In ChipScope versions 8.2.04i, 9.1.01i, and 9.1.02i, the PRBS data that is generated is inverted from the ITU-T specification O.150. This inversion occurs at the transmitter and at the receiver. This problem affects only the PRBS patterns; the user patterns are not inverted.
To work around this issue in the affected versions, follow these steps:
1. Using the IBERT console, select the PRBS on the GTP under test.
2. Invert the TX output channels of the GTP under test.
3. Invert the RX input channels of the GTP under test.
This issue is fixed in ChipScope 9.1i Service Pack 3.