'get existing info'

def get_existing(self):

    if self.vni2bd_info:
        self.existing['vni_to_bridge_domain'] = self.vni2bd_info['vni2BdInfos']
    if self.nve_info:
        self.existing['nve_interface_name'] = self.nve_info['ifName']
        self.existing['source_ip'] = self.nve_info['srcAddr']
        self.existing['nve_mode'] = self.nve_info['nveType']
        self.existing['vni_peer_list_ip'] = self.nve_info['vni_peer_ips']
        self.existing['vni_peer_list_protocol'] = self.nve_info['vni_peer_protocols']
