flowcontrol

45-5

45
Example
The following example configures Ethernet port 5 capabilities to 100half and 100full.
Related Commands
negotiation (45-3)
speed-duplex (45-2)
flowcontrol (45-5)
flowcontrol
This command enables flow control. Use the no form to disable flow control.
Syntax
[no] flowcontrol
Default Setting
Disabled
Command Mode
Interface Configuration (Ethernet, Port Channel)
Command Usage
• Flow control can eliminate frame loss by “blocking” traffic from en d stations or
segments connected directly to the switch when its buffers fill. When enabled,
back pressure is used for half-duplex operation and IEEE 802.3-2005
(formally IEEE 802.3x) for full-duplex operation.
• To force flow control on or off (with the flowcontrol or no flowcontrol
command), use the no negotiation command to disable auto-negotiation on
the selected interface.
• When using the negotiation command to enable auto-negotiation, the
optimal settings will be determined by the capabilities command. To enable
flow control under auto-negotiation, “flowcontrol” must be included in the
capabilities list for any port
• Avoid using flow control on a port connected to a hub unless it is actually
required to solve a problem. Otherwise back pressure jamming signals may
degrade overall performance for the segment attached to the hub.
Example
The following example enables flow control on port 5.
Console(config)#interface ethernet 1/5
Console(config-if)#capabilities 100half
Console(config-if)#capabilities 100full
Console(config-if)#
Console(config)#interface ethernet 1/5
Console(config-if)#flowcontrol
Console(config-if)#no negotiation
Console(config-if)#