How to Connect GNS3 to a Physical Network | A Step by Step Guide
This article How to Connect GNS3 to a Physical Network is a no nonsense step by step guide to setting up a full hands on GNS3 lab for the serious network engineer or student. This How to Connect GNS3 to a Physical Network lab is what it says on the tin. Routing, Switching, Firewall Security, Infrastructure, Virtualisation and Internet all made possible by this advanced lab created by some of the smartest network engineers of today.
How to Connect GNS3 to a Physical Network | Connecting Switch Uplink Interfaces (Introduction)
Trust me, we understand your frustration. You really want a handson lab but GNS3 has some gotcha’s, and it’s no longer economically efficient to have a lot of kit so what do you do? Thank God, we have the answer in the steps below. It will cost you next to nothing but guaranteed to give you the full blown hands-on experience without any compromises.
You will be able to create a myriad of labs, change network topologies without much effort and extra configuration. This lab is suitable for a business, university or individuals. It’s vendor agnostic and so can support your Next-Generation ASA Firewall, Sonic Wall, Juniper, Palo Alto, HP Aruba Switch, Cisco Catalyst Switches, Windows Servers and to make it even more interesting, if it has an interface, you can lab it.
The advantage here is that you can practice full switching and routing protocols like HSRP | GLBP | VRRP, STP, OSPF, EIGRP to name but a few.
Let us put together our kit list (Some of these you may already have at your disposal)
Hardware Kit
- 1 x Desktop Computer or Workstation with Expansion Slots (If you own a laptop, you will need USB C to Ethernet Adapters) – Not truly reliable hence the workstation preference.
- 2 x 4 Port PCI-E 1Gbps Network Interface Card | 2 Access Buildings
- 2 x Access Switches | Cisco Catalyst Switches or HPE Aruba Switches | Vendor Agnostic
Software and Operating System
Figure 1.0 – Connect Network Device to Ethernet Adapter
Figure 1.1 – 4 Port Ethernet Adapter
Figure 1.2 – Connect Switch Uplink Interfaces
Interface 47 and 48 are our respective uplinks to Core Routers R1 and R2 respectively. To make the interface layer 3 or routed, the following configuration converts them to routed interfaces.
Example of Configuration
switch(config)# interface Fa0/47 switch(config-if)# no switchport switch(config-if)#
switch(config)# interface Fa0/48 switch(config-if)# no switchport switch(config-if)#
Figure 1.3 – Uplinks of Switches 1 and 2
Access Switch 1
switch(config)# interface 47 switch(config-if)# untagged vlan 1008 switch(config-if)# ip address 172.16.254.10
switch(config)# interface 48 switch(config-if)# untagged vlan 1012 switch(config-if)# ip address 172.16.254.14
Access Switch 2
switch(config)# interface 47 switch(config-if)# untagged vlan 1016 switch(config-if)# ip address 172.16.254.18
switch(config)# interface 48 switch(config-if)# untagged vlan 1020 switch(config-if)# ip address 172.16.254.22
Figure 1.4 – Switches Uplinks at back of Desktop connected to Physical Interfaces
Step 1 – Connect Ethernet Interfaces to Desktop Network Adapters
How to Connect GNS3 to a Physical Network | Configuring Physical Network Interfaces (Part 1)
Identify Interfaces on your computer
Command: nmcli dev status
# nmcli dev status DEVICE TYPE STATE CONNECTION eth1 ethernet connected eth1 eth0 ethernet connected eth0 eth2 ethernet disconnected -- lo loopback unmanaged --
Command: ifconfig
eno1: flags=4099mtu 1500 ether 40:a8:f0:49:7b:0a txqueuelen 1000 (Ethernet) RX packets 0 bytes 0 (0.0 B) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 0 bytes 0 (0.0 B) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0 device interrupt 20 memory 0xf7c00000-f7c20000 lo: flags=73 mtu 65536 inet 127.0.0.1 netmask 255.0.0.0 inet6 ::1 prefixlen 128 scopeid 0x10 loop txqueuelen 1000 (Local Loopback) RX packets 24697 bytes 24138502 (24.1 MB) RX errors 0 dropped 0 overruns 0 frame 0 TX packets 24697 bytes 24138502 (24.1 MB) TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
Step 2 – Configure IP Addresses for Uplink Interfaces
How to Connect GNS3 to a Physical Network | Configuring IP Addresses for Network Interfaces (Part 2)
Step 3 – Connect Uplinks to Core Routers
How to Connect GNS3 to a Physical Network | Connecting Switch Uplinks to Core Routers (Part 3)
Step 4 – Test Connectivity with Pings
How to Connect GNS3 to a Physical Network | Test Connectivity with ICMP Pings (Part 4)
Download the full lab here: Connecting GNS3 to Physical Network – Multilayer Network Access Design
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