This MIB is intended to be implemented on all those devices operating as Central controllers, that terminate the Light Weight Access Point Protocol tunnel from Cisco Light-weight LWAPP Access Points. This MIB provides the information about the operational parameters of the 802.11 networks. References about specific type of 802.11 flavors like 802.11a/b/g or 802.11n will be made whereever required to indicate that the respective parameters are applicable only to that particular type of 802.11 networks. The relationship between CC and the LWAPP APs can be depicted as follows: +......+ +......+ +......+ + + + + + + + CC + + CC + + CC + + + + + + + +......+ +......+ +......+ .. . . .. . . . . . . . . . . . . . . . . . . +......+ +......+ +......+ +......+ + + + + + + + + + AP + + AP + + AP + + AP + + + + + + + + + +......+ +......+ +......+ +......+ . . . . . . . . . . . . . . . . . . . +......+ +......+ +......+ +......+ + + + + + + + + + MN + + MN + + MN + + MN + + + + + + + + + +......+ +......+ +......+ +......+ The LWAPP tunnel exists between the controller and the APs. The MNs communicate with the APs through the protocol defined by the 802.11 standard. LWAPP APs, upon bootup, discover and join one of the controllers and the controller pushes the configuration, that includes the WLAN parameters, to the LWAPP APs. The APs then encapsulate all the 802.11 frames from wireless clients inside LWAPP frames and forward the LWAPP frames to the controller. GLOSSARY Access Point ( AP ) An entity that contains an 802.11 medium access control ( MAC ) and physical layer ( PHY ) interface and provides access to the distribution services via the wireless medium for associated clients. LWAPP APs encapsulate all the 802.11 frames in LWAPP frames and sends them to the controller to which it is logically connected. Gratuitous Probe Response (GPR) The Gratuitous Probe Response feature aids in conserving battery power of WLAN-enabled cell phones by providing a high rate packet on the order of tens of milliseconds such that these kind of phones can wake up and wait at predefined intervals, to reduce battery power. The GPR packet is transmitted from the AP at a predefined time interval. Light Weight Access Point Protocol ( LWAPP ) This is a generic protocol that defines the communication between the Access Points and the Central Controller. Mobile Node ( MN ) A roaming 802.11 wireless device in a wireless network associated with an access point. Mobile Node and client are used interchangeably. TU A measurement of time in units of 1024 microseconds. 802.11n 802.11n builds upon previous 802.11 standards by adding MIMO (multiple-input multiple-output). MIMO uses multiple transmitter and receiver antennas to allow for increased data throughput through spatial multiplexing and increased range . A-MPDU An aggregated format that consists of several MAC Protocol Data Units being aggregated and transmitted in one PHY Service Data Unit. A-MSDU An aggregated format that consists of several MAC Service Data Units being aggregated and transmitted in one MAC Protocol Data Unit. Reduced Inter-Frame Space ( RIFS ) A time interval between multiple transmissions of a single transmitter used to reduce overhead and increase network efficiency. Modulation and Coding Scheme ( MCS ) This is a value that determines the modulation, coding and number of spatial channels. Each scheme specifies the modulation technique, coding rate , number of spatial streams etc and the corresponding data rate. Guard Interval Guard intervals are used to ensure that distinct transmissions do not interfere with one another. The purpose of the guard interval is to introduce immunity to propagation delays, echoes and reflections, to which digital data is normally very sensitive. Media Access Control ( MAC ) The Media Access Control Layer is one of two sublayers that make up the Data Link Layer. The MAC layer is responsible for moving data packets to and from one Network Interface Card (NIC) to another across a shared channel. Suppression Table When the Band Select feature is ON, AP suppresses the probe response to mobile stations on 2.4 GHz. AP suppresses probe response to new mobile stattions for all SSIDs that are being Band Select enabled. Suppressed mobile station and corresponding suprression counts are recorded in a table known as Suppression Table which is stored in internal database of controller. Entries of this table aged-out to make place for new entries. Dual Band Table When AP sees probe request from any mobile station in both 2.4GHz and 5GHz band AP will know that mobile station is capable of operating on both band. Dual band capable mobile stations are recorded in a table known as dual band table which is stored in internal database of controller. This record are kept to make sure 5GHz capable mobile station should join 5GHz band only. Entries in the table will be age out to make space for new entries. The AP will not respond to the dual band mobile station's 2.4GHz probe until is removed from the dual band table. AP fills the dual band table in the following order until it is full: 1) mobile station with 5GHz probe that have associated to 2.4GHz. 2) mobile station with 5GHz probe that also have 2.4GHz probes. 3) mobile station with just 5GHz probe detected and 5GHz association. RSSI Received Signal Strength Indication (RSSI), the IEEE 802.11 standard defines a mechanism by which RF energy is to be measured by the circuitry on a wireless NIC. Its value is measured in dBm and ranges from -128 to 0. REFERENCE [1] Wireless LAN Medium Access Control ( MAC ) and Physical Layer ( PHY ) Specifications. [2] Draft-obara-Capwap-lwapp-00.txt, IETF Light Weight Access Point Protocol. [3] Enhanced Wireless Consortium MAC Specification, v1.24. [4] Enhanced Wireless Consortium PHY Specification, v1.27.