Cisco Catalyst 2950 Command Reference Manual page 145

Chapter 2 Catalyst 2950 and 2955 Cisco IOS Commands
Usage Guidelines Use the flowcontrol command only on 10/100/1000, GBIC-module ports, and SFP-module ports.
We strongly recommend that you do not configure IEEE 802.3x flowcontrol when quality of service
(QoS) is configured on the switch. Before configuring flowcontrol on an interface, make sure to disable
QoS on the switch.
Note that when used with receive, the on and desired keywords have the same result.
When you use the flowcontrol command to set a port to control traffic rates during congestion, you are
setting flow control on a port to one of these conditions:
•
•
•
•
•
•
Table 2-3
settings. The table assumes that for receive, using the desired keyword has the same results as using the
on keyword.
Table 2-3 Flow Control Settings and Local and Remote Port Flow Control Resolution
Flow Control Settings
Local Device
send on/receive on
send on/receive off
OL-10102-01
receive on and send on: Flow control operates in both directions; pause frames can be sent by both
the local device and the remote device to show link congestion.
receive on and send desired: The port can receive pause frames and is able to send pause frames if
the attached device supports them.
receive on and send off: The port cannot send pause frames, but can operate with an attached device
that is required to or is able to send pause frames; the port is able to receive pause frames.
receive off and send on: The port sends pause frames if the remote device supports them, but cannot
receive pause frames from the remote device.
receive off and send desired: The port cannot receive pause frames, but can send pause frames if
the attached device supports them.
receive off and send off: Flow control does not operate in either direction. In case of congestion, no
indication is given to the link partner, and no pause frames are sent or received by either device.
shows the flow control resolution achieved on local and remote ports by a combination of
Remote Device
send on/receive on
send on/receive off
send desired/receive on
send desired/receive off
send off/receive on
send off/receive off
send on/receive on
send on/receive off
send desired/receive on
send desired/receive off
send off/receive on
send off/receive off
Flow Control Resolution
Local Device
Sends and receives
Does not send or receive
Sends and receives
Does not send or receive
Sends and receives
Does not send or receive
Does not send or receive
Does not send or receive
Sends only
Does not send or receive
Sends only
Does not send or receive
Catalyst 2950 and Catalyst 2955 Switch Command Reference
flowcontrol
Remote Device
Sends and receives
Does not send or receive
Sends and receives
Does not send or receive
Receives only
Does not send or receive
Does not send or receive
Does not send or receive
Receives only
Does not send or receive
Receives only
Does not send or receive
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