L2TP (Layer 2 Tunneling Protocol)

A tunneling protocol used for secure node-to-node communi-

cations by Internet service providers (ISPs) and other virtual private network (VPN) service providers in support of multiple, simultaneous tunnels in the network core. End users gain access to the service provider on an unencrypted basis, with the service provider assuming the responsibility for encryption at the edge of the packet network. L2TP is an extension to the Point-to-Point Protocol (PPP) that evolved from a combination of Microsoft’s PPTP and Cisco’s Layer 2 Forwarding (L2F) protocol. L2TP is described in IETF RFC 2661. See also encryption, ISP, PPP, PPTP, protocol, tunneling, and VPN.

• PSC (Public Service Commission)
• PSE (Power Sourcing Equipment)
• pseudonoise (PN)
• pseudoquaternary coding
• pseudorandom noise (PN)
• pseudowire
• pseudowire emulation edge to edge (PWE3)
• pseudowire emulation (PWE)
• PSK (Phase-Shift Keying)
• PSP (Payphone Service Provider)
• PSQM (Perceptual Speech Quality Measurement)
• PSQM+ (Perceptual Speech Quality Measurement plus)
• PSS1 (Private Signaling System No. 1)
• PSTN (Public Switched Telephone Network)
• PSTS (Public Switched Telephone System)
• PTE (Path Terminating Equipment)
• PTI (Payload Type Indicator)
• PTT
• PTT
• public data network (PDN)
• public domain
• public IP address
• public key encryption
• public key infrastructure (PKI)
• Public Safety Access Point (PSAP)