[Day 9] 5. Virtual Local Area Network (VLAN)

Introduction

A VLAN creates logical partitions within a physical switch, allowing for better traffic management, security, and network organization. By segmenting networks, VLANs reduce broadcast domains and help optimize network performance.

Concurrent Sessions: A VLAN supports up to 16 Telnet sessions simultaneously, enabling multiple remote connections to the switch.
VLAN Numbering: VLANs are typically numbered from 1 to 1005, but VLANs 1002 to 1005 are reserved for system use. VLANs 1 to 1001 are available for regular configuration, and extended VLANs can go up to 4096.
Default VLAN: The default VLAN on a switch is VLAN 1, often referred to as the Management, Parent, or Untagged VLAN, and it is used for general switch management tasks.

Configuration of VLAN 1

Power on the switch:
```
switch> on
```
Enter global configuration mode:
```
switch# conf t
```
Enter the interface configuration mode for VLAN 1:
```
switch(config)# int vlan1
```
Enable the interface (bring it up):
```
switch(config-if)# no shut
```

Assign an IP address and subnet mask to VLAN 1:

switch(config-if)# ip address 172.16.100.10 255.255.255.0

Exit interface configuration mode:
```
switch(config-if)# exit
```

Set the default gateway for the switch:

switch(config)# ip default-gateway 172.16.10.1

Enter interface configuration mode for a physical port (e.g., fa1/0):
```
switch(config)# int fa1/0
```
(This is the switch port configuration)
Configure port security by setting a MAC address:
```
switch(config-if)# switchport port-security mac-address <MAC address>
```
- Note: Instead of using a static MAC address, the
```
sticky
```
  keyword can be used to automatically learn and assign the MAC address to the port, making it permanent.
```
switch(config-if)# switchport port-security mac-address sticky
```
Set the violation action to shutdown if an unauthorized device tries to access the port:
```
switch(config-if)# switchport port-security violation shutdown
```
- Explanation: If a device with an unknown MAC address attempts to connect, the port will shut down automatically and will only be re-enabled by an administrator.

Configuration for Multiple Ports at Once

To configure a range of ports (e.g., fa1/0 to fa1/8):
```
switch(config)# int range fa1/0 - 8
```
Apply port security with the
```
sticky
```
MAC address option to all selected ports:
```
switch(config-if)# switchport port-security mac-address sticky
```
Set the violation action to shutdown for all selected ports:
```
switch(config-if)# switchport port-security violation shutdown
```

Steps to Configure VLANs

Create a new VLAN:
```
switch(config)# vlan2
```
Assign a name to the VLAN:
```
switch(config-vlan)# name sales
```
Exit VLAN configuration mode:
```
switch(config-vlan)# exit
```
Create another VLAN:
```
switch(config)# vlan3
```
Assign a name to the second VLAN:
```
switch(config-vlan)# name purchase
```
Exit VLAN configuration mode:
```
switch(config-vlan)# exit
```
To allocate ports to a VLAN, select an interface:
```
switch(config)# int fa1/1
```

Assign the port to VLAN 2:

switch(config-if)# switchport access vlan 2

Alternatively, you can use the range command to configure multiple ports at once:

Select a range of ports:
```
switch(config)# int range fa1/1-8
```

Assign the selected ports to VLAN 2:

switch(config-if-range)# switchport access vlan 2

[Day 9] 5. Virtual Local Area Network (VLAN)

Introduction

Configuration of VLAN 1

Configuration for Multiple Ports at Once

Steps to Configure VLANs

Read Next

[Day 9] 6. VTP (VLAN Trunking Protocol)

[Day 9] 7. Inter-VLAN Connection