How to prevent certain subnet from ISPA not goes to ISPB using an iRule

Hi folks,

 

I need to implement iRule in Link Controller.

 

Currently our customer have subnet x.x.x.x configured on ISP_A and y.y.y.y subnet on ISP_B. Link controller has translated all the traffic went to internet based on round robin mechanism inside the default_gateway_pool configuration. This become problem when ISP_A only allows x.x.x.x to relaying their mail server and ISP_B allowed subnet y.y.y.y. This particular smtp traffic must be managed with proper isp links. It would be great if you have an idea in iRule for how to prevent/ discard the smtp traffic from subnet x.x.x.x goes to ISP_B's smtp server or vice versa.:P

 

 

Cheers,

 

foot|oose