This feature enables adding of guest ip ranges (public ips) form different subnets.
In order to provide the dhcp service to a different subnet we create an ipalias on the router. This allows the router to listen to the dhcp request from the guest vms and respond accordingly. Every time a vm is deployed in the new subnet we configure an ip alias on the router. Cloudstack uses dnsmasq to provide dhcp service. We need to configure the dnsmasq to issue ips on the new subnets. Added a new class dnsmasqconfigurator which generates the dnsmasq confg file, this file replaces the old config in the router.
The details of the alias ips are stored in db in the nic_ip_alias table. Every time a new subnet is added one of the ip from the subnet is used to configure the ip alias.
I have pushed the code to https://github.com/bvbharatk/cloud-stack/tree/Cloudstack-702 , also rebased the code with master.
I need to test the code for advanced sg enabled network using kvm.
I have added the unit test
Marvin tests are at https://git-wip-us.apache.org/repos/asf?p=cloudstack.git;h=53e4965
Also accomodated some of the changes suggested by koushik.
corrected the import statements. renamed the IpAlias command to createIpAlias command.
This feature supports only ipv4
