Forum Discussion

Christopher_Ach's avatar
Christopher_Ach
Icon for Nimbostratus rankNimbostratus
Dec 16, 2008

Can a Irule do this 0.0.0.0-->LB-->to one of 2 SNAT Pools

Hi

 

 

I have a incoming traffic stream that I want to SNAT.

 

I want to control the way I SNAT the traffic based on a defined ratio (60-40).

 

 

So I want to have 2 separate SNAT Pools with obviously different Subnets in each.

 

This needs to be a pure routing function on the LTM at Fast-L4

 

 

So im thinking a single VIP 0.0.0.0 and 2 SNAT pools.

 

Traffic is destined for the Internet and is random so I cant make a decision using the source or destination IPs. Also the outbound GW is the same for both SNAT pools, so the LTM has a default route to that GW.

 

 

Can an Irule do this?

 

 

All traffic in --> LB to one of two Snat Pools based on (traffic ratio or Least cons)

 

Any ideas?

 

 

Chris
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  • dennypayne's avatar
    dennypayne
    Icon for Employee rankEmployee
    Dec 16, 2008
    This sounds do-able, I'm not sure of the best way to do the ratio but certainly you can use the snatpool command based on a decision that is made in the iRule logic of when to use each one.

     

     

    My first thought is just a loop from 1 to 10 where the first 6 connections are sent to snatpool 1 and the rest to snatpool 2. Someone can probably think of a more efficient way to do that but here goes...

     

     

    pseudocode:

     

     

         
    when RULE_INIT {     
    set counter 0     
    }     
     when CLIENT_ACCEPTED {     
         if $counter < 6 {     
           snatpool pool-1     
         } else {     
           snatpool pool-2     
         }  
      increment $counter  (not sure of the best syntax here)      
        if $counter > 9 {     
         set counter 0     
        }     
     }

     

     

     

    Denny

     

     

    EDIT: edited the code a bit...
  • Christopher_Ach's avatar
    Christopher_Ach
    Icon for Nimbostratus rankNimbostratus
    Dec 17, 2008
    Hi Denny

     

     

    Thanks and yes this is somewhat on the lines of what im looking for, I thought perhaps we could have the use of the inbuilt algorithms like "round robin" or "least cons" but at this stage all I really need is a ratio and i guess this is a great start.

     

     

    Chris