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funkdaddy_31014's avatar
funkdaddy_31014
Icon for Nimbostratus rankNimbostratus
Mar 15, 2012

Internal VIP with pool members on same internal network

This is a pretty basic question, but I couldn't find the answer in the docs anywhere.

 

 

Thusfar, we only use our LTM with VIPs configured on the External network and pool members on the Internal network. Can you configure a VIP on the Big-IP's Internal network, and load balance across a pool of servers on the same network?

 

 

I've got a couple servers on my 10.2.x network and I'd like to create a VIP on this same network that load balances across these members.

 

 

Is there any restriction from the VIP's IP being on the same network as the pool members?

 

 

Is there any special configuration for this, or does the LTM just know to use the Internal VLAN because of the IP specified?

 

 

Is there any downside to this?

 

 

Thanks!

 

-Funkdaddy

 

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  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Mar 15, 2012
    Can you configure a VIP on the Big-IP's Internal network, and load balance across a pool of servers on the same network?yes

     

     

    Is there any special configuration for this? you have to configure snat, e.g. snat automap under virtual server setting, to enforce return traffic coming back to bigip. otherwise, return traffic from pool member will directly go to client which is in the same subnet.
  • Sly_85819's avatar
    Sly_85819
    Icon for Nimbostratus rankNimbostratus
    Mar 20, 2012
    You can use SNAT (automap or pool) to make it work. Basically you need a way so that server send the request back to the LTM. With SNAT, the server sees request coming from LTM and sends the response back to LTM. If this VS is going to have heavy traffic or if you multiple VS using SNAT then I would suggest using SNAT POOL. Basically SNAT automap, NAT's client to the exit interface IP address. You can reach the ephemeral ports limit with heavy traffic (I had seen this DNS flood). With SNAT pool, you define pool of IP's which are specifically used for NAT. You have to also consider the idle time values for SNAT.