From owner-freebsd-stable@freebsd.org  Wed Mar  1 14:07:03 2017
Return-Path: <owner-freebsd-stable@freebsd.org>
Delivered-To: freebsd-stable@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 DA31ECEE7D6
 for <freebsd-stable@mailman.ysv.freebsd.org>;
 Wed,  1 Mar 2017 14:07:03 +0000 (UTC)
 (envelope-from lutz@donnerhacke.de)
Received: from annwfn.iks-jena.de (annwfn-eth.iks-jena.de
 [IPv6:2001:4bd8:0:104:20a:e4ff:fe80:3138])
 (using TLSv1 with cipher AES256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 7D5A9AA3
 for <freebsd-stable@freebsd.org>; Wed,  1 Mar 2017 14:07:03 +0000 (UTC)
 (envelope-from lutz@donnerhacke.de)
X-SMTP-Sender: IPv6:2001:4bd8:59:1:172:27:107:102
Received: from lyoness (lyoness.intern.iks-service.de
 [IPv6:2001:4bd8:59:1:172:27:107:102])
 by annwfn.iks-jena.de (8.14.9/8.14.1) with ESMTP id v21E6kbx028481;
 Wed, 1 Mar 2017 15:06:50 +0100
From: "Lutz Donnerhacke" <lutz@donnerhacke.de>
To: <ari@ish.com.au>
Cc: <freebsd-stable@freebsd.org>
Subject: Re: CARP forcing failover
Date: Wed, 1 Mar 2017 15:06:46 +0100
Message-ID: <000001d29295$1260ec90$3722c5b0$@donnerhacke.de>
MIME-Version: 1.0
Content-Type: text/plain;
	charset="utf-8"
Content-Transfer-Encoding: quoted-printable
X-Mailer: Microsoft Outlook 15.0
Thread-Index: AdKSlQ8et6UbuWEtQV28Tzu40YmLJg==
Content-Language: de
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-stable>, 
 <mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable/>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 01 Mar 2017 14:07:03 -0000

> igb0.2: flags=3D8943<UP,BROADCAST,RUNNING,PROMISC,SIMPLEX,MULTICAST> =
metric 0 mtu 1500
> 	status: active
> 	vlan: 2 vlanpcp: 0 parent interface: igb0
> 	carp: BACKUP vhid 3 advbase 1 advskew 50
> 	groups: vlan
>=20
> That's two internal vlans and one external network. Each interface has =
its
> own vhid since that's the advice I had in the past.
>=20
> Now, what command can I type that I could run remotely (SSH over the =
em0
> link) to force all the CARP addresses simultaneously to decrease the =
advskew
> and become MASTER. Alternatively I could run something on the MASTER =
to make
> it BACKUP. Everything I've done so far is one command per interface =
which has
> got me in trouble before as I manage to accidentally remove my own =
access to
> the box before I'm done.


You have to provide the correct subset of the parameters to change the =
behaviour without changing the other properties.

# ifconfig igb0.2 vhid 3 advbase 1 advskew 250 pass 'xxxx'

This will change the parameters for the vhid 3 on the interface igb0.2 =
only.
But the change will cover *all* vhid parameters, so if you left some =
off, they will vanish.

Of course, you are free to use multiple IPs per interface using the =
"alias" option.
It does work even for carp instances.

VHIDs needs to be unique per layer2 segment, because they are used as =
selectors for the kernel code to validate the CARP packet.
Please note, that VRRP/HSRP/GLBP may use the same packet format as CARP, =
so their VHIDs should be different from yours.