Re: [quicwg/base-drafts] Revalidation for ECN (#4037)

Gorry Fairhurst <> Thu, 20 August 2020 07:49 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 956523A099B for <>; Thu, 20 Aug 2020 00:49:52 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -3.1
X-Spam-Status: No, score=-3.1 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_IMAGE_ONLY_32=0.001, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id QbnpZ-xNIazN for <>; Thu, 20 Aug 2020 00:49:51 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 00B483A0954 for <>; Thu, 20 Aug 2020 00:49:50 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 07EDA900057 for <>; Thu, 20 Aug 2020 00:49:50 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1597909790; bh=N7Ws0eC5VGH3OfhXWSdNefonkuotItWptrSpo6PbN2w=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=Hri5QtGAxLom8GJzAWTmqF9pas9j5+iCFpLmO8PhZkBHNFbIPBd10MhXskSlass9n YOY5xAqp9ZFynKCxelh7+rN3WCHXhoTkWZVJaMg8Jyn00mHYokNSbB71LLbQZLWDDD nFcNku1vJThdw3pSZhZNbYl02NPME6+lFqAJaDyY=
Date: Thu, 20 Aug 2020 00:49:49 -0700
From: Gorry Fairhurst <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/pull/4037/review/>
In-Reply-To: <quicwg/base-drafts/pull/>
References: <quicwg/base-drafts/pull/>
Subject: Re: [quicwg/base-drafts] Revalidation for ECN (#4037)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5f3e2b1ded059_77f119641580a1"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: gorryfair
X-GitHub-Recipient: quic-issues
X-GitHub-Reason: subscribed
X-Auto-Response-Suppress: All
Archived-At: <>
X-Mailman-Version: 2.1.29
List-Id: Notification list for GitHub issues related to the QUIC WG <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Thu, 20 Aug 2020 07:49:53 -0000

@gorryfair commented on this pull request.

> @@ -3892,6 +3889,7 @@ errors are detected.
 Endpoints validate ECN for packets sent on each network path independently.  An
 endpoint thus validates ECN on new connection establishment, when switching to a
 server's preferred address, and on active connection migration to a new path.
+If validation fails, an endpoint could also periodically attempt validation.

Why is this a could. Ignoring ECN is inappropriate and dangerous to the health of other flows. (If a flow received CE-marks it could reasonably assume ECN is working, if it see nothing it needs at some point to recheck this works.)

I'd expect this to be needed: Why therefore is this not a SHOULD?

> @@ -3843,11 +3843,8 @@ instead of dropping it.  Endpoints react to congestion by reducing their sending
 rate in response, as described in {{QUIC-RECOVERY}}.
 To use ECN, QUIC endpoints first determine whether a path supports ECN marking
-and the peer is able to access the ECN codepoint in the IP header.  A network
-path does not support ECN if ECN marked packets get dropped or ECN markings are
-rewritten on the path. An endpoint validates the use of ECN on the path, both
-during connection establishment and when migrating to a new path
+and the peer is able to access the ECN codepoint in the IP header; see

I think the new text is wrong. Support by the endpoint isn't sufficient. The path validation is required to use ECN, and this spec needs to say this for each new path.

You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub: