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Category Archives: Network Emulations

Using Cisco VIRL for CCIE Preparation by Brian McGahan


After long anticipation, Cisco’s Virtual Internet Routing Lab (VIRL) is now publicly available. VIRL is a network design and simulation environment that includes a GNS3-like frontend GUI to visually build network topologies, and an OpenStack based backend which includes IOSv, IOS XRv, NX-OSv, & CSR1000v software images that run on the built-in hypervisor. In this post I’m going to outline how you can use VIRL to prepare for the CCIE Routing & Switching Version 5.0 Lab Exam in conjunction with INE’s CCIE RSv5 Advanced Technologies Labs.

The first step of course is to get a copy of VIRL. VIRL is currently available for purchase from in two forms, a “Personal Edition” for a $200 annual license, and an “Academic Version” for an $80 annual license. Functionally these two versions are the same. Next is to install VIRL on a hypervisor of your choosing, such as VMWare ESXi, Fusion, or Player. Make sure to follow the installation guides in the VIRL documentation, because the install is not a very straightforward process. When installing it on VMWare Player I ran into a problem with the NTPd not syncing, which resulted in the license key not being able to register. In my case I had to edit the /etc/ntp.conf file manually to specify a new NTP server, which isn’t listed as a step in the current install guide. If you run into problems during install check the VIRL support community, as it’s likely that someone has already run into your particular install issue, and a workaround may be listed there.

Once VIRL and VM Maestro (the GUI frontend) is up and running, the next step is to build your topology. For the INE CCIE RSv5 Advanced Technology Labs, this topology will be 10 IOS or IOS XE instances that are connected to a single vSwitch. All you need to do to build this is to add the 10 IOS instances, and then connect them all to a single “Multipoint Connection”. Logical network segments will then later be built based on the initial configurations that you load on the routers for a specific lab. The end result of the topology should look something like this:

You may also want to add some basic customization to the topology file and the VM Maestro interface. I set the hostnames of the devices to R1 – R10 by clicking on the router icon, then setting the “Name” under the Properties tab.

Next under the File > Preferences > Terminal > Cisco Terminal you can set the options to use your own terminal software instead of the built in one. In my case I set the “Title format” variable to “%s”, which makes it show just the hostname in the SecureCRT tab, and set the “Telnet command” to “C:\Program Files\VanDyke Software\SecureCRT\SecureCRT.exe /T /N %t /TELNET %h %p”, which makes it spawn a SecureCRT tabbed window when I want to open the CLI to the routers. Your options of course may vary depending on your terminal software and its install location.

Next, click the “Launch Simulation” button on the topology to start the routers. Assuming everything is correct with your install, and you have enough CPU & memory resources, the instances should boot and show the “ACTIVE” state, similar to what you see below:

If you right click on the device name you’ll see the option to telnet to the console port. Note that the port number changes every time you restart the simulation, so I found it easier just to launch the telnet sessions from here instead of creating manual sessions under the SecureCRT database.

You should now be able to connect to the consoles of the routers and see them boot, such as you see below:

R1 con0 is now available

Press RETURN to get started.

* IOSv is strictly limited to use for evaluation, demonstration and IOS  *
* education. IOSv is provided as-is and is not supported by Cisco's      *
* Technical Advisory Center. Any use or disclosure, in whole or in part, *
* of the IOSv Software or Documentation to any third party for any       *
* purposes is expressly prohibited except as otherwise authorized by     *
* Cisco in writing.                                                      *
R1#show version
Cisco IOS Software, IOSv Software (VIOS-ADVENTERPRISEK9-M), Experimental Version 15.4(20141119:013030) [jsfeng-V154_3_M 107]
Copyright (c) 1986-2014 by Cisco Systems, Inc.
Compiled Tue 18-Nov-14 20:30 by jsfeng

ROM: Bootstrap program is IOSv

R1 uptime is 46 minutes
System returned to ROM by reload
System image file is "flash0:/vios-adventerprisek9-m"
Last reload reason: Unknown reason

This product contains cryptographic features and is subject to United
States and local country laws governing import, export, transfer and
use. Delivery of Cisco cryptographic products does not imply
third-party authority to import, export, distribute or use encryption.
Importers, exporters, distributors and users are responsible for
compliance with U.S. and local country laws. By using this product you
agree to comply with applicable laws and regulations. If you are unable
to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

If you require further assistance please contact us by sending email to

Cisco IOSv (revision 1.0) with  with 484729K/37888K bytes of memory.
Processor board ID 9B2DD0A36JBLXZY7SLJTF
2 Gigabit Ethernet interfaces
DRAM configuration is 72 bits wide with parity disabled.
256K bytes of non-volatile configuration memory.
2097152K bytes of ATA System CompactFlash 0 (Read/Write)
0K bytes of ATA CompactFlash 1 (Read/Write)
0K bytes of ATA CompactFlash 2 (Read/Write)
1008K bytes of ATA CompactFlash 3 (Read/Write)

