Access Port vs Trunk Port – Configuration & Key Differences

 

 Introduction

When working with VLANs in real networks, you’ll often hear about Access Ports and Trunk Ports. These two port types are the backbone of switch-to-device and switch-to-switch communication.

If you are preparing for CCNA or starting in network engineering, understanding this difference is a must. In this blog, we’ll cover:

• What Access and Trunk Ports are.

• How they work in VLAN environments.

• Key differences with real examples.

• Basic configuration commands for Cisco switches.

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 What is an Access Port?

An Access Port is a switch port that carries traffic for only one VLAN.

👉 It is used to connect end devices like PCs, laptops, or printers.
👉 The connected device does not know about VLANs – the switch handles it.

Example:

• Port FastEthernet0/1 is assigned to VLAN 10.

• Any device connected here will always be in VLAN 10.

Cisco Configuration Example:

Switch(config)# interface fa0/1
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 10

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 What is a Trunk Port?

A Trunk Port is a switch port that can carry multiple VLANs simultaneously.

👉 Mostly used between switch-to-switch or switch-to-router connections.
👉 VLAN information is preserved using tags (802.1Q protocol).

Example:

• A trunk port connects two switches.

• VLAN 10 (HR), VLAN 20 (IT), and VLAN 30 (Finance) can all travel across the trunk.

Cisco Configuration Example:

Switch(config)# interface fa0/24
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport trunk allowed vlan 10,20,30

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Key Differences Between Access and Trunk Ports

Feature	Access Port	Trunk Port
Purpose	Connects end devices (PCs, printers)	Connects switches, routers, or servers
VLAN Support	Carries 1 VLAN only	Carries multiple VLANs
Tagging	No VLAN tags (untagged traffic)	Uses 802.1Q VLAN tags
Use Case	User devices	Switch-to-Switch, Switch-to-Router
Configuration	switchport mode access	switchport mode trunk

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 Real-Life Analogy

Think of a switch like an apartment building:

• Access Port → A single apartment key (you can only enter one room = one VLAN).

• Trunk Port → A master key (you can open multiple rooms = multiple VLANs).

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 Why This Matters in Networking

• Without access ports → End devices wouldn’t know which VLAN they belong to.

• Without trunk ports → VLANs couldn’t travel across multiple switches.

👉 In simple words: Access = users, Trunk = network backbone.

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 Conclusion

• Access Ports connect end devices to a single VLAN.

• Trunk Ports connect network devices and carry multiple VLANs.

• Both are essential for creating a scalable, secure VLAN-based network.

If you’re preparing for CCNA, make sure to practice configuring both port types in Packet Tracer or GNS3.

Previous blog read here;

https://techbyrathore.blogspot.com/2025/08/week-1-switching-vlan-basics.html