  Mission critical systems deployed in data centers today are facing more
sophisticated failures. Byzantine fault tolerant (BFT) protocols are capable of
masking these types of failures, but are rarely deployed due to their
performance cost and complexity. In this work, we propose a new approach to
designing high performance BFT protocols in data centers. By re-examining the
ordering responsibility between the network and the BFT protocol, we advocate a
new abstraction offered by the data center network infrastructure. Concretely,
we design a new authenticated ordered multicast primitive (AOM) that provides
transferable authentication and non-equivocation guarantees. Feasibility of the
design is demonstrated by two hardware implementations of AOM -- one using HMAC
and the other using public key cryptography for authentication -- on
new-generation programmable switches. We then co-design a new BFT protocol,
Matrix, that leverages the guarantees of AOM to eliminate cross-replica
coordination and authentication in the common case. Evaluation results show
that Matrix outperforms state-of-the-art protocols on both latency and
throughput metrics by a wide margin, demonstrating the benefit of our new
network ordering abstraction for BFT systems.
