(Sold together with IEEE Std 802.6h-1993.) A Physical Layer Convergence Procedure (PLCP) in which the Distributed Queue Dual Bus (DQDB) Layer is mapped into a public network standard DS1 transmission system is provided. The relationship of DS1 to the PLCP and the DS1 PLCP frame format are covered in IEEE Std 802.6c-1993. Enhancements to the Distributed Queue Dual Bus (DQDB) subnetwork of a MAN standard are defined that support applications requiring periodic, recurring bandwidth. The use of Pre-Arbitrated functions to support a variety of isochronous service rates is addressed, although the use of Queued Arbitrated functions will be standardized at a future date. Procedures for establishing, maintaining, and releasing an isochronous connection are not addressed in IEEE Std 803.6h-1993.