'get_existing'

def get_existing(self):

    if self.intf_info:
        self.existing['interface'] = self.intf_info['ifName']
        self.existing['mtu'] = self.intf_info['ifMtu']
    if self.intf_info:
        if (not self.existing['interface']):
            self.existing['interface'] = self.interface
        if (len(self.jbf_config) != 2):
            return
        self.existing['jumboframe'] = ('jumboframe    enable    %s    %s' % (self.jbf_config[0], self.jbf_config[1]))
