Which action should be taken to ensure that packets do not use the shared buffer space when put into a queue?

In Nokia's SR OS, the Maximum Burst Size (MBS) defines the total buffer space a queue can occupy, while the Committed Burst Size (CBS) defines the portion of that space that is reserved exclusively for the queue. The buffer space between the CBS and MBS values (MBS - CBS) is drawn from a shared buffer pool common to other queues. To ensure a queue uses only its reserved (committed) buffer space and does not draw from the shared pool, its maximum allowable burst (MBS) must be configured to be equal to its committed burst (CBS). This effectively sets the allowable shared buffer portion to zero.

A. Set the queue’s CBS to 0: This removes any reserved buffer space, forcing the queue to rely entirely on the shared buffer pool, which is the opposite of the desired outcome.

C. Set the queue’s high-priority-only equal to the MBS: The high-priority-only parameter reserves a portion of the shared buffer space for high-priority packets; it does not prevent the queue from using the shared space.

D. Set the queue’s MBS to 0: This would prevent the queue from buffering any packets at all (as CBS cannot exceed MBS), effectively disabling it rather than just restricting its buffer source.

E. Set the queue’s high-priority-only to 0: This removes the reservation for high-priority packets within the shared buffer but does not stop the queue from using the shared buffer for all packet types.

1. Nokia 7750 SR OS, Quality of Service Guide, Release 21.10.R1: In the "Queue Buffer Management" section, it is detailed that "The portion of the MBS above the CBS is drawn from the shared buffer pool... To configure a queue to not use the shared buffer pool, the MBS for the queue must be configured to be equal to the CBS for the queue." (Reference based on typical content structure in QoS guides for SR OS).

2. Nokia SRC-PE Courseware (Quality of Service Module): University-level and official training materials for the Nokia Service Routing Architect (SRA) certification path explain this principle. The module on "Queueing and Scheduling" explicitly states that the difference between MBS and CBS represents the queue's access to the shared buffer pool. Setting MBS = CBS is the standard method to isolate a queue from the shared buffer. (Reference to concepts taught in official Nokia training programs like the one leading to the 4A0-107 exam).