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CWNP Certified Wireless Network Administrator CWNA-109 · Domain 3: WLAN protocols and devices

Interframe spaces (SIFS, DIFS, AIFS), random backoff and contention windows

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Last reviewed September 25, 2026 · Leer en español

CSMA/CA does not let a station transmit the instant the medium goes quiet. Instead, stations wait for a defined interframe space (IFS) and then a random backoff. The length of each wait sets priority: frames that wait less get the medium first. Knowing the IFS types and how backoff works explains both QoS and why busy channels slow down.

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