Configuring L2TP Services

L2TP Network Server (LNS)

The L2TP network server (LNS) is a router that resides at the corporate network and serves as the termination point for L2TP tunnels and sessions.

The LNS authenticates the PPP connection request and allows the end-to-end PPP tunneled connection. The LNS may also perform user authentication with a RADIUS server to prevent unauthorized users from accessing the network; however, user authentication may also be done by the LNS itself.

An LNS can support multiple remote users, each communicating within their own L2TP session. The L2TP session is the virtual end-to-end connection over which the LAC sends data to the LNS.

The Bay Networks router is an LNS. For information about the Bay Networks LNS, see “ Bay Networks L2TP Implementation” on page 1-11.

RADIUS Server

An L2TP network may include a Remote Authentication Dial-in User Service (RADIUS) server. The RADIUS server has three main functions in an L2TP network:

Authenticating the remote users

Assigning IP addresses to the remote users

Providing accounting services for corporate billing

The RADIUS server database centralizes the authentication function, eliminating the need to configure each LNS with user names and passwords. It also assigns an IP address to a remote host to identify the host. Finally, the RADIUS server can provide accounting services for the corporate network, calculating billing charges for an L2TP session.

For information about the Bay Networks implementation of RADIUS user authentication and accounting, see “ RADIUS User Authentication” on page 1-14 and “ RADIUS Accounting” on page 1-15.

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Nortel Networks manual L2TP Network Server LNS, Radius Server

L2TP specifications

Nortel Networks L2TP, or Layer 2 Tunneling Protocol, is a widely recognized networking protocol that enables the tunneling of data over various networks. Initially developed as an extension of the Point-to-Point Tunneling Protocol (PPTP), L2TP integrates components from both PPTP and Layer 2 Forwarding (L2F). Nortel Networks played a significant role in the development and implementation of L2TP, making it a prominent choice for service providers and enterprise networks seeking secure and efficient connectivity.

One of the primary features of L2TP is its ability to encapsulate data packets, allowing the transport of PPP (Point-to-Point Protocol) frames without necessitating the traditional point-to-point connections. This means L2TP can operate across different networks, facilitating remote access connections and VPNs (Virtual Private Networks). As a result, organizations can achieve greater flexibility in managing their communications infrastructure.

Another key characteristic of L2TP is its support for both IPv4 and IPv6, ensuring compatibility with current and future networking environments. L2TP operates at the link layer of the OSI model, which means it functions between the data link and network layers, making it versatile for various applications. By using UDP (User Datagram Protocol) as a transport protocol, L2TP ensures efficient data transmission while maintaining lower latencies.

Security is a critical aspect of L2TP. While L2TP itself does not provide encryption, it is often paired with IPSec (Internet Protocol Security) for enhanced security protocols. This combination offers both tunneling and encryption, creating a secure framework for transmitting sensitive information across potentially insecure networks, such as the Internet.

L2TP also features various authentication methods, allowing for robust access control. It supports various schemes like PAP (Password Authentication Protocol) and CHAP (Challenge Handshake Authentication Protocol), giving network administrators a range of options to ensure the legitimacy of users accessing the network.

In summary, Nortel Networks L2TP is a powerful tunneling protocol known for its flexibility, compatibility, and security features. Its ability to encapsulate data for efficient transport makes it ideal for remote access and VPN applications. As organizations continue to demand secure, seamless connectivity, L2TP remains a resilient choice within the shifting landscape of networking technologies.