Re: [DNSOP] Consensus suggestion for EDE and the TC bit
Michael StJohns <msj@nthpermutation.com> Wed, 04 December 2019 06:31 UTC
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To: Ralf Weber <dns@fl1ger.de>
Cc: dnsop@ietf.org
References: <yblzhgpwwit.fsf@wu.hardakers.net> <07cdee93-eb69-9a67-65d8-ea85e82a8761@nthpermutation.com> <A2BE987F-09ED-4992-977C-FB3A702B8FE5@fl1ger.de>
From: Michael StJohns <msj@nthpermutation.com>
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Date: Wed, 04 Dec 2019 01:31:50 -0500
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Subject: Re: [DNSOP] Consensus suggestion for EDE and the TC bit
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On 12/3/2019 5:21 PM, Ralf Weber wrote: > Moin! > > On 3 Dec 2019, at 3:15, Michael StJohns wrote: >> From 2181: >> >>> The TC bit should be set in responses only when an RRSet is required >>> as a part of the response, but could not be included in its >>> entirety. >>> The TC bit should not be set merely because some extra information >>> could have been included, but there was insufficient room. >> >> I finally got a chance to go back and do some reading and found the >> above. >> >> The way I read this is that setting the bit simply because you >> couldn't include diagnostic info is a no-no. Let's not do it. > I disagree. The EDNS0 OPT RRSet is needed and thus if can not be > fitted entirely a TC bit has to be set. Also 2181 was before EDNS0 so > IMHO it doesn’t apply here anyway. EDE is all is new stuff we have to > decide over what do with it now and not some ancient RFC. And a lot of > people (including me) have said that they, because of the rare cases > this appears, see TC as the right solution as it is simple and > backwards compatible. EDE already is complex we should not increase it > complexity for a rare corner case. *bleah* In the querying EDNS0 set a bit (EDERequested) that says "Consider EDE as 'important' in the response - return TC if there is an overflow and EDE is omitted". Maybe set a second bit (EDERequired) that says "EDE is more important than any other data - return it at the head of the response and drop something else in preference." Responder: If EDERequested or EDERequired is set, and overflow occurs because of the EDE, set the TC bit on the response. If EDERequired is set, return the EDE EDNS0 option in preference to any other data - you may still end up setting the TC bit if other info is omitted. The first bit says that the client understands EDE and that it considers it is as important as any other data and should not be omitted without setting the TC bit. Clients that don't understand EDE (e.g. most of them right now) that would ignore EDE anyways don't need to re-query for data that they don't understand. Clients that do understand EDE leave both bits unset if they really don't care about the reasons why (e.g. the typical end user), can set the first bit if they do (typical resolver) and can set both bits for debugging (the geeks in the DNSOP group). In the case of truncation due to EDE, omit the EDE option from the response EDNS0 RR. If you're still overflowing, set the TC. (E.g. this isn't about omitting the EDNS0 in the response, only about removing bloat when the client hasn't indicated the bloat is useful. Later, Mike > > So long > -Ralf > —-- > Ralf Weber
- [DNSOP] Consensus suggestion for EDE and the TC b… Wes Hardaker
- Re: [DNSOP] Consensus suggestion for EDE and the … Ben Schwartz
- Re: [DNSOP] Consensus suggestion for EDE and the … Viktor Dukhovni
- Re: [DNSOP] Consensus suggestion for EDE and the … Wes Hardaker
- Re: [DNSOP] Consensus suggestion for EDE and the … Wes Hardaker
- Re: [DNSOP] Consensus suggestion for EDE and the … Petr Špaček
- Re: [DNSOP] Consensus suggestion for EDE and the … Bob Harold
- Re: [DNSOP] Consensus suggestion for EDE and the … Ray Bellis
- Re: [DNSOP] Consensus suggestion for EDE and the … Wes Hardaker
- Re: [DNSOP] Consensus suggestion for EDE and the … Peter van Dijk
- Re: [DNSOP] Consensus suggestion for EDE and the … Ben Schwartz
- Re: [DNSOP] Consensus suggestion for EDE and the … Eric Orth
- Re: [DNSOP] Consensus suggestion for EDE and the … Michael StJohns
- Re: [DNSOP] Consensus suggestion for EDE and the … Puneet Sood
- Re: [DNSOP] Consensus suggestion for EDE and the … Vittorio Bertola
- Re: [DNSOP] Consensus suggestion for EDE and the … Ralf Weber
- Re: [DNSOP] Consensus suggestion for EDE and the … Paul Vixie
- Re: [DNSOP] Consensus suggestion for EDE and the … Michael StJohns
- Re: [DNSOP] Consensus suggestion for EDE and the … Wes Hardaker