Packet Delay Estimation With Minimum FIFO Block Based On Asymmetric PTP Network

The symmetry of packet delay is one of basic assumption of PTP (Precision Time Protocol). But most existing networks could not meet this assumption to achieve high accuracy PTP synchronization. The FIFO block is one of main reasons that lead packet delay asymmetry according to the research. So the packet delay estimation with minimum FIFO block is put forward to try to select those "lucky packets" which survived from FIFO block in packet stack to achieve good PTP performance. The boundary conditions of this algorithm is decided by the mean time interval using to select "lucky packets". Its expression has been deduced. Verified by some meaningful tests, in the asymmetry network, the accuracy of packet delay estimation increases almost 25ns with stability increasing almost 2 order, and the accuracy of PTP synchronization increases more than one-fold with stability increasing almost four-fold, compared with no optimization.