Network congestion and deadlock

[lplana]

Network congestion is present in large networks and congestion leads to packet dropping.

• dropped packets are not necessarily a correctness issue as they are reinjected and correctly processed.
• dropped packets are a performance issue, as dropped packets are delayed, in turn delaying computation.

Occasionally, dropped packets can not be picked up by the reinjector and are permanently lost. leading to deadlock as every packet is required to complete the computation.

• permanently lost packets are a correctness issue.

The current implementation does not have a way of dealing with permanently lost packets.