I need to simulate an ISP's network with at least 20 routers, I can use IOS images and topology which i have with me.
a. What kind of system can host 20 virtual routers? I need to know the hardware configuration required for the host system with CentOS/Ubuntu Linux?
b. What precautions needs to be taken to move/replicate a setup from one machine to another, once this setup is done we may need to replicate it on some other machines also?
c. I created a simple topology with two routers and both are able to communicate with each other on serial and FastEthernet ports but how to connect my host machine with this as i wish to replay some collected data on these virtual network.
I am working on a project and doing some test cases, so once these setup is complete and test cases are done, i will upload the complete findings to share with others.
Wish to get an informative response.
Did you managed to create the network ? Can you send me an example of it?
I Believe that you can run this scenario in Linux(Debian or Xubuntu) with 3GB ram memory.
If you need to collect data between to router, try to use Wireshark.
My GNS box is Athlon II X2 255, 8G of RAM and I use Linux Debian. CPU is 2-core unit, so max CPU usage is 200% for single process (as reported by top). So, in my case: having 100% CPU means 1 core is funnning at full speed while second is idle. Or, both of two cores are running at half speed.
I created topology with 12 routers (c3660-jk9o3s, some of 12.4 line) and have 90-110% cpu utilization, with pure routing (no access lists, IPSec and so on), and witout generating or capturing traffic on project's network. So, in theory, I can have 20-30 routers running.
According to http://www.cpubenchmark.net/cpu.php?cpu ... 255&id=139 - My CPU scored at 1838, so having system with CPU score 2500-3000 (of course more is better) should handle any topology with 20-25 routers, even in worst scenario. If you're about upgrade your current platform, you can check CPU scores based on CPU socket and check if your system is worth upgrading.
My (mentioned above) topology consumed circa 1.1GB of RAM, and I took high memory mark with all routers running (with my config) for a few minutes, with console access to all routers (konsole). The low memory mark was taken after closing topolgy AND gns3.
and, you should download and read an old but still valuable document named "GNS3-0.5-tutorial.pdf" (google for that name, it's available from sourceforge).