In An 802.11 Data Frame, What Is The Size Of The Frame Check Sequence Field?

In An 802.11 Data Frame, What Is The Size Of The Frame Check Sequence Field?

In an 802.11 data frame, the size of the frame check sequence field is 6 bytes. Today, let us discuss the 802.11 data frame in detail. The below figure represents the 802.11 data frame. If we observe the data frame, we can see that it has frame control, duration, address 1, 2, and 3 sequential, address 4, and then the checksum. As we can see below, the frame control has some of the subfields that include the version, its type, its subtype, to the destination address, from the destination address, MF, retry power, more, W and O.

Here we can see that all the 802.11 data frames are represented in the form of bytes and all its subfields are represented in the form of bits. Now, let us discuss each of these in detail.

The first field is frame control, the frame control is the size of two bytes that contains 11 subfields. This field will have all the control information of the frame. All this control information is present in its subfields.

• The first subfield is version, this version is the protocol subfield which is set to zero. It contains all the future versions of the 802.11 data frame that can operate simultaneously.
• Another subfield is a type which is of size 2 bits, this field mainly specifies the type of frame it is storing in it.
• Following the type filed, we have a sub-type which is of 4 bits. this field says whether the field is requested to send or it is clear to send. Initially, the value will be set to zero.
• To DS represents whether the frame is going to the access point and from ds represents whether the frame is going away from the access point.
• The other filed is more fragments, when we set its value to 1 then that indicates more to follow.
• Another one is retried, the retry is nothing but the retransmission of the previous frame.

The last field in the 802.11 data frame is the frame check sequence, which can identify error detection, we add the extra error detection code to the frame in a communication protocol. These frames are normally used to send the upper layer of the data and finally the application data from the source to the destination address. The detection doesn’t say any error recovery.

The Ethernet will say to discard the frame if any damage has occurred but it doesn’t specify any action to retransmit the frame. The frame check sequence will identify the errors that come from the various sources. Based on the data that is present in the frame, the frame check sequence will calculate the source node. After it reaches the destination address, the destination address will recalculate and compares with the previously calculated value before it started sending.

After we compare the two frames, if the value is not equal then it is considered as an error and if they are equal then we can say that no errors or corruption occurred in the data frame.