Setup Guide

Managing Hardware Buer Statistics
The memory management unit (MMU) is 12.2 MB in size. It contains approximately 60,000 cells, each of which is 208 bytes in size. MMU
also has another portion of 3 MB allocated to it. The entire MMU space is shared across a maximum of 104 logical ports to support the
egress admission-control functionality to implement scheduling and shaping on per-port and per-queue levels. Also, the MMU buer cells
can be used by each port or queue either as a static partition or as a dynamic partition. With dynamic mode, you can specify the
percentage of available buer that is utilized by a queue. This dynamic partition or block is set to be two-thirds of the available buers for
all unicast queues and one-fth of the available buers for all multicast queues on these platforms.
The maximum number of ports, including fan-out, supported is 104 and the maximum number of queues supported is 21. Analyzing and
evaluating buer statistics enables monitoring of resources and tuning of allocation of buers. Max Use count mode provides the maximum
values of counters accumulated over a period of time. Current Use count mode enables you to obtain a snapshot of the counters, at a
particular time, using a triggering utility. The trigger can either be software-based or based on a predetermined threshold event. Software-
based triggers are supported, which are the values derived from the show command output in the Max Use count mode. In Dell EMC
Networking OS Release 9.3(0.0), only the Max Use count mode of operation is supported for the computation of maximum counter values.
Depending on the buer space statistical values that you can obtain, you can modify the settings for buer area to achieve enhanced
reliability and eciency in the handling of packets. This evaluation and administration of buer statistics is useful and important in
deployments that experience congestion frequently. The receive buer must be large enough to save all data that is received when the
system processes a PFC PAUSE frame.
You can use the service-class buffer shared-threshold-weight queue0 ... queue7 number command in Interface
Conguration mode to specify the threshold weight for the shared buer for each of the queues per port.
1 Create a 10-Gigabit Ethernet interface.
DellEMC(conf)#interface TenGigabitEthernet 1/1/1/1
2 Congure the threshold weight of the shared buer for the queues you want. In this example, this setting is congured for queues 5
and 7.
DellEMC(conf-if-te-1/1/1/1)#Service-class buffer shared-threshold-weight queue5 4 queue7 6
Enabling Buer Statistics Tracking
You can enable the tracking of statistical values of buer spaces at a global level. The buer statistics tracking utility operates in the max
use count mode that enables the collection of maximum values of counters.
To congure the buer statistics tracking utility, perform the following step:
1 Enable the buer statistics tracking utility and enter the Buer Statistics Snapshot conguration mode.
CONFIGURATION mode
DellEMC(conf)#buffer-stats-snapshot
DellEMC(conf)#no disable
Enable this utility to be able to congure the parameters for buer statistics tracking. By default, buer statistics tracking is disabled.
2 Enable the buer statistics tracking utility and enter the Buer Statistics Snapshot conguration mode.
CONFIGURATION mode
DellEMC(conf)#buffer-stats-snapshot
DellEMC(conf)#no disable
800
Quality of Service (QoS)