[lvs-users] LVS Clarification

Subramanian, ChithiraiVadivu (IE10) ChithiraiVadivu.Subramanian at honeywell.com
Thu Jul 23 10:10:59 BST 2009


Hi,

 

Having one clarification in LVS-NAT. Can we connect to VIP from Real
Server which is routed to the same real server?

 

Configuration: 
Load Balancer has 2 NICs one is connected to external network (VIP) and
the other to the internal network to which Real Server 1 & 2 is
connected. 
The gateway for Real server 1 and 2 are configured to be the Load
Balancer's internal network. 
 
Virtual Service Configuration: 
LoadBalancer VIP:80 rr    Weight 
RealServer1  RS1:80         1 
RealServer2  RS2:80         1 
 
The internal routing in RealServer is removed and  
 
netstat -r shows  
 
link-local      *               255.255.0.0     U         0 0          0
eth0 
default         director        0.0.0.0         UG        0 0          0
eth0 
 
 
Testing scenario: 
 
When external client is accessing VIP:80 it works perfectly. First it is
routed to RS1 and then to RS2 and again to RS1 .... 
 
>From RS1 - 
      Trying to access http://VIP:80 and tcpdump is used for debugging 
      1. When VIP routes the call to RS2:80, RS1 is getting ack and
works fine. 
      2. When VIP routes the call to RS1:80 no ack signal is received
and keeps sending the request. 
     tcpdump in LoadBalancer at this stage: 
            RS1->VIP  
            RS1->RS1 
            RS1->VIP 
            RS1->RS1 
         and this goes on... 
          
Is anything needs to be done apart from these setup?       

 

Thanks & Regards,

Chithra.S

 

 




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