happens.

8. You can't use GNS3 for the SWITCH studies, GNS3 only has basic switch capabilities.

9. You can create computers and run ping's/telnet with VPC, the document attached shows you how, its very simple to follow. I did find that it takes a few times for it to accept being a cloud, once you click ok just open it back up and check it.

10. I personally find that it is best to connect your links between routers when they are switched off, sometimes i find it fails otherwise.

11. You can create a router to act like a pc, this is shown below but it is also in the document.


Router(config)# no ip routing         Turns off IP routing function
Router(config)# interface fa0/0      Switches to FastEthernet interface
Router(config-if)# ip address address subnet_mask Assigns IP address and subnet mask to interface
Router(config-if)# no shutdown      Turns interface on
Router(config-if)# exit                     Returns to global configuration mode
Router(config)# ip default-gateway gateway_address Configures the default gateway
Router(config)# ip http server         Optional – starts http server process
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12. You can connect GNS3 to real equipment, i have not done this yet myself, it is in the document attached how to do this.

13. When using windows 64 bit GNS3 will default to program files (x86). GNS3 is a 32 bit program for windows so point it to program files not the (x86).

14. I have a Lenovo Thinkpad with a i7 processor and 4GB of RAM. With 7 routers of the same type my processor is running between 8 and 15 %, my RAM consumption is around 2.3 to 2.8 GB. That is also using a few other programs on my laptop at the sometimes.