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Forum Discussion

aquispe17_31055's avatar
aquispe17_31055
Icon for Nimbostratus rankNimbostratus
May 20, 2018

iRule to forward traffic based in state pool member

Hi eveyone, I have my F5 connected with 3 Internet Service Provider. I have a pool with 3 pool members: Router Provider A, Router Provider B and Router Provider C. I have an irule to take decision ab...
application delivery
BIG-IP
big-ip ltm
iRules
Simon_Blakely's avatar
Simon_Blakely
Icon for Employee rankEmployee
May 20, 2018

So you have a gateway pool, with gateway_icmp monitors (maybe with a transparent monitor).

You need to select the appropriate SNAT IP address based on the selected outgoing router.

I would apply priority group settings so that you have a preferred router (10.0.0.1) and fallback routers (10.0.0.2, 10.0.0.3).

Then use an irule similar to the following: 
    when CLIENT_ACCEPTED {
      if {[LB::status pool default_gateway_pool member 10.0.0.1 0] eq "up"}
         Preferred router 10.0.0.1 up, so use correct SNAT
        { snat 10.1.0.1 }
      elseif {[LB::status pool default_gateway_pool member 10.0.0.2 0] eq "up"}
         Preferred Router not up, Fallback1 router 10.0.02 up, 
        { snat 10.2.0.1 }
      elseif {[LB::status pool default_gateway_pool member 10.0.0.3 0] eq "up"}
         Preferred router, Fallback1 router not up,
        { snat 10.3.0.1 }
      }

I hope this helps.