GNS3 - How many routers can you use?

Node ManNode Man Member Posts: 668 ■■■□□□□□□□
Hi Everyone,
Just a general question, i presume it has to do with cpu strength and settings in GNS3. But i wanted to ask, how many routers can you personally get to work on GNS? I was getting 5, but now they run very slowly and pings are failing (LOL).

Just wondering.


  • networker050184networker050184 Mod Posts: 11,962 Mod
    I don't know if GNS3 has a limit, but cpu and memory will obviously hold you back. We had a server up and running a pretty large setup around 20+ routers with dynamips. I've ran 8 router setups on an old Vista PC with 1G RAM without an issue so any modern computer should be able to run 5+ easily. Just have to work on your idle PC values.

    I have a standard 5 router setup I have running all the time (running right now!) with BGP/MPLS/OSPF for quick tests and never noticed any kind of performance issues from it.
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  • Node ManNode Man Member Posts: 668 ■■■□□□□□□□
    Another perfect answer Mr Networker. Thank you! icon_smile.gif
  • ZartanasaurusZartanasaurus Member Posts: 2,008 ■■■■■■■■■□
    Make sure you set the idle PC value for each router platform you use. Some of our test network runs through GNS3. You get crappy performance (about 25ms RTT) when running real traffic through it, but I have about 10 devices, including ASAs, running on a Windows server with no problem. I've run as many as 20+ devices on both Windows and Linux.
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  • Mrock4Mrock4 Banned Posts: 2,359 ■■■■■■■■□□
    I run around 15-20 routers with my work laptop (8GB of RAM), so as mentioned, as long as your IDLE PC value is set, you'll be OK for about as many as you need.
  • DevilWAHDevilWAH Member Posts: 2,997 ■■■■■■■■□□
    with the latest GNS3, and its ability to auto pick an good Idle PC value for you its go a lot easier. But aways once you have got a good value by what ever method, a half decent PC/Laptop (4-8 gig ram) will run 15-20 with out any issues.

    My desk top PC is a basic Dell 990 with 4gig memory and I have had a lab with 16 routers running non stop for about 2 weeks in the back ground as I work with no noticeable slow downs, CPU is idling at about 10-15%

    If you need more than you computer can handle (and I would bet you could get close to 30 with a decent spec PC) you can always set up a second PC to run the dynimips emulation as an external hypervisor, at one place I had GNS3 GUI on an old laptop controlling 5 servers that run that actually routers, once got 100 running at once :).

    In all honesty though 20 routers is enough for almost any labing you likely to do.
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