A method and apparatus for analyzing and monitoring packet streams in “real time”. The packet analyzer comprises an input buffer, a real-time analysis unit, a non-real-time analysis unit, a graphics unit, a monitor and a flushing circuit. A packet stream is received into the input buffer where the data is either read by the real-time analysis unit or flushed by the flushing circuit. Messages are passed between the real-time analysis unit and the non-real-time analysis unit to report on detected errors or to update packet stream information. In turn, real time packet stream information are displayed and updated on a display via the graphic unit. A method of detecting framing errors in a packet stream is incorporated by setting a 9th bit in the input buffer for each byte of data in a packet.