/**
 * display a mac address in hex format: e.g. 00-60-6E-70-0D-A2
 * @param 48-bit physical Ethernet Mac Address
 * @return string hex format dash-separated
 */
public static String macToString ( long mac )
   {
   StringBuffer sb = new StringBuffer( 17 );
   for ( int i=44; i>=0; i-=4 )
      {
      int nibble =  ((int)( mac >>> i )) & 0xf;
      char nibbleChar = (char)( nibble > 9 ? nibble + ('A'-10) : nibble + '0' );
      sb.append( nibbleChar );
      if ( (i & 0x7) == 0 && i != 0 )
         {
         sb.append( '-' );
         }
      }
   return sb.toString();
   }