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Corporate Internet Dial-Out regardless of the MG the L2TP tunnel is connected to

IP.com Disclosure Number: IPCOM000010404D
Original Publication Date: 2002-Dec-25
Included in the Prior Art Database: 2002-Dec-25

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In contradiction to the internet dial-in, which is established from a PSTN (Public Switched Telephone Network) network user to an IP (Internet Protocol) network user, the internet dial-out connection is established from an IP network user to a PSTN network user. In a configuration with a narrow band (NB) based virtual private network (VPN) the LNS (Layer Two Tunneling Protocol Network Server) of the corporate network is connected via an L2TP (Layer Two Tunneling Protocol) dial-out tunnel to a fixed single Media Gateway (MG) at the wholesalers IP back-bone. A corporate remote user, which is only reachable via TDM (Time Division Multiplex), may not necessarily be linked to the MG above. In case of a corporate subscriber in the local area network (LAN) wants to connect to the corporate remote user, the MG must be matched. Instead of offering a fixed MG to the routing process of the PSTN network like in current solutions, the PSTN network determines the MG based on the selection of the optimal route to the corporate remote user by means of selecting the best suitable MG for the PSTN part of the dial-out connection indepen-dent from the LAC (L2TP Access Concentrator), and conecting the MG and LAC (in case of different MGs) to each other over the wholesalers IP backbone. This is achieved by either the combination of the dial-out mechanism with the MMP (Multi-link Multi-node PPP mechanism) or an eventually adap-ted MGCP/MEGACO (Media Gateway Control Protocol / Media Gateway Controller Protocol) protocol for dial-out that mirrors the information about the involved MGs over the MGC (Media Gateway Cont-roller) or a mixture of both. The procedure is achieved as follows: 1. The wholesaler‘s IP backbone only requests a dial-out session to the PSTN via the LAC and MGC without specifying any routing preferences to the PSTN network. 2. The MGC selects an optimal routing path to reach the corporate remote user. By the routing path selection also the MG (Network Access Server #2 – NAS#2 in figure 1) is selected. The NAS#2 must be capable to link forward the dial-out session to the original LAC (NAS#1). 3. To identify the NAS#1 as LAC for the corporate dial-out session the following scenarios apply: