IEEE 802.6c:1993

Amendment Standard - Inactive-Withdrawn.
(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.

This clause provides a convergence procedure in which the DQDB Layer is mapped into a public network
standard DS1 transmission system. A DS1 frame is divided into 24 octets preceded by one bit containing the
Framing (F) bit, for a total of 193 bits. The 193 bits are transmitted at a rate of 1.544 Mbit/s, which equates
to a frame duration of 125
ms. The DS1 frame provides for an information payload of 24 octets and an information
payload rate of 1.536 Mbit/s. The F-bit will be used to frame upon the Extended Superframe (ESF),
which consists of 24 consecutive DS1 frames and a frame duration equal to 3 ms. The DS1 information payload (i.e., the 24 octets of each DS1 frame contained within the 24 consecutive DS1 frames) is available every 3 ms time period for use by the DS1 PLCP.