一个155如何实现提供63对2M

2.048-C12-VC12
                           -TU12*3
                                       -TUG2*7
                                                      -TUG3*3
                                                                    -VC4
                                                                             -AU4
                                                                                     -AUG
                                                                                                -STM-1
STM-1的速率为（155.520M）bps   3-7-3结构

SDH的复用原理标准是155M可下63对2M，3*7*3=63

除去控制开销等 最多63

参照SDH的复用映射结构
2.048-C12-VC12-TU12*3-TUG2*7-TUG3*3-VC4-AU4-AUG-STM-1

34M-C3-VC3-TU3-TUG3

140M-C4-VC4


STM-1的速率为（155.520M）bps ；一个STM-1信号只可以复用进1个140Mbit/s的信号，也就是说从140Mbit/s复用进STM-1，此时STM-1信号的容量相当于64个2Mbit/s的信号。
同样的从34Mbit/s的信号复用进STM-1信号，STM-1可容纳3个34Mbit/s的信号，也就是说有48×2Mbit/s的容量。
从2Mbit/s信号复用进STM-1信号，STM-1可容纳3×7×3＝63个2Mbit/s信号。
从上可看出，从140Mbit/s和从2Mbit/s复用进SDH的STM-N中，信号利用率较高。而从34Mbit/s复用进STM-N，一个STM-1只能容纳48个2Mbit/s的信号，利用率较低。

2.048-C12-VC12
                           -TU12*3
                                       -TUG2*7
                                                      -TUG3*3
                                                                    -VC4
                                                                             -AU4
                                                                                     -AUG
                                                                                                -STM-1
STM-1的速率为（155.520M）bps   3-7-3结构

学习中，还是不怎么懂