The device supports MDC only when it is operating in standalone mode. For more information about the standalone mode and device models that support MDC, see Virtual Technologies Configuration Guide.

PFC is supported only on the SC modules prefixed with LSCM2 and SD interface modules.

As a best practice, do not configure PFC on IRF physical interfaces. For more information about IRF, see IRF configuration in Virtual Technologies Configuration Guide.

display priority-flow-control

Use display priority-flow-control to display the PFC information for an interface.

Syntax

display priority-flow-control interface [ interface-type [ interface-number ] ]

Views

Any view

Predefined user roles

network-admin

network-operator

mdc-admin

mdc-operator

Parameters

interface-type: Specifies an interface type. If you do not specify an interface type, the command displays the PFC information for all Ethernet interfaces.

interface-number: Specifies an interface number. If you do not specify an interface number, the command displays the PFC information for all Ethernet interfaces of the specified type.

Examples

# Display the PFC information for all Ethernet interfaces.

<Sysname> display priority-flow-control interface

Conf -- Configured mode Ne -- Negotiated mode P -- Priority

Interface Conf Ne Dot1pList P Recv Sent Inpps Outpps

XGE3/0/1 Auto On 0,2-3,5-6 0 178 43 12 15

Table 1 Command output

Field	Description
Conf -- Configured mode	Locally configured PFC status.
Ne -- Negotiated mode	Negotiated PFC status.
P -- Priority	802.1p priority value for which PFC is enabled.
Interface	Abbreviated name of the interface.
Conf	Locally configured PFC status: · Auto—The interface is configured to autonegotiate the PFC status with the remote end. · Off—PFC is disabled for the interface. · On—PFC is enabled for the interface.
Ne	Negotiated PFC status: · Off—PFC is disabled. · On—PFC is enabled.
Dot1pList	802.1p priorities that are enabled with PFC. 802.1p priority values 0 through 7 are available.
P	An 802.1p priority is displayed only when the 802.1p priority is enabled with PFC and the interface has received or sent packets with the 802.1p priority. In the current software version, this field only displays 0.
Recv	Number of received PFC pause frames.
Sent	Number of sent PFC pause frames.
Inpps	Incoming PFC frame rate in pps for the 802.1p priority.
Outpps	Outgoing PFC frame rate in pps for the 802.1p priority.

‌

Related commands

priority-flow-control

priority-flow-control no-drop dot1p

display priority-flow-control dscp-mapping statistics

Use display priority-flow-control dscp-mapping statistics to display DSCP mapping statistics.

NOTE:

This command is supported only on the SF interface modules.

‌

Syntax

In standalone mode:

display priority-flow-control dscp-mapping statistics [ slot slot-number ]

In IRF mode:

display priority-flow-control dscp-mapping statistics [ chassis chassis-number slot slot-number ]

Views

Any view

Predefined user roles

network-admin

network-operator

mdc-admin

mdc-operator

Parameters

slot slot-number: Specifies a card by its slot number. If you do not specify a card, this command displays the DSCP mapping statistics for the all cards. (In standalone mode.)

chassis chassis-number slot slot-number: Specifies a card on an IRF member device. The chassis-number argument represents the member ID of the IRF member device. The slot-number argument represents the slot number of the card. If you do not specify a card, this command displays the DSCP mapping statistics for the all cards. (In IRF mode.)

Examples

# (In standalone mode.) Display DSCP mapping statistics.

<Sysname> display priority-flow-control dscp-mapping statistics

O/N: Original/New

slot 1:

OutInterface Priority(O/N) DSCP(O/N) Count LastMappingTime

XGE3/0/1 1/2 11/12 2001 2021-08-10 08:18:01

# (In IRF mode.) Display DSCP mapping statistics.

<Sysname> display priority-flow-control dscp-mapping statistics

O/N: Original/New

chassis 1 slot 1:

OutInterface Priority(O/N) DSCP(O/N) Count LastMappingTime

XGE3/0/1 1/2 11/12 2001 2021-08-10 08:18:01

Related commands

priority-flow-control dscp-mapping

priority-flow-control (Ethernet interface view)

Use priority-flow-control to enable PFC on an Ethernet interface.

