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Hierarchy Level


Explicitly enable or disable symmetric Ethernet PAUSE flow control, which regulates the flow of packets from the switch to the remote side of the connection by pausing all traffic flows on a link during periods of network congestion. Symmetric flow control means that Ethernet PAUSE is enabled in both directions. The interface generates and sends Ethernet PAUSE messages when the receive buffers fill to a certain threshold and the interface responds to PAUSE messages received from the connected peer.

You can configure asymmetric flow control by including the configured-flow-control statement at the [edit interfaces interface-name ether-options hierarchy level. Symmetric flow control and asymmetric flow control are mutually exclusive features. If you attempt to configure both, the switch returns a commit error.


Ethernet PAUSE temporarily stops transmitting all traffic on a link when the buffers fill to a certain threshold. To temporarily pause traffic on individual “lanes” of traffic (each lane contains the traffic associated with a particular IEEE 802.1p code point, so there can be eight lanes of traffic on a link), use priority-based flow control (PFC).

Ethernet PAUSE and PFC are mutually exclusive features, so you cannot configure both of them on the same interface. If you attempt to configure both Ethernet PAUSE and PFC on an interface, the switch returns a commit error.

  • flow-control—Enable flow control; flow control is useful when the remote device is a Gigabit Ethernet switch.

  • no-flow-control—Disable flow control.


Whether flow control is enabled or disabled by default depends on the platform. Run show interfaces interface-name to see whether flow control is enabled on an interface.

Required Privilege Level

interface—To view this statement in the configuration.interface-control—To add this statement to the configuration.

Release Information

Statement introduced in Junos OS Release 11.1.