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List: keepalived-devel
Subject: Re: [Keepalived-devel] Fwd: inconsistent behaviour with failover on 2 combo router-server nodes?
From: Alexander Ufimtsev <alexu () ucd ! ie>
Date: 2014-01-24 15:06:09
Message-ID: CAJDHVWzh-AkTWNgin-uUeU=Oawvcupy++KjDZkr69Ewmx6SMTQ () mail ! gmail ! com
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Hi Paul,
No, I'm not using conntrackd. However, I think I found the answer to my
question: it just took some connections longer to time out (a few mins), so
no inconsistencies.
Thanks again for reply.
Regards,
Alexander
On 22 January 2014 20:28, Paul Robert Marino <prmarino1@gmail.com> wrote:
> Are you using conntrackd?
>
>
> On Wed, Jan 22, 2014 at 3:09 PM, Alexander Ufimtsev <alexu@ucd.ie> wrote:
> > Hello All,
> >
> > I'm running keepalived on two nodes that work both as routers and
> servers,
> > using lo:0 interface for virtual ip and iptables to mark packets for real
> > servers. Server 1 has priority over server 2 and thus control the virtual
> > ip. The workload consists of clients establishing a long-running tcp
> > connections to the servers.
> >
> > I've noticed an interesting behavour during failover: when server 1 fails
> > over, all existing tcp connections to server 1 are gone and clients
> > reconnect to server 2, which is 100% correct and expected behaviour.
> > However, when server 1 comes back and takes over virtual ip, some
> clients on
> > server 2 get disconnected and then have to dial back to server 1. This
> seems
> > to happen only for clients that connected to server 2 when server 1 was
> > offline. The clients that were connected to server 2 before server 1 went
> > down remain connected to server 2.
> >
> > Is this due to the fact that before server 2 takes over virtual ip on
> eth0,
> > clients bind to lo:0 and after virtual ip takeover they bind to virtual
> ip
> > on eth0? If so, is there any way to teach them to bind to lo:0 instead so
> > they do not disconnect the moment another server takes over the virtual
> ip?
> >
> > Many thanks,
> > Alexander
> >
> > --
> > Alexander Ufimtsev
> > School of Computer Science and Informatics
> > University College Dublin, Belfield, D4, Ireland
> > Phone: +353 1 716 2926 Fax: +353 1 269 7262
> >
> >
> >
> ------------------------------------------------------------------------------
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> > https://lists.sourceforge.net/lists/listinfo/keepalived-devel
> >
>
[Attachment #5 (text/html)]
<div dir="ltr">Hi Paul,<div><br></div><div style>No, I'm not using conntrackd. \
However, I think I found the answer to my question: it just took some connections \
longer to time out (a few mins), so no inconsistencies.</div>
<div style><br></div><div style>Thanks again for reply.</div><div \
style><br></div><div style>Regards,</div><div style>Alexander</div></div><div \
class="gmail_extra"><br><br><div class="gmail_quote">On 22 January 2014 20:28, Paul \
Robert Marino <span dir="ltr"><<a href="mailto:prmarino1@gmail.com" \
target="_blank">prmarino1@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex">Are you using conntrackd?<br> <div><div class="h5"><br>
<br>
On Wed, Jan 22, 2014 at 3:09 PM, Alexander Ufimtsev <<a \
href="mailto:alexu@ucd.ie">alexu@ucd.ie</a>> wrote:<br> > Hello All,<br>
><br>
> I'm running keepalived on two nodes that work both as routers and \
servers,<br> > using lo:0 interface for virtual ip and iptables to mark packets \
for real<br> > servers. Server 1 has priority over server 2 and thus control the \
virtual<br> > ip. The workload consists of clients establishing a long-running \
tcp<br> > connections to the servers.<br>
><br>
> I've noticed an interesting behavour during failover: when server 1 \
fails<br> > over, all existing tcp connections to server 1 are gone and \
clients<br> > reconnect to server 2, which is 100% correct and expected \
behaviour.<br> > However, when server 1 comes back and takes over virtual ip, some \
clients on<br> > server 2 get disconnected and then have to dial back to server 1. \
This seems<br> > to happen only for clients that connected to server 2 when server \
1 was<br> > offline. The clients that were connected to server 2 before server 1 \
went<br> > down remain connected to server 2.<br>
><br>
> Is this due to the fact that before server 2 takes over virtual ip on eth0,<br>
> clients bind to lo:0 and after virtual ip takeover they bind to virtual ip<br>
> on eth0? If so, is there any way to teach them to bind to lo:0 instead so<br>
> they do not disconnect the moment another server takes over the virtual ip?<br>
><br>
> Many thanks,<br>
> Alexander<br>
><br>
> --<br>
> Alexander Ufimtsev<br>
> School of Computer Science and Informatics<br>
> University College Dublin, Belfield, D4, Ireland<br>
> Phone: +353 1 716 2926 Fax: +353 1 269 7262<br>
><br>
><br>
</div></div>> ------------------------------------------------------------------------------<br>
> CenturyLink Cloud: The Leader in Enterprise Cloud Services.<br>
> Learn Why More Businesses Are Choosing CenturyLink Cloud For<br>
> Critical Workloads, Development Environments & Everything In Between.<br>
> Get a Quote or Start a Free Trial Today.<br>
> <a href="http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk" \
target="_blank">http://pubads.g.doubleclick.net/gampad/clk?id=119420431&iu=/4140/ostg.clktrk</a><br>
> _______________________________________________<br>
> Keepalived-devel mailing list<br>
> <a href="mailto:Keepalived-devel@lists.sourceforge.net">Keepalived-devel@lists.sourceforge.net</a><br>
> <a href="https://lists.sourceforge.net/lists/listinfo/keepalived-devel" \
target="_blank">https://lists.sourceforge.net/lists/listinfo/keepalived-devel</a><br> \
><br> </blockquote></div><br></div>
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