Re: [quicwg/base-drafts] Required state for retaining unacked RETIRE_CONNECTION_ID frames is unbound (#3509)

Kazuho Oku <> Tue, 31 March 2020 05:28 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id B46293A1B67 for <>; Mon, 30 Mar 2020 22:28:17 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: 1.967
X-Spam-Level: *
X-Spam-Status: No, score=1.967 tagged_above=-999 required=5 tests=[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_28=0.726, HTML_MESSAGE=0.001, HTML_OBFUSCATE_20_30=2.441, MAILING_LIST_MULTI=-1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=no autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id OFLeAKfaCgZP for <>; Mon, 30 Mar 2020 22:28:16 -0700 (PDT)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id 6DB693A1B66 for <>; Mon, 30 Mar 2020 22:28:16 -0700 (PDT)
Received: from ( []) by (Postfix) with ESMTP id 2D7A68C122A for <>; Mon, 30 Mar 2020 22:28:15 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1585632495; bh=RO5Ec3hH/FRyzYC8M6MZ1WhsV6yPBZ/kjfqKMRuGCoI=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=DJHvmrZR6zE+2aIBaucuti6G4TRp5WhsYGVQrducPv0OIQ0oxO7IkR0hWoMpbGZkf V6YmDRzu2LiaCnO3eip6BWQ43RvH8PZpEvS9E0JNcnAK5VgJoIHnCEpPAGADhiLRpm 1PkZgfR8R/jV20VJWooJ9oIKEd9Q7TuFJx9JzjuI=
Date: Mon, 30 Mar 2020 22:28:15 -0700
From: Kazuho Oku <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/issues/3509/>
In-Reply-To: <quicwg/base-drafts/issues/>
References: <quicwg/base-drafts/issues/>
Subject: Re: [quicwg/base-drafts] Required state for retaining unacked RETIRE_CONNECTION_ID frames is unbound (#3509)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5e82d4ef1ec64_a193fdcaa4cd96818193a"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: kazuho
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: Tue, 31 Mar 2020 05:28:18 -0000

Just to give another example of how an endpoint might end up required to track the retirement of more than active_connection_id_limit:
* A server tries to supply three active CIDs to the peer. At the moment, it has provided CID<sub>0</sub>, CID<sub>1</sub>, CID<sub>2</sub> to the client.
* The client sends RCID(CID<sub>1</sub>),  RCID(CID<sub>2</sub>). The server provides NCID(CID<sub>3</sub>), NCID(CID<sub>4</sub>). The two NCID frames are delivered to the client, but the ACK for the RCID frames gets lost.
* The client decides to probe two paths concurrently, by using CID<sub>3</sub> and CID<sub>4</sub>, but shortly after the packets are sent using those paths, the underlying network for those two paths disappear.
* The client now needs to make sure that RCID frames carrying 4 CIDs reach the peer.

In this example, we might argue that it would be possible for the client to figure out that CID<sub>3</sub> and CID<sub>4</sub> were provided as substitutions for CID<sub>1</sub> and CID<sub>2</sub>. But do we want to implement logic that detects such condition into our code? Note that tracking of substitutions can become tricky; if RCID(CID<sub>1</sub>) and RCID(CID<sub>2</sub>) were sent in different packets, it would be impossible for the client to see if CID<sub>4</sub> was provided as a supplement for CID<sub>1</sub> or for CID<sub>2</sub>.

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