Subject: [DNSOP] I-D Action: draft-ietf-dnsop-svcb-httpssvc-03.txt

From: [email-masked]
Date: Thu, 11 Jun 2020 19:25:06 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Domain Name System Operations WG of the IETF.

        Title           : Service binding and parameter specification via the DNS (DNS SVCB and HTTPSSVC)
        Authors         : Ben Schwartz
                          Mike Bishop
                          Erik Nygren
	Filename        : draft-ietf-dnsop-svcb-httpssvc-03.txt
	Pages           : 39
	Date            : 2020-06-11

Abstract:
   This document specifies the "SVCB" and "HTTPSSVC" DNS resource record
   types to facilitate the lookup of information needed to make
   connections for origin resources, such as for HTTPS URLs.  SVCB
   records allow an origin to be served from multiple network locations,
   each with associated parameters (such as transport protocol
   configuration and keys for encrypting the TLS ClientHello).  They
   also enable aliasing of apex domains, which is not possible with
   CNAME.  The HTTPSSVC DNS RR is a variation of SVCB for HTTPS and HTTP
   origins.  By providing more information to the client before it
   attempts to establish a connection, these records offer potential
   benefits to both performance and privacy.

   TO BE REMOVED: This proposal is inspired by and based on recent DNS
   usage proposals such as ALTSVC, ANAME, and ESNIKEYS (as well as long
   standing desires to have SRV or a functional equivalent implemented
   for HTTP).  These proposals each provide an important function but
   are potentially incompatible with each other, such as when an origin
   is load-balanced across multiple hosting providers (multi-CDN).
   Furthermore, these each add potential cases for adding additional
   record lookups in addition to AAAA/A lookups.  This design attempts
   to provide a unified framework that encompasses the key functionality
   of these proposals, as well as providing some extensibility for
   addressing similar future challenges.

   TO BE REMOVED: The specific name for this RR type is an open topic
   for discussion.  "SVCB" and "HTTPSSVC" are meant as placeholders as
   they are easy to replace.  Other names might include "B", "SRV2",
   "SVCHTTPS", "HTTPS", and "ALTSVC".

   TO BE REMOVED: This document is being collaborated on in Github at:
   https://github.com/MikeBishop/dns-alt-svc [1].  The most recent
   working version of the document, open issues, etc. should all be
   available there.  The authors (gratefully) accept pull requests.

The IETF datatracker status page for this draft is:
https://datatracker.ietf.org/doc/draft-ietf-dnsop-svcb-httpssvc/

There are also htmlized versions available at:
https://tools.ietf.org/html/draft-ietf-dnsop-svcb-httpssvc-03
https://datatracker.ietf.org/doc/html/draft-ietf-dnsop-svcb-httpssvc-03

A diff from the previous version is available at:
https://www.ietf.org/rfcdiff?url2=draft-ietf-dnsop-svcb-httpssvc-03

Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

---

From: Ben Schwartz <[email-masked]>
Date: Thu, 11 Jun 2020 22:44:27 -0400

Thank you to the many participants who've written detailed feedback on this
draft over the last few months.  This draft includes a wide variety of
textual updates based on your observations.

There are two significant changes that I think are worth highlighting.
First, the requirements related to chain lengths have been adjusted.
Previously, the relevant text (a placeholder to invite discussion) said

> Chains of consecutive SVCB and CNAME records SHOULD be limited to (8?) ...

Based on the discussions on this list, the text now says

> To avoid unbounded alias chains, clients and recursive resolvers MUST
impose a limit on the total number of SVCB aliases they will follow for
each resolution request. This limit MUST NOT be zero, i.e. implementations
MUST be able to follow at least one AliasForm record. The exact value of
this limit is left to implementations.

Second, the IANA registration rules for SvcParamKeys (i.e. new extensions)
have changed.  Previously, almost all of the 16-bit values were "Expert
Review", except for 256 reserved for Private Use (i.e. experimentation in
closed settings).  In this draft, 32512 values are under Expert Review,
32512 are First-Come-First-Served, 255 are Private Use, and 257 are subject
to Standards Action.  We hope that this will enable more rapid public
experiments without risking key space exhaustion.

On Thu, Jun 11, 2020 at 10:25 PM <[email-masked]> wrote:

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