A method and system for evaluating performance of a device by on-chip
determination of BER may include establishing and generating PRBS test
packets in a closed communication path internally within a physical layer
device (PLD) and a remote PLD. A BER for the PLD may be determined from
within the PLD based on a comparison of at least a portion of the
generated test packets with at least a portion of the generated test
packets transmitted over the closed communication path received by the
PLD via the closed communication path from the remote PLD. A transmit
path of the PLD may be internally coupled to a receive path of the PLD,
and a receive path of the PLD may be internally coupled to a transmit
path of the PLD. The PLD may be internally configured to operate in an
internal optical loopback mode or an internal electrical loopback mode.