Virtual Local Area Network (VLAN) Trunk

Again consider a scenario of being a network engineer in a bank.The Treasury department and  the Procurement department are on two different LAN's meaning they are connected to two separate  switches. So now your boss wants you to make a separate domain which includes both department. Now you cannot just take both switches and started putting both departments cables in one which would obviously disturb the bank activities.Instead what you will do is that you are going to connect both switches with each other and then you assign both the department to a separate VLAN with both having the same VLAN number and use a concept called VLAN Trunking which will help them to communicate with each other even being on a separate domain. Now I will show you how to perform VLAN trunking in Cisco Packet Tracer.

Open your Cisco Packet Tracer. Take 4 PC's and 2 switches and connect 2 PC's with one switch using a straight cable on interface 0/3 and 0/5. Same process is for the remaining PC's and switch also and connect them with interface 0/3 and 0/6. Now connect both switches with each other using both interfaces 0/1 with a crossover cable. Assign APIPA IP to all PC's by going to the IP configuration and clicking on DHCP. Name the PC which are on fa 0/3 as Treasury and Procurement and name the rest PC's as Finance and Logistics.

Now if you have read my previous post you must know how to make VLAN and assign them to interfaces. if you haven't then go to my blog and read the post Virtual Local Area Network (VLAN).
Now for switch0, create VLAN 3 and VLAN 5 and assign VLAN 3 to interface 0/3 and VLAN 5 to interface 0/5.Then in Switch1, create VLAN 3 and VLAN 6 and assign VLAN 3 to interface 0/3 and VLAN 6 to interface 0/6. Now ping any PC with each other other and you will see that the reply is not coming so the VLAN's are created perfectly. Now our main task is to make communication between the Treasury and the Procurement depart through VLAN trunking. Now go to switch0 and do the following configuration in config mode

switch(config)#interface fastethernet 0/1
switch(config-if)#switchport mode trunk 
switch(config-if)#exit

Your VLAN trunking is now enabled and now you can send packets from the treasury to the procurement department even being in a separate domain.

if you want see that trunking is enabled, write the command "show interface trunk" on privileged mode and you will see the trunk status.