Differences between Emulation and Simulation

Network simulator software uses two methods to create virtual devices. These methods are emulation and simulation. This tutorial compares both methods and explains their key differences in detail.

Network simulation software

Network simulation software allows you to create network topologies in a virtual environment. In network topologies, you can add many types of networking devices. You can configure and use these devices in the virtual environment the same way you do in the real environment.

A virtual environment lets you test and troubleshoot your configuration without affecting the real network. For example, you want to modify a router's configuration but are not sure how this change will affect your network. In this situation, you can create your network in a virtual environment and test the change you want to make.

You can also use a virtual environment to practice exam topics. Many networking certification courses need hands-on experience with networking devices. For example, CCNA/CCNP/CCIE exams need hands-on experience on Cisco routers and switches. Cisco routers and switches are expensive. Purchasing them only for practice is not possible for many students. They can use network simulator software to practice their exam topics. Network simulator software provides a cost-effective solution for hardware devices. Cisco Packet Tracer, Cisco VIRL, and GNS3 are popular network simulation software.

Emulation V/s Simulation

If network simulator software creates a virtual copy of a physical device, it is called emulation. If the software uses emulation to create a virtual device, the virtual device must replicate the physical device's hardware and software configurations. For example, if the physical device requires 256 MB of RAM, the virtual copy of the physical device also requires the same size RAM. If the physical device needs an IOS to run, the emulated virtual copy of the device also needs the same IOS. If network simulator software creates a virtual copy of a physical device's features and functions, it is called simulation. If software uses a simulation process to create a virtual device, the virtual device does not need the hardware and software configurations of the physical device. It copies some features, commands, and functions from the physical device and implements them on a virtual device. Since the virtual device provides only a subset of the physical device's functions, it requires minimal hardware configuration. For example, if a physical device needs 256MB of RAM, the simulated virtual copy of the device may need only 56 MB.

In simple terms, during emulation, the network simulator software creates a copy of the actual device's hardware. If you emulate a Cisco device, you need the same IOS image file for the emulated device that the actual device uses. During simulation, the software creates a copy of selected features and functions from the actual device. If you simulate a device, you do not need an IOS image file to operate it. The network simulator automatically installs a minimal OS on each simulated device.

Simulation and emulation on Cisco Packet Tracer, Cisco VIRL, and GNS3

Cisco Packet Tracer does not support emulation. GNS3 supports emulation but does not include Cisco IOS image files. You must obtain all necessary IOS image files and import them into GNS3. You can get an IOS image file from many sources. You can download it from the Internet, purchase it from Cisco, or copy it from a running Cisco device. Cisco VIRL supports emulation. It includes Cisco IOS images. You can use Cisco VIRL out of the box. Cisco Packet Tracer, Cisco VIRL, and GNS3 support simulation. They include many built-in simulation devices you can use to test running configurations on emulated devices. PCs, Hubs, and layer-2 switches are some examples of simulated devices.

Differences between emulation and simulation

The following table lists key differences between emulation and simulation.

Conclusion

Understanding the differences between emulation and simulation is crucial for effectively utilizing network simulator software. Emulation provides an exact virtual copy of a physical device, replicating its hardware and software configurations. It is beneficial for advanced users and complex networks. On the other hand, simulation offers a more straightforward approach, focusing on selected features and functions without requiring extensive hardware resources. It is ideal for beginners. Cisco Packet Tracer, Cisco VIRL, and GNS3 are examples of network simulators and emulators. By using these tools, you can gain hands-on experience with Cisco devices without purchasing them and confidently prepare for various Cisco networking certifications.