mailsent/ December 3, 2011/ Technical Notes, Uncategorized

GNS3 stands for Graphic Network Simulator and can be used to simulate Cisco routers.  I first came across this when I want to try out Cisco SDM and could not do this in Packet Trace.

The Cisco SDM is a web base management for Cisco device which take the command line away and provides a GUI for administrators. or the Cisco CCNA it is on the syllabus to understand how SDM works and set up logon.

So this post is going to go over the following:

  1. Loopback interface
  2. GNS3
  3. Config router
  4. ip address
  5. SSH login
  6. Ping test
  7. SDM login

Step 1 Loopback

With GNS 3 downloaded and install you need to create and interface from your PC back to GNS 3.  To do this in MS Windows we create a Microsoft windows loopback interface and give this an address.

Windows XP

  1. Click Start, and then click Control Panel.
  2. If you are in Classic view, click Switch to Category View under Control Panel in the left pane.
  3. Double-click Printers and Other Hardware, and then click Next.
  4. Under See Also in the left pane, click Add Hardware,and then click Next.
  5. Click Yes, I have already connected the hardware, and then click Next.
  6. At the bottom of the list, click Add a new hardware device, and then click Next.
  7. Click Install the hardware that I manually select from a list, and then click Next.
  8. Click Network adapters, and then click Next.
  9. In the Manufacturer box, click Microsoft.
  10. In the Network Adapter box, click Microsoft Loopback Adapter, and then click Next.
  11. Click Finish.

Windows 7 & Vista

  1. Click the Start menu.
  2. Search for “cmd”.
  3. Right-click on “cmd” and select “Run as Administrator”
  4. Enter “hdwwiz.exe”

From that point on it’s the same approach as under Vista, i.e.:

  1. In the “Welcome to the Add Hardware Wizard”, click Next.
  2. Select “Install the hardware that I manually select from a list (Advanced)” and click Next.
  3. Scroll down and select “Network adapters” and click Next.
  4. Select under Manufacturer “Microsoft” and then under Network Adapter “Microsoft Loopback Adapter” and click Next.

As can been see the loopback for the machine is and the default gateway is, when we set the router up it will have this address.

Step 2 GNS basic setup

Inside GNS3 you will need to make sure the IOS for the routers have been downloaded and added to the set up.  I will write another post about this and place a link here soon. Once this has been done then we create a cloud interface inside GNS3 which will provide the interface between our machine and the router.

Start GNS3

On project name: SDM testing press ok

Drag the cloud icon out

Double click on the cloud and select c1

Under the ‘Generic Ethernet NIO’ select the loopback interface (see screen shot)


Press ok and drag a Router c2961 on to the work area.

Now connect the router FastEthernet interface with the cloud

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