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Re: [tcpm] RFC793bis draft 14 Reserved Bits

Mike Kosek <Mike.Kosek@comsys.rwth-aachen.de> Tue, 03 December 2019 17:18 UTC

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From: Mike Kosek <Mike.Kosek@comsys.rwth-aachen.de>
To: Joe Touch <touch@strayalpha.com>, "Rodney W. Grimes" <4bone@gndrsh.dnsmgr.net>
CC: "tcpm@ietf.org" <tcpm@ietf.org>
Thread-Topic: [tcpm] RFC793bis draft 14 Reserved Bits
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Date: Tue, 03 Dec 2019 17:18:09 +0000
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Subject: Re: [tcpm] RFC793bis draft 14 Reserved Bits
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Hi,

I would second the proposal to be more explicit. If we would add a MUST of unaltered traversal in this specific case, I am wondering if this should be addressed in other fields as well. Obviously there are limitations for certain option types, or src/dst port, but Flags and Window Size seem like perfect fits. Flags would also be the subsequent step of Rodney's and Joe's proposal, as bits would not be covered any longer if they are assigned.

Best,
Mike


On 28. Nov 2019, at 04:52, Joe Touch <touch@strayalpha.com<mailto:touch@strayalpha.com>> wrote:



On Nov 27, 2019, at 6:44 PM, Rodney W. Grimes <4bone@gndrsh.dnsmgr.net<mailto:4bone@gndrsh.dnsmgr.net>> wrote:

Hi tcpm,

Sorry for bumping this, maybe it got overlooked during 106.

Catching up on draft-ietf-tcpm-rfc793bis-14, I was wondering why the rsrvd bits are not explicitly stated as a formal MUST requirement:

"Must be zero in generated segments and must be ignored in received segments, if corresponding future features are unimplemented by the sending or receiving host."

To my understanding, the current phrasing is up to interpretation, i.e., someone might opt to not implement it as stated due to the missing formal MUST - Please prove me wrong if I am missing something.

I would even like to see it go further and add "they MUST be ignored by the network, and traverse the network unchanged.”

Perhaps further explicitly:

they MUST be ignored by the network and MUST traverse the network unchanged

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