Mike Hearn said the following:

The reason the true limit seems to be 700 kilobytes instead of the theoretical 1000 is that sometimes miners produce blocks smaller than allowed and even empty blocks, despite that there are lots of transactions waiting to confirm — this seems to be most frequently caused by interference from the Chinese “Great Firewall” censorship system.

Also, he mentioned on another occasion that the bandwidth through the GFW, is only about 50 KB/s, sometimes less. In the best scenario you can get 3 MB/s, according to Scaling Bitcoin Conference.

Mike put lots of accusations towards the Chinese regarding blockchain development, but how much of that is true and if there's some solution, what will be the solution?

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    It seems to me that the title and the body of your question are somewhat disconnected. The title seems to ask whether there are any Chinese Bitcoin developers, while the body appears to talk about the relevance of the GFW for the Blocksize debate. Please clarify your question.
    – Murch
    Jan 15, 2016 at 15:25
  • Thank you for your help @Murch, I was asking about the relevance of the GFW for the Blockchain debate.
    – nelruk
    Jan 15, 2016 at 16:37
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    There was a bit of work done on this by Jonathan Toomim, at SB/HK, using testnet - so it's not exactly an analysis of live bitcoin, but it's informative. Here are his slides; toom.im/files/… And here is the video of him presenting this; youtube.com/watch?v=ivgxcEOyWNs&t=2h25m30s Jan 19, 2016 at 5:56
  • Hello @DavidManheim you should make an asnwer and explain with more details.
    – nelruk
    Jan 19, 2016 at 15:00

2 Answers 2


Yes, data has shown, that GFW has effects on packet propagation, but not much. The major cause of delay is distance. As you can see here, the median propagation time is comparable for various locations.Complete details can be seen here.

Interestingly, this issue highlights that more than the effect of GFW, it is the effect of large blocks propagation delay & rather serves as a case for even smaller blocks, which Mike was against.

Possible solutions:

  1. O(1) block propagation : "If memory pools were perfectly synchronized and all miners had exactly the same policy for choosing which transactions to include in their blocks and in what order to include them, then miners could just announce new blocks as the fixed 80-byte block header and the coinbase transaction; there would be no need to include any transaction data at all, it could be reconstructed from their peers' memory pools."

  2. Blocktorrent : "a leech(node) will begin to upload chunks of data as soon as it gets them and confirms both PoW and hash/data integrity instead of waiting for a fully copy with full verification."

  3. A miner backbone network : "a hub-and-spoke network, which consists of servers set up in eight well-connected Internet traffic hubs: New York, Seattle, Amsterdam, Beijing, Tokyo, Singapore, Hong Kong and Novosibirsk (located in central Russia). Additionally, the relay network uses a fairly basic compression algorithm. Any Bitcoin node can connect to the nearest hub on Corallo's relay network, and send and receive transactions and blocks to and from other connected nodes."

  4. Cache transaction validation : memoization of transaction validation

  5. Surprisingly enough, blocks smaller than 1 mb!

on top of bitcoin would enable off-chain transactions & be like the visa protocol over the fiat layer.

  1. Stratum Mining : The miner in china delegates the block header creation to a server outside china. Probably, the best short-term solution.
  • The proposition number 6, is it possible? What are the chinese comments about that?
    – nelruk
    Jan 16, 2016 at 19:51

Seems the Chinese government could with DPI definitely decide to block Bitcoin network if they wanted with the Great Firewall Source: Anonymster

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    If you could effectively block the bitcoin nodes from talking, you'd basically end up with two chains, one building in the rest of the world, and one in China. It would be interesting to see the results, most of the hashpower is in China, if their chain grew longer, and communications were reestablished, it would wipe out the other chain. Jun 7, 2017 at 12:19

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