Systems and Network Infrastructure Integration. Saida Helali
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It is possible to integrate virtualized Windows and Linux operating systems via VirtualBox or other virtualization solutions.
– GNS3 provides a link between the simulated network and the real physical network so that the virtual and physical components function together.
2.3.2. Limitations
GNS3 only works with specific types of routers. The IOS must be compatible with these types of routers. An IOS image cannot be used for a 2,800 router on a platform emulated for a 3,725. Moreover, GNS3 does not currently work with switch platforms. Generic switches can be integrated to simulate basic switching functions.
2.3.3. GNS3 installation
GNS3 exists for Windows, Linux and Mac, and can be downloaded from https://www.gns3.com/. You must create an account in order to download GNS3 for free.
You should follow the recommendations pertaining to the hardware configuration of your system. The minimal configuration is made up of a two-core processor, 4 GB of RAM and 1 GB of hard disk space for installation.
Only a few tests can be carried out with this configuration, due to lack of resources. The more powerful the system configuration, the more new routers, switches and other virtual servers can be added, and the larger the scale of the tests that can be conducted.
GNS3 uses well-known software programs from the systems and network sphere as components, some of which are required, including WinPcap, Wireshark, Dynamips, VPCS, and other optional programs such as SolarwindsResponse and Virtviewer.
2.3.4. Getting started with GNS3
Once installation is complete, we must first create a new project.
Figure 2.1. Creation of a new project. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
When the project is created, the main window with various toolbars appears.
Figure 2.2. Description of GNS3 interface. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
The outlined parts of Figure 2.2 are defined below.
Create/open a project
The first button allows you to connect with one click to the consoles of each device in the model. The second displays the configuration terminal of a router or a switch.
– The first button is the Start button, which launches the model's hardware.
– The second button pauses it.
– The third button turns it off.
– The fourth button restarts the whole thing.
– The fifth button displays the client's virtual machine.
The first two buttons are used to zoom (this can be useful when working with a large model).
The third button takes a snapshot of the model (to send to the client, for example).
2.3.4.1. Integration of IOS image
Using peripheral device selection, we can select a router and drag it toward the main window; however, this only works for previously configured equipment.
To do this, we first go to the menu bar in EDIT | IOS IMAGE AND HYPERVISORS to add the IOS image we have obtained (paid or free).
Figure 2.3. Adding IOS Image. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
We select the image file as well as the corresponding platform and model before saving.
A base configuration is saved as a text file (baseconfig.txt) that is automatically created in the specified path. This text file is later used to customize the base configuration of all routers according to the need.
The Cisco 1700 router is added and the following message appears: “Warning: IDLE PC will have to be configured!”
Figure 2.4. Example of a router image. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
IDLE PC
The field “IDLE PC” is a value that enables the optimization of CPU resource allocation.
GNS3 consumes a very large amount of resources. Without additional configuration, a single router in GNS3 can use 100% of the processor. However, it is possible to reduce this drain on resources by defining an IDLE PC value. To do this, right-click on the router and then click the Start button. Next, right-click again and select IDLE PC.
Figure 2.5. Using the IDLE PC function. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
GNS3 calculates the possible values for IDLE PC and offers a range of choices, as shown in Figure 2.6.
Figure 2.6. Suggested range of IDLE PC values. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
Using the Task Manager, we can test the extent to which applying the suggested IDLE PC value will affect the processor load.
2.3.4.2. Constructing a simple network topology
We begin by selecting a router. Only the types of routers for which we have already provided an IOS image are available; all others are grayed out. In Figure 2.7, we have two router models available (the previously added C1700 and the existing C3600).
Figure 2.7. Available router images. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
Using Drag & Drop, we drag the desired routers into the main window.
Figure 2.8. Adding routers to a topology. For a color version of the figure, see www.iste.co.uk/helali/systems.zip
To configure a router, right-click and select CONFIGURE.