VLAN Virtual LAN

VLAN Virtual LAN


VLAN Virtual LAN

Layer 2 security.
Its divides single broadcast domain into multiple broadcast domains.
By default all port of switch are in VLAN 1
This VLAN is known as administrative Vlan or management Vlan
Vlan can be created from 2- 1001
Can be configured on manageable switch only

Creating a Static VLAN

 

VLAN Virtual LAN

IOS commands to create VLAN 10 and name VLAN 10 as ‘marketing’.

switch1>enable
switch1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch1(config)#vlan 10
switch1(config-vlan)#name marketing
switch1(config-vlan)#exit
switch1(config)#exit
switch1#

Below are IOS commands to create another VLAN, VLAN 20 and name VLAN 20 as ‘sales’.

switch1>enable
switch1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch1(config)#vlan 20
switch1(config-vlan)#name sales
switch1(config-vlan)#exit
switch1(config)#exit
switch1#

To delete the VLAN

switch1(config)#no vlan 10

To view VLAN configuration information

switch1>enable
switch1#show vlan

There are 2 types of VLAN and membership

1) Static Vlan

2) Dynamic VLan

1) Static Vlan

Network administrator creates a VLAN and assigns ports to the VLAN.
Are based on port number
Need to manually assign a port on switch to a Vlan.
Also called port based Vlan
Can be member of single Vlan and not multiple Vlan

2) Dynamic VLan

It automatically assign the port to VLAN
Based on MAC address of PC
Each port can be a member of multiple Vlan
For dynamic VLAN configuration a software called VMPS(Vlam membership policy server) is needed.

There are two types of links switch network

Access link is used to connect PC, and this type of link is only part of is referred to as native VLAN of the port
Trunk link is used to connect switch. Trunk can carry multiple VLAN and originally change their name after the telephone system .Trunk that carry multiple telephone conversation.

Difference between access and trunk links.

Access and trunk links

Here dotted lines are access links

What is Native VLAN

How to configure and assign a Cisco switch access port to a VLAN?

switch1>enable
switch1#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
switch1(config)#interface fa0/1
switch1(config-if)#switchport mode access
switch1(config-if)#switchport access vlan 10
switch1(config-if)#exit
switch1(config)#interface fa0/10
switch1(config-if)#switchport mode access
switch1(config-if)#switchport access vlan 20
switch1(config-if)#exit
switch1(config)#exit
switch1#

Virtual LAN Trunking Protocol (VTP)

Virtual LAN Trunking Protocol (VTP) is a Cisco proprietary protocol used to share the Vlan configuration with multiple switches.The VLAN Trunking Protocol (VTP) is a very useful protocol to create, manage and maintain a large network with many interconnected switches.

VLAN Trunking Protocol (VTP).

Three different modes

• Server Mode

• Client Mode

• Transparent Mode

1) Server Mode : A switch configure in server mode can Add, Modify and Delete VLAN.VLAN Trunking Protocol (VTP) Server mode is the default VTP mode for all Catalyst switches.

2) Client Mode : A switch configure in the client mode can’t Add, Modify, Delete Vlan Configuration.LAN Trunking Protocol (VTP) client mode switches listen to VTP advertisements from other switches and modify their VLAN configurations accordingly

3) Transparent Mode : Can Add, Modify and Delete Vlan configuration, changed in one transparent switch will not affect other any other machine.

VLAN Trunking Protocol (VTP) Pruning

configure VLAN Trunking Protocol (VTP)

From The below example Switch 1 as VTP server and Switch 2 as VTP client.

we configure the VTP domain as ‘kencorner.com’, VTP mode as ‘Server’ and VTP password as ‘kencorner’.

kencorner.com.sw01>enable
kencorner.com.sw01#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
kencorner.com.sw01(config)#vtp domain kencorner.com
Changing VTP domain name from NULL to kencorner.com
kencorner.com.sw01(config)#vtp mode server
Device mode already VTP SERVER.
kencorner.com.sw01(config)#vtp password kencorner
Setting device VLAN database password to kencorner
kencorner.com.sw01(config)#exit
kencorner.com.sw01#

Open a console connection to Switch 2 and enter the following IOS commands,
we configure the VTP domain as ‘kencorner.com’, VTP mode as ‘Client’ and VTP password as ‘kencorner’.

kencorner.com.sw02>enable
kencorner.com.sw02#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
kencorner.com.sw02(config)#vtp domain kencorner.com
Domain name already set to kencorner.com.
kencorner.com.sw02(config)#vtp mode client
Setting device to VTP CLIENT mode.
kencorner.com.sw02(config)#vtp password kencorner
Setting device VLAN database password to kencorner
kencorner.com.sw02(config)#exit
kencorner.com.sw02#

run the ‘show vlan’ command on Switch 2.

To view VLAN Trunking Protocol (VTP) configuration information on Switch 1

kencorner.com.sw01>enable
kencorner.com.sw01#show vtp status
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 255
Number of existing VLANs : 7
VTP Operating Mode : Server
VTP Domain Name : kencorner.com
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x06 0xBA 0x4C 0xA5 0x98 0xCA 0x97 0x44 
Configuration last modified by 0.0.0.0 at 3-1-93 01:28:36
Local updater ID is 0.0.0.0 (no valid interface found)
kencorner.com.sw01#

To view VLAN Trunking Protocol (VTP) configuration information on Switch 2

kencorner.com.sw02>enable
kencorner.com.sw02#show vtp status
VTP Version : 2
Configuration Revision : 0
Maximum VLANs supported locally : 255
Number of existing VLANs : 7
VTP Operating Mode : Client
VTP Domain Name : kencorner.com
VTP Pruning Mode : Disabled
VTP V2 Mode : Disabled
VTP Traps Generation : Disabled
MD5 digest : 0x06 0xBA 0x4C 0xA5 0x98 0xCA 0x97 0x44 
Configuration last modified by 0.0.0.0 at 3-1-93 01:28:36

STP ( Spanning Tree Protocol )

Uses Spanning Tree algorithm to avoid loops of switch in the layer 2 device.
STP works when multiple switches are used with redundant link avoiding broadcast storms, multiple frame copies and database instability.

Note : By default all the port are the member of Vlan 1.



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