Wi-Fi’s Secret Packet Loss Revealed

A new Veriwave test debunked notions that wireless standards — 802.11a, 802.11b and 802.11g — have zero error in data transmission. It found an “unavoidable packet loss” due to the fundamental transmission protocol used in wireless networks.

The 802.11 standards supposedly have “foolproof” mechanisms that allow for detection of corrupt data and retransmission. The test demonstrated that such system is much weaker than previously thought. Because each packet only has a single bit parity check, a receiving station may be vulnerable to mistaking the size and speed of an incoming packet and be blinded for “milliseconds” in case it detects a longer data stream than what was actually transmitted. As it fails to obtain any acknowledgment of the packet, the sending station would then retransmit it but would eventually cancel this action and drop the packet because the receiving station has stopped waiting for the mistaken longer stream.

According to Tom Alexander of Veriwave, the error is “extremely small, around .001 percent.” Still, the loss is “never zero” and “that’s not what the protocol says.” Aruba architect Partha Narasimhan believes the problem could become very evident in voice applications. Veriwave noted the same issue in a secure hand-off using EAP and could prompt a system reset and a 30-second break.
Via [techworld.com]

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