Increase Clique DIFF_INTURN

[soc1c]

From EIP-1955: ethereum#1955

• Additionally, the DIFF_INTURN was increased from 2 to 7 to avoid situations where two different chain heads have the same total difficulty. This prevents the network from getting stuck by making in-turn blocks significantly more heavy than out-of-turn blocks.

Using this as discussion-to: tracker. See also ref #7

[soc1c]

Also, as suggested in the original EIP discussion I would auggest co-prime numbers for InTurn and OutOfTurn blocks. 7 and 3 respectively.

ethereum#1955 (comment)

This might need some decent simulations.

[soc1c]

• The proposal bumps the DIFF_INTURN to 7, which in all honesty seems like a random number you just picked. You would need to explore this number in detail and support why this number is better than anything else. The original choice of 2 was made to ensure that a) in-turn blocks cannot be forced out; and 2) that signers cannot censor each other. With a 7/1 difficulty setting - it would seem to me that - a node can actually censor out a whole lot of blocks before it (up to 6). Maybe I'm wrong, but the point here is that there was nothing provided to rationalize this number. Why 7? Why not 5 or 11? I'd expect this number to be better being dynamic in the number of signers and not static. I think you'd need to provide some experiments, simulations, etc to see how the network would behave with different difficulties, different number of signers, and different number of online signers.

ethereum#1955 (comment)

[soc1c]

some simulations https://github.com/goerli/diff-simulation