Re: [quicwg/base-drafts] Describe PMTU probing that includes source connection ID for routing … (#2402)

Igor Lubashev <> Mon, 04 February 2019 21:33 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 7B55E126DBF for <>; Mon, 4 Feb 2019 13:33:28 -0800 (PST)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -12.553
X-Spam-Status: No, score=-12.553 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIMWL_WL_HIGH=-4.553, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, MAILING_LIST_MULTI=-1, RCVD_IN_DNSWL_HI=-5, 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 qVYZl-yKdxxw for <>; Mon, 4 Feb 2019 13:33:26 -0800 (PST)
Received: from ( []) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by (Postfix) with ESMTPS id BFE24124B0C for <>; Mon, 4 Feb 2019 13:33:26 -0800 (PST)
Date: Mon, 04 Feb 2019 13:33:25 -0800
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=pf2014; t=1549316006; bh=8ztXe5kfhC1BLCAwYBUMZ1VCXgVVIwUnOJi9mrRnk1M=; h=Date:From:Reply-To:To:Cc:In-Reply-To:References:Subject:List-ID: List-Archive:List-Post:List-Unsubscribe:From; b=v1xIrED02/GkaNIIjo7chlavCz3ZLQrpfdcL2pfoIyrjr0Urygkk0sEtDU6RaiYLh IDTu2ZlCT+2n3g04AMAUYEU1OC+5QVl9D6A0bYW4odd9sdLzPACeZUX4xNTOU3Dcfz sbdZkUSKceIrBbMv4pcSCgZfmqiAomRaqwFo4Yog=
From: Igor Lubashev <>
Reply-To: quicwg/base-drafts <>
To: quicwg/base-drafts <>
Cc: Subscribed <>
Message-ID: <quicwg/base-drafts/pull/2402/review/>
In-Reply-To: <quicwg/base-drafts/pull/>
References: <quicwg/base-drafts/pull/>
Subject: Re: [quicwg/base-drafts] Describe PMTU probing that includes source connection ID for routing … (#2402)
Mime-Version: 1.0
Content-Type: multipart/alternative; boundary="--==_mimepart_5c58afa5d83cd_57d73ff0426d45bc1838a9"; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Precedence: list
X-GitHub-Sender: igorlord
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: Mon, 04 Feb 2019 21:33:28 -0000

igorlord commented on this pull request.

> @@ -3274,6 +3274,22 @@ The considerations for processing ICMP messages in the previous section also
 apply if these messages are used by DPLPMTUD.
+### PMTU Probes Containing Source Connection ID
+Endpoints that rely on the destination connection ID for routing QUIC packets
+are likely to require that connection ID included in PMTU probe packets in order
+to route resulting ICMP messages ({{icmp-pmtud}}) back to the correct endpoints.
+Only long header packets ({{long-header}}) contain source connection IDs, but
+long header packets will not be acknowledged once the connection has been
+established.  One way to construct a PMTU probe is to coalesce (see
+{{packet-coalesce}}) a Handshake packet ({{packet-handshake}}) with a short

> it might be better to suggest use of any coalescible long header packet rather than specifically suggesting the use of a Handshake packet.

Here are the long header packet types:

1. Initial.
I hesitate to use _initial_, because it is plaintext (no decryption failures) and has an ability to actually create new connections due to unfortunate delays / mis-routing.  Load balancer infrastructure may treat them differently from other packets.

2. 0-rtt.
These are supposed to be client-to-server only.  Having servers send them may be a bit unexpected.

3.  Handshake.
That's what I picked.

4.  Retry.
This does not have length, so it is not eligible.

That leaves only Handshake as the best candidate.  And one type is enough.

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