How To Create A Vlan On A Cisco Router

This tutorial explains how to create and assign VLAN, VLAN Membership (Static and Dynamic), Router on Stick and Spanning Tree Protocol (STP) in detail with practical examples in packet tracer. Learn how to create and manage VLAN in Cisco switch step by step.

Create a practice lab in packet tracer as shown in following figure or download pre-created practice lab from second part of this tutorial.

Initial topology for the practice of VLAN, VTP, DTP and Router on Stick

This is the last part of our article "VLAN, VTP, DTP, STP and Router on Stick Explained with Examples". You can read other parts of this article here:-

VLAN Basic Concept Explained with Examples

This is the first part of this article. In this part we explained basic concepts of VLAN such as What VLAN is, Advantage of VLAN, VLAN membership Static and Dynamic, VLAN Connections; Access link and trunk links, trunk tagging and how VLAN add additional layer of security with examples.

VLAN Practice LAB Setup on Packet Tracer

This is the second part of this article. In this part we explained how to create a practice lab in Packet Tracer. You can create practice lab by following the instruction or alternatively download pre created lab. This lab will we used to demonstrate the configuration part of VLAN, VTP, DTP, STP and router on stick.

Configure VTP Server and Client in Switch

This the third part of this article. In this part we explained VTP mode with examples including VTP Server mode, VTP Client mode and VTP transparent mode. Later we configured VTP protocol in our practice lab.

VLAN Tagging Explained with DTP Protocol

This the fourth part of this article. In this part we explained access link, trunk link, VLAN tagging process, VLAN tagging protocol ISL and 802.1Q, Dynamic trunking protocol and DTP mode with examples. Later in this part we configured trunking in our practice lab.

Creating VLAN

In practice lab network Office1 Switch is configured as VTP Server. Office2 and Office3 switches are configured as VTP clients. We only need to create VLANs in VTP Server. VTP Server will propagate this information to all VTP clients automatically.

vlan vlan number command is used to create the VLAN.

Office 1 Switch

S1(config)#vlan 10 S1(config-vlan)#exit S1(config)#vlan 20 S1(config-vlan)#exit S1(config)#

Assigning VLAN Membership

VLAN can be assigned statically or dynamically. CCNA exam only includes static method; therefore we will also use static method to assign VLAN membership. switchport access vlan [vlan number ] command is used to assign VLAN to the interface. Following commands will assign VLANs to the interfaces.

Office 1 Switch

S1(config)#interface fastEthernet 0/1 S1(config-if)#switchport access vlan 10 S1(config-if)#interface fastEthernet 0/2 S1(config-if)#switchport access vlan 20

Office 2 Switch

S2(config)#interface fastEthernet 0/1 S2(config-if)#switchport access vlan 10 S2(config-if)#interface fastEthernet 0/2 S2(config-if)#switchport access vlan 20

Office 3 Switch

S3(config)#interface fastEthernet 0/1 S3(config-if)#switchport access vlan 10 S3(config-if)#interface fastEthernet 0/2 S3(config-if)#switchport access vlan 20

We have successfully assigned VLAN membership. It's time to test our configuration. To test this configuration, we will use ping command. ping command is used to test connectivity between two devices. As per our configuration, devices from same VLAN can communicate. Devices from different VLANs must not be able to communicate with each other without router.

Testing VLAN configuration

Access PC's command prompt to test VLAN configuration. Double click PC-PT and click Command Prompt

Access command prompt of PC in Packet Tracer

We have two VLAN configurations VLAN 10 and VLAN 20. Let's test VLAN 10 first. In VLAN 10 we have three PCs with IP addresses 10.0.0.2, 10.0.0.3 and 10.0.0.4. These PCs must be able to communicate with each other's. At this point PCs from VLAN 10 should not be allowed to access PCs from VLAN 20. VLAN 20 also has three PCs 20.0.0.2, 20.0.0.3 and 20.0.0.4.

VLAN Test

We have successfully implemented VLAN 10 now test VLAN 20.

Same as VLAN 10, PCs from VLAN 20 must be able to communicate with other PCs of same VLAN while they should not be able to access VLAN 10.

Test VLAN

Congratulations we have successfully achieved one more mile stones of this article.

Configure Router on Stick

Typically routers are configured to receive data on one physical interface and forward that data from another physical interface based on its configuration. Each VLAN has a layer 3 address that should be configured as default gateway address on all its devices. In our scenario we reserved IP address 10.0.0.1 for VLAN 10 and 20.0.0.1 for VLAN 20.

