Configuring L2TP Services

Table C-1.

Common L2TP Network Problems and Solutions (continued)

 

 

 

Problem

 

What to Do

 

 

L2TP session is not active.

The LNS failed to negotiate the PPP LCP options.

 

 

Reconfigure the host at the remote site dialing in to

 

 

the ISP.

 

 

For a Bay Networks router at the remote site, check

 

 

the PPP MRU/MRRU size. The LNS supports an

 

 

MRU/MRUU size of 1500 only.

 

 

Use the following guidelines to configure a Bay

 

 

Networks router at the remote site:

 

 

• For router software versions up to and including

 

 

11.02/rel, use an MTU size of 1510, which is the

 

 

default.

 

 

• For router software versions 11.02/rev and later

 

 

set the PPP parameter RFC1661 Compliance to

 

 

Enable.

 

 

You can also check the session statistics, which are

 

 

automatically enabled on the LNS.

 

 

Bay Networks router at the remote

Check the IP address assigned by the RADIUS

site cannot tunnel into the

server. There may be a mismatch between the

corporate network.

address of the remote router dialing in to the LAC

 

 

and the address that the RADIUS server assigns.

 

 

For example, router A dials in with its IP address of

 

 

1.1.1.3 and the RADIUS server assigns an incorrect

 

 

IP address of 1.1.1.5.

 

 

 

C-2

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Nortel Networks manual Table C-1 Common L2TP Network Problems and Solutions
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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.
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