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QUIC, dig in: Microsoft open-sources MsQuic, its implementation of Google-spawned TCP-killer QUIC

The sequel to Pac-Man was Ms. Pac-Man. And Microsoft’s QUIC library is called MsQuic

Microsoft has revealed it's a user of QUIC – the TCP successor that's integral to HTTP3 but hasn't quite excited too many folk beyond Google and Cloudflare.

QUIC – an acronym for Quick UDP Internet Connections – is a Google emission from 2013 that aims to help the internet scale and speed up by offering an alternative to TCP's chatty and OS-dependent ways. Google and Cloudflare, who both have an interest in faster and more elegant internetworking, eased QUIC into an IETF standards process and the protocol has become a part of HTTP/3.

While QUIC has made it into Chrome, observers like W3Techs detect just 3 or 4 per cent of websites using the protocol.

Which is why Microsoft putting its hand up as a user, advocate and source of code with which to implement QUIC caught your vulture's eye!

Microsoft said it would be shipping Windows with general purpose QUIC library MsQuic in the kernel "to support various inbox features". The company’s post added:

  • The Windows HTTP/3 stack is being built on top of MsQuic.
  • Microsoft 365 is testing a preview version of IIS using HTTP/3 to reduce tail loss latencies in the last mile. This is currently active in internal dogfood environments.
  • .NET Core has built HTTP/3 support into Kestrel and HttpClient on top of MsQuic. HTTP/3 support is in experimental preview for the 5.0 release of .NET Core.
  • SMB in Windows is also prototyping MsQuic usage. QUIC brings several benefits for SMB, such as better internet reachability, a secured connection based on industry standard TLS and server authentication with certificate validation. Best of all, this brings a completely different workload on top of MsQuic, strengthening the general-purpose nature of the transport.

The post also tells us a little about why Microsoft is playing with QUIC:

“MsQuic brings performance and security improvements to many important networking scenarios. Our online services benefit the most from performance improvements like reduced tail latency and faster connection setup. Our connections will be able to seamlessly switch networks because they can survive IP address/port changes. This equates to better user experience on our edge devices.”

QUIC is still on the IETF’s standards track. Microsoft says MsQuic is “ready for prototyping and testing” and has promised a deeper dive into its implementation of the protocol soon. ®

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