What Is Tunnelling?

Date First Published: 4th April 2022

Topic: Computer Networking

Subtopic: Data Transmission Technologies

Article Type: Computer Terms & Definitions

Difficulty Level: 6/10

Learn more about what tunnelling is in this article.

Tunnelling is a technology that enables data to be moved from one network to another. It enables one network to send data through the connection of another network. This technology is most commonly used in VPNs, since they establish a secure and private connection over another internet connection and the sent data is encrypted through the VPN, which is known as an 'encrypted tunnel'. Tunnelling can be used for other purposes, like setting up efficient and secure connections between networks and bypassing firewalls.

How Does Tunnelling Work?

Tunnelling works by enclosing the data packets sent from the other network by the second network. Similar to how tunnelling is a method of crossing boundaries that could not normally be crossed in the everyday world, tunnels are a method of transferring data across a network using protocols that are not supported by that network.

The data sent is broken down into data packets before it is sent. Afterwards, the data packets are encrypted as they move along the tunnel for transport. The private network data and the protocol that comes with it are encapsulated for sending. The process encapsulation is when one type of data packet is enclosed with another. In addition, encapsulation enables data packets to reach their final destination. After encapsulation, decapsulation and decryption take place.

Protocols

Two protocols are used to enable tunnelling to take place. PPTP (Point-To-Point Tunnelling Protocol) is an essential protocol that secures data over networks. L2TP (Layer Two Tunnelling Protocol) combines the features of Layer 2 Forwarding and PPTP.

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