Use undo priority-flow-control to disable PFC.

Syntax

priority-flow-control { auto | enable }

undo priority-flow-control

Default

PFC is disabled on Ethernet interfaces.

Views

Ethernet interface view

Predefined user roles

network-admin

mdc-admin

Parameters

auto: Specifies PFC in auto mode. In this mode, the local end automatically negotiates the PFC status with the remote end.

enable: Forcibly enables PFC.

Usage guidelines

The local device notifies the remote end to stop sending packets carrying the specified 802.1p priority if all of the following conditions exist:

· Both the local end and the remote end have PFC enabled.

· Both the local end and the remote end have the priority-flow-control no-drop dot1p dot1p-list command configured.

· The specified 802.1p priority is in the 802.1p priority list specified by the dot1p-list argument.

· The local end receives packets carrying the specified 802.1p priority, and the received packets cause congestion.

When congestion is eliminated, the local end notifies the remote end to continue to send packets carrying the specified 802.1p priority. In this way, the local device can forward packets carrying 802.1p priorities in the specified 802.1p priority list without packet drops.

When you enable Rx PFC, the device can receive but cannot send PFC pause frames. When you enable Tx PFC, the device can send but cannot receive PFC pause frames. If neither receive nor send is specified, this command enables both Rx PFC and Tx PFC.

If you execute this command in system view and Ethernet interface view multiple times, the most recent configuration takes effect.

Examples

# Enable PFC on Ten-GigabitEthernet 3/0/1.

<Sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control enable

Related commands

display priority-flow-control

priority-flow-control (system view)

priority-flow-control no-drop dot1p

priority-flow-control (system view)

Use priority-flow-control to enable PFC on all Ethernet interfaces.

Use undo priority-flow-control to disable PFC on all Ethernet interfaces.

Syntax

priority-flow-control { auto | enable }

undo priority-flow-control

Default

PFC is disabled on Ethernet interfaces.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

auto: Specifies PFC in auto mode. In this mode, the local end automatically negotiates the PFC status with the remote end.

enable: Forcibly enables PFC.

Usage guidelines

The local device notifies the remote end to stop sending packets carrying the specified 802.1p priority if all of the following conditions exist:

· Both the local end and the remote end have PFC enabled.

· Both the local end and the remote end have the priority-flow-control no-drop dot1p command configured.

· The specified 802.1p priority is in the 802.1p priority list specified by the dot1p-list argument.

· The local end receives packets carrying the specified 802.1p priority, and the received packets cause congestion.

If you execute this command in system view and Ethernet interface view multiple times, the most recent configuration takes effect.

Examples

# Enable PFC on all Ethernet interfaces.

<Sysname> system-view

[Sysname] priority-flow-control enable

Related commands

display priority-flow-control

priority-flow-control (Ethernet interface view)

priority-flow-control no-drop dot1p

priority-flow-control deadlock auto-recover cos

Use priority-flow-control deadlock auto-recover cos to configure the delay timer for PFC deadlock detection automatic recovery.

Use undo priority-flow-control deadlock auto-recover cos to delete the delay timer for PFC deadlock detection automatic recovery.

Syntax

priority-flow-control deadlock auto-recover cos cos-value delay delay-interval

undo priority-flow-control deadlock auto-recover cos [ cos-value ]

Default

The delay timer for PFC deadlock detection automatic recovery is not configured.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

cos cos-value: Specifies the CoS value of packets, in the range of 0 to 7. Different CoS values correspond to different 802.1p priority values. To see the CoS-to-802.1p mapping, execute the display qos map-table dot1p-lp command.

delay delay-time: Specifies the delay timer for PFC deadlock detection automatic recovery in the range of 1 to 15.

Usage guidelines

PFC deadlock detection periodically detects whether deadlock occurs to packets carrying the specified CoS value. If the device enters the PFC deadlock state and PFC deadlock detection is recovered in automatic mode, the device automatically recovers PFC deadlock detection after the delay timer expires. The delay timer is determined by this command and the PFC deadlock detection timer precision.

This command takes effect only in automatic recovery mode.

The specified CoS value must be within the 802.1p priority values configured by using the priority-flow-control no-drop dot1p command.

