Reference Guide

Congure PFC
Priority ow control (PFC) provides a pause mechanism based on the 802.1p priorities in ingress trac. PFC prevents frame loss due to
network congestion. Congure PFC lossless buers, and enable pause frames for dot1p trac on a per-interface basis. Repeat the PFC
conguration on each PFC-enabled interface. PFC is disabled by default.
Decide if you want to use the default dot1p-priority-to-trac class mapping and the default trac-class-to-queue mapping. See PFC
conguration notes to change the default settings.
Conguration steps:
1 Create PFC dot1p trac classes.
2 Congure ingress buers for PFC trac.
3 Apply a service policy and enable PFC.
4 (Optional) Congure the PFC shared buer for lossless trac.
Create PFC dot1p trac classes
1 Create a network-qos class map to classify PFC trac classes in CONFIGURATION mode (1 to 7). Specify the trac classes using
the match qos-group command. Qos-groups map 1:1 to trac classes 1 to 7 (qos-group 1 corresponds to trac 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 congure additional PFC trac-class class-maps.
Congure pause and ingress buers for PFC trac
See PFC conguration notes for the default ingress queue settings and the default dot1p priority-queue mapping.
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 Congure default values for ingress buers used for the network-qos class maps in POLICY-CLASS-MAP mode.
pause
(Optional) Change the default values for the ingress-buer size reserved for the network-qos class-map trac and the thresholds
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 trac in POLICY-CLASS-MAP mode. The dot1p values must be the same as the qos-
group (trac class) numbers in the class map in Step 2. Enter a single dot1p value (1-7), a hyphen-separated range, or multiple dot1p
values separated by commas.
pfc-cos dot1p-priority
5 (Optional) Set the static and dynamic thresholds used to limit the shared buers allocated to PFC trac-class queues. Congure a
static, xed queue-limit (in kilobytes) or a dynamic threshold (weight 1-10; default 9) based on the available PFC shared buers.
queue-limit thresh-mode {static kilobytes | dynamic weight}
6 (Optional) Repeat Steps 2–4 to congure PFC on additional trac classes.
Apply service policy and enable PFC
Converged data center services
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