Re: Options for QUIC Multipath

Behcet Sarikaya <> Mon, 15 February 2021 15:48 UTC

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From: Behcet Sarikaya <>
Date: Mon, 15 Feb 2021 09:48:21 -0600
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Subject: Re: Options for QUIC Multipath
To: Christian Huitema <>
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On Sun, Feb 14, 2021 at 4:23 PM Christian Huitema <>

> I authored two drafts proposing two different solutions for Multipath
> QUIC: QUIC Multipath Negotiation Option (
>; and,
> in collaboration with colleagues at Ali Baba, Multipath Extension for QUIC (
> Apart from
> some details that could easily be aligned, the main difference is that the
> “negotiation option” maintains the property of QUIC Transport
> <> to have a
> single packet number space for all application packets while the “multipath
> extension for QUIC” specifies that there will be a specific packet number
> space for each path. I have now implemented both options in Picoquic. This
> blog describes what I learned:
> .
> To summarize, I believe now that both options work. The simple option
> requires some additional work for managing acknowledgement, but the
> multiple number space option adds a lot more complexity (41 new code
> branches compared to only 6), and will require a lot more testing because
> it also change the processing of the "single path" scenarios. The multiple
> number space option also prevents the use of zero-length connection IDs,
> and thus causes additional overhead in some important deployment scenarios.
> So, yes, both options work, but the simpler option provides simpler code
> and also less overhead.

I thought it was a given.

Thanks for your hard work Christian.


> In any case, I hope that this exercise will inform our efforts to
> standardize multipath support in QUIC.
> -- Christian Huitema