Date: Fri, 21 Aug 2015 12:06:53 +0500 From: "Eugene M. Zheganin" <emz@norma.perm.ru> To: freebsd-stable@freebsd.org Subject: Re: [POSSIBLE BUG] 10-STABLE CARP erroneously becomes master on boot Message-ID: <55D6CE0D.9030806@norma.perm.ru> In-Reply-To: <CAE63ME5eMhtnoKXqb6H-CfKBXUqBrVvTuFaSgWf6sc-PXLgGXQ@mail.gmail.com> References: <CAE63ME70yRFuTbVQnZ9w%2Byf2dZAQkxsdddUhTsqBtms_F%2BdibA@mail.gmail.com> <CAOjFWZ5YBEpWBUMDgmoPqkyUiuCR7QSaZg-bByizwYimXA4NUA@mail.gmail.com> <CAE63ME5030t%2BfDCLgmiY-qgJc36D%2Byq5nv0U6P4gPjUyW6HShw@mail.gmail.com> <CAE63ME4hLrVGCLwaXd4-44qkVYeQx=f6pkD%2BY78CdH6zt9nDSw@mail.gmail.com> <CAE63ME5tTuQ3tsQrsj86ujchtKk5bQycbaoqXiHjpgYTar2FPw@mail.gmail.com> <CAE63ME5eMhtnoKXqb6H-CfKBXUqBrVvTuFaSgWf6sc-PXLgGXQ@mail.gmail.com>
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Hi. On 20.08.2015 14:51, Damien Fleuriot wrote: > > Hello list, > > > > We've managed to find the source of the bug, if it is indeed a bug. > > It all comes down to the order in which the IP addresses are assigned to > the interface from /etc/rc.conf. > > > When using the following syntax, the physical IP address is configured > AFTER the CARPs on the interface, which results in the CARP advertisements > being sourced from the CARP IP, triggering the double MASTER situation : > ipv4_addrs_int="1.2.3.4/24" > ifconfig_int_alias0="1.2.3.6/32 vhid 1 pass test advskew 20" > > When using either of the following syntaxes, the physical IP address is > configured BEFORE the CARPs, which results in the CARP advertisements being > sourced from the physical IP and restoring normal functionality : > ifconfig_int="inet 1.2.3.4/24" > ifconfig_int_alias0="1.2.3.6/32 vhid 1 pass test advskew 20" > OR > ifconfig_int_alias0="1.2.3.4/24" > ifconfig_int_alias1="1.2.3.6/32 vhid 1 pass test advskew 20" > It has been there since carp-ng was commited to the 10-CURRENT 2 years ago. The thing is, carp-ng doesn't need a non-carp address on an interface anymore, both nodes can work fine using only shared address. This isn't comfortable in lots of cases, but still. Thus, kernel sends carp advertisements from a primary address on the interface (which is normal behavior for any known network stack) and for FreeBSD that primary address has always been the first address on an interface for a given AF. Thus, your split-brain carp situation cause lies definitely somewhere else. I'm running carp on FreeBSD for years, including legacy one; if there is a bug - the situation you are describing probably isn't one. Eugene.
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