Final answer:
A control law based on additive increases and decreases may not be effective for bandwidth allocation as it does not account for non-linear relationships, network dynamics, and may lead to slow adjustment to congestion, potentially causing under-utilization or over-utilization of network resources.
Step-by-step explanation:
A control law based on additive increases and additive decreases might not be effective for bandwidth allocation due to several potential issues. Additive changes assume a linear relationship between the allocation and its effects, which may not hold in complex network environments where the relationship could be non-linear. If the bandwidth allocation to a flow increases additively in response to low congestion, it may be too slow to fully utilize available bandwidth, especially for high-capacity links. Conversely, if the allocation decreases additively when congestion is detected, it could lead to under-utilization of the network resources during transient congestion events.
Furthermore, the network dynamics such as the round-trip time and the level of multiplexing among flows are not considered in the simplistic approach of additive changes. This could result in inefficient allocations that do not adequately respond to the varying conditions and demands of the network traffic over time. An intelligent bandwidth allocation scheme should be dynamic and responsive, also considering the bandwidth-delay product and differentiating between transient and persistent congestion levels.