3Com SuperStack II PathBuilder S330 Reference Manual page 251

Figure 173 DCE Allows DTE to Participate in ATM Network through ATM DXI
DTE SDU
DXI Data Link
DXI Physical
DTE
DXI mode 1A is designed to allow legacy routers to use 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 174.)
Figure 174 DXI Format Mode 1A
DTE
SDU
Error Check
DTE to DSU
Flag FCS
DXI Frame
Octet 1
DSU to ATM
Network
Translation
SAR-PDU
AAL 5
SAR-PDU
SAR
DXI Protocol Mode 1A
DTE SDU
DXI Data Link
DXI Physical
DXI
DTE Service Data Unit
Data DXI Information Flag
2 0-9232
AAL 5 CPCS-PDU
SAR-PDU
SAR-PDU
ATM Cell
Serial Interface
AAL 5 CPCS
AAL 5 SAR
ATM
UNI Physical
DCE
2 1
DSU
01111110
Address Maps
to/from VPI/VCI
243
UNI