Importance

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Abstract

A subscriber bus interface (SBI) frame format provides discrimination between asymmetrical digital subscriber line (ADSL) signal traffic and non-ADSL traffic. In the frame format, ASDL identification tag (AIT) bits are assigned to a higher order byte of an SBI time slot of an SBI frame for identifying whether or not a line card transmitting the SBI frame is an ADSL line card. Further, an overhead byte is assigned to a lower order byte of the SBI time slot. The overhead byte includes cell type indicator bits for indicating if the SBI frame contains asynchronous transfer mode (ATM) payload bytes found in ADSL signal traffic. The AIT bits of the higher order byte include an alternating pattern of binary '0's and '1's to prevent accidental generation of the AIT bits by a non-ADSL line card. The AIT byte and overhead byte are stored in the first time slot of the SBI frame so that the AIT byte will be received first by a control unit to allow the control unit to quickly identify if the frame is being transmitted from an ADSL line card.

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First Claim