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Leased Line DTE Migration to ISDN Switched Network

IP.com Disclosure Number: IPCOM000034541D
Original Publication Date: 1989-Mar-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Besseyre, J: AUTHOR

Abstract

Disclosed are new leased-line Data Terminal Equipment (DTE) interfaces allowing secure leased-line operation on Integrated Services Digital Network (ISDN) switched networks. The introduction of ISDN leads to the design of Terminal Adapters which will insure migration of existing DTEs towards ISDN. Among those DTEs are X.21 bis leased interface DTEs and X.21 leased interface DTEs. Until now, DTEs designed for leased-line operation assume that unless some failure has occurred on the leased line, the line is available and the DCEs attaching to the leased line are powered ON and ready (data set ready (DSR) 107 is ON at the X.21 bis interface). If the link is not available anymore, failure of the line or outage of the DCEs, the interface will indicate Data Set Not Ready and the DTE terminates the session(s) on that line.

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Leased Line DTE Migration to ISDN Switched Network

Disclosed are new leased-line Data Terminal Equipment (DTE) interfaces allowing secure leased-line operation on Integrated Services Digital Network (ISDN) switched networks. The introduction of ISDN leads to the design of Terminal Adapters which will insure migration of existing DTEs towards ISDN. Among those DTEs are X.21 bis leased interface DTEs and X.21 leased interface DTEs. Until now, DTEs designed for leased-line operation assume that unless some failure has occurred on the leased line, the line is available and the DCEs attaching to the leased line are powered ON and ready (data set ready (DSR) 107 is ON at the X.21 bis interface). If the link is not available anymore, failure of the line or outage of the DCEs, the interface will indicate Data Set Not Ready and the DTE terminates the session(s) on that line. The terminal adapter (TA) indicates ready regardless of the actual state of the switched network, allows the DTE to clear the link by actually signalling Data Set Not Ready at the end of the switched connection. However, the TA or DCE which converts a leased-line DTE to a switched network comes back to the initial state of Data Set Ready, once the DTE has cleared the leased-line session(s). The purpose of this article is to describe a proposed solution to be implemented in the TAs in particular and in DCEs adapting leased- line DTEs to switched network more generally. For that purpose, DSR is forced b...