[lvs-users] One realserver must connect to services to other realservers (routing problem).

Markus Hofer hofmarkus at gmail.com
Fri Aug 26 10:58:40 BST 2011

Hello Léon,

>>/  REALSERVER (A)            REALSERVER (B)/
>/>  (            (

Yes i have made a typo. Correct is:

          Loadbalancer (LVS) (IP
         ^                              |
         |                              |
         |                              |
         |                              |
         |                              V

(            (

>You probably made a typo here since they both have the same RIP. Anyway,
>in LVS-NAT you indeed set the default gateway to the VIP of the
>director. On a /24 network you would set it to 192.168.0.x

>/>  The problem is, that realserver B see that the question for the service/
>/>  comes from the network and then goes/
>/>  directly to A, but couldn't work out the answer, because realserver A/
>/>  ask and not

>That's odd. Why would rs A 'ask' 200.15? Why not simply connect to rs B?
>In that case the SRC IP would be the RIP from rs A.

>Or maybe i'm misunderstanding your question and you actually want to
>connect from rs A to VIP:service, which then redirects it to a rs?

The problem is that we have a lot of different services and DNS-Names
in our REALSERVERs. We have more than 10 Realservers and more than 50 different
DNS-Names (VIP:service) (with different VIP-IPs) on that.

For example:
Realserver A must go to meteo.example.com ( (VIP: service), which then redirects it
to the realserver B, but i do not receive on realserver A answer from realserver B.
I go from outside the realserver-range it isn't a problem.
Alredey my trick is to insert a different DNS entry in the hostfile of realserver A for meteo.example.com (
and then i haven't problems.
My problem is that for me isn't easy to insert for all our services on every realserver hostfile a diffent DNS-entry.
Exist not some ohter way to work around for this problem, like

If the realserver go outside for services i have insert a SNAT on
Insert PREROUTING something??

Thanks in advance!


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