Dell EMC SmartFabric OS10 User Guide Release 10.5.0

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Configure ingress buffer

By default, all traffic classes map to the default priority group (PG) 7 for ingress buffers. The buffer reservation is based on the default priority group ID 7. All buffers are part of the default pool and all ports share buffers from the default pool. When you configure a network qos policy map, a new priority group is created for which buffers are assigned from the lossless pool. The rest of the traffic classes that are not mapped to any PFC-related PGs, use the default buffer.

The reserved buffer size is 9360 bytes for the speed of 10G, 25G, 40G, 50G, and 100G. The supported speed varies for different platforms.

Table 1. Maximum buffer sizeMaximum buffer size
Platforms	Max buffer size
S4000	12 MB
S6010–ON, S4048–ON	16 MB
S4100-ON Series	12 MB
S4200-ON Series	6 GB
S5200-ON Series	32 MB
Z9100–ON	16 MB
Z9264F-ON	42 MB

The following table lists the values allocated for the default ingress buffers on the S4100-ON series platform. These values may differ for different platforms and speeds. Use the show qos ingress buffers command to view the default ingress buffers on your switch.

Table 2. Default ingress buffers on the S4100-ON series platformDefault ingress buffers on the S4100-ON series platform
Speed	10G	25G	40G	50G	100G
Reserved buffers for PG 7 (default)	9KB	9KB	9KB	9KB	9KB

The following lists the link-level flow control (LLFC) buffer settings for default priority group 7:

Table 3. Default setting for LLFCDefault setting for LLFC
Speed	10G	25G	40G	50G	100G
Default reserved buffer	9KB	9KB	18KB	18KB	36KB
Default Xon threshold	36KB	45KB	75KB	91KB	142KB
Default Xoff threshold	9KB	9KB	9KB	9KB	9KB
Default dynamic shared buffer threshold (alpha value)	9KB	9KB	9KB	9KB	9KB

NOTE The supported speed varies for different platforms. After the reserved buffers are used, each LLFC starts consuming shared buffers from the lossless pool with the alpha value determining the threshold except for the S4200-ON series platform.

The following table lists the priority flow control (PFC) buffer settings per PFC priority group:

Table 4. Default settings for PFCDefault settings for PFC
Speed	10G	25G	40G	50G	100G
Default reserved buffer for S4000, S4048–ON, S6010–ON	9KB	NA	9KB	NA	NA
Default reserved buffer for S41xx, Z9100–ON	9KB	9KB	18KB	18KB	36KB
Default Xoff threshold	36KB	45KB	75KB	91KB	142KB
Default Xon threshold	9KB	9KB	9KB	9KB	9KB
Default dynamic share buffer threshold (alpha value)	9KB	9KB	9KB	9KB	9KB

NOTE The supported speed varies for different platforms. After the reserved buffers are used, each PFC starts consuming shared buffers from the lossless pool with the alpha value determining the threshold.

You can override the default priority group settings when you enable LLFC or PFC.

Create a network-qos type class-map to match the traffic classes. For LLFC, match all the traffic classes from 0 to 7. For PFC, match the required traffic class.
```
OS10(config)# class-map type network-qos example-cmap-in-buffer
OS10 (config-cmap-nqos)# match qos-group 0-7
```

Create network-qos type policy-map to define the actions for traffic classes, such as a buffer configuration and threshold.

OS10(config)# policy-map type network-qos example-pmap-in-buffer
OS10(config-pmap-network-qos)# class example-cmap-in-buffer
OS10 (config-pmap-c-nqos)# pause buffer-size 300 pause-threshold 200 resume-threshold 100
OS10 (config-pmap-c-nqos)# queue-limit thresh-mode dynamic 5