CLOUDSTACK-2719: Additional public IP is getting acquired during Cisco VNMc provider Guest Network restart (cleanup=true)
An extra public ip is acquired while implementing the vnmc element as there is a limitation where in the source nat cannot be used as asa outside ip.
As a result of this when the network gets re-implemented an additional ip is acquired every time. The fix involves checking for existing public ips
in the network and reuse it in case it is not a source nat ip for assigning to asa outside interface.