[lvs-users] How does the director server connect with eah real server ?

Horst Venzke-Fa Remsnet Ltd support at remsnet.de
Wed Jan 1 15:44:32 GMT 2014


Dear  Hatt Tom,

see http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/LVS-HOWTO.LVS-DR.html
docu sample for keepalived as LB : www.keepalived.org/pdf/UserGuide.pdf‎
docu sample for ldirectord as LB : http://www.tomvernon.co.uk/blog/2012/03/load-balanced-linux-web-cluster/

For real Productive Internet Services i wuold suggeest  don´t  use rfc1912 addresses at LVS-DR and realservers with LVS-DR.

see page : http://www.ultramonkey.org/papers/lvs_tutorial/html
Figure 2: LVS Direct Routing

In some words :

An Traffik-requestor ( end user with webbrowser i.e ) request to open i.e www.test.org at his PC
That page  have IP 217.145.96.131 as it sample ( VIP ) IP

The LB´s( 2 or more servers)  manage the Virtual IP(VIP ) , IPVS kernel table been managed by keepalived  or ldirectord .

Thus , the traffik that reach the VIP been redirected from the LB´s IPVS  to realserver using arp discover
( some allowed to correct my wording here .. :-) )
Real servers must be configured to accept traffic for the virtual server's IP address ( configured at lo:? , noarp usage at kernel)
Then the realserver directly answer to the traffik requestor.

see page : http://www.ultramonkey.org/papers/lvs_tutorial/html
Figure 2: LVS Direct Routing

There are more DR configuration variants  with i.e fwmark . 
Depends on your network setup ( i.e behind an filewall, NAT Router or others )

My own HOME Cluster setup are use rfc1912 , i am BEHIND an NAT Router have only one Public IPv4 but an dynamic class /48 IPV6  as well.
Sutch apply with  strange behavios ( i.e arp issues ) some times .


--
Mit freundlichen Grüßen / Best Regards

Horst Venzke ; PGP NET : 1024G/082F2E6D ;  http://www.remsnet.de

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> Gesendet: Mittwoch, 01. Januar 2014 um 15:30 Uhr
> Von: "Hatt Tom" <net.study.sea at gmail.com>
> An: "LinuxVirtualServer.org users mailing list." <lvs-users at linuxvirtualserver.org>
> Betreff: Re: [lvs-users] How does the director server connect with eah real server ?
>
> thanks for reply !
> 
> Actually I meaned the DR mode , The document says that the Load
> balancer will transfer user's packets to realserver ,
> then realserver will reply directly to user   after processing the packets .
> 
> my question is how does the real server reply directly to users ?
> does real server have public ip ?
> 
> 
> 
> 
> 
> 
> 
> 2014/1/1 Horst Venzke-Fa Remsnet Ltd <support at remsnet.de>:
> > Hello Hatt Tom,
> >
> > That depends on what LVS Mode you use.
> >
> > at LVS DR , the LVS Director (  aka "LB") the LB and realservers are allmost the same network .
> > default Route of realservers  to network´s default route
> >
> > at LVS NAT , the LVS Director (  aka "LB") realservers are not at the same network ,
> > LB are in Front of the Realservers.
> > default Route of realservers  to LB ´s NAT network.
> >
> > see http://www.austintek.com/LVS/LVS-HOWTO/HOWTO/
> >
> >
> > --
> > Mit freundlichen Grüßen / Best Regards
> >
> > Horst Venzke ; PGP NET : 1024G/082F2E6D ;  http://www.remsnet.de
> >
> > Legal Notice: This transmittal and/or attachments may be privileged or confidential. It is intended solely for the addressee named above. Any review, dissemination, or copying is strictly prohibited. If you received this transmittal in error, please notify us immediately by reply and immediately delete this message and all its attachments. Thank you.
> >
> >
> >> Gesendet: Mittwoch, 01. Januar 2014 um 14:45 Uhr
> >> Von: "Hatt Tom" <net.study.sea at gmail.com>
> >> An: "LinuxVirtualServer.org users mailing list." <lvs-users at linuxvirtualserver.org>
> >> Betreff: [lvs-users] How does the director server connect with eah real server ?
> >>
> >> Does director server and real server working in on LAN ?
> >> If so , could I consider the director server as on route of the LAN ?
> >> Does it has many network interfaces to connect with several real
> >> servers ?
> >>
> >>
> >>
> >> --
> >> Best Regards!
> >>
> >> _______________________________________________
> >> Please read the documentation before posting - it's available at:
> >> http://www.linuxvirtualserver.org/
> >>
> >> LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
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> >> 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
> 
> 
> 
> -- 
> Best Regards!
> 
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
> 
> LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
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