Configuring PFC on an Ethernet interface
If both the local end and the peer end have PFC enabled and have the priority-flow-control no-drop dot1p command configured, the local device sends a PFC pause frame to the peer when network congestion occurs. The peer stops sending packets carrying an 802.1p priority within the list specified by the dot1p-list argument until the congestion is removed.
The state of the PFC function is determined by the PFC configuration on the local end and on the peer end. In Table 1, the first line lists the PFC configuration on the local port, the first column lists the PFC configuration on the peer, and enabled and disabled are two possible negotiation results. Make sure all ports that a data flow passes through have the same PFC configuration.
Table 1: PFC configurations and negotiation results
Local (right) Peer (below) | enable | auto | disable |
|---|---|---|---|
enable | Enabled | Enabled. | Disabled |
auto | Enabled |
| Disabled |
disable | Disabled | Disabled. | Disabled |
Configuration restrictions and guidelines
When you configure PFC, follow these restrictions and guidelines:
This feature is applicable to only these interface cards: LST1XP48LFD1, LST1XP40RFD1, LST1XP40RFG1, LST1CP4RFD1, LST1CP4RFG1.
In standalone mode, you can enable PFC for up to three 802.1p priorities among 802.1p priorities 1 through 7 on an interface. In IRF mode, You can enable PFC for up to three 802.1p priorities among 802.1p priorities 1 through 6 on an interface.
Physical IRF ports do not support PFC. In IRF mode, do not enable PFC on physical IRF ports of IRF member devices. For more information, see Virtual Technologies Configuration Guide.
This feature is mutually exclusive with generic flow control.
Before enabling PFC on an interface, make sure the 802.1p priorities on the interface have been mapped to the local priorities as shown in Table 2. For more information, see ACL and QoS Configuration Guide.
Table 2: 802.1p-local priority mappings
dot1p | lp |
|---|---|
0 | 0 |
1 | 1 |
2 | 2 |
3 | 3 |
4 | 4 |
5 | 5 |
6 | 6 |
7 | 7 |
Configuration procedure
To configure PFC on an Ethernet interface:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter Ethernet interface view. | interface interface-type interface-number | N/A |
3. Enable PFC through automatic negotiation or forcibly. | priority-flow-control { auto | enable } | By default, PFC is disabled. To enable PFC for specific 802.1p priorities, you must enable PFC first. |
4. Enable PFC for specific 802.1p priorities. | priority-flow-control no-drop dot1p dot1p-list | By default, PFC is disabled for all 802.1p priorities.
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