[lvs-users] How to make LVS Direct Route work for UDP programs?

Simon Horman horms at verge.net.au
Thu Nov 24 03:29:33 GMT 2011


On Thu, Nov 24, 2011 at 10:15:30AM +0800, wang yi wrote:
> On Thu, Nov 24, 2011 at 8:09 AM, Simon Horman <horms at verge.net.au> wrote:
> > On Thu, Nov 24, 2011 at 11:16:10AM +1300, Roger Littin wrote:
> >> Hi Wang,
> >>
> >> I have had similar problems where the director thinks the packet size is larger than mtu of the real
> >> server and sends back this message.  Do you see anything in wireshark to indicate this.  Overly
> >> large udp packet size?
> >>
> >> I think when the network layer hands off the packet to lvs, it may have already reassembled any
> >> fragments and then when lvs hands it back to the network layer, it is rejected because it is too
> >> large.
> >
> > Hi Roger,
> >
> > if you are seeing that problem then I suggest turning off
> > both GRO and LRO on the interface on the director that receives
> > the packets.
> >
> > e.g.
> > # ethtool -k eth0 | egrep '(receive-offload)'
> > generic-receive-offload: on
> > large-receive-offload: on
> >
> > # ethtool -K eth0 lro off
> > # ethtool -K eth0 gro off
> >
> > # ethtool -k eth0 | egrep '(receive-offload)'
> > generic-receive-offload: off
> > large-receive-offload: off
> >
> >
> > IPVS may be used in conjunction with GRO since 2.6.39,
> > so it should not be necessary to disable GRO if
> > a 2.6.39 is used.
> >
> > IPVS is not compatible with LRO as of 3.1 (or 3.2, when it is released)
> >
> > LRO is specific to TCP.
> > GRO affects both TCP and UDP (and other protocols IIRC).
> >
> > _______________________________________________
> > Please read the documentation before posting - it's available at:
> > http://www.linuxvirtualserver.org/
> >
> > LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
> > Send requests to lvs-users-request at LinuxVirtualServer.org
> > or go to http://lists.graemef.net/mailman/listinfo/lvs-users
> >
> 
> 
> 
> Hi, Simon
> 
>     Since you have mentioned kernel version here, I checked about that
> and I'm running 2.6.18-238.19.1.el5.centos.plus, is that a bit too
> old?

No, I don't think it is too old for the features you are using to work.




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