Building Your Own Lab: CML, EVE-NG, and GNS3
Building Your Own Lab: CML, EVE-NG, and GNS3
Introduction
The CCNA 200-301 certification is the entry-level credential that validates your foundational networking skills. While studying theory is essential, hands-on exercises are a must for anyone serious about passing the exam. Reading about VLANs, OSPF, or NAT will only take you so far — you need a place to type real commands, make mistakes, troubleshoot, and build confidence before exam day.
This lesson walks you through the three primary approaches to building a CCNA practice lab: network simulation platforms, network emulation platforms, and physical equipment. By the end, you will understand the differences between these approaches, know the cost and resource requirements for each, and be able to choose the option that fits your budget, hardware, and certification goals. We will also cover how to align your lab work directly with the CCNA 200-301 exam blueprint so that every hour you spend in the lab translates into exam readiness.
Key Concepts
Before diving into specific platforms, it is important to understand two terms that are often confused.
A simulator recreates the behavior of network devices in software. It does not run actual Cisco IOS code — instead, it mimics how a router or switch would respond to commands. The experience feels similar, but the underlying engine is purpose-built software rather than a genuine operating system image.
An emulator, on the other hand, runs actual IOS code images inside a virtualized environment. The device you interact with behaves exactly as a real router or switch would because it is executing the same software. This distinction matters because emulators provide broader feature support and a more authentic experience, while simulators are lighter on resources and easier to get started with.
Platform Comparison
The table below provides a side-by-side look at the three main categories of CCNA lab deployments:
| Category | Platform Type | Cost | Hardware Required | Devices Supported | Connection Types | Best Used For |
|---|---|---|---|---|---|---|
| Cisco Packet Tracer | Simulator | Free | Laptop or Desktop | IOS | Serial and Ethernet | CCNA Only |
| Cisco Modeling Labs (CML) | Emulator | $0 - $349 | Server / Laptop / PC | IOS, IOS-XR, NX-OS | Serial* and Ethernet | CCNA, CCNP, CCIE |
| Physical Equipment | Physical | Varied | Multiple Devices | Dependent on Devices | Device Dependent | CCNA, CCNP, CCIE |
Note: Serial interface support in CML is available through IOL (IOS on Linux) device images starting with CML 2.9.
Each option has a different balance of cost, realism, and complexity. Let us examine them in detail.
How It Works
Option 1: Cisco Packet Tracer (Simulation)
Cisco Packet Tracer is a network simulation platform closely associated with the Cisco Networking Academy. It runs locally on your personal computer and supports Windows, Mac, and Linux. As a simulator, it does not use actual IOS code — it provides a purpose-built environment that closely mimics device behavior.
Advantages:
- Low resource requirements — runs comfortably on a standard laptop or desktop
- Supports all device types tested on the CCNA exam
- Free to download and use
- User-friendly interface with an easy learning curve
- Topology files can be saved or exported for later use
- Provides a realistic CLI experience geared to beginning-level students
Disadvantages:
- Limited feature support — certain features such as VRRP and iBGP are not available
- Does not execute actual IOS code
- Unsuitable for higher-level certifications like CCNP or CCIE
- Cannot integrate with devices outside the platform
- Limited
showanddebugcommand support - Great for beginners but insufficient for more advanced study
Packet Tracer is an excellent starting point if you are new to networking and want a zero-cost way to begin practicing. However, if you plan to continue beyond CCNA, you will eventually outgrow it.
Option 2: Cisco Modeling Labs / CML (Emulation)
Cisco Modeling Labs is a network emulation platform that was originally released in late 2014. It was formerly known as VIRL (Virtual Internet Routing Labs). Unlike Packet Tracer, CML runs actual IOS code images, giving you an authentic lab experience comparable to working on real devices.
CML requires a server to run optimally, whether that is bare-metal hardware or a hypervisor. It is suitable for studying at all certification levels — CCNA, CCNP, and CCIE.
Three consumer-level license tiers are available:
| License Tier | Node Limit | Cost |
|---|---|---|
| CML-Free | 5 nodes | $0.00 |
| CML-Personal | 20 nodes | $199.00 |
| CML-Personal Plus | 40 nodes | $349.00 |
Advantages:
- Authentic lab experience comparable to actual devices
- Outside devices can be integrated with CML topologies
- Virtualized environment that can scale based on available resources
- Lower cost to deploy and operate compared to physical devices
- Supports NX-OS and IOS-XR devices in addition to IOS/IOS-XE
- Supports clustering and scaling options
- Can be used for network testing and modeling beyond certification studies
- IOL versions included match the type of platforms used in lablets on the exams
Disadvantages:
- Resource intensive — demands significant CPU, RAM, and disk space
- Some ASIC-specific functions are not supported in the virtual environment
- Lower licensing tiers have restricted node counts (for example, 20 nodes on the Personal tier)
- No built-in topology files, though community samples are available
- Adding third-party devices is complex
- Larger topologies can take a while to initialize
- Limited interface support (serial interfaces available only in IOL)
- Some modifications to an active topology require a node restart
Best Practice: If you are committed to a career in networking and plan to pursue CCNP or CCIE after CCNA, investing in CML early saves you from needing to switch platforms later.
Option 3: Physical Cisco Equipment
Physical equipment is the original approach to lab practice — before simulators and emulators existed, it was the only option. This method involves procuring actual Cisco routers and switches, racking and cabling them, and managing the hardware yourself.