You can set the same delay timer for different CoS values.

If you execute this command multiple times for the same CoS value, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# Set the delay timer for PFC deadlock detection automatic recovery to 5 for packets carrying CoS value 7.

<Sysname> system-view

[Sysname] priority-flow-control deadlock auto-recover cos 7 delay 5

Related commands

display qos map-table dot1p-lp (ACL and QoS Command Reference)

priority-flow-control deadlock precision

priority-flow-control no-drop dot1p

priority-flow-control deadlock cos

Use priority-flow-control deadlock cos to set the PFC deadlock detection interval for the specified CoS value.

Use undo priority-flow-control deadlock cos to delete the PFC deadlock detection interval for the specified CoS value or all CoS values.

Syntax

priority-flow-control deadlock cos cos-value interval interval

undo priority-flow-control deadlock cos [ cos-value ]

Default

The PFC deadlock detection interval for a CoS value is not set.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

cos cos-value: Specifies the CoS value of packets, in the range of 0 to 7.

interval interval: Specifies the PFC deadlock detection interval in the range of 1 to 15.

If you do not specify this keyword, the PFC feature and PFC deadlock detection feature are automatically recovered on an interface when the detection interval expires, no matter whether the interface receives PFC pause frames.

Usage guidelines

The PFC deadlock detection feature periodically detects whether deadlock occurs to packets that carry the specified CoS value. To obtain the length of time for the detection interval, multiply the detection interval by the precision of the PFC deadlock detection timer.

The specified CoS value must be within the 802.1p priority list specified by using the priority-flow-control no-drop dot1p command. To view the 802.1p priority for each CoS value, execute the display qos map-table dot1p-lp command.

You can set the same detection interval for different CoS values.

If you execute this command for the same CoS value multiple times, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# (In standalone mode.) Set the PFC deadlock detection interval to 5 for packets carrying CoS value 7 on slot 1.

<Sysname> system-view

[Sysname] priority-flow-control deadlock slot 1 cos 7 interval 5

Related commands

display qos map-table dot1p-lp (ACL and QoS Command Reference)

priority-flow-control deadlock precision

priority-flow-control no-drop dot1p

priority-flow-control deadlock enable

Use priority-flow-control deadlock enable to enable PFC deadlock detection on an interface.

Use undo priority-flow-control deadlock enable to disable PFC deadlock detection on an interface.

Syntax

priority-flow-control deadlock enable

undo priority-flow-control deadlock enable

Default

PFC deadlock detection is disabled on an interface.

Views

Ethernet interface view

Predefined user roles

network-admin

mdc-admin

Usage guidelines

The device enters the PFC deadlock state if the following conditions exist on an interface:

· PFC for 802.1p priorities is enabled by using the priority-flow-control and priority-flow-control no-drop dot1p commands.

· Packets carrying the specified 802.1p priority are transmitted in a loop.

· No packets in the data buffer can be forwarded.

This command enables periodically detecting whether the device is in PFC deadlock state.

This command is supported only on SF interface modules.

Examples

# Enable PFC deadlock detection on Ten-GigabitEthernet 3/0/1.

<Sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control deadlock enable

Related commands

priority-flow-control

priority-flow-control deadlock cos

priority-flow-control no-drop dot1p

priority-flow-control deadlock precision

Use priority-flow-control deadlock precision to set the precision for the PFC deadlock detection timer.

Use undo priority-flow-control deadlock precision to restore the default.

Syntax

priority-flow-control deadlock precision { high | low | normal }

undo priority-flow-control deadlock precision

Default

The PFC deadlock detection timer uses normal precision.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

high: Specifies the high precision for the PFC deadlock detection timer.

low: Specifies the low precision for the PFC deadlock detection timer.

normal: Specifies the normal precision for the PFC deadlock detection timer.

Usage guidelines

Use this command to adjust the precision for the PFC deadlock detection timer and change the PFC deadlock detection interval.

This command is supported only on SF interface modules.

If you execute this command multiple times, the most recent configuration takes effect.

