Re: [tcpm] 793bis ready to go?

Wesley Eddy <wes@mti-systems.com> Tue, 04 May 2021 02:32 UTC

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From: Wesley Eddy <wes@mti-systems.com>
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Subject: Re: [tcpm] 793bis ready to go?
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On 2/16/2021 3:58 AM, Scharf, Michael wrote:
> I'd also be interested in more details. Unfortunately, I am not familiar with BSD.
>
> For what it is worth, RFC 1122 Section 4.2.3.6 "TCP Keep-Alives" states:
>
>              Keep-alive packets MUST only be sent when no data or
>              acknowledgement packets have been received for the
>              connection within an interval.
>
> So, the latter part of the sentence originates from RFC 1122.
>
> Could somebody comment on whether recent BSD stacks would deviate from the proposed text in 793bis? That would be an important insight!


This is not answering your question about BSD, but just for reference, 
the change in that sentence came from consolidated review comments from 
Microsoft colleagues that was sent to the mailing list:

https://mailarchive.ietf.org/arch/msg/tcpm/rqHhtpqW3m0QikJnaz_4y-y7NyQ/


Section 3.7.4
"Keep-alive packets MUST only be sent when no data or acknowledgement
    packets have been received for the connection within an interval
    (MUST-26).

"

It's important to call out an additional condition - that sends are not already outstanding. When a send is outstanding, it is retransmitted and serves as an implicit liveness check.