The popularity of permissioned blockchain systems demands BFT SMR protocols that are efficient under good network conditions (synchrony) and robust under bad network conditions (asynchrony). The state-of-the-art partially synchronous BFT SMR protocols provide optimal linear communication cost per decision under synchrony and good leaders, but lose liveness under asynchrony. On the other hand, the state-of-the-art asynchronous BFT SMR protocols are live even under asynchrony, but always pay quadratic cost even under synchrony. In this paper, we propose a BFT SMR protocol that achieves the best of both worlds -- optimal linear cost per decision under good networks and leaders, optimal quadratic cost per decision under bad networks, and remains always live.

中文翻译：

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网络变坏时做好准备：异步视图更改协议

许可的区块链系统的普及要求BFT SMR协议在良好的网络条件下（同步）有效，而在不良的网络条件下（异步）具有鲁棒性。最新的部分同步BFT SMR协议可在同步和良好领导者的情况下为每个决策提供最佳的线性通信成本，但在异步条件下会失去活力。另一方面，最先进的异步BFT SMR协议即使在异步条件下仍然有效，但即使在同步条件下也始终要支付二次成本。在本文中，我们提出了一种BFT SMR协议，该协议可实现两全其美-在良好的网络和领导者下，每个决策的最佳线性成本，在糟糕的网络下，每个决策的最佳二次成本，并且始终有效。