Network v20 Scope and Upgrade Timeline

[q9f]

Creating a discussion for nv20 as this is somewhat bundled with nv19 to roll out FIP-0061 in two stages, in case someone in future is looking for a reference. Link: filecoin-project/community#74

As you may have noticed, that we are doing a two-stage incremental network upgrades in this release. This essentially means that there will be two network versions rolled out together -- nv19 and nv20.
The two stage roll out is required for FIP-0061 - which introduces a new proof that reduces the grindability of windowPoSt and furthur secures the network. At the first upgrade, the new proof type will start to be accepted by the protocol, while the second upgrade (nv20) marks the spot when the old proof type will no longer be accepted. This allows for a smooth rollover period during which both proof types are accepted. Lotus will start generating the new proof types immediately after the nv19 upgrade.
This is something we've safely done before. The second upgrade is something of a "ghost" upgrade -- no migration runs, and no code changes, except that clients will start reporting the new network version of nv20 to the FVM.

Calibration:

• nv20 - 2023-04-21T16:00:00Z at epoch 492214

Mainnet:

• nv20 - 2023-05-18T13:00:00Z at epoch 2870280

Lotus: filecoin-project/lotus#10686

Venus: filecoin-project/venus#5678

Forest: ChainSafe/forest#2763