Juniper ACX5448-D Hardware Manual page 73

Table 33 on page 75 describes the signals on each fiber.
connections for proper polarity.
Table 33: QSFP+ MPO Cable Signals
Fiber
1
2
3
4
5
6
7
8
9
10
11
12
Table 34: QSFP+ MPO Fiber-Optic Crossover Cable Pinouts
Pin
1
2
3
4
5
6
Table 34 on page 75
Signal
Tx0 (Transmit)
Tx1 (Transmit)
Tx2 (Transmit)
Tx3 (Transmit)
Unused
Unused
Unused
Unused
Rx3 (Receive)
Rx2 (Receive)
Rx1 (Receive)
Rx0 (Receive)
Pin
12
11
10
9
8
7
shows the pin to pin
75