C
HAPTER
11
| Port Commands
– 286 –
DEFAULT SETTING
Disabled
COMMAND USAGE
◆ Flow control can eliminate frame loss by “blocking” traffic from end
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.
◆ When auto-negotiation is used, this parameter indicates the flow
control capability advertised to the link partner. When the speed and
duplex mode are manually set, the Rx Pause field indicates whether
pause frames are obeyed by this port, and the Tx Pause field indicates
if pause frames are transmitted from this port (as shown in the
following example).
◆ 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
Port>flow control 5 enable
Port>flow control 5
Port Flow Control Rx Pause Tx Pause
---- ------------ -------- --------
5 Enabled Enabled Enabled
Port>
port state This command displays the administrative state, or sets it enabled or
disabled.
SYNTAX
port state [port-list] [enable | disable]
port-list - A specific port or a range of ports. (Range: 1-28, or all)
enable - Enables the specified ports.
disable - Disables the specified ports.
DEFAULT SETTING
Enabled
COMMAND USAGE
This command allows you to disable a port due to abnormal behavior
(e.g.,excessive collisions), and then re-enable it after the problem has
been resolved. You may also want to disable a port for security reasons.
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