What is L2TP (Layer 2 Tunneling Protocol)?

The L2TP layer 2 tunneling protocol is one of the most popular options for seamless access to various Internet sites. The basic principle of its operation is to create a reliable connection between the consumer and the VPN server.

Due to the lack of encryption and privacy, the layer 2 protocol is usually combined with the IPsec protocol, which leads to end-to-end L2TP packet encryption and data control in the tunnel. The confidentiality of transmitted information is guaranteed.

Encryption of this format is absolutely safe. However, this is a slower solution than using the OpenVPN software. Traffic is converted to L2TP and encoded using IPsec. This is a two-step process that results in a reduction in speed.

Features of use

Purposes of using L2TP:

  • supports VPN service ;
  • use by an ISP to encapsulate customer data into its IP network;
  • a local hub in the circuit does not imply international charges;
  • used by clients to connect to a remote LAN server from anywhere;
  • helps to use network connections so that endpoints can be on different machines.

L2TP is used as the configuration protocol for VPN services.

Work principles

In order to understand what PPTP and L2TP are, one should clarify the nuances of their functioning.

As a standard, the Layer 2 Tunneling Protocol is a set of procedures that govern digital communication processes. It was first proposed in 2000. If you want to understand how the L2TP protocol works, you need to remember that it is based on two older tunneling protocols:

  1. Layer 2 forwarding protocol from Cisco
  2. The outdated and insecure PPTP from Microsoft.

If you are interested in understanding what the L2TP protocol is, then this is an extended version of PPTP, and providers use it to connect private virtual networks. This approach ensures the safety of data while passing through the tunnel using encryption.

It consists of two main components:

  • Access Concentrator – the device that terminates the call;
  • LNS Network Server A network server is a device that defines and terminates PPTP.

The procedure allows you to run protocols on networks that cannot support them or securely transfer private information. This becomes possible because the data of the former is packed in a way convenient for the latter. L2TP handles the tunneling part.

In the course of work, different tunnels can be involved. By comparison, PPTP can only be used over IP networks.

L2TP between two points with different QoS can support more than one tunnel.

Benefits of the L2TP protocol

Layer 2 tunneling has its strengths.

The 12TP protocol is flexible, lightweight, and quickly customizable. It can be adapted to any encryption method.

  1. It is popular, so it is quite easy to implement. Supported by most operating systems.
  2. It uses a high-quality and secure encryption algorithm AES-256.
  3. Compresses headers to a size of 4 bytes.

L2TP Disadvantages

You should also be aware of the vulnerabilities of this version:

  • port 500 used by the protocol can be blocked;
  • due to the double encapsulation of user data, it hides or restricts direct access to them, which limits the speed of work;
  • is not always able to help avoid network restrictions.
  • due to security inconsistencies, low speeds, limited port support, and interruptions in data transfer may occur.

Despite the presence of certain disadvantages, there are much more amenities and advantages for users.

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