Examples

# (In standalone mode.) Set the high precision for the PFC deadlock detection timer on slot 1.

<Sysname> system-view

[Sysname] priority-flow-control deadlock slot 1 precision high

priority-flow-control deadlock threshold

Use priority-flow-control deadlock threshold to configure the upper threshold for PFC deadlock times within the specified period.

Use undo priority-flow-control deadlock threshold to restore the default.

Syntax

priority-flow-control deadlock threshold cos cos-value period period count count [ down-auto-recovery | error-down ]

undo priority-flow-control deadlock threshold cos [ cos-value ]

Default

The upper threshold for PFC deadlock times within the specified period is not configured.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

period period: Specifies the period for detecting PFC deadlock times, in the range of 1 to 60 seconds.

count count: Specifies the upper threshold for PFC deadlock times within the specified period, in the range of 1 to 500.

down-auto-recovery: Configures PFC to shut down a port when the number of PFC deadlocks within the specified period reaches the upper threshold on the port. After the port status detection timer set by using the shutdown-interval priority-flow-control command expires, the device will set the port status to the port's physical status and restore PFC on the port. If this parameter is not specified, the port will be shut down and PFC will be disabled for the corresponding 802.1p priority on the port when the number of PFC deadlocks within the detection period reaches the upper limit.

error-down: Shuts down an interface when the number of PFC deadlock times within the detection period reaches the upper threshold. If you do not specify this keyword, PFC will be disabled for the corresponding 802.1p priority when the number of PFC deadlock times within the detection period reaches the upper threshold.

Usage guidelines

After this command is executed, when the number of PFC deadlock times within the detection period reaches the upper threshold on an interface, how the device reacts depends on the command settings:

· If the error-down keyword is not specified, the device disables PFC for the corresponding 802.1p priority on the interface. To recover PFC on the interface in this case, you can execute the undo priority-flow-control deadlock threshold command to recover PFC on an interface. However, this command might affect the PFC state on multiple interfaces. Use this command as needed.

· If the error-down keyword is specified, the device will shut down the interface. To bring up the interface and recover PFC on the interface, execute the undo shutdown command on the interface.

When the number of PFC deadlock times within the detection period reaches the upper threshold on an interface, how the device reacts depends on the configuration in system view and interface view.

· If the priority-flow-control deadlock threshold action command is not executed on the interface, the priority-flow-control deadlock threshold command in system view takes effect. If the priority-flow-control deadlock threshold action command is executed on the interface, this command takes effect.

· If the priority-flow-control deadlock threshold command is not executed in system view, the priority-flow-control deadlock threshold action command on the interface does not take effect.

The detection period specified in this command must be longer than the PFC deadlock detection interval configured by using the priority-flow-control deadlock cos command, so that you can determine whether the device frequently enters the PFC deadlock state.

The specified CoS value must be within the 802.1p priority values configured by using the priority-flow-control no-drop dot1p command.

You can set the same detection period for different CoS values.

If you execute this command multiple times for the same CoS value, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# Set the upper threshold for PFC deadlock times to 100 within the period of 5 seconds.

<Sysname> system-view

[Sysname] priority-flow-control deadlock threshold cos 7 period 5 count 100

Related commands

priority-flow-control deadlock cos

priority-flow-control deadlock threshold action

priority-flow-control no-drop dot1p

shutdown-interval priority-flow-control

priority-flow-control deadlock threshold action

Use priority-flow-control deadlock threshold action to configure the action to take on an interface when the number of PFC deadlock times within the specified detection period exceeds the upper threshold.

Use undo priority-flow-control deadlock threshold action to restore the default.

Syntax

priority-flow-control deadlock threshold action { down-auto-recovery | error-down | turn-off }

undo priority-flow-control deadlock threshold action

Default

The action specified by the priority-flow-control deadlock threshold command in system view takes effect.

Views

Ethernet interface view

Predefined user roles

network-admin

mdc-admin

Parameters

error-down: Shuts down an interface when the number of PFC deadlock times within the specified detection period reaches the upper threshold and stops traffic forwarding on the interface.

turn-off: Disables PFC for the corresponding 802.1p priority when the number of PFC deadlock times within the specified detection period reaches the upper threshold.

