3Com 3C63311 Reference Guide - Page 229

Serial Interface 217 Through ATM DXI, the DCE allows the DTE to participate in an ATM network. (See Figure 157.) Figure 157 DCE Allows DTE to Participate in ATM Network through ATM DXI DTE SDU DXI Data Link DXI Physical DTE SDU AAL 5 CPCS DXI Data Link AAL 5 SAR ATM DXI Physical UNI Physical DXI DTE UNI DCE DXI Mode 1A is designed to allow legacy routers to utilize frame-based transmission to transmit an ATM network to the DXI Mode 1A device (PathBuilder S330/S310 serial interface), which then will perform SAR and AAL5 mapping to an ATM PVC. It provides simple and efficient encapsulation of your service data unit and supports AAL5 transit encapsulation. (See Figure 158.) Figure 158 DXI Format Mode 1A DTE SDU DTE Service Data Unit Error Check DTE to DSU DXI Frame Flag FCS Data DXI Information Flag Octet 12 0-9232 2 1 DSU to ATM Network Translation AAL 5 SAR AAL 5 CPCS-PDU DSU 01111110 SSAARR--PPDDUU SAR-PDU SAR-PDU Address Maps to/from VPI/VCI DXI Protocol Mode 1A ATM Cell