L2TP is an industry-standard Internet tunneling protocol, and its functions are roughly similar to the PPTP protocol. For example, it can also encrypt network data streams. However, there are differences. For example, PPTP requires the network to be an IP network, and L2TP requires a point-to-point connection for data packets; PPTP uses a single tunnel, and L2TP uses multiple tunnels; L2TP provides packet header compression and tunnel authentication, while PPTP does not support it.
Both PPTP and L2TP use the PPP protocol to encapsulate data, and then add additional headers for data transmission over the Internet. Although the two protocols are very similar, there are still differences in the following aspects:
1. PPTP requires the Internet to be an IP network. L2TP only requires the tunnel medium to provide a packet-oriented point-to-point connection. L2TP can be used over IP (using UDP), Frame Relay Permanent Virtual Circuits (PVCs), X.25 Virtual Circuits (VCs) or ATM VCs networks.
2. PPTP can only establish a single tunnel between two endpoints. L2TP supports the use of multiple tunnels between two endpoints. With L2TP, users can create different tunnels for different quality of service.
3. L2TP can provide header compression. When compressing the header, the system overhead occupies 4 bytes, while it occupies 6 bytes under the PPTP protocol.
4. L2TP can provide tunnel authentication, while PPTP does not support tunnel authentication. But when L2TP or PPTP is used together with IPSEC, the tunnel verification can be provided by IPSEC, and there is no need to verify the tunnel on the Layer 2 protocol
. L2TP Access Concentrator (LAC) is a device attached to the network with PPP end system and L2Tpv2 protocol processing capability. It is generally a network access server software that completes network access services on remote clients. function.
6. The L2TP Network Server (L2TP Network Server, LNS) is software for processing the server side of the L2TP protocol.
Protocols supported by L2TP
IP protocol, IPX protocol and NetBEUI protocol