Usage guidelines

The threshold for PFC deadlock times and the detection period are configured by using the priority-flow-control deadlock threshold command in system view. If the priority-flow-control deadlock threshold action command is not executed on the interface, the priority-flow-control deadlock threshold command in system view takes effect. If the priority-flow-control deadlock threshold action command is executed on the interface, this command takes effect.

If the priority-flow-control deadlock threshold command is not executed in system view, the priority-flow-control deadlock threshold action command on the interface does not take effect.

If the turn-off keyword is specified, the device disables PFC for the corresponding 802.1p priority on the interface when the number of PFC deadlock times within the specified detection period exceeds the upper threshold. To recover PFC on the interface in this case, you can execute the undo priority-flow-control deadlock threshold command to recover PFC on the interface. However, this command might affect the PFC state on multiple interfaces. Use this command as needed.

If the error-down keyword is specified, the device shuts down the interface when the number of PFC deadlock times within the specified detection period exceeds the upper threshold on the interface. To bring up the interface and recover PFC on the interface in this case, execute the undo shutdown command on the interface.

This command is supported only on SF interface modules.

If the down-auto-recovery keyword is specified, the device shuts down the interface when the number of PFC deadlock times within the specified detection period exceeds the upper threshold on the interface. After the port status detection timer set by using the shutdown-interval priority-flow-control command expires, the device will set the port status to the port's physical status and restore PFC on ports are shut down the port.

Examples

# Configure PFC to shut down the interface when the PFC deadlock times within the specified period reaches the upper threshold.

<Sysname> system-view

[Sysname] interface gigabitethernet 1/0/1

[Sysname-GigabitEthernet1/0/1] priority-flow-control deadlock threshold action error-down

Related commands

priority-flow-control deadlock threshold

shutdown-interval priority-flow-control

priority-flow-control dot1p headroom

Use priority-flow-control dot1p headroom to set the headroom buffer threshold.

Use undo priority-flow-control dot1p headroom to restore the default.

Syntax

priority-flow-control dot1p dot1p headroom headroom-number

undo priority-flow-control dot1p dot1p headroom

Default

The headroom buffer threshold is not set.

Views

Ethernet interface view

Predefined user roles

network-admin

Parameters

dot1p: Specifies an 802.1p priority in the range of 0 to 7.

headroom-number: Specifies the headroom buffer threshold in the range of 8 to 70000.

Usage guidelines

Before executing this command, you must use the priority-flow-control no-drop dot1p command to enable PFC for the specified 802.1p priority.

If you execute this command multiple times for the same 802.1p priority, the most recent configuration takes effect.

When two directly connected interfaces transmit data, the buffers of interfaces are used for buffering received data. A longer transmission distances needs a large buffer size. You can use this command to set the headroom buffer threshold to implement zero packet loss.

This command is supported only on SF interface modules.

Examples

# Set the headroom buffer threshold to 1000 for 802.1p priority 1 on Ten-GigabitEthernet 3/0/1.

<sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control dot1p 1 headroom 1000

Related commands

priority-flow-control no-drop dot1p

priority-flow-control dot1p ingress-buffer static

Use priority-flow-control dot1p ingress-buffer static to set the static back pressure frame triggering threshold.

Use undo priority-flow-control dot1p ingress-buffer to restore the default.

Syntax

priority-flow-control dot1p dot1p ingress-buffer static threshold

undo priority-flow-control dot1p dot1p ingress-buffer

Default

The static back pressure frame triggering threshold is not set.

Views

Ethernet interface view

Predefined user roles

network-admin

Parameters

dot1p: Specifies an 802.1p priority in the range of 0 to 7.

threshold: Specifies the static back pressure frame triggering threshold in the range of 1 to 20000.

Usage guidelines

Before executing this command, you must use the priority-flow-control no-drop dot1p command to enable PFC for the specified 802.1p priority.

If you execute this command for the same 802.1p priority multiple times, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# Set the static back pressure frame triggering threshold to 1000 for 802.1p priority 1 on Ten-GigabitEthernet 3/0/1.

<sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control dot1p 1 ingress-buffer static 1000

Related commands

priority-flow-control no-drop dot1p

priority-flow-control dot1p ingress-threshold-offset

Use priority-flow-control dot1p ingress-threshold-offset to set the offset between the back pressure frame stopping threshold and triggering threshold.

