def max_prefix_get
      str = config_get('bgp_neighbor_af', 'max_prefix', @get_args)
      return nil if str.nil?

      regexp = Regexp.new('maximum-prefix (?<limit>\d+)' \
                          ' *(?<threshold>\d+)?' \
                          ' *(?<opt>restart|warning-only)?' \
                          ' *(?<interval>\d+)?')
      regexp.match(str)
    end
def max_prefix_get
      str = config_get('bgp_neighbor_af', 'max_prefix', @get_args)
      return nil if str.nil?

      regexp = Regexp.new('maximum-prefix (?<limit>\d+)' \
                          ' *(?<threshold>\d+)?' \
                          ' *(?<opt>restart|warning-only)?' \
                          ' *(?<interval>\d+)?')
      regexp.match(str)
    end
-----------------------
 <state> maximum-prefix <limit> <threshold> <opt>

 <threshold> : optional
 <opt> : optional = [ restart <interval> | warning-only ]