irules with internal and external IP address pools

What is being considered is having an external pool, pool-3 which would contain the server IP's for the

 

web site as hosted in the new datacenter (dcb), but the NOC for (dca) has balked, claiming that redirecting

 

traffic to an external pool cannot be done in our current configuration.if there is routing, i do not understand why it cannot be done. didn't they give you more explanation??