Assessing the real impact of 802.11 WLANs: a large-scale comparison of wired and wireless traffic

We compared the traffic from hosts connected to the network via a wired or wireless interface, emphasizing the impact of 802.11 on packet delay and loss. Our study uses only passive monitoring techniques, namely, inference from TCP header traces. This enabled us to study a population of several thousand hosts in a real production environment, in which more than 31 million TCP connections were made. Our first contribution is methodological. Passive methods always have some degree of uncertainty, and we overcome this limitation by mostly relying on relative differences between wired and wireless traffic. Our analysis revealed that wireless clients experienced substantially higher packet delay variability than wired clients but their loss rates are surprisingly similar. We found that both the number of unnecessary TCP retransmissions and, even more substantially, the number of interrupted connections are higher for the wireless LAN than for the wired LAN. To the best of our knowledge, this is the first research effort to directly contrast wired and wireless traffic of a large production network