Use undo priority-flow-control dot1p ingress-threshold-offset to restore the default.

Syntax

priority-flow-control dot1p dot1p ingress-threshold-offset offset-number

undo priority-flow-control dot1p dot1p ingress-threshold-offset

Default

The offset between the back pressure frame stopping threshold and triggering threshold is not set.

Views

Ethernet interface view

Predefined user roles

network-admin

Parameters

dot1p: Specifies an 802.1p priority in the range of 0 to 7.

offset-number: Specifies the offset between the back pressure frame stopping threshold and triggering threshold in the range of 1 to 20000.

Usage guidelines

Before executing this command, you must use the priority-flow-control no-drop dot1p command to enable PFC for the specified 802.1p priority.

If you execute this command multiple times, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# Set the offset between the back pressure frame stopping threshold and triggering threshold to 1000 for 802.1p priority 1 on Ten-GigabitEthernet 3/0/1.

<sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control dot1p 1 ingress-threshold-offset 1000

Related commands

priority-flow-control no-drop dot1p

priority-flow-control dot1p reserved-buffer

Use priority-flow-control dot1p reserved-buffer to set the PFC reserved threshold.

Use undo priority-flow-control dot1p reserved-buffer to restore the default.

Syntax

priority-flow-control dot1p dot1p reserved-buffer reserved-number

undo priority-flow-control dot1p dot1p reserved-buffer

Default

The PFC reserved threshold is not set.

Views

Ethernet interface view

Predefined user roles

network-admin

Parameters

dot1p: Specifies an 802.1p priority in the range of 0 to 7.

reserved-number: Specifies the PFC reserved threshold in the range of 1 to 20000.

Usage guidelines

Before executing this command, you must use the priority-flow-control no-drop dot1p command to enable PFC for the specified 802.1p priority.

If you execute this command multiple times for the same 802.1p priority, the most recent configuration takes effect.

This command is supported only on SF interface modules.

Examples

# Set the PFC reserved threshold to 1000 for 802.1p priority 1 on Ten-GigabitEthernet 3/0/1.

<sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control dot1p 1 reserved-buffer 1000

Related commands

priority-flow-control no-drop dot1p

priority-flow-control dscp-mapping

Use priority-flow-control dscp-mapping to configure DSCP mappings for packets on an interface.

Use undo priority-flow-control dscp-mapping to restore the default.

NOTE:

This command is supported only on the SF interface modules.

‌

Syntax

priority-flow-control dscp-mapping { original-dscp original-dscp-value to priority priority [ dscp dscp-value ] }&<1-4>

undo priority-flow-control dscp-mapping

Default

No DSCP mappings are configured.

Views

Ethernet interface view

Predefined user roles

network-admin

mdc-admin

Parameters

original-dscp original-dscp-value: Specifies the original DSCP value in the range of 0 to 63.

priority priority: Specifies the 802.1p priority for the packets, in the range of 0 to 7.

dscp dscp-value: Specifies the new DSCP value in the range of 0 to 63. If this keyword is not specified, the DSCP value of packets is not changed.

&<1-4>: Indicates a maximum of four values can be entered.

Usage guidelines

A device assigns an incoming packet to a queue with an 802.1p priority based on the DSCP value of the packet and the DSCP-802.1p priority map. When packets carrying the specified 802.1p priority are transmitted in a loop, each node on the path stops transmitting packets with the specified DSCP values. In this case, a PFC deadlock occurs. To prevent PFC deadlocks, you can modify the DSCP-802.1p mappings for packets. The packets will be forwarded based on the new DSCP value.

This command enables the device to modify the 802.1p priority and DSCP value of packets when forwarding them.

A maximum number of two DSCP mappings can be configured, and the original DSCP values must be different.

Examples

# On Ten-GigabitEthernet 3/0/1, map DSCP value 2 to DSCP value 4 in packets and assign the packets to the queue with 802.1 priority 3.

<Sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control dscp-mapping original-dscp 2 to priority 3 dscp 4

# On Ten-GigabitEthernet 3/0/2, assign the packets with DSCP value 3 to the queue with 802.1p priority 3.

<Sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/2

[Sysname-Ten-GigabitEthernet3/0/2] priority-flow-control dscp-mapping original-dscp 3 to priority 3

priority-flow-control inner-port enable

Use priority-flow-control inner-port enable to enable PFC on inner interfaces.

Use undo priority-flow-control inner-port enable to disable PFC on inner interfaces.

Syntax

priority-flow-control inner-port enable

undo priority-flow-control inner-port enable

Default

PFC is disabled on inner interfaces.

Views

System view

Predefined user roles

network-admin

mdc-admin

Usage guidelines

This command is supported only on SF interface modules.

As a best practice, configure PFC on inner interfaces in the default MDC. Then, the configuration will be synchronized to non-default MDCs. For more information about MDC, see MDC configuration in Virtual Technologies Configuration Guide.

An inner interface is the inner Ethernet interface through which a card communicates with the device, and is invisible for users.

With PFC enabled on an inner interface, when the traffic from an LPU to a switching fabric module is congested, the inner interface on the switching fabric module sends PFC pause frames to the inner interface on the LPU to notify the LPU to stop sending packets to the switching fabric module. When congestion is eliminated, the inner interface on the switching fabric module notifies the LPU to continue to send packets to the switching fabric module. This rule also applies to the traffic from a switching fabric module to an LPU.

Examples

# Enable PFC on inner interfaces.

<Sysname> system-view

[Sysname] priority-flow-control inner-port enable

Related commands

priority-flow-control inner-port no-drop

Use priority-flow-control inner-port no-drop to enable PFC for 802.1p priorities on inner interfaces.

Use undo priority-flow-control inner-port no-drop to disable PFC for 802.1p priorities on inner interfaces.

Syntax

priority-flow-control inner-port no-drop dot1p dot1p-list [ headroom cell-count | ingress-buffer static threshold-value | ingress-threshold-offset offset-value | reserved-buffer reserved-value ] *

undo priority-flow-control inner-port no-drop dot1p dot1p-list

Default

PFC is disabled for all 802.1p priorities on inner interfaces.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

dot1p-list: Specifies an 802.1p priority (or dot1p priority) list to identify flows that are subject to PFC (for example: 1,3-5). A hyphen (-) connects two numeric values, which together indicate a continuous value range. Different values or value ranges are separated with commas (,). You can configure up to 16 characters for this argument.

headroom cell-count: Specifies the maximum number of cell resources that can be used in the headroom storage space for queues, in the range of 8 to 15000.

ingress-buffer static threshold-value: Specifies the static back pressure frame triggering threshold, in the range of 100 to 20000.

ingress-threshold-offset offset-value: Specifies the offset between the back pressure frame stopping threshold and triggering threshold, in the range of 1 to 100.

reserved-buffer reserved-value: Specifies the PFC reserved threshold, in the range of 1 to 300.

Usage guidelines

This command is supported only on SF interface modules.

With PFC enabled and this command configured on inner interfaces, when an inner interface is congested, the inner interface will send PFC pause frames to notify the peer inner interface to stop sending packets carrying the specified 802.1p priorities to prevent these packets from being dropped due to congestion. For more information about 802.1p priorities, see ACL and QoS Configuration Guide.

Examples

# Enable PFC for 802.1p priority 1 on inner interfaces.

<Sysname> system-view

[Sysname] priority-flow-control inner-port no-drop dot1p 1

Related commands

priority-flow-control inner-port enable

priority-flow-control no-drop dot1p (Ethernet interface view)

Use priority-flow-control no-drop dot1p to enable PFC.

Use undo priority-flow-control no-drop dot1p to disable PFC for 802.1p priorities on an Ethernet interface.

Syntax

priority-flow-control no-drop dot1p dot1p-list

undo priority-flow-control no-drop dot1p

Default

PFC is disabled for all 802.1p priorities on an Ethernet interface.

Views

Ethernet interface view

Predefined user roles

network-admin

mdc-admin

Parameters

Usage guidelines

If you enable PFC and execute this command on both the local and peer devices, the local device will notify the peer device to stop transmitting packets with the specified 802.1p priority when congestion occurs. When congestion is removed, the local device notifies the peer device to transmitting the packets again. This prevents packet loss for traffic with the specified priority. For more information about 802.1p priority, see QoS configuration in ACL and QoS Configuration Guide.

