802.11b Packet Formats
What is the basic structure of an 802.11b packet?
It consists of a MAC header, payload (data), and Frame Check Sequence (FCS) for error detection.
What fields are included in the 802.11b MAC header?
Frame Control, Duration/ID, Address fields, Sequence Control, and sometimes QoS control.
How many address fields can an 802.11b packet have?
Up to four address fields to support different types of networks like infrastructure and ad hoc.
What is the purpose of the Frame Control field?
It defines the frame type, subtype, protocol version, and control flags like retry and power management.
What types of frames exist in 802.11b packet formats?
Management frames, control frames, and data frames.
What is the Duration/ID field used for?
It indicates the time the channel will be reserved or carries the association ID in power save mode.
What does the Sequence Control field do?
It helps in ordering packets and detecting duplicates by providing sequence numbers and fragment numbers.
What kind of control frames are defined in 802.11b?
ACK, RTS (Request to Send), CTS (Clear to Send), and PS-Poll frames.
How is fragmentation handled in 802.11b packets?
Large packets can be split into fragments, each with its own header and sequence number.
What is the role of the Frame Check Sequence (FCS)?
It provides error detection using a cyclic redundancy check (CRC).
Are there differences between management and data frame formats?
Yes, management frames have specific subfields for network control, while data frames focus on payload transmission.
How do QoS features affect 802.11b packet formats?
Basic 802.11b does not support QoS; later amendments like 802.11e add QoS control fields.
How are multicast and broadcast addressed in packet formats?
They use special MAC address values and are indicated in the Frame Control field.
What is the maximum payload size in 802.11b packets?
The maximum MSDU size is typically 2304 bytes before fragmentation.
How does the Address 4 field work in 802.11b packets?
It is used in Wireless Distribution System (WDS) or mesh networks to support four-address frames.
Are the packet formats compatible with other 802.11 standards?
Yes, 802.11b uses similar MAC frame formats as 802.11a/g with some PHY differences.
What role does the Sequence Control play in retransmissions?
It helps identify duplicate frames to avoid processing retransmitted packets multiple times.
How is frame aggregation handled in 802.11b?
Frame aggregation is not supported in basic 802.11b; it is introduced in later standards like 802.11n.
What ensures interoperability in packet formats?
Strict adherence to IEEE 802.11 MAC frame format specifications enables devices from different vendors to communicate.
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