Advantages:
- Provides the single most realistic experience possible
- Feature and interface support is under your complete control
- All applicable features are available to the user
- Equipment can be obtained from many sources including online marketplaces, spare or retired equipment from work, or purchased new
- Rack rentals can provide a similar hands-on experience without owning hardware
Disadvantages:
- Affordable equipment may not provide full feature support for current exam topics
- Time-consuming to deploy and make changes
- Fixed topology requires manual work to reconfigure
- No vendor support (no SmartNet or TAC)
- Consumes physical space and electrical power, increasing operating costs
- May require additional purchases such as console cables, serial cables, and power strips
- Inflexible compared to virtual alternatives
- Can be loud, especially with high-RPM cooling fans
Physical equipment still has its place, but for most CCNA candidates the cost, effort, and inflexibility make virtual platforms a more practical choice.
Configuration Example
Once your lab environment is set up — whether in Packet Tracer, CML, or on physical gear — the real work begins: translating the CCNA 200-301 exam blueprint into hands-on lab tasks.
Starting with the Exam Blueprint
The CCNA 1.1 exam (200-301) covers six major domains with the following weights:
| Domain | Weight |
|---|---|
| Network Fundamentals | 20% |
| Network Access | 20% |
| IP Connectivity | 25% |
| IP Services | 10% |
| Security Fundamentals | 15% |
| Automation and Programmability | 10% |
The blueprint identifies the skills measured on the exam, allowing you to focus your lab efforts and avoid wasting time on irrelevant topics. Each blueprint item uses a verb that tells you what you are being asked to do — configure, verify, describe, explain, analyze, or evaluate. Items that say "configure and verify" map directly to hands-on command tasks in your lab.
Translating Blueprint Items Into Lab Tasks
Here are the explicit configuration and verification tasks from the CCNA 200-301 blueprint that you should build lab exercises around:
! Blueprint Task 1.6 — IPv4 Addressing and Subnetting
interface GigabitEthernet0/0
ip address 192.168.1.1 255.255.255.0
no shutdown
! Blueprint Task 1.8 — IPv6 Addressing and Prefix
interface GigabitEthernet0/0
ipv6 address 2001:DB8:1::1/64
no shutdown
! Blueprint Task 2.1 — VLANs Spanning Multiple Switches
vlan 10
name SALES
vlan 20
name ENGINEERING
! Blueprint Task 2.2 — Interswitch Connectivity (Trunk)
interface GigabitEthernet0/1
switchport mode trunk
switchport trunk allowed vlan 10,20
! Blueprint Task 2.3 — Layer 2 Discovery Protocols
cdp run
lldp run
! Blueprint Task 3.3 — IPv4 and IPv6 Static Routing
ip route 10.0.0.0 255.255.255.0 192.168.1.2
ipv6 route 2001:DB8:2::/64 2001:DB8:1::2
! Blueprint Task 3.4 — Single Area OSPFv2
router ospf 1
network 192.168.1.0 0.0.0.255 area 0
! Blueprint Task 4.1 — NAT (Static and Pool)
ip nat inside source static 192.168.1.10 203.0.113.10
! Blueprint Task 4.2 — NTP Client and Server
ntp server 10.0.0.1
! Blueprint Task 4.6 — DHCP Client
interface GigabitEthernet0/0
ip address dhcp
Important: Note any blueprint items that are not supported by your chosen lab platform. For example, Packet Tracer does not support VRRP or iBGP, so those topics would need to be studied through other means.
Understanding Blueprint Verbs
When reading a blueprint item such as "2.1 Configure and verify VLANs (normal range) spanning multiple switches," pay attention to the verb structure:
- Configure and Verify = Apply/Implement the feature, then confirm it works using
showcommands - Describe/Explain = Understand the concept well enough to answer knowledge-based questions
- Analyze = Examine output and draw conclusions
- Evaluate = Assess whether a configuration or design meets requirements
Your lab exercises should prioritize the "configure and verify" tasks since those require the most hands-on practice.
Real-World Application
The skills you build in your practice lab extend far beyond the exam. In production networks, engineers regularly use the same platforms for testing and validation:
- Pre-deployment testing: Before pushing a configuration change to production, network teams use CML to model the change in a virtual environment and verify the expected behavior. This catches errors before they affect live traffic.
- Topology modeling: CML supports scaling and clustering, making it useful for modeling complex network designs that mirror production topologies. Engineers can test routing protocol convergence, failover behavior, and policy changes in a safe environment.
- Training and onboarding: Organizations use virtual labs to train new team members on the specific configurations and topologies used in their networks, without any risk to the production environment.
- Troubleshooting practice: When a production issue occurs, engineers can recreate the topology and conditions in a lab to isolate the root cause without impacting users.
When choosing a platform, consider where you want to be in two to three years. Packet Tracer is perfectly adequate for CCNA preparation alone, but if you plan to pursue CCNP or CCIE, starting with CML means you will not need to learn a new platform or migrate your lab work later. The IOL images in CML match the platforms used in lablets on the actual exams, giving you the closest possible experience to what you will encounter on test day.
Summary
- Hands-on practice is essential for CCNA success — reading alone is not enough to build the command-line fluency the exam demands.
- Three platform options exist: Packet Tracer (free simulator, CCNA only), CML (emulator with actual IOS images, $0-$349, all cert levels), and physical equipment (most realistic but most expensive and inflexible).
- Start with the exam blueprint to guide your lab exercises. The CCNA 200-301 covers six domains, and every "configure and verify" task should become a hands-on lab exercise.
- CML provides the best long-term value for candidates planning to pursue higher certifications, since it runs real IOS code and supports IOS-XR and NX-OS in addition to IOS/IOS-XE.
- Note platform limitations — no single platform supports every feature. Track which blueprint items your chosen platform cannot cover and plan accordingly.
In the next lesson, we will begin building out a lab topology and start working through the Network Fundamentals and Network Access domains with hands-on configuration exercises.