Which of the following is NOT a disadvantage of the traditional congestion avoidance mechanism (tail drop)?

The traditional congestion avoidance mechanism known as tail drop indeed has several well-documented disadvantages. Global TCP synchronization refers to the phenomenon where multiple TCP connections, upon experiencing packet loss, simultaneously reduce their transmission rates and then ramp back up, leading to a cycle of congestion and under-utilization of the link. This synchronization can severely impact overall network performance.

High jitter and long delays are common outcomes of tail drop as well. When packets are simply dropped without any mechanism to manage the flow or prioritize traffic, the retransmissions can cause significant variations in delays, leading to an unpleasant experience for applications sensitive to timing, such as voice over IP and video streaming.

When it comes to the notion of cost, tail drop itself does not directly incur high operational costs. It primarily deals with how packets are managed in congestion scenarios without an inherent cost implication. The concept of packets being discarded without differentiating priority is indeed a significant disadvantage of tail drop, as it leads to treating all traffic the same regardless of its importance, further exacerbating issues for critical applications.

In summary, while tail drop has inherent problems like global TCP synchronization, high jitter, long delays, and a lack of prioritization in packet handling, it does not inherently involve high cost as a disadvantage.