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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
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
DXI
DCE
UNI
DTE SDU
AAL 5 CPCS
AAL 5 SAR
DXI Data Link
DXI Physical
UNI Physical
ATM
DTE SDU
DXI Data Link
DXI Physical
DTE
SDU
DTE Service Data Unit
DTE to DSU
DXI Frame
Flag FCS Data DXI Information Flag
12 2 10-9232
Octet
AAL 5 CPCS-PDU
DSU to ATM
Network
Translation
Error Check
01111110
DSU
AAL 5
SAR
SAR-PDU
DXI Protocol Mode 1A
Address Maps
to/from VPI/VCI
ATM Cell
SAR-PDU
SAR-PDU
SAR-PDU