| 摘要 |
A method and apparatus for hitless path switching whereby synchronous traffic is re-directed from an alternate path back over a primary path. A trace message is inserted at an originating path terminal into an information signal and the information signal is transmitted along the primary path and the alternate path. The information signal experiences different delays along the primary and alternate paths. The receiving path terminal is provided with two pointer processors, one for the primary path and one for the alternate path. The pointer processors use a first and a second buffer, respectively, for storing a number of frames of the respective information signal. The information signals arrive at the selector phase aligned, after the pointer processors perform positive and negative stuffing, respectively. Alignment is determined by the relationship 0<=(Wint+Wext)-2R-M<=1, where were M is the size of the buffers, R is the read address, Wint is the current write address in the first buffer, and Wext is the write address in the second buffer.
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