IETF Logo Mail Archive

Re: [TICTOC] [ntpwg] Antw: operational experience with NTP symmetric mode

Miroslav Lichvar <mlichvar@redhat.com> Mon, 09 May 2016 08:24 UTC

Return-Path: <mlichvar@redhat.com>
X-Original-To: tictoc@ietfa.amsl.com
Delivered-To: tictoc@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 54EB112B067 for <tictoc@ietfa.amsl.com>; Mon, 9 May 2016 01:24:38 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -7.918
X-Spam-Level:
X-Spam-Status: No, score=-7.918 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, RP_MATCHES_RCVD=-0.996, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id m3ALLK9Pm440 for <tictoc@ietfa.amsl.com>; Mon, 9 May 2016 01:24:36 -0700 (PDT)
Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 9A0F512B036 for <tictoc@ietf.org>; Mon, 9 May 2016 01:24:36 -0700 (PDT)
Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0343581121; Mon, 9 May 2016 08:24:35 +0000 (UTC)
Received: from localhost (dhcp-24-154.brq.redhat.com [10.34.24.154]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u498OYEJ009241; Mon, 9 May 2016 04:24:35 -0400
Date: Mon, 09 May 2016 10:24:34 +0200
From: Miroslav Lichvar <mlichvar@redhat.com>
To: Hal Murray <hmurray@megapathdsl.net>
Message-ID: <20160509082434.GB5044@localhost>
References: <Ulrich.Windl@rz.uni-regensburg.de> <57304DEC020000A100021281@gwsmtp1.uni-regensburg.de> <20160509073337.E14F0406061@ip-64-139-1-69.sjc.megapath.net>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <20160509073337.E14F0406061@ip-64-139-1-69.sjc.megapath.net>
User-Agent: Mutt/1.5.24 (2015-08-30)
X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26
Archived-At: <http://mailarchive.ietf.org/arch/msg/tictoc/DV73041EZDUJbE7vhDJGYFE1NmI>
Cc: ntpwg@lists.ntp.org, Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>, "tictoc@ietf.org" <tictoc@ietf.org>
Subject: Re: [TICTOC] [ntpwg] Antw: operational experience with NTP symmetric mode
X-BeenThere: tictoc@ietf.org
X-Mailman-Version: 2.1.17
Precedence: list
List-Id: Timing over IP Connection and Transfer of Clock BOF <tictoc.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tictoc>, <mailto:tictoc-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tictoc/>
List-Post: <mailto:tictoc@ietf.org>
List-Help: <mailto:tictoc-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tictoc>, <mailto:tictoc-request@ietf.org?subject=subscribe>
X-List-Received-Date: Mon, 09 May 2016 08:24:38 -0000

On Mon, May 09, 2016 at 12:33:37AM -0700, Hal Murray wrote:
> Peering seems natural for the case where you have 2 equal servers and you 
> want them to keep an eye on each other.  Aside from reducing the number of 
> packets by a factor of 2, are there any reasons for using peer rather than 
> server?  Is there any extra information exchanged?

Two reasons:
- ability to push synchronization to the other host, which may
  simplify configuration management a bit as only one peer (active)
  has to be configured with the address of the other peer (passive)
- interleaved mode, which allows the peers to exchange transmit
  timestamps after packets are sent in order to improve accuracy with
  HW timestamping

-- 
Miroslav Lichvar

v2.23.0 | Report a Bug | By Email