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Old 11-18-2010, 04:13 PM   #1
spoovy
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Virtual networks as a learning environment?


Hi i'm just after any general opinions here if anyone feels they have anything useful for me.

I've been learning linux for a while now with half an eye on making a career out of it in future. One sizeable gap in my knowledge at the moment is networking. So, the question is..

Is it feasible/desirable to set up a network of virtual machines to use as an environment to learn networking?

My budget is non-existent so I was hoping to be able to get a basic understanding of the principles from installing a few desktops, a virtual gateway etc on VMware workstation on my laptop, and doing a lot of reading online.

Is this feasible, or will I just end up learning about virtual networks instead of real ones? Also how much power would be required, because my 3GB RAM lappy has just gone bang and all I have now is a (new) 1GB RAM lappy.

Cheers

Spoov
 
Old 11-18-2010, 04:17 PM   #2
jefro
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Virtual machines could be used to configure any number of test environments as long as you know exactly how the VM's work.

There are 4 ways a VM can be connected. Bridged, Natted, Local and not at all. Each one has to be understood.

Your problem might be the 1G. Be stingy on your VM's or you will run out of ram in a hurry. You may not be able to run more than 3.

Qemu can be used but it is pretty slow if you exceed actual ram. Other VM's won't allow you to use more than available.
 
Old 11-18-2010, 04:21 PM   #3
spoovy
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I was hoping that being very stingy with the desktops (no desktop GUIs at all if possible, otherwise very minimal setups) would work, and that 3 machines (one gateway, two clients) would be enough.

I am waiting for CentOS 6 as well cos apparently it's very efficient at virtualisation. I need to look into Qemu I don't know it at the moment - would you recommend it above VMWare?
 
Old 11-18-2010, 04:24 PM   #4
TobiSGD
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I always test my ideas on virtual networks, before I do test runs on real machines. This way I have learned a lot, and of course it is much cheaper (and less space-consuming) than having servers and clients every time available just for testing. It is faster to switch between virtual machines instead of real machines, too.
Memory will be your main problem if you are thinking about running more than two machines at the same time, but that depends on what you plan to do. If you set up a simple "one server, one client" network to learn how to configure Samba you can live with both machines set to 256MB (or less if you don't install/run a GUI on one of the machines), but if you want to setup more machines you will need more RAM (and depending on what you want to do maybe a better CPU).
I have hardly any problems setting up virtual networks on my main machine, but it is a true power-horse.
 
Old 11-18-2010, 04:29 PM   #5
spoovy
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Thanks guys. I'm very pleased that it's a sensible idea at least! I will hopefully get my decent laptop fixed soonish which is a dual-core 3GB machine. I can set up at the least a few different types of pairs (server-desktop, gateway-server etc) to run in the meantime, and then plan a larger network for when my better pc is fixed.
 
Old 11-18-2010, 05:37 PM   #6
okcomputer44
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Hi,

You could try the GNS3 application too.http://gns3.net/ This is a real Cisco emulator.

It uses the real Cisco IOS software so you can learn Cisco stuff without any budget. In my lab right now I have 7 routers and one Cisco PIX firewall and they connected into my real network. So this is a really good application to study networking.

I think the VMware server is the best choice to emulate clients on your Laptop/Desktop computer. The server is able to share SCSI bus so you could try to study the clustering too with it.

Laz.
 
Old 11-18-2010, 07:51 PM   #7
jefro
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I haven't tried it but there is a web based VM out there. You'd have to play with it to see if it could reduce ram usage.

It is a Java based Virtual machine (I know, it is a real vmplayer type VM not a normal java vm)

http://jpc.sourceforge.net/home_home.html
 
Old 11-19-2010, 10:46 AM   #8
spoovy
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JPC looks a bit beyond me to be honest. Interesting though i might have more of a look in future.

GNS3 looks brilliant though - assuming I can work out how to use it that is. Does it work with actual virtual machines that I will create in VMware, or is it a standalone application that models network behaviour without using existing vms?

Would you recommend VMware server over workstation then? Server is harder to install on Slackware you see, and i already have workstation up and running.
 
Old 11-19-2010, 11:23 AM   #9
okcomputer44
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Well if you have the Workstation installed already I guess just carry on useing it. The Workstation nearly as same as the Server.

The GNS3 is a standalone application you don't need any VM to use it. This is for pure networking. The application is able to connect to your real network through your machine's network adapter or you could bridge it to any Virtual Machine too. (When it bridged the router behaves as it plugged into the real LAN)

The GNS3 site documentation contains everything you need to build your own lab on your computer. http://gns3.net/documentation
It is a bit deep water in the first time but Cisco is the leader in networking so we don't have a choice.
All the docs have got videos. So it is relatively easy to setup just need time/patient to get it done.

You can download IOS(the router operating system) for the router(s) here: http://jonsfiles.com/IOS%20Images%20...2610XM-2611XM/ or you could google it: http://www.google.com/search?hl=en&q...0directory+bin

I hope you can untie my English

Laz.
 
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Old 11-20-2010, 10:41 AM   #10
spoovy
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Great, thanks very much. Your English is fine btw, no untie necessary.
 
Old 11-21-2010, 04:35 PM   #11
okcomputer44
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Don't mention it. I hope this application can help you out.
 
  


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