Dell C9010 Modular Chassis Switch EMC Networking Command-Line Reference Guide - Page 565

Example: Headroom Cells following informational message is displayed on the console:%Info: Data for instance id id is not available. For example, if you configured 5 as the maximum instances with linear periodicity and a polling interval of 10 seconds, 1 as the multiplier, then 5 instances will be polled at 10, 20, 30, 40, and 50 seconds incrementally. If you attempt to enter the show command to display the fifth instance after 30 seconds of enabling polling, the aforementioned information message is shown. If specified instance ID is higher than the size of the maximum number of snapshot instances configured, the following error message is displayed on the console:%Error: Instance Id is not valid. Configured max snapshot instances are If you configured the maximum number of instances as 5 and attempt to view the buffer statistics tracking details for the instance ID of 6, the aforementioned error is shown. In the following example, the Headroom Cells field indicates the amount of shared buffer area that is allocated to store packets that are received after the pause frame is received or a priority-based flow control pause frame is enabled. When an inbound interface halts the sending of traffic, it must have the buffer space to save all of the packets currently in the buffer, and also all of the packets that were received before the device stops the sending of packets. Headroom space is used for high-priority traffic that needs to be queued and preserved above the input queue limit, such as keepalives and hello messages. You can use the sample command output to obtain a consolidated, whole-scale set of statistical counters of buffer resource utilization in the system and identify the ports that you want. All resources will be cleared after their values are displayed. Dell#show hardware stack-unit 0 buffer-stats-snapshot unit 0 resource all Stack-unit: 0 unit: 0 port: 1 (interface Fo 0/0) PG# SHARED CELLS HEADROOM CELLS 0 0 0 1 0 0 2 0 0 3 0 0 4 0 0 5 0 0 6 0 0 7 0 0 Q# TYPE Q# TOTAL BUFFERED CELLS UCAST 0 0 UCAST 1 0 UCAST 2 0 UCAST 3 0 UCAST 4 0 UCAST 5 0 UCAST 6 0 UCAST 7 0 UCAST 8 0 UCAST 9 0 UCAST 10 0 UCAST 11 1 MCAST 0 0 MCAST 1 0 MCAST 2 0 MCAST 3 0 MCAST 4 0 MCAST 5 0 MCAST 6 0 MCAST 7 0 MCAST 8 0 Stack-unit: 0 unit: 0 port: 5 (interface Fo 0/4) PG# SHARED CELLS HEADROOM CELLS Data Center Bridging (DCB) 565