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m4rtin
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possibilities for computer emulation in GNS3

Mon Jan 23, 2012 8:53 pm

Which computer simulation, emulation or virtualization techniques do you use in GNS3? What are the advantages and disadvantages?

So far I have tried:

1) Virtual PC Simulator It's rather lightweight as it takes less than 10% of CPU utilization:

Code: Select all
$ cpuid | grep -i brand
Extended brand string: "Intel(R) Core(TM) Duo CPU      T2400  @ 1.83GHz"
$ ps -eo %cpu,%mem,args | grep vpcs
 9.5  0.0 ./vpcs32
 0.0  0.0 grep --color=auto vpcs
$


..while simulating nine computers. VPCS is not the traditional PC, it is just a program running on the Linux or Windows, and only few network commands can be used in it. And it's very limited in terms of functionality :) All one can do within the simulated PC is listed here:

Code: Select all
VPCS[1]> ?

show                       Print the net configuration of PCs
d                          Switch to the PC[d], d is digit, range 1 to 9
history                    List the command history
ip [arguments]             Configure PC's IP settings
dhcp                       Configure host/gateway address using DHCP
arp                        Show arp table
ping address [options]     Ping the network host
tracert address [maxhops]  Print the route packets take to network host
echo [text]                Display text in output
clear [arguments]          Clear ip/ipv6, arp/neighbor cache
set [arguments]            Set hostname, connection port and echo on or off
load filename              Load the configuration/script from the file 'filename'
save filename              Save the configuration to the file 'filename'
ver                        Show version
?                          Print help
quit                       Quit program

VPCS[1]>


It's difficult to see a point in VPCS in GNS3- a Cisco router is able to perform all those tasks easily and doesn't put much more load on the host PC. Or am I missing something here?


2) emulated Tiny Core Linux using the Qemu. It's lightweight as well and Tiny Core Linux has some useful tools(tcpdump, iptables, traceroute) already shipped with the distribution and even has a packet-manager with additional programs. On the other hand, it's a very stripped down distribution..


3) connected my own workstation with GNS3 using the TUN/TAP device. This allows one to connect his own workstation to network topology created with GNS3- all the tools(from nmap to Wireshark) can be used to analyze or modify network traffic in the GNS3 topology. In addition, it doesn't put any additional load to host PC.


4) OS virtualization using the [url=VirtualBox]https://www.virtualbox.org/[/url]. This seems to be most functional so far- one can run multiple virtualized workstations/servers(different operating systems of course) each bridged with one interface to LAN(and have Internet access) and bridge other interfaces with routers in GNS3 topology.


Any other possibilities for computer emulation, virtualization or simulation in GNS3? Which one of those provide the best memory/CPU utilization VS functionality ratio? :roll:

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Re: possibilities for computer emulation in GNS3

Tue Jan 24, 2012 4:56 am

I'm lazy. I use routers (3725) with 'no ip routing', 'no cdp run' and a default route.
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mellowd
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Re: possibilities for computer emulation in GNS3

Tue Jan 24, 2012 4:58 am

Yes I just use routers as hosts. After all, you're really just testing reacability now aren't you?

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dude_
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Re: possibilities for computer emulation in GNS3

Tue Jan 24, 2012 5:30 am

m4rtin wrote: Which one of those provide the best memory/CPU utilization VS functionality ratio? :roll:


During enumeration you already have answered that. Just decide the level of OS functionality you'll need and pick one accordingly.

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Halo
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Re: possibilities for computer emulation in GNS3

Tue Jan 24, 2012 5:33 am

If I'm testing something specific, I'll run a box in vmware workstation and connect it via a tun/tap interface.

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