5.1.1.5. Error handling

5.1.1.5.1. Broken or missing packets

SPEAD can handle broken or missing data packages but has no mechanism to request resending missing data [AD3].
The SDP shall be capable of accepting all valid data, including out-of-order data, from CSP that arrives no later than the travel-time from CSP-SDP + 100ms from the time it is sent.

5.1.1.5.2. Recovery from receiver failure

How to recover when a receiver (SDP node) fails or loses sync with the stream is TBD-001.
5.1.1.6. Variability
This section shows the variability than can be expected and any constraints on specific use cases of the interface or particular aspects of the interface.
Note that parameter values for modes shown in this section are expected or typical values and are provided for information only. This interface does not constrain parameter values unless explicitly stated as a constraint. Actual parameter values will be chosen by Telescope Manager (for each scheduling block and its scans) according to the requirements of the observation and any constraints imposed by components of the telescope [AD6].

5.1.1.6.1. Maximum supported data rate

The maximum data rates calculated here is based on the following parameters (as specified for this interface):
Additional overheads are included to account for heap header packets and for packets that are only partially filled with payload data (the last packet from each CSP Node in the heap).
The maximum allowed correlator output data rate summed over all simultaneous scheduling blocks11Reference is made here to simultaneous scheduling blocks instead of subarrays since SKA1-SYS_REQ-3026 (Mid) constrains the total number of simultaneous scheduling blocks. Subarrays that are not allocated a scheduling block (like a maintenance subarray) do not produce data and therefore should not constrain the data rate. is shown in the table below. Refer to the [RD7] for the detailed calculations.
5: Maximum Allowed