Proposed Specification of BX.25 Link Layer Protocol
Robert P. Kurshan · AT&T Technical Journal · 1985
The BX.25 link-layer protocol is a standardized procedure for establishing and maintaining a connection across a data link. Virtually all such standardized communication protocols worldwide are defined through English-language specifications. While the English-language BX.25 specification was developed with exceptional care and in fact represents an improvement over the international standard X.25, it is argued here that it, or any English-language specification, can be expected to fall short of the implicit objective: to define implementations that will be mutually compatible and satisfy given performance criteria. An alternative formal specification is presented. Among its attributes are that it is by its nature mathematically precise; it provides a medium for formal structured development and formal proof of performance of a task (validation) independent of any implementations; and the formal specification may be implemented into software or hardware in an automated fashion, reducing the need for laborious and repetitive implementations and virtually eliminating the need for “certification” of implementations. The specification given here can also be used to resolve issues of vagueness, ambiguity, and contradiction as they arise in the English-language BX.25 specification standard.