Configuration register is 0x0


With this basic topology you should have the 10 IOSv instances connected on their Gig0/1 interface to the same segment. The Gig0/0 interface is used for scripting inside the VIRL application, and can be shutdown for our purposes. The end result after the images boot should be something similar to this:

R1#show cdp neighbor
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,
                  D - Remote, C - CVTA, M - Two-port Mac Relay 

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
                 Gig 0/1           177              R B   IOSv      Gig 0/1
                 Gig 0/1           167              R B   IOSv      Gig 0/1
                 Gig 0/1           155              R B   IOSv      Gig 0/1
                 Gig 0/1           177              R B   IOSv      Gig 0/1
                 Gig 0/1           156              R B   IOSv      Gig 0/1
                 Gig 0/1           146              R B   IOSv      Gig 0/1
                 Gig 0/1           129              R B   IOSv      Gig 0/1
                 Gig 0/1           153              R B   IOSv      Gig 0/1
                 Gig 0/1           146              R B   IOSv      Gig 0/1

Total cdp entries displayed : 9

Next you can load your initial configs for the lab you want to work on, and you’re up and running! I’ve taken the liberty of converting the CSR1000v formatted initial configs for our Advanced Technologies Labs to the IOSv format, as the two platforms use different interface numbering. Click here to download these initial configs as well as the .virl topology file that I created.

For further discussions on this see the IEOC thread Building INE’s RSv5 topology on VIRL.


GNS3 Launch Video

List of Simulation Tools

Developed by: Chris McDonald – University of Western Australia Available at:

Abstract CNET is a simulator of computer networks. This simulator is not really focused on industrial simulation ‘per-se’, but to an aspect of it. It is a discrete-event network simulator enabling experimentation with various data-link layer, network layer, routingand transport layer networking protocols. It has been specifically developed for, and used in, undergraduate computer networking courses taken by thousands of students worldwide.
Keywords: network simulation
Last checked: 1 September 2008
Developed by: UCLA Available at:

Abstract GloMoSim is a scalable simulation environment for wireless and wired network systems. It employs the parallel discrete-event simulation capability provided by Parsec. GloMoSim currently supports protocols for a purely wireless network. In the future, we anticipate adding functionality to simulate a wired as well as a hybrid network with both wired and wireless capabilities. GloMoSim source and binary code can be downloaded only by academic institutions for research purposed. Commercial users must use QualNet, the commercial version of GloMoSim.
Keywords: network simulation, cellular network simulation
Last checked: 1 September 2008
Developed by: GeorgiaTech Available at:

Abstract The Georgia Tech Network Simulator (GTNetS), developed by Dr George Riley, is a full-featured network simulation environment that allows researchers in computer networks to study the behavior of moderate to large scale networks, under a variety of conditions. The design philosophy of GTNetS is to create a simulation environment that is structured much like actual networks are structured. For example, in GTNetS, there is clear and distinct separation of protocol stack layers. It is availabe for download from the website.
Keywords: network simulation
Last checked: 1 September 2008
Developed by: University of Twente Available at:

Abstract The NCTUns is a high-fidelity and extensible network simulator and emulator capable of simulating various protocols used in both wired and wireless IP networks. Its core technology is based on the novel kernel re-entering methodology. NCTUns can be used as an emulator, it directly uses the Linux TCP/IP protocol stack to generate high-fidelity simulation results, and it has many other interesting qualities. It is commercialised by SimReal Inc.
Keywords: network simulation
Last checked: 1 September 2008
Developed by: tetcos Available at:

Abstract NetSim is developed by Tetcos and it is an educational network simulation software. It contains modules for network programming and real time packet capture. The protocols covered in simulation are aloha, slotted aloha, Ethernet, Token Ring, Token Bus, W Lan, X.25 Frame Relay, ATM, TCP (Tahoe, reno and sack flavors) as well as devices like switches,routers APs etc. A demo version can be downloaded from the website.
Keywords: network simulation
Last checked: 1 September 2008
The Network Simulator – ns2
Developed by: University of Southern California Available at:

Abstract Ns2 is a discrete event simulator targeted at networking research. Ns provides substantial support for simulation of TCP, routing, and multicast protocols over wired and wireless (local and satellite) networks. Ns is devloped by ISI, the Information Sciences Institute at the USC school of engineering. The full source code of ns 2 can be downloaded and it can be compiled of multiple platform, including most popular Unix flavours and Windows.
Keywords: network simulation
Last checked: 1 September 2008
Developed by: OMNeT++ Community Site Available at:

