Redundant pair and switch fault tolerance

i want add some questions to this diagram,

 

 

if i want connect bigip units cross to Cisco 6500; it means new topology would be like this;

 

 

 

bigip 1; vlanx (1.1 and 1.2); 1.1 connected cisco1 and 1.2 connected cisco2

 

bigip 2; vlanx (1.1 and 1.2); 1.1 connected cisco1 and 1.2 connected cisco2

 

 

and bigip1-2 directly connected

 

 

rstp enabled on cisco and cisco blocks 1.2 interfaces path

 

the problem is cisco guys traffic on 1.2 ports and its not working

 

it means, client ping vips traffic pass over 1.1 interface but responces goes over 1.2 (blocked on cisco interface)

 

 

how can i solve this problem?

 

 

regards

 

 

zafer