It is necessary for Tier 1 schedulers to obtain bandwidth from a higher tier scheduler.

The statement is false. In the Nokia Service Router Operating System (SR OS) Hierarchical Quality of Service (HQoS) model, Tier 1 schedulers are at the top of the hierarchy. They are typically associated with a physical port and are responsible for managing the total bandwidth available on that port. They allocate bandwidth down to lower-tier schedulers (Tier 2 and Tier 3), but they do not obtain bandwidth from a "higher tier" because no tier exists above them. The Tier 1 scheduler is the root of the scheduling hierarchy for a given port.

The "True" option is incorrect because it fundamentally misunderstands the hierarchical structure of the Nokia QoS model. The flow of bandwidth allocation is from the top down. A Tier 1 scheduler is the source of bandwidth for the tiers below it, not a recipient from a non-existent higher tier.

1. Nokia 7750 SR OS, 7450 ESS, and 7950 XRS Quality of Service Guide, Release 21.10.R1, Document Part Number: 3HE 17275 AAAD TQZZA, Section: Scheduler Policies.

Page 131, "Scheduler Policies Overview": This section describes the three-tiered scheduling hierarchy. It states, "Tier 1 schedulers are also known as the port schedulers. The port scheduler is created when a scheduler policy is applied to a port." This establishes the Tier 1 scheduler at the port level, the highest point of the hierarchy for that interface.

2. Nokia 7750 SR OS, 7450 ESS, and 7950 XRS Quality of Service Guide, Release 21.10.R1, Document Part Number: 3HE 17275 AAAD TQZZA, Section: Hierarchical Scheduling.

Page 132, Figure 23 "Scheduler Policy Hierarchy": The diagram in this section visually confirms the hierarchy, showing the "Port Scheduler (Tier 1)" at the very top, with arrows indicating bandwidth allocation flowing downwards to Tier 2 and subsequently to Tier 3 schedulers and their associated queues. There is no entity depicted above the Tier 1 scheduler from which it would draw bandwidth.