FlyBy is a Rust pipeline framework aimed at high-rate ingest: source, decode, transform, route, sink. The hardware story is AF_XDP, io_uring, DPDK, SPDK. Those backends need Linux privileges and machines most laptops are not.

Part VI of the project treats the simulator as a product feature, not a test stub. You can develop, demo, and CI the pipeline on macOS. Throughput numbers from these runs are simulated. Do not quote them as hardware.

This series follows the four seed posts in the FlyBy articles/ catalog. Each installment has a named workload you can reproduce from the repo:

./scripts/reproduce-article.sh part-vi-simulator-intro

The same catalog maps each slug to a Git tag (medium/<slug>), a built-in scenario or pcap fixture, and expected CLI output.

Articles in this series

  1. FlyBy: A Simulator Before the Hardware — Part 1: why FlyBy ships a first-class simulator, how VirtualNic and virtual time work, and how to run the constant_rate baseline at 100 kpps without privileged networking.
  2. FlyBy: Deterministic Fault Injection — Part 2: LCG-seeded packet drops in FlyBy’s packet_loss scenario—5% drop at 10 kpps for 10 virtual seconds, with counters you can assert in CI.
  3. FlyBy: Protocol-Aware Traffic Generators — Part 3: FlyBy’s protocol_quotes scenario fills 34-byte binary market quotes (AAPL) through VirtualNic so decoders see structured payloads, not random pads.
  4. FlyBy: Replaying Classic Pcap Captures — Part 4: replay FlyBy’s udp_quotes.pcap through the simulator—20 UDP binary quotes, full-speed or original timing, classic pcap only.