Getting Real with GNS3 – connecting to physical networks

This short guide shows how you can connect emulated routers with physical routers using GNS3 and the Ethernet NIO. This is a cheap method for expanding your home networking lab, and it is amazingly simple. Whilst I’m using Windows, the same method will work with Linux too.

All you need to do is add a cloud, bind it to your NIC as an ethernet NIO, and connect it to a router. It’s really that simple. I’ll show a couple of screenshots though to demonstrate.

Here’s the network layout:

Here’s the configuration for the cloud:

As you can see from the prompt of GNS_R1, it can see the cisco AS2509-RJ I have plugged into the Ethernet port on my laptop:

GNS3_R1#config t
Enter configuration commands, one per line.  End with CNTL/Z.
GNS3_R1(config)#int fast 0/0
GNS3_R1(config-if)#ip address
GNS3_R1(config-if)#no shut
*Mar  1 00:02:07.575: %SYS-5-CONFIG_I: Configured from console by cosole
GNS3_R1#show cdp neighbors
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
access           Fas 0/0            127           R       AS2509-RJ Eth 0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/36/108 ms

14 thoughts on “Getting Real with GNS3 – connecting to physical networks”

  1. hi chris ! i have a problem. When i put a cloud actually i have an empy list and i dont see any ethernet nio…. any clues?

    1. Open GNS3 as an administrator. On Windows, right-click on GNS3 program and select ‘Run as administrator’. Once up and running you should be able to see a list of network connections in the cloud.

  2. hi i have a problem while connecting my laptop with GNS3 router..
    should any one help me…
    to archive it

  3. I did configure the way you’ve suggested and i can ping my interface of my laptop but not the Default-Gateway (my ADSL Router). Any Idea?

    I’ve seen many who faced this problem in other forums, but none got an answer.. please advise.

    1. Hey dude !
      I think you need to add route pointing your the ip add you can ping :
      example: ip route
      If you still cant ping your default gw , i suggest you check your firewall rules of your windows or Linux… It worked for me

  4. Hi, I configured isis on my router, I can ping to physical interface, but I can`t ping to loopback interface, I`m connecting two computers. Could you help me please….

  5. I am facing a wierd problem doing this on Ubuntu 12.04, I don’t know what is wrong.
    My system’s eth0 is connected to a ADSL modem and I have connected a router in GNS3 to this interface directly through the cloud.
    In the router I have done the following config

    Interface FastEthernet 0/0
    ip address dhcp
    no shutdown

    The router gets the IP address via DHCP from the ADSL modem and I am also able to ping ANY internet address/hostname but I am unable to ping my Ubuntu physical machine. I have disabled IPTables also. Please advice.

  6. I am trying to do this in GNS3 Workbench by rednectar (ubuntu basically) and have no luck whatsoever. It is a VM, but I have it bridged to my physical network. I just dont get it.

    If you have any insight, it would be appreciated.



  7. what address will you give the 1 gns device interface connected to the cloud
    2 the physical interface of the device
    3 the external device.

    do they all need to have addresses on them if so do they all need to be in same subnet.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.