Asymmetry in link capacity

A key feature of some access network technologies is the asymmetry between the capacities of the "uplink" (from terminal to network) and "downlink" (from network to terminal) paths; ADSL is the most common example. In general, these types of access networks assume that the network's customers are primarily "consumers" of information, in which case it's reasonable to allocate more capacity to the downstream path.

In this context of asymmetry, TCP performance degrades in terms of available capacity utilization, compared with a "symmetrical" network –, i.e. with the same transmission capacity in both paths of the access link –. This degradation is a consequence of congestion problems on the...