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What is L2TP?

Layer 2 Tunnelling Protocol (L2TP) is a networking protocol used for establishing virtual private network (VPN) connections.

What is L2TP (Layer 2 Tunnelling Protocol)?

Layer 2 Tunnel Protocol (L2TP) is a networking protocol used for establishing VPN (virtual private network) connections. Learn more about L2TP and where it sits among other VPN protocol options for your IoT projects.

What is L2TP?

A VPN secures your computer or IoT device data for transmission over the public internet. A crucial part of this involves encapsulating (i.e. surrounding and bundling your data) prior to transmission. A tunneling protocol is a set of procedures that governs how the data is encapsulated and the process by which data packets reach their intended destination.

L2TP is one such protocol. It dates back to 2000 and comprises elements from two older tunneling protocols: Microsoft’s PPTP (Point to Point Tunneling Protocol) and Cisco’s Layer 2 Forwarding Protocol.

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What do we use L2TP for?

The L2TP protocol only governs tunneling. We can’t use it for the other important element of VPN connectivity; i.e. encryption. This is why L2TP is never really used in isolation. Rather, it’s deployed in conjunction with another VPN protocol; IPsec (see below).

What is the difference between PPTP and L2TP?

Originally released alongside Windows 95, Point to Point Tunneling Protocol (PPTP) is one of the oldest VPN protocols.

PPTP encapsulates and encrypts data prior to transmission. It’s very easy to configure and is also one of the fastest protocols. The flipside however, is that it’s also one of the least secure protocols, with a list of known vulnerabilities that date back more than two decades. PPTP is not generally seen as a viable option for businesses that want to transmit data securely.

When L2TP is used alongside IPSec, it does a similar job to PPTP in that it ‘double wraps’ your data with encapsulation and encryption. However, IPSec uses AES-256 bit encryption, a much more robust and up-to-date encryption standard. This means that L2TP is still widely used, whereas its older cousin PPTP is largely defunct.

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What are the advantages of L2TP?

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When L2TP is configured alongside IPSec, its advantages are:

Security

L2TP VPN effectively prevents data from being altered in transmission. Meanwhile, the IPSec protocol provides a further level of protection in the form of highly secure 256-bit encryption. This makes it a good VPN option where security is a top priority, including situations (e.g. healthcare and finance) where IoT devices are transmitting data of a sensitive nature.

Performance

In theory, because an L2TP/IPsec configuration effectively encapsulates the data twice, it results in slower connections than some other VPN models (e.g. OpenVPN). However, with L2TP, the encryption/decryption process takes place in the kernel rather than the user space. Further, the protocol facilitates multi-threading (i.e. the ability to handle multiple requests at once). As a result of all of this, data bandwidth and throughput is maximised.

What is L2TP over IPSec?

Because it does not encrypt data directly, L2TP is almost always deployed in conjunction with another protocol, Internet Protocol Security (IPSec). This means that L2TP governs tunneling and encapsulating the data, while IPSec is responsible for encrypting it.

This L2TP/IPSec combination results in a highly effective way of protecting your data in transmission. Choice of VPN for your IoT project generally depends on multiple factors, including the precise type of application and the nature of the data being transmitted. However, especially where security trumps data speed as a priority, L2TP/IPSec is often a highly attractive option.

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