  In this paper, we investigate the possibility of building a data center
network (DCN) with simplified zero-buffer switches. It exposes a stringent
requirement to the traffic control scheme to ensure perfect collision-free
between packets. We find it is infeasible, if not impossible, to make a
large-scale DCN completely zero buffering. We take a step back and propose
Fastpod, a new data center architecture that enables zero buffering in pod
scale, which can be expanded with buffered devices. With time synchronization,
Fastpod avoids collisions by performing fine-grained centralized control on
data packets and coordination-free scheduling on control packets. It leverages
an optimistic sending mechanism to reduce the latency overhead induced by the
centralized control.
  Our preliminary simulation results indicate that Fastpod successfully meets
the requirement of collision-free in the zero-buffer pod and maintains similar
performance with conventional buffered DCN. It follows the trend of simplifying
the network by pushing the functionalities to the edge. Fastpod explores an
extreme end of the design spectrum and can be treated as a thought experiment
to raise discussion in the community of data center networks.
