# Show HN: BBRv3 for gVisor's netstack, visualized in the browser

> Source: <https://ccsim.apoxy.dev>
> Published: 2026-07-22 15:15:04+00:00

Hello HN,

We’ve built a BBRv3 congestion control implementation for gVisor’s netstack (userspace Linux TCP/IP stack implementation in Go). As part of testing it I realized we can actually compile the whole thing into WASM and run it from the browser to get some cool visualizations from the original BBR paper: [https://research.google/pubs/bbr-congestion-based-congestion...](https://research.google/pubs/bbr-congestion-based-congestion-control-2/)

The project is built using Fable 5 and GPT-5.6 Sol. I’ve manually reviewed actual BBRv3 implementation line-by-line, fixed bugs and made it to conform to -03 draft spec (well, mostly). The react/wasm bindings code was only lightly skimmed and obvious UI issues were chased out - there was a lot.

If you’d like learn more, there’s an accompanying (no pun intended) blog explaining CC basics and BBR insights: [https://apoxy.dev/blog/netstack-bbrv3](https://apoxy.dev/blog/netstack-bbrv3)

The code: [https://github.com/apoxy-dev/ccsim](https://github.com/apoxy-dev/ccsim)

If anyone has ideas what other cool things we can simulate with this stack please share!

Cheers, -Dmitry

Comments URL: [https://news.ycombinator.com/item?id=49008138](https://news.ycombinator.com/item?id=49008138)

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