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Re: [lvs-users] Correct configuration for ARP on real servers.

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Correct configuration for ARP on real servers.
From: Jamie Dahl <jamied@xxxxxxxxxxxx>
Date: Tue, 18 Aug 2015 17:33:01 -0700
should that not be something like a sysctl setting?   i can post the real 
values laterbut i have always used sysctl to prevent linux from tripping over 
itself

this was pounded out on my iPhone and i have fat fingers plus  two left thumbs 
:)


> On Aug 18, 2015, at 10:54, israel@xxxxxxxx wrote:
> 
> 
> Hello,
> 
> I just configured an environment of two LVS servers with three real 
> servers, and it works fine ... in the same network. When we try to 
> access the web server through the virtual IP from another network, 
> suddenly it doesn't work, this noted in the fact that we can't access 
> the VIP, but it still works in the same network. But, if I shutdown one 
> of the servers, it works perfectly.
> 
> My configuration is Direct Routing. My doubt is in the ARP 
> configuration. I read on section 6.8 at 
> http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.arp_problem.html 
> that the following commands must be executed to properly configure 
> arptables on every real server:
> 
> # arptables -A IN -d $VIP -j DROP
> # arptables -A OUT -s $VIP -j mangle --mangle-ip-s $RIP
> 
> 
> But looking at RedHat documentation (I'm working with RHEL servers) 
> mentions on section 3.2.1 at 
> https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/4/html/Virtual_Server_Administration/s1-lvs-direct-VSA.html#s2-lvs-direct-arptables-VSA
>  
> that the configuration to use is:
> 
> arptables -A IN -d <virtual_ip> -j DROP
> arptables -A OUT -d <virtual_ip> -j mangle --mangle-ip-s <real_ip>
> 
> 
> So ... Austintek uses the VIP as a source on the OUT chain, but RedHat 
> uses it as a destiny. Can anyone tell me what is the right 
> configuration? And could it be the cause of my problem, not being able 
> to access my balancers with three real servers from outside the network? 
> Funny thing is, both configurations seem to work the same way, which one 
> is correct?
> 
> Thanks in advance.
> 
> Israel.
> 
> 
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