CAN/CSA-ISO/IEC ISP 10609-21-99 (R2007)

The international community has decided to make this standard available only in the English language version. It has been adopted as a National Standard of Canada on this basis. This National Standard of Canada is equivalent to International Standard ISO/IEC ISP 10609-21:1995. 1 Scope ISO/IEC ISP 10609 is applicable to end systems concerned with operating in the Open Systems Interconnection (OSI) environment. It specifies a combination of OSI standards, which collectively provide the connection-mode Transport Service using the connection-mode Network Service. This part of ISO/IEC ISP 10609 specifies the requirements for Network Layer and Data Link Layer that apply specifically to configurations involving access to an ISDN subnetwork for B-channel X.25 DTE to DTE operation (Semi-permanent or Circuit-mode service).