With default configuration we need two physical interfaces on router to make this intra VLAN communication. Due to price of router, it's not a cost effective solution to use a physical interface of router for each VLAN. Usually a router has one or two Ethernet interface. For example if we have 50 VLANs, we would need nearly 25 routers in order to make intra VLANs communications. To deal with situation we use Router on Stick.

Router on Stick is router that supports trunk connection and has an ability to switch frames between the VLANs on this trunk connection. On this router, single physical interface is sufficient to make communication between our both VLANs.

Access command prompt of Router

To configure Router on Stick we have to access CLI prompt of Router. Click Router and Click CLI from menu items and Press Enter key to access the CLI

Access CLI prompt of Router in Packet Tracer

Run following commands in same sequence to configure Router on Stick

Router>enable Router#configure terminal Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#interface fastEthernet 0/0 Router(config-if)#no ip address Router(config-if)#no shutdown Router(config-if)#exit Router(config)#interface fastEthernet 0/0.10 Router(config-subif)#encapsulation dot1Q 10 Router(config-subif)#ip address 10.0.0.1 255.0.0.0 Router(config-subif)#exit Router(config)#interface fastEthernet 0/0.20 Router(config-subif)#encapsulation dot1Q 20 Router(config-subif)#ip address 20.0.0.1 255.0.0.0 Router(config-subif)#exit

In above configuration we broke up single physical interface [FastEthernet 0/0] into two logical interfaces, known as sub-interfaces. Router supports up to 1000 interfaces including both physical and logical.
By default interface link works as access link. We need to change it into trunk link. encapsulation commands specify the trunk type and associate VLAN with sub-interface.
In next step we assigned IP address to our sub-interface.

That's all configuration we need to switch VLANs. Now we can test different VLAN communications. To test intra VLANs communication open command prompt of PC and ping the PC of other VLAN.

Test intra VLAN comunication

PC [10.0.0.3] from VLAN 10 can now access PC [20.0.0.2] from VLAN 20.

Spanning Tree Protocol (STP)

STP is a layer 2 protocol, used for removing loops. For backup purpose we typically create backup links for important resources. In our scenario, all offices have backup links that create loops in topology. STP automatically removes layer 2 loops. STP multicasts frame that contain information about switch interfaces. These frames are called BPDU (Bridge Protocol Data Units). Switch use BPDUs to learn network topology. If it found any loop, it will automatically remove that. To remove loop, STP disables port or ports that are causing it.

STP Blocking Port

How to configure VLAN VTP DTP cheat sheet

Command	Descriptions
Switch(config)#vtp mode server	Configure Switch as VTP Server
Switch(config)#vtp mode client	Configure Switch as VTP Client
Switch(config)#vtp mode transparent	Configure Switch as VTP Transparent
Switch(config)#no vtp mode Configure	Switch to default VTP Server Mode
Switch(config)#vtp domain domain-name	Set VTP Domain name.
Switch(config)#vtp password password	Set VTP password. Password is case sensitive
Switch#show vtp status	Display VTP status including general information
Switch#show vtp counters	Show VTP counters of switch
Switch(config-if) #switchport mode trunk	Change interface mode in Trunk
Switch(config)#vlan 10	Create VLAN and associate number ID 10 with it
Switch(config-vlan)#name Sales	Assign name to VLAN
Switch(config-vlan)#exit	Return in Global configuration mode from VLAN configuration mode
Switch(config)#interface fastethernet 0/1	Enter in interface configuration mode
Switch(config-if)#switchport mode access	Set interface link type to access link
Switch(config-if)#switchport access vlan 10	Assign this interface to VLAN 10
Switch#show vlan	Displays VLAN information
Switch#show vlan brief	Displays VLAN information in short
Switch#show vlan id 10	Displays information VLAN ID 10 only
Switch#show vlan name sales	Displays information about VLAN named sales only
Switch(config)#interface fastethernet 0/8	Enter in Interface configuration mode
Switch(config-if)#no switchport access vlan 10	Removes interface from VLAN 10 and reassigns it to the default VLAN - VLAN 1
Switch(config-if)#exit	Move back to Global configuration mode
Switch(config)#no vlan 10	Delete VLAN 10 from VLAN database
Switch#copy running-config startup-config	Saves the running configuration in NVRAM

Use this configured topology for cross check if you are not getting the same output after following all steps.

Working topology for cross check

That's all for this article. I hope you have enjoyed this tutorial.

By ComputerNetworkingNotes Updated on 2018-08-06 00:41:51 IST