A bit array that contains the value of the
front panel transmit traffic LEDs (for POS Module Only). This is a packed bit string; 
each LED is encoded into 1 bit for each switch
port.  The maximum number of ports in one chassis 
is 24 that means 24 Ports Transmit Traffic LEDs. The expansion port 
number always begins from the last main port number.  
The following shows the meaning of each bit for each 
switch port:

  bit value  meaning
  --------   ---------  
         0         off (no transmit traffic)
         1         on  (transmit traffic)

The bitmap of LEDs are as following: 

                 (Port1)            (Port4)                    (Port8)
Bit      (Bit0)             (Bit3)                      (Bit7)
Byte 1:  LED1   LED2   LED3  LED4   LED5   LED6   LED7   LED8    
Byte 2:  LED9   LED10  LED11 LED12  LED13  LED14  LED15  LED16     
Byte 3:  LED17  LED18  LED19 LED20  LED21  LED22  LED23  LED24
(It was obsoleted after release 07100, replaced by snAgentBrdTxTrafficLedString)