Configuring a hub using GNS3

Using GNS3 we can configure a network! 

We will be using GNS3 the graphical network simulator We can view this in a graphical workspace which allows us to visualize the arrangements of nodes and links. we can also configure Network topologies and emulate appliances within this program. Again, we are using a linux based environment.

I prefer before starting to set my view to show the entire layout, show grid, and to show layers

Here, we have an environment set up with several PC’s and a hub.

Lets start off by checking the connections of the PC’s. as we open PC1 console and try to ping PC2 and PC3

We have a good connection with PC2 but not PC3… we can see why, looking at the graphical image of the small network we see that there is no connection from the hub to PC3

Lets add a link! We can do this with the program.

We chose open ethernet ports and configure it to connect.

Once it is connected. We can use wireshark to capture the traffic and confirm the connection

 Wireshark is listening! Let's make some noise

We will hop back into PC1 and ping PC3. Let's simply send 1 ping request and we should have 2 packers displayed on wireshark for that ping.

Our command will be ping 10.0.0.3 -c 1 

A successful ping. Lets open Wireshark

So, here we can see the ping request and the ping reply - great!

But, we also see packets labeled ARP address resolution protocol. This was sent out with the ping broadcasting to the network. Because we are on the same network and using a hub (this sends info out to the entire network) and asks every device if they have that specific IP.

At this point PC3 sees this and responds saying, I DO! And here is my MAC address.

A hub is old technology and is mainly not used in todays day and age, yet still a fun project, here we can see how a hub works.

How does this work tho? 

a hub recieviews the information and it sends the information out to everyone on that network! 

At which point, the device (specifically the network interface card) reads that information and determines if the request is for that device or not

If the IP numbers match, then the packet gets sent up to that device!

If the IP address does not match up then the packet simply gets ignored and destroyed. 

As you can see, this is a very interesting concept and I can see how networks could work better using a switch technology. 

At this point we can confirm that we have configured the PC3 to the network.