3Com 3C63311 Reference Guide - Page 249

CBR Module 237 Unstructured DS1 Implement unstructured DS1 service when you want DS1 tunneling through an ATM system. DS1 tunneling allows an entire DS1 frame, including framing bits, to travel across an ATM network. See Figure 176. Figure 176 DS1 Unstructured Tunneling Data Service Unit T1 Unstructured ATM Network Data Service Unit Channel Service Unit Channel Service Unit DS1 Signal Tunneled Through a PVC Use unstructured services when DS0 midspan access is not required and end-to-end DS1 service is required; for example, to provide CSU or DSU end-to-end connectivity. The encapsulation of unstructured DS1 occupies DS1 bandwidth on the VCC and uses AAL 1 SAR. Structured versus Unstructured Summary Use Table 32 to determine whether to use structured or unstructured DS1 CBR. Table 32 When to use Structured Versus Unstructured Service DSO midspan drop and insert DSO access grooming DS1 network management end to end DS1 end to end (no DSO access) DS1 CBR 1.536 Mbps of bandwidth DS1 CBR 1.544 Mbps of bandwidth Dynamic Bandwidth Allocation (DBA) Structured X X X X X Unstructured X X X X