From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-il1-f179.google.com (mail-il1-f179.google.com [209.85.166.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id C05A73B29E; Mon, 17 May 2021 11:46:13 -0400 (EDT) Received: by mail-il1-f179.google.com with SMTP id l15so1315295iln.8; Mon, 17 May 2021 08:46:13 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Xj0GICNR8IWAaclww0+eIt0DMorw7KE+fCcVpNv0+WY=; b=Onz4uwM0ibnINBz6jkdT/fSEyNI2kGl8dr7bGO6A7w+Zr91kTW7xIROYRIeXMGwlYy l2jhoa5z2bTKCxEv7pev6MP4lH1/Pmgb0MfGXDxu8mM/mbHyQwKxec1Z4XifL2Xz0sza ofvke2KGEKfRHLINf5obu7HldM9qr8Ht0oVioITJoMFXziZsQqXyXoiwEcpTP78e1wq6 a7xwgxLQyyx3FVxL8QOYmqXHHs451u9FfWT7vs4vxBRdKBXVG33brqlqqNvaKT8JujKS Y1Nf85ooDdCV4JyUmy1haX7W4wPmvGSGqVrXB2KOzM3MGzYv/GImYc7q5BspbVL9H/Wp Xr1g== X-Gm-Message-State: AOAM530HwF3i8IWZauyaxYHDPueO12Usx0nNbLNl0PtKXprJrzuGa5PR KK1MfypwsWcnqxeL03TrJA7GDhqkFC3Cb+tkd64= X-Google-Smtp-Source: ABdhPJyNjct0Nm1hJBXWFxlW4Vs8U5nc00eVIvOfgyl/voEfb/8kW20ijXPShK8p5GzN68lvt4zYzgJM04Uk9f3u0GU= X-Received: by 2002:a92:c607:: with SMTP id p7mr273611ilm.97.1621266373179; Mon, 17 May 2021 08:46:13 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Jim Gettys Date: Mon, 17 May 2021 11:46:01 -0400 Message-ID: To: Neal Cardwell Cc: Matt Mathis , starlink@lists.bufferbloat.net, bloat Content-Type: multipart/alternative; boundary="000000000000427d2405c2887e70" Subject: Re: [Bloat] starlink bloat in review X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 17 May 2021 15:46:13 -0000 --000000000000427d2405c2887e70 Content-Type: text/plain; charset="UTF-8" As always, we have the problem of the last mile, in this case the hop into the starlink network, and whatever is going on in the home router end. Most Wi-Fi bloat is much worse than the last mile bloat, but you have to set out to measure each independently. When I first ran into buffer bloat, I measured 8 second latencies on the bed upstairs, which if you moved the laptop even a few inches might drop to something sane. The customer doesn't care where the bloat is, just that it's happening... Jim On Mon, May 17, 2021, 11:08 AM Neal Cardwell via Bloat < bloat@lists.bufferbloat.net> wrote: > On Sat, May 15, 2021 at 7:00 PM Matt Mathis via Bloat > wrote: > > > > I don't understand: starlink doesn't terminate the TCP connection, > > does it? Or are you referring to YT's BBR adequately addressing > > Starlinks variable RTT? "Adequately" is probably the operative word. > > It is not too hard to imagine what goes wrong with BBR if the actual > > path length varies, and on an underloaded network, you may not be able > > to even detect the symptoms. > > On that note, the article mentions: > "Starlink itself measures ping times for Counter-Strike: Go and > Fortnite in its app, and I rarely saw those numbers dip below 50ms, > mostly hovering around 85-115ms." > > If the range 50ms to 115ms is representative of two-way propagation > delays on their network, then it sounds like BBR can probably perform > reasonably well in that environment. The algorithm is designed to > tolerate factor-of-two variations in RTT and still maintain full > utilization, if there is reasonable buffering. > > neal > _______________________________________________ > Bloat mailing list > Bloat@lists.bufferbloat.net > https://lists.bufferbloat.net/listinfo/bloat > --000000000000427d2405c2887e70 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
As always, we have the problem of the last mile, in this = case the hop into the starlink network, and whatever is going on in the hom= e router end. Most Wi-Fi bloat is much worse than the last mile bloat, but = you have to set out to measure each independently.

When I first ran into buffer bloat, I measured 8 secon= d latencies on the bed upstairs, which if you moved the laptop even a few i= nches might drop to something sane.

The customer doesn't care where the bloat is, just that it= 9;s happening...

Jim
=

On Mon, May 17, 2021, 11:08 AM Neal Cardwell via Bloat <bloat@lists.bufferbloat.net&= gt; wrote:
On Sat, May 15, 2021 at = 7:00 PM Matt Mathis via Bloat
<bloat@lists.bufferbloat.net> wrote:
>
> I don't understand: starlink doesn't terminate the TCP connect= ion,
> does it?=C2=A0 =C2=A0Or are you referring to YT's BBR adequately a= ddressing
> Starlinks variable RTT?=C2=A0 =C2=A0"Adequately" is probably= the operative word.
> It is not too hard to imagine what goes wrong with BBR if the actual > path length varies, and on an underloaded network, you may not be able=
> to even detect the symptoms.

On that note, the article mentions:
=C2=A0 "Starlink itself measures ping times for Counter-Strike: Go and=
Fortnite in its app, and I rarely saw those numbers dip below 50ms,
mostly hovering around 85-115ms."

If the range 50ms to 115ms is representative of two-way propagation
delays on their network, then it sounds like BBR can probably perform
reasonably well in that environment. The algorithm is designed to
tolerate factor-of-two variations in RTT and still maintain full
utilization, if there is reasonable buffering.

neal
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