Transceivers

• Most transceivers are stamped or molded to show which port is transmit and which port is receive:

Polarity Examples

Juniper QFX5100/QFX5110

• On Juniper QFX5100 and QFX5110:
  • Even ports (top row) will have the transmitter on left, receiver on the right
  • Odd ports (bottom row) will have the receiver on the left, transmitter on the right

*This photo also shows attenuation, more notes on that at Optical: Power and Calculating Loss on a Fiber Span

ASR920

• On the Cisco ASR-920-4SZ-A:
  • Odd ports (top row, ports 3 and 5) will have the transmitter on left, receiver on the right
  • Even ports (bottom row, ports 2 and 4) will have the receiver on the left, transmitter on the right