Abstract OMNeT++ is a component-based, modular and open-architecture simulation environment with strong GUI support and an embeddable simulation kernel. The simulator can be used for modelling: communication protocols, computer networks and traffic modelling, multi-processors and distributed systems, etc. OMNeT++ also supports animation and interactive execution. It is freely distributed under an academic public license.
Keywords: network simulation, object-oriented simulation
Last checked: 1 September 2008
Developed by: OPNET Technologies Available at:

Abstract OPNET’s suite of products combine predictive modeling and a comprehensive understanding of networking technologies to enable customers to design, deploy, and manage network infrastructure, network equipment, and networked applications. In particular OPNET Modeler is a development environment, allowing you to design and study communication networks,devices, protocols, and applications.
Keywords: network simulation
Last checked: 1 September 2008
Developed by: RSoft Design Group Available at:

Abstract OptSim 4.7 is the result of the merge between the former OptSim 3.6 sample mode engine, implementing simulation in the time domain sample by sample using a linear convolution algorithm, and the LinkSIM block mode engine, impelenting the Frequency Domain Split Step. It is an intuitive modeling and simulation environment supporting the design and the performance evaluation of the transmission level of optical communication systems.
Keywords: network simulation, communication systems simulation
Last checked: 06.06.2008
Developed by: UCLA Parallel Computing Laboratory Available at:

Abstract Parsec is a C-based simulation language, developed by the Parallel Computing Laboratory at UCLA, for sequential and parallel execution of discrete-event simulation models. It can also be used as a parallel programming language. It is available in binary form only for academic institutions. Commercial users are directed to its commercial implementation QualNet, marketed by Scalable Networks technologies (
Keywords: discrete event simulation, parallel simulation, distributed simulation, network simulation
Last checked: 06.06.2008
Developed by: Tetcos Available at:

Abstract PhySim allows for creation of Baseband, RF, Channel and Receiver chain and comes with inbuilt Oscilloscope, Spectrum Analyzer and Polar Plot. Techniques covered include ASK, FSK, PSK, DPSK, QPSK, PAM, PWM, PPM, TDM – PAM, AM-DSB-SC, SSB – SC , PCM, DM,Transmission Line, IF, RF, Dipole and AWGN. A free download of PhySim demo version is available at
Keywords: communication systems simulation
Last checked: 17 August 2009
QualNet Developer
Developed by: Scalable Network Technologies Available at:

Abstract QualNet is a modelling tool for wireless and wired network,. The QualNet suite is composed of QualNet Simulator, which claims to be the fastest for real-time traffic modelling. QualNet Animator allows to graphically design the network model (using a wide library of components) and it displays the results of simulation runs. QualNet Designer allos to create Finite State Automata to describe the behaviour of your network, while with QualNet Analyzer and Designer you can interpret and make sense of simulation results. Windows and Linux versions are available. A demo can be downloaded on request.
Keywords: network simulation, parallel simulation
Last checked: 06.06.2008
Shunra Virtual Enterprise
Developed by: Shunra Available at:

Abstract Shunra VE network simulation is a tool for pre-deployment testing and capacity planning and can be used for a wide variety of applications and projects. Shunra VE website claims its use by over 1700 customers within the financial services, retail, manufacturing, energy, technology and telecommunications, healthcare and pharmaceutical, travel, media and hospitality industries as well as government agencies and militaries. Shunra Virtual Enterprise (Shunra VE) is a powerful network simulation solution that creates an exact model of any production environment. This includes the network, remote locations, and the number and distribution of local and remote end-users. With Shunra VE, you can test the functionality, performance, scalability and robustness of any application or network infrastructure under current and future real-world conditions.
Keywords: capacity planning, network simulation
Last checked: 1 September 2008
Developed by: Rimon Barr – Cornell University Available at:

Abstract SWANS is a scalable wireless network simulator built atop the JiST platorm. SWANS is organized as independent software components that can be composed to form complete wireless network or sensor network configurations. Its capabilities are similar to ns2 and GloMoSim, but is able to simulate much larger networks. SWANS leverages the JiST design to acheive high simulation throughput, save memory, and run standard Java network applications over simulated networks. In addition, SWANS implements a data structure, called hierarchical binning, for efficient computation of signal propagation
Keywords: network simulation, java
Last checked: 1 September 2008
Developed by: Erlang Software Available at:

Abstract Traffic version 2 is a simulation product designed to solve complex call-centre modelling problems, where traditional Erlang equations fail, but it can also be applied to any other queueing problem. It has an easy to use graphical interface and it runs under Windows
Keywords: network simulation, call centre simulation
Last checked: 1 September 2008
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