  The paper introduces an original MAC protocol for a passive optical
metropolitan area network using time-domain wavelength interleaved networking
(TWIN)% as proposed recently by Bell Labs . Optical channels are shared under
the distributed control of destinations using a packet-based polling algorithm.
This MAC is inspired more by EPON dynamic bandwidth allocation than the
slotted, GPON-like access control generally envisaged for TWIN. Management of
source-destination traffic streams is flow-aware with the size of allocated
time slices being proportional to the number of active flows. This emulates a
network-wide, distributed fair queuing scheduler, bringing the well-known
implicit service differentiation and robustness advantages of this mechanism to
the metro area network. The paper presents a comprehensive performance
evaluation based on analytical modelling supported by simulations. The proposed
MAC is shown to have excellent performance in terms of both traffic capacity
and packet latency.
