  Permissioned Blockchains are increasingly considered in enterprise use-cases,
many of which do not require geo-distribution, or even disallow it due to
legislation. Examples include country-wide networks, such as Alastria, or those
deployed using cloud-based platforms such as IBM Blockchain Platform. We expect
these blockchains to eventually run in environments with high bandwidth and low
latency modern networks, as well as, advanced programmable hardware
accelerators in servers.
  Even though there is renewed interest in BFT consensus algorithms with
various proposals targeting Permissioned Blockchains, related work does not
optimize for fast networks and does not incorporate hardware accelerators -- we
make the case that doing so will pay off in the long run. To this end, we
re-implemented the seminal PBFT algorithm in a way that allows us to measure
different configurations of the protocol. Through this we explore the benefits
of various common optimization strategies and show that the protocol is
unlikely to saturate more than 10Gbps networks without relying on specialized
hardware-based offloading. We discuss two concrete ways in which the cost of
consensus in Permissioned Blockchains could be reduced in high speed networking
environments, namely, offloading to SmartNICs and implementing the protocol on
standalone FPGAs.
