Tick synchronisation is incomplete

[lplana]

The arrival of the following packets is not verified before moving to the next processing tick:

• forward-phase broadcast STOP packets
• backprop-phase broascast SYNC packets
• backprop-phase multicast (s-core to w-cores) LDSA packets
• any-phase broadcast DLRV packets
• forward-phase broadcast NET STOP packets

Arrival of these packets is difficult to verify due to their multicast/broadcast nature.

These packets are transmitted during periods of quiet network traffic and have a low probability of being dropped and missed, i.e., they are unlikely to be dropped and, if indeed dropped, they are very likely to be picked up and successfully reinjected.