[lvs-users] ipvsadm and packets leaving a gre tunnel

Marco Lorig MLORIG at gmx.net
Tue Jul 22 15:03:13 BST 2008


addressing the server directly, without ipvsadm works fine and the pmtudisc seems to function properly.
It looks like Linux buffers the result of pmtudisc or at least the correct mtu size to reach the destination. Connecting now to the ipvsadm works also fine.
~10Mintues later, addressing the ipvsadm no longer  works and the file transfer hangs.

Reconnecting to the server directly again, still solves the problem with ipvsadm.

I would be very grateful if anyone can explain this behaviour to me.

Thanks in advance



-------- Original-Nachricht --------
> Datum: Tue, 22 Jul 2008 15:10:42 +0200
> Von: "Marco Lorig" <MLORIG at gmx.net>
> An: "LinuxVirtualServer.org users mailing list." <lvs-users at linuxvirtualserver.org>
> Betreff: Re: [lvs-users] ipvsadm and packets leaving a gre tunnel

> Hi Joe
> > have you read the section in the HOWTO on MTU?
> I´ve read the section but as i understand correctly the only solution in
> a LVS-NAT env is to set the MTU by hand on each route or interface on the
> realservers, which unfortunately I haven´t access to.
> We have been running this env since 2002 with Kernel 2.4.19 with no
> problems (running director on gre_interface). Actually we have upgraded our
> systems to kernel 2.6.18 which causes this problems.
> The gre tunnel exists between the directors because of  failover reasons (
> each director is located in a seperate datacenter interconnected by WAN).
> Copying files like this: 
> Client ---scp----> Director ---GRE Tunnel nopmtudisc --> Director ----scp
> ---> Server and vice versa.
> works fine but if the ipvsadm is enabled on the second director to serve
> multiple servers, the mtu problem happens.
> thanks in advance
> Marco
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