Flow Control for Ethernet Interfaces
SUMMARY Learn about flow control for Ethernet interfaces, how to enable and disable flow control for Ethernet interfaces.
Flow Control Overview
Flow control on an Ethernet interface regulates traffic flow to prevent frames from dropping during network congestion. Flow control stops and resumes the transmission of network traffic between two connected peer nodes on a full-duplex Ethernet physical link. Controlling the flow by pausing and restarting prevents node buffers from overflowing and dropping frames.
Ethernet PAUSE is a congestion relief feature that works by providing link-level flow control for all traffic on a full-duplex Ethernet link. Ethernet PAUSE works in both directions on the link. In one direction, an interface generates and sends Ethernet PAUSE messages to stop the connected peer from sending more traffic. In the other direction, the interface responds to Ethernet PAUSE messages it receives from the connected peer to stop sending traffic. Ethernet PAUSE also works on aggregated Ethernet interfaces.
Symmetric Flow Control
Symmetric flow control configures both the receive and transmit buffers in the same state. The interface send and respond Ethernet PAUSE messages when flow control is enabled. The interface does not send or respond Ethernet PAUSE messages when flow control is disabled.
To enable symmetric flow control, use the flow-control statement at
the [edit interfaces interface-name
ether-options] hierarchy level.
To permit unrestricted traffic, disable the flow control. To disable the flow
control, use the no-flow-control statement the [edit
interfaces interface-name ether-options] hierarchy
level.
When you enable symmetric flow control on an interface, the Ethernet PAUSE behavior depends on the configuration of the connected peer.