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

Roger Littin roger at rlmedia.co.nz
Wed Nov 23 22:16:10 GMT 2011


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.

Roger.

On 24/11/2011, at 3:45 AM, wang yi wrote:

> Yes, I tried to make my application listen to real IP / virtual IP /
> INADDR_ANY, not working.
> 
> But I think the problem isn't that.
> As I mentioned in the original post, the LVS router seemed not
> delivering client packets to real servers, instead, it generated ICMP
> message(Destination unreachable), and the packets may be dropped.
> 
> Wang
> 
> On Wed, Nov 23, 2011 at 6:30 PM, Roger Littin <roger at rlmedia.co.nz> wrote:
>> Hi,
>> 
>> I think you need to set your application on the real servers to listen to the udp port on all ip's or at least the real ip and then it needs to respond to the client on the vip.
>> 
>> Roger.
>> 
>> On 23/11/2011, at 10:06 PM, wang yi wrote:
>> 
>>> Hi, all
>>>    I've set up LVS with DR mode for Apache, it worked OK. Then I set
>>> up another Virtual Service for an UDP based program on the same boxes,
>>> but it won't work.
>>> 
>>>   Running Wireshark on the director showed that it got the UDP
>>> packets from client, but responsed these packets with an ICMP message,
>>> Destination unreachable (Port unreachable)
>>> 
>>>   I cannot find any information about this. Anything special about
>>> UDP based program?
>>>   Regards.
>>> Leo
>>> 
>>> _______________________________________________
>>> Please read the documentation before posting - it's available at:
>>> http://www.linuxvirtualserver.org/
>>> 
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>> 
>> 
>> _______________________________________________
>> 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
>> 
> 
> _______________________________________________
> 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





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