User's Manual

Configuring the traffic interfaces | 114
HSS synchronous clock selection modes
The following section describes in detail each of the recommended HSS Synchronous Clock Selection
modes for both DTE to DCE and DCE to DCE modes of operation.
The HSS clocking can be configured for clocking types of Internal clocking, pass-through clocking, and
primary / secondary master clocking. The topology of the client network determines the clock mode
that is used.
Note: Modes 3 and 4 provide only physical layer support, not X.21 protocol support.
Terminal 1 HSS as a DTE and terminal 2 HSS as a DCE - “Pipe Mode”
Mode Synchronous Clock Selection mode Clocking Type
0 Internal Clocks – No overhead Not supported
1 RxC + XTxC – 40 kbit/s overhead Not supported
2 RxC + TxC – 56 kbit/s overhead Pass-through clocking
3 RxC (X.21) – 40 kbit/s overhead Pass-through clocking (X.21 only)
4 RxC (X.21) – No overhead Not supported
5
XTxC → RxC – 40 kbit/s overhead
Pass-through clocking
6
RxC → RxC – No overhead
Primary/ Secondary Master clocking
Note: The designation for mode 5 is shown as ‘XTxC → RxC – 40 kbit/s overhead’ but currently
relates to ‘RxC → RxC - 40 kbit/s overhead’ for DTE to DCE.
Terminal 1 HSS as a DCE and terminal 2 HSS as a DCE - “Cloud Mode”
Mode Synchronous Clock Selection mode Clocking Type
0 Internal Clocks – No overhead Internal clocking
1 RxC + XTxC– 40 kbit/s overhead Not supported
2 RxC + TxC– 56 kbit/s overhead Not supported
3 RxC (X.21) – 40 kbit/s overhead Not supported
4 RxC (X.21) – No overhead Internal clocking (X.21 only)
5
XTxC → RxC – 40 kbit/s overhead
Pass-through clocking
6
RxC → RxC – No overhead
Not supported