Are nodes currently able to detect a network split / isolation?

Thought experiment:

I'm a vendor in some authoritarian country that does local business transactions via the Ethereum smart contract system. Before I declare a tx as done I wait some SAFETY_BUFFER blocks to be safe in case of a block reversal.

Suddenly the country's regime is cutting off the internet or the Ethereum network without me noticing it. As the network inside the country has a much smaller hashing power, after reconnect and syncing the blocks created in this country will be reversed.

As a vendor I may get into trouble when I declare txs as done that are older than SAFETY_BUFFER but get reversed after reconnect. It seems obvious to me that the nodes in this country should in such a case just stop accepting txs and wait for the reconnection to the global network to avoid the reversion of seemingly safe txs.

AFAIK the block time in the now isolated network would suddenly increase x-fold (and then slowly adjust) due to the sudden drop in PoW power compared to the previous blocks. Thereby a network isolation seems easily detectable.

My question is: Do nodes already look out for such abnormalities and stop accepting txs in case of isolation and other extreme abnormalities? Is there an effortless way for light clients to detect / check it by themselves?

Submitted July 07, 2018 at 04:54AM }
via reddit