4
Physical Connection
•The
wires connecting switches can be either unidirectional -- all wires transmit the
same way,
which alternates -- or bidirectional -- half of the wires are permanently set
to transmit in each direction
•For
sustained information flow in both directions, the bandwidth and
latency are the same
•For one packet in the network, the latency is the same, but the bandwidth
is doubled with unidirectional
A “flit” is a flow-control unit
A “phit” is a physical-transmission
unit