Dell EMC SmartFabric OS10 User Guide Release 10.5.0

PFC provides a pause mechanism that is based on the 802.1p priorities in ingress traffic. PFC prevents frame loss due to network congestion. Configure PFC lossless buffers, and enable pause frames for dot1p traffic on a per-interface basis. Repeat the PFC configuration on each PFC-enabled interface. PFC is disabled by default.

Decide if you want to use the default dot1p-priority-to-traffic class mapping and the default traffic-class-to-queue mapping. To change the default settings, see PFC configuration notes.

Create PFC dot1p traffic classes

1. Create a network-qos class map to classify PFC traffic classes in CONFIGURATION mode, from 1 to 7. Specify the traffic classes using the match qos-group command. QoS-groups map 1:1 to traffic classes 1 to 7; for example, qos-group 1 corresponds to traffic class 1. Enter a single value, a hyphen-separated range, or multiple qos-group values separated by commas in CLASS-MAP mode.

   class—map type network-qos class—map-name
      match qos-group {1-7}
      exit

2. (Optional) Repeat Step 1 to configure additional PFC traffic-class class-maps.

Configure pause and ingress buffers for PFC traffic

For the default ingress queue settings and the default dot1p priority-queue mapping, see PFC configuration notes.

1. Create a network-qos policy map in CONFIGURATION mode.

   policy-map type network-qos policy—map-name

2. Associate the policy-map with a network-qos class map in POLICY-MAP mode.

   class class-map-name

3. Configure default values for ingress buffers used for the network-qos class maps in POLICY-CLASS-MAP mode.

   pause

   (Optional) Change the default values for the ingress-buffer size that is reserved for the network-qos class-map traffic and the thresholds that are used to send XOFF and XON pause frames in kilobytes.

   pause [buffer-size kilobytes {pause-threshold kilobytes | resume-threshold kilobytes}]

4. Enable the PFC pause function for dot1p traffic in POLICY-CLASS-MAP mode. The dot1p values must be the same as the qos-group traffic class numbers in the class-map in Step 2. Enter a single dot1p value, from 1 to 7, a hyphen-separated range, or multiple dot1p values separated by commas.

   pfc-cos dot1p-priority

5. (Optional) Set the static and dynamic thresholds that are used to limit the shared buffers that are allocated to PFC traffic-class queues. Configure a static, fixed queue-limit (in kilobytes) or a dynamic threshold (weight 1-10; default 9) based on the available PFC shared buffers.

   queue-limit thresh-mode {static kilobytes | dynamic weight}

6. (Optional) Repeat Steps 2–4 to configure PFC on additional traffic classes.

Apply service policy and enable PFC

1. Apply the PFC service policy on an ingress interface or interface range in INTERFACE mode.

   interface ethernet node/slot/port:[subport]
      service-policy input type network-qos policy—map-name

   interface range ethernet node/slot/port:[subport]-node/slot/port[:subport]
      service-policy input type network-qos policy—map-name

2. Enable PFC without DCBX for FCoE and iSCSI traffic in INTERFACE mode.

   priority-flow-control mode on

Configure PFC

PFC is enabled on traffic classes with dot1p 3 and 4 traffic. The two traffic classes require different ingress queue processing. In the network-qos pp1 policy map, class cc1 uses customized PFC buffer size and pause frame settings; class cc2 uses the default settings.

OS10(config)# system qos
OS10(config-sys-qos)# trust-map dot1p default

OS10(config)# system qos
OS10(config-sys-qos)# exit

OS10(config)# class-map type network-qos cc1
OS10(config-cmap-nqos)# match qos-group 3    
OS10(config-cmap-nqos)# exit

OS10(config)# class-map type network-qos cc2
OS10(config-cmap-nqos)# match qos-group 4    
OS10(config-cmap-nqos)# exit

OS10(config)# policy-map type network-qos pp1
OS10(config-pmap-network-qos)# class cc1
OS10(config-pmap-c-nqos)# pause buffer-size 30 pause-threshold 20 resume-threshold 10 
OS10(config-pmap-c-nqos)#pfc-cos 3
OS10(config-pmap-c-nqos)#exit
OS10(config-pmap-network-qos)# class cc2
OS10(config-pmap-c-nqos)# pause  
OS10(config-pmap-c-nqos)#pfc-cos 4
OS10(config-pmap-c-nqos)#exit

OS10(config)# interface ethernet 1/1/1
OS10(conf-if-eth1/1/1)# service-policy input type network-qos pp1

OS10(conf-if-eth1/1/1)# priority-flow-control mode on
OS10(conf-if-eth1/1/1)# no shutdown

View PFC configuration and operational status

OS10(conf-if-eth1/1/1)# do show interface ethernet 1/1/1 priority-flow-control details 
ethernet1/1/1
Admin Mode : true
Operstatus: true
PFC Priorities: 3,4
Total Rx PFC Frames: 300
Total Tx PFC frames: 200
Cos    Rx             Tx
-------------------------
0      0              0              
1      0              0              
2      0              0              
3      300            200              
4      0              0              
5      0              0              
6      0              0              
7      0              0  

View PFC ingress buffer configuration

OS10# show qos ingress buffers interface ethernet 1/1/1
Interface : ethernet1/1/1
Speed : 0
Priority-grp      Reserved        Shared-buffer       Shared-buffer       XOFF                                                                                         XON
    no           buffer-size         mode              threshold        threshol                                                                             d       threshold
--------------------------------------------------------------------------------                                                                             --------------------------------------------
0                 -                 -                 -                 -                                                                                              -
1                 -                 -                 -                 -                                                                                              -
2                 -                 -                 -                 -                                                                                              -
3                 -                 -                 -                 -                                                                                              -
4                 -                 -                 -                 -                                                                                              -
5                 -                 -                 -                 -                                                                                              -
6                 -                 -                 -                 -                                                                                              -
7                 9360              static            12779520          -                                                                                              -

View PFC system buffer configuration

OS10# show qos system ingress buffer
All values are in kb
Total buffers                                 - 12187
    Total lossless buffers                    - 0
      Maximum lossless buffers                - 5512
      Total shared lossless buffers           - 0
      Total used shared lossless buffers      -
    Total lossy buffers                       - 11567
      Total shared lossy buffers              - 11192
      Total used shared lossy buffers         - 0


OS10# show qos system egress buffer
All values are in kb
Total buffers                              - 12187
    Total lossless buffers                 - 0
      Total shared lossless buffers        - 0
      Total used shared lossless buffers   -
    Total lossy buffers                    - 11567
      Total shared lossy buffers           - 9812
      Total used shared lossy buffers      - 0
    Total CPU buffers                   - 620
      Total shared CPU buffers          - 558
      Total used shared CPU buffers        - 0

View PFC ingress buffer statistics

OS10(config)# show qos ingress buffer-stats interface ethernet 1/1/15
Interface : ethernet1/1/15
Speed : 10G
Priority Used reserved     Used shared  Used HDRM  
 Group   buffers           buffers      buffers    
------------------------------------------------
0         9360              681824       35984      
1         0                 0            0          
2         0                 0            0          
3         0                 0            0          
4         0                 0            0          
5         0                 0            0          
6         0                 0            0          
7         0                 0            0