Frames received by the accelerator have variable latency from arriving at the accelerator and until the host processes the frames, due to accelerator buffers and delay in transfer to host. Frames are therefore provided with a time stamp showing the receive time in the accelerator, so the host has information about the original frame receive time.
Multiple accelerators can be synchronized in order to ensure that the time difference between the accelerators is small. The receive time of frames in different hosts on the same site, or hosts on different sites through the use of GPS, can thereby be compared. Different possible uses are shown in this section.
Accelerator to accelerator
Direct time synchronization from one accelerator to another using either the external or the internal time synchronization connectors can be used to synchronize two accelerators as shown in this figure.
Daisy-chaining of accelerators
One accelerator can also synchronize a number of accelerators when the slave accelerators are daisy-chained as shown in this figure.