Command Line Reference Guide

tx on Enter the keywords tx on to send control frames from this port to
the connected device when a higher rate of traffic is received. This is
the default value on the send side.
tx off Enter the keywords tx off so that flow control frames are not sent
from this port to the connected device when a higher rate of traffic is
received.
Defaults rx off tx off
Command Modes INTERFACE
Command History
Version 9.0(1.3) Introduced on the S5000.
Usage
Information
The globally assigned 48-bit Multicast address 01-80-C2-00-00-01 is used to send and receive
pause frames. To allow full-duplex flow control, stations implementing the pause operation
instruct the MAC to enable the reception of frames with a destination address equal to this
multicast address.
An Ethernet interface starts to send pause frames to a sending device when the transmission
rate of ingress traffic exceeds the egress port speed. The interface stops sending pause
frames when the ingress rate falls to less than or equal to egress port speed.
Changes in the flow-control values may not be reflected automatically in show interface
output. To display the change, apply the new flow-control setting, perform a shutdown
followed by a no shutdown on the interface, and then check re-display the show
interface output for the port.
Important Points to Remember
• On the S5000, Ethernet Pause Frame flow control is not supported if PFC is enabled on
one or more interfaces.
• On the S5000, threshold settings on the transmission pause (tx on) are not supported
for Ethernet Pause Frame flow control.
• Do not enable tx pause when buffer carving is enabled. For information and
assistance, contact Dell Networking TAC.
NOTE: If you disable rx flow control, Dell Networking recommends rebooting
the system.
Example
FTOS(conf-if-gi-0/1)#show config
!
interface GigabitEthernet 0/1
no ip address
switchport
no negotiation auto
flowcontrol rx off tx on
no shutdown
...
Example (Values)
This Example shows how FTOS negotiates the flow control values between two switches
connected back-to-back using 1G copper ports.
Configured
LocRxConf LocTxConf RemoteRxConf RemoteTxConf
off off off off
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