If you execute the flow-control or flow-control receive enable command when PFC is enabled, the command will not take effect. If you execute the flow-control or flow-control receive enable command when PFC is disabled, the command can take effect.

If you execute this command multiple times in system view and interface view, the most recent configuration takes effect.

Examples

# Enable PFC in auto mode on Ten-GigabitEthernet 3/0/1, and enable PFC for 802.1p priority 5.

<Sysname> system-view

[Sysname] interface ten-gigabitethernet 3/0/1

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control auto

[Sysname-Ten-GigabitEthernet3/0/1] priority-flow-control no-drop dot1p 5

Related commands

display priority-flow-control

flow-control (Interface Command Reference)

flow-control receive enable (Interface Command Reference)

priority-flow-control

priority-flow-control no-drop dot1p (system view)

Use priority-flow-control no-drop dot1p to enable PFC for 802.1p priorities on all Ethernet interfaces.

Use undo priority-flow-control no-drop dot1p to disable PFC for 802.1p priorities on all Ethernet interfaces.

Syntax

priority-flow-control no-drop dot1p dot1p-list

undo priority-flow-control no-drop dot1p

Default

PFC is disabled for all 802.1p priorities on all Ethernet interfaces.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

Usage guidelines

The local device notifies the remote end to stop sending packets carrying the specified 802.1p priority if all of the following conditions exist:

· Both the local end and the remote end have PFC enabled.

· Both the local end and the remote end have the priority-flow-control no-drop dot1p command configured.

· The specified 802.1p priority is in the 802.1p priority list specified by the dot1p-list argument.

· The local end receives packets carrying the specified 802.1p priority, and the received packets cause congestion.

If you execute this command in system view and Ethernet interface view multiple times, the most recent configuration takes effect.

Examples

# Enable PFC for 802.1p priority 5 globally.

<Sysname> system-view

[Sysname] priority-flow-control no-drop dot1p 5

Related commands

priority-flow-control no-drop dot1p (Ethernet interface view)

shutdown-interval priority-flow-control

Use shutdown-interval priority-flow-control to set the port status detection timer for the ports that are shut down because the number of PFC deadlocks within the specified period reaches the upper limit.

Use undo shutdown-interval priority-flow-control to restore the default.

Syntax

shutdown-interval [ priority-flow-control ] interval

undo shutdown-interval [ priority-flow-control ]

Default

The system does not automatically restore the port status.

Views

System view

Predefined user roles

network-admin

mdc-admin

Parameters

priority-flow-control: Specifies the PFC feature. If this keyword is not specified, this command sets the global port status detection timer.

interval: Specifies the port status detection timer value in seconds, in the range of 0 to 300 seconds. The value of 0 indicates that port status detection is not automatically performed, and you need to execute the undo shutdown command to restore the port status manually.

Usage guidelines

Certain protocols will automatically shut down a specific port in certain circumstances. For example, when a BPDU guard-enabled port receives a configuration BPDU, MSTP will automatically shut down that port. The device starts a port status detection timer when a port is shut down by a protocol. If the port has been in down state before the timer expires, the device will set the port status to the port's physical status.

If you change the timer setting during port detection, the device compares the new setting (T1) with the time that elapsed since the port was shut down (T).

· If T < T1, the port will be brought up after T1 – T seconds.

· If T ≥ T1, the port is brought up immediately.

For example, the timer setting is 30 seconds. If you change it to 10 seconds 2 seconds after the port is shut down, the port will come up 8 seconds later. If you change the timer setting to 2 seconds 10 seconds after the port is shut down, the port comes up immediately.

Examples

# Set the port status detection timer to 100 seconds for the ports that are shut down because the number of PFC deadlocks within the specified period reaches the upper limit.

<Sysname> system-view

[Sysname] shutdown-interval priority-flow-control 100

04-Layer 2—LAN Switching Command Reference

priority-flow-control no-drop dot1p (Ethernet interface view)

shutdown-interval priority-flow-control

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