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

• Microsoft Windows
• Linux Ubuntu
• GNS3 Application

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=4099  mtu 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

Related Post:How to Connect GNS3 to Internet

For a real network hands-on experience it is a must for you know how toconnect gns3 to the internet so you can perform nat rules, access statements, routing protocols and what have you. I hope that this expert article helps you achieve gns3 connectivity to the internet.

A few versions ago, the gns3 cloud node was dragged into a project and it helped to bridge your lab to the real world’s internet connection. The newer GNS3 has caused some troubles for many making it difficult for them to understand how to connect gns3 to internet. I am here to help you set up your lab and get your network devices speaking with the internet.

Basic requirements:
GNS3VM – In my case running in VMWare Workstation 12

My GNS3 VM Appliance has 2 Interfaces – VMnet2 and VMnet0.

I have configured an additional interface VMnet0 which bridges to my host machine’s network. This provides internet for the gns3 vm appliance and to verify this, I have perform a connectivity test as per the screenshot below;

Check your network from your host machine and note down the default gateway

Wireless LAN adapter WiFi:
Connection-specific DNS Suffix . : expertnetworkconsultant.local
Link-local IPv6 Address . . . . . : fe80::75f1:94d9:398d:4bb3%17
IPv4 Address. . . . . . . . . . . : 192.168.1.37
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1

Configure your VMWare Network Bindings similar to Hyper-V and Workstation platforms as well.

On Host PC – I am using a VPC – Look at this cheat sheet to configure the essential aspects required to successfully connect gns3 to internet.

Let us start configuring gns3 to connect to the internet

On R1 configure the Inside IP Address on R1 FastEthernet0/0,

R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#int f0/0
R1(config-if)#ip addres
R1(config-if)#ip address 172.16.40.1 255.255.255.0
R1(config-if)#no shut
R1(config-if)#

R1#ping 172.16.40.30

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.40.30, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/36/40 ms

On host machine;

VPCS> ip 172.16.40.30/24 172.16.40.1
Checking for duplicate address...
PC1 : 172.16.40.30 255.255.255.0 gateway 172.16.40.1


VPCS> ping 172.16.40.1
172.16.40.1 icmp_seq=1 timeout
84 bytes from 172.16.40.1 icmp_seq=2 ttl=255 time=10.436 ms
84 bytes from 172.16.40.1 icmp_seq=3 ttl=255 time=1.598 ms
84 bytes from 172.16.40.1 icmp_seq=4 ttl=255 time=6.562 ms
84 bytes from 172.16.40.1 icmp_seq=5 ttl=255 time=9.780 ms

Configure the Outside Interface IP Address on R1 FastEthernet0/1

R1(config)#int f0/1
R1(config-if)#ip address 192.168.1.100 255.255.255.0
R1(config-if)#no shut
R1(config-if)#

R1(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.1

R1(config-if)#ip nat inside

Perform the NAT rules
Identify Connected Inside and Outside interfaces

R1#show ip int brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            172.16.40.1     YES manual up                    up
Serial0/0                  unassigned      YES unset  administratively down down
FastEthernet0/1            192.168.1.100   YES manual up                    up



Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#int f0/0
R1(config-if)#ip nat inside
R1(config-if)#int f0/1
R1(config-if)#ip nat outside
R1(config-if)#exit

PC: 172.16.40.30 (Locally Accessible IP)
PC: 192.168.1.55 (Publically Accessible IP - Logical IP)

R1(config)#ip nat inside  source static 172.16.40.30 192.168.1.55

Perform a NAT Overload

R1(config)#ip nat inside source list 1 interface f0/1 overload

Verification on R1c- Ping Google’s DNS 8.8.8.8 via the FastEthernet 0/0 interface which sits on the Inside network.

R1#ping 8.8.8.8 source 172.16.40.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 8.8.8.8, timeout is 2 seconds:
Packet sent with a source address of 172.16.40.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 8/16/32 ms

Now verify if you can ping from your host machine;

VPCS> ping 151.101.193.67
84 bytes from 151.101.193.67 icmp_seq=1 ttl=54 time=31.869 ms
84 bytes from 151.101.193.67 icmp_seq=2 ttl=54 time=27.550 ms
84 bytes from 151.101.193.67 icmp_seq=3 ttl=54 time=24.736 ms
84 bytes from 151.101.193.67 icmp_seq=4 ttl=54 time=30.051 ms
84 bytes from 151.101.193.67 icmp_seq=5 ttl=54 time=25.672 ms

Set DNS on Machine and perform test;

VPCS> ip dns 192.168.1.1

VPCS> ping cnn.com
cnn.com resolved to 151.101.193.67
84 bytes from 151.101.193.67 icmp_seq=1 ttl=54 time=31.678 ms
84 bytes from 151.101.193.67 icmp_seq=2 ttl=54 time=41.772 ms
84 bytes from 151.101.193.67 icmp_seq=3 ttl=54 time=31.583 ms
84 bytes from 151.101.193.67 icmp_seq=4 ttl=54 time=100.448 ms
84 bytes from 151.101.193.67 icmp_seq=5 ttl=54 time=27.358 ms

I hope this has been informative for you and I thank you for reading on how to connect gns3 to internet.