extremeWirelessClientAssocInfoRateIE 1.3.6.1.4.1.1916.1.25.1.34.1.9

This is the value of the rate IE carried in the last ASSOC REQ packet if this wireless interface is configured to keep IEs. If it's not, this will be NULL. The IE is encoded as a series of bytes exactly as the value portion of the IE in the PDU.