| 摘要 |
PURPOSE: A loopback method of virtual container level in synchronous type transmission apparatus is provided to implement loopback in a virtual container(VC) level in synchronous digital hierarchy(SDH), thereby capable of controlling loopback minutely. CONSTITUTION: Firstly, a specific value is set up as a logic value of VC loopback indicating bit and defined to direct the loopback of VC signal level(S510). The lowest signal bit is used as a VC loopback bit and if the bit has a logic value of '1'. Thereafter, if the tributary unit(TU) processed at present is for transmitting, a step is to confirm whether there is an instruction of loopback of VC signal level(S521). If there is an instruction of loopback, loopback indicating bit of V4 byte constituting the transmission TU is set up as a regulation value(S522). Thereafter, a TU is constituted by using V4 byte and transmitted(S523). |
