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.