How to Create a VLAN on a Cisco Switch

2025-02-02

Step 1: Enter Global Configuration Mode

1. Access the switch via console, SSH, or Telnet.

2. Enter privileged EXEC mode:

Switch> enable 
Switch# 

3. Enter global configuration mode:

Switch# configure terminal 
Switch(config)# 

Step 2: Create the VLAN

1. Use the following command to create a VLAN:

   Switch(config)# vlan 10 
   

2. (Optional) Assign a name to the VLAN:

Switch(config-vlan)# name Sales 

3. Exit VLAN configuration mode:

Switch(config-vlan)# exit 

Step 3: Assign Ports to the VLAN

1. Select the interface (port) to assign to VLAN 10:

   Switch(config)# interface fastethernet 0/9 
   

2. Set the port to access mode (not trunk):

   Switch(config-if)# switchport mode access 
   

3. Assign the port to VLAN 10:

Switch(config-if)# switchport access vlan 10 

4. Exit interface configuration mode:

Switch(config-if)# exit 

Step 4: Verify VLAN Configuration

1. Check VLAN details:

Switch# show vlan brief 

2. Check interface VLAN assignment:

Switch# show interfaces fastethernet 0/9 switchport 

Additional Notes:

• By default, all ports belong to VLAN 1.
• VLANs exist only on the switch unless configured with a router or Layer 3 switch for inter-VLAN routing.
• Save the configuration to avoid loss after a reboot.

What Undercode Say

Creating and managing VLANs on a Cisco switch is a fundamental skill for network administrators, ensuring efficient network segmentation and improved security. VLANs allow you to logically separate networks, reducing broadcast traffic and enhancing performance. The process involves entering global configuration mode, creating the VLAN, assigning ports, and verifying the setup.

For Linux users working in cyber environments, understanding VLANs is equally important. Tools like `vconfig` or `ip` commands can be used to configure VLANs on Linux systems. For example, to add a VLAN interface:

sudo ip link add link eth0 name eth0.10 type vlan id 10 
sudo ip addr add 192.168.10.1/24 dev eth0.10 
sudo ip link set dev eth0.10 up 

To verify the VLAN configuration, use:

ip -d link show eth0.10 

For inter-VLAN routing, Linux can act as a router using `iptables` or nftables. For instance:

sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE 

To save configurations on Linux, tools like `netplan` or manual scripting can be employed. For Cisco switches, always remember to save the configuration using:

Switch# write memory 

For further reading on VLANs and Linux networking, visit:
– https://www.cisco.com/c/en/us/support/docs/lan-switching/inter-vlan-routing/41860-howto-L3-intervlanrouting.html
– https://linux.die.net/man/8/vconfig
– https://netplan.io/examples

Mastering VLANs and their implementation across different platforms is crucial for building robust and secure networks. Whether on Cisco switches or Linux systems, the principles remain consistent, emphasizing the importance of proper configuration and verification.

References:

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