Re: [lvs-users] Mysterious documentation - what if the real servers are

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Mysterious documentation - what if the real servers are Windows? I know I can add a loopback device to them too. Any how-toos you would recommend?
From: Don Steiny <steiny@xxxxxxxxxxxxx>
Date: Wed, 20 May 2009 09:15:39 -0700
Thanks so much.  The realservers are on both a private and public net.  
Should I use their public IPs?  I guess I will have to with DR because 
DR sends the stuff right back to them, correct?   Also the realservers 
are Windows 2003.  I know I can add a loopback device to them.  Are 
there any good how tos about doing this?

> Hi,
> On Wed, 2009-05-20 at 06:53 -0700, Don Steiny wrote:
>> I am doing DR and the ARP problem makes sense.   The part I still don't 
>> understand is "I need a public and private VIP."  The ISP I am using has 
>> assigned me some IP addresses.  I know how to use ifconfig to put 
>> multiple addresses on an interface, that is no big deal, but what I 
>> can't figure out is how to decide what IP address to use for the VIP. 
> Pick any public IP you have that's not being used for anything yet. You
> say you have multiple IP addresses assigned to you by your ISP so that's
> great. Use one for the IP that isn't already used. 
>>  I 
>> have looked up VIP and found many explanations, including ones that tie 
>> it to lo, ones that say that it does not need to be tied to an interface 
>> (and I don't know how to do that).  Unless it is one of the ones my ISP 
>> lets me use, then no one can get to me from the outside.  I need to both 
>> configure the machine and use it from outside the data center.  I have 
>> an IP address that I go into with ssh.  If that is my RIP, then what 
>> address should my VIP be?  Should I request an address from my ISP that 
>> I can use for the VIP and configure it on eth0?  Do I get an address 
>> from the ISP and have them configure the router so people can get to it? 
> Since you're going to use DR, you'll need to configure a loopback device
> on your realservers (provided you're using a fairly recent kernel - see
> the HOWTO for other solutions if this is not the case) that has the VIP
> (the public yes, you're not using anything else on the director)
> configured with a netmask of /32 and solve the arp problem (again look
> in the HOWTO for methods per kernel) if they are running Linux.
> This way the packets destined for the VIP get handled by the director
> and sent to one of the realservers configured in the LVS table. The
> realserver gets the Link Layer packet, sees its destination (the VIP),
> recognizes that it has that ip configured (the loopback device), handles
> the request (eg. a http request) and sends the reply back to the
> src_addr (the client).

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