Re: statement regarding keepalives

Spencer Dawkins at IETF <spencerdawkins.ietf@gmail.com> Fri, 20 July 2018 13:40 UTC

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In-Reply-To: <alpine.DEB.2.20.1807201340240.14354@uplift.swm.pp.se>
From: Spencer Dawkins at IETF <spencerdawkins.ietf@gmail.com>
Date: Fri, 20 Jul 2018 08:39:47 -0500
Message-ID: <CAKKJt-ciwgFpcc1NWpZxNz2HqGVFEpJ+-PwJhNxEyF9Hm3YvSQ@mail.gmail.com>
Subject: Re: statement regarding keepalives
To: Mikael Abrahamsson <swmike@swm.pp.se>
Cc: Kent Watsen <kwatsen@juniper.net>, "tsv-area@ietf.org >> tsv-area@ietf.org" <tsv-area@ietf.org>, tsvwg-ads@tools.ietf.org, tls-ads@ietf.org, netconf-chairs@ietf.org
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Hi, Mikael,

On Fri, Jul 20, 2018 at 6:48 AM Mikael Abrahamsson <swmike@swm.pp.se> wrote:

>
> Hi,
>
> While I agree with the sentiment here, I have personally been in positions
> where application programmers were unable to (in a timely manner) modify
> whatever was running, to implement a keepalive protocol. In that case,
> turning on TCP keepalives was a very easy thing to do that immediately
> would yield operational benefits.
>
> So I'd like to see in the text that we recommend to do it as "high up" in
> the stack as possible, but still don't put off people turning on TCP
> keepalives "because the IETF doesn't recommend that", and thus they do
> nothing at all and the problem just persists.
>
> Also, should we talk about recommendations for what these timers should
> be? In my experience, it's typically in tens of seconds up to 5-10 minutes
> that makes sense for Internet use. Shorter than that might interrupt the
> connection prematurely, longer than that causes things to take too long to
> detect a problem. Of course it's up to the application/environment to
> choose the best value for each use-case, but some text on this might be
> worthwhile to have there?
>

This is exactly the kind of feedback I'd like to reflect in whatever
guidance we give, in whatever form. Thank you for that.

Other thoughts?

Spencer

(And, yes, there's a tension between "why would I tear down a perfectly
good idle connection because it might not work the next time I try to use
it? for real" and "OMG, I need to send a message to the other side, but my
idle connection is now timing out, so I have to set up a new connection,
secure it, and do whatever else I need to do with the other side before I
can send a message!!!". That's a good thing to include in our advice)