Comparing Networking Hardware
This is helpful to know for an IT Technician who supports Managed Service Provider (MSP). MSP helps businesses install and manage their computer networks. One of the compliance is that every network deployment, must be modelled in a Graphical Network Simulator v3 (GNS3) project. This allows for pre-installation testing and also supports post-deployment troubleshooting. For example, if there was an isolated network segment comprising a single switch with four PCs connected to it and you are left with what another technician did not complete. This is a test environment for you and you need to test it.
GNS3 = (Graphical Network Simulator v3) is a software that allows simulated and emulated appliances and virtual machines to be configured into network topologies within a graphical workspace, making it easy to visualize the arrangement of nodes and links. It is widely used for network development, testing, and training.
Open a GNS3 project and from the dock, select the GNS3 icon.
From the project dialog, select the project that relates to the project you are working on. The one I had worked on is for the COMPTIA A+ certification, instruction provided by Western Governor’s University (WGU). I had an existing topology that contained a switch and four end systems (4 PCs), placed in the main workspace pane. PC4 is not connected to the switch yet.
On the main toolbar, I had selected the green triangular icon to Start/Resume all nodes. A window had popped up, selected Yes to confirm the prompt.
Right clicked the line between the switch and PC1, and from the shortcut menu, selected Start Capture.
In the Packet capture dialog, selected the check box for the Start the capture visualization program. Selected OK to confirm the prompt. A Wireshark app window opened up.
From the dock, selected GNS3 icon. Right-clicked PC1 and selected Console. A terminal window opened with PC1 identified in the title bar. This node used the Virtual PC Simulator (VPCS) software to mimic a basic host.
In the PC1 terminal window, used the help command to view which commands are available.
PC1> help
Ping 10.0.0.2 in the terminal. This command verifies connectivity with PC2. It generated five replies, indicating that a link is present.
In the Wireshark window, observed the traffic generated by the probe. Selected the first frame in the top pane where the protocol is ICMP. In the middle pane, double clicked the Ethernet II value to expand it.
The MAC address value showed in the source and destination fields. The source address of PC1 showed as 00:50:79:66:68:00.
Selected the PC1 terminal window and ran the command ping 10.0.0.4 to check connectivity with PC4. PC4 was not connected to the network, so there were no replies received and the error message returned was “not reachable”.
CONNECT NODE
The devices toolbar docked to the left-hand side of the GNS3 window is used to add nodes and links to the workspace. Connected the PC4 node to the switch and tested the connection.
In the GNS3 app, from the Devices toolbar, selected the Add a link icon.
The cursor went from pointer to a cross. Selected the PC4 node. From the drop down menu, selected Ethernet0. Moved cursor to the Switch node and clicked it. From the drop down menu, selected Ethernet0. This simulates using a cable to connect the network adapter interface on PC4 with one of the ports on the switch.
Clicked the Add a link icon again to disable the tool and return the normal mouse pointer. Selected the PC1 terminal window. Ran ping 10.0.0.4 -c 1 to check connectivity. Switched to the Wireshark window and scrolled the first pane to the end of the capture which then I had selected the last ICMP packet.
This is a great way to use the Ethernet II frame details to record the Ethernet address of PC4. Ran another probe and used Wireshark to identify PC3’s hardware address.
