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Adapter for Connecting a Multipoint Modem Network to the Public Switched Network

IP.com Disclosure Number: IPCOM000059602D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Cholat-Namy, J: AUTHOR [+2]

Abstract

In the multipoint modem network shown in Fig. 1, the host computer communicates on leased lines L1a and L1b with several remote Data Terminal Equipments (DTEs) through the intermediary of a primary modem CTL at one end and tributary modems T1, T2 and T3 at the other end arranged in a multipoint configuration. If one of the links to the tributary modems fails, such as the connection with T3 indicated by a cross in Fig. 1, a solution is to connect modem T3 directly on the public switched network by lines L2a and L2b. On the host computer side, the best way is to use a special modem MSP which is connected between the switched network and the host computer.

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Adapter for Connecting a Multipoint Modem Network to the Public Switched Network

In the multipoint modem network shown in Fig. 1, the host computer communicates on leased lines L1a and L1b with several remote Data Terminal Equipments (DTEs) through the intermediary of a primary modem CTL at one end and tributary modems T1, T2 and T3 at the other end arranged in a multipoint configuration. If one of the links to the tributary modems fails, such as the connection with T3 indicated by a cross in Fig. 1, a solution is to connect modem T3 directly on the public switched network by lines L2a and L2b. On the host computer side, the best way is to use a special modem MSP which is connected between the switched network and the host computer. The two modems CTL and MSP are connected to the host computer through a BRIDGE device so that the link between modem MSP and modem T3 is of the point-to- point type whereas the host computer keeps on treating modem T3 as a tributary modem of a multipoint network. Assume that the adapter with the BRIDGE and the modem MSP are permanently disposed after the host computer, as shown in Fig. 2, and leads Request To Send (RTS) and Transmit Data (TD) from the host computer are connected in parallel to the transmit portion (XMT) of both modems CTL and MSP. When the host computer raises RTS, either modem CTL or modem MSP sends back Ready for Sending (RFS) to the host computer. After receiving RFS, the host can start sending data on lead TD eith...