From owner-freebsd-net@freebsd.org  Tue Sep  6 08:22:28 2016
Return-Path: <owner-freebsd-net@freebsd.org>
Delivered-To: freebsd-net@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id 97298A9D394
 for <freebsd-net@mailman.ysv.freebsd.org>;
 Tue,  6 Sep 2016 08:22:28 +0000 (UTC)
 (envelope-from kpielorz_lst@tdx.co.uk)
Received: from smtp.krpservers.com (smtp.krpservers.com [62.13.128.145])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "*.krpservers.com", Issuer "RapidSSL SHA256 CA" (verified OK))
 by mx1.freebsd.org (Postfix) with ESMTPS id 44AC87FB
 for <freebsd-net@FreeBSD.org>; Tue,  6 Sep 2016 08:22:27 +0000 (UTC)
 (envelope-from kpielorz_lst@tdx.co.uk)
Received: from [10.12.30.106] (vpn01-01.tdx.co.uk [62.13.130.213] (may be
 forged)) (authenticated bits=0)
 by smtp.krpservers.com (8.15.2/8.15.2) with ESMTPSA id u868Ddtf030546
 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO)
 for <freebsd-net@FreeBSD.org>; Tue, 6 Sep 2016 09:13:40 +0100 (BST)
 (envelope-from kpielorz_lst@tdx.co.uk)
Date: Tue, 06 Sep 2016 09:13:28 +0100
From: Karl Pielorz <kpielorz_lst@tdx.co.uk>
To: freebsd-net@FreeBSD.org
Subject: lagg Interfaces - don't do Gratuitous ARP?
Message-ID: <0D84203FAAFD0A8E7BBB24A3@[10.12.30.106]>
X-Mailer: Mulberry/4.0.8 (Win32)
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 06 Sep 2016 08:22:28 -0000


Hi,

We've just changed the network config on a box - going from a single 'em1' 
adapter to a lagg failover of em0, em1.

This works - but we noticed after the machine rebooted, we couldn't ping it 
from other hosts.

Checking on other machines on the LAN they still had an ARP entry for the 
changed hosts old em1's MAC.

On the lagg machine - the MAC used for the NIC's (and lagg) was now the MAC 
for em0 (which I believe is correct behaviour).

Should the act of lagg / IP's coming up not send a gratuitous ARP for them 
or something to avoid this?

As it was we had to log into a number of key boxes and 'arp -d' the IP's - 
and take a ~800 second 'hit' on other boxes timing out the old MAC.


-Karl