This section describes the fields in the show command outputs that help you monitor queue high water marks for different traffic classes and scenarios.
The table presents the common fields displayed in the show command output for queue high water marks.
Table 2.
Common Fields
| Field |
Description |
| Interval Start and End (periodic only) |
Displays the periodic collection interval number, and the start and end time of that interval. |
| TC_Number = (Number range is 0-7) |
Identifies the traffic class associated with the high water mark data. For periodic output, the field appears only for the traffic class’s first interval. |
The table describes queue occupancy fields in the show command output, including maximum occupancy values, delay, source port details, and timestamps.
These fields report the maximum queue occupancy values observed for a traffic class. Use them to determine how full the queue became and the conditions under which that peak occurred.
Table 3.
Queue Occupancy Fields
| Field |
Description |
| Max Occupancy % |
Displays the maximum queue occupancy for this traffic class as a percentage of the total queue size. Because of limited queue quantization thresholds provided by the NPU, this value is an estimate and may differ from the actual maximum occupancy. |
| Max Occupancy kilobytes |
Displays the maximum queue occupancy for this traffic class in kilobytes. The value is calculated assuming that all buffers are fully packed (for example, 384 bytes per Shared Memory System buffer). As a result, the displayed value may be higher than the actual number of kilobytes queued. |
| Queue Delay ns |
Displays the delay, in nanoseconds, when the maximum queue occupancy high water mark occurred. |
| Src Sys Port Slot/NPU/Slc/Gid |
Identifies the slot, NPU, slice, and global identifier (GID) of the virtual output queue where the queue occupancy high water mark occurred. The GID is the global identifier of the source system port whose packet was dequeued when the maximum occupancy was reached. In most cases, all ports on a slice share a virtual output queue. The identified source port may not be the only contributor; other ports sharing the same queue could also have contributed to the burst of packets.
Note
In fair-4 or fair-8 VOQ mode, each source port has its own virtual output queue. In Priority Flow Control (PFC) buffer-internal mode, a port may share a virtual output queue with other ports in the same interface group (IFG). Each slice has two IFGs.
Use the show controllers npu voq-usage command to verify which other ports share a virtual output queue with the identified source port. |
| Timestamp (monotonic only) |
Displays the timestamp when the maximum queue occupancy high water mark was recorded. The timestamp reflects when the NPU reported the data, not when the event occurred. Because the NPU is queried every 30 seconds, the timestamp shows the end of the 30-second window during which the high water mark occurred. For example, a timestamp of 16:56:44 indicates that the event occurred sometime between 16:56:14 and 16:56:44. |
The table describes the queue delay fields in the show command output, including maximum delay, occupancy details, source port identifiers, and timestamps.
These fields report the maximum queue delay experienced by a traffic class. Use them to understand the delay impact and the corresponding queue occupancy at the time of the peak delay.
Table 4.
Queue Occupancy Fields
| Field |
Description |
| Max Queue Delay ns |
Displays the maximum delay experienced by this traffic class, in nanoseconds. |
| Queue Occupancy % |
Displays the queue occupancy as a percentage of the total queue size when the maximum queue delay high water mark occurred. Because of limited queue quantization thresholds provided by the NPU, this value is an estimate and may differ from the actual maximum occupancy. |
| Queue Occupancy kilobytes |
Displays the queue occupancy in kilobytes at the time the maximum queue delay high water mark occurred. The value is calculated assuming all buffers are fully packed (for example, 384 bytes per Shared Memory System buffer). As a result, the displayed value may be higher than the actual number of kilobytes queued. |
| Src Sys Port Slot/NPU/Slc/Gid |
Identifies the slot, NPU, slice, and global identifier (GID) of the virtual output queue where the maximum queue delay high water mark occurred. The GID identifies the source system port whose packet was dequeued when the maximum delay was reached. In most cases, all ports on a slice share a virtual output queue. The identified source port may not be the only contributor; other ports sharing the same queue could also have contributed to the burst of packets.
Note
In fair-4 or fair-8 VOQ mode, each source port has its own virtual output queue. In Priority Flow Control buffer-internal mode, a port may share a virtual output queue with other ports in the same interface group (IFG). Each slice has two IFGs.
Use the show controllers npu voq-usage command to verify which other ports share a virtual output queue with the identified source port. |
| Timestamp (monotonic only) |
Displays the timestamp when the maximum delay high water mark was recorded. The timestamp reflects when the NPU reported the data, not when the event occurred. Because the NPU is queried every 30 seconds, the timestamp shows the end of the 30-second window during which the event occurred. For example, a timestamp of 16:56:44 indicates that the high water mark was observed sometime between 16:56:14 and 16:56:44. |