C
HAPTER
12
| Port Commands
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COMMAND USAGE
N
OTE
:
The 1000BASE-T standard does not support forced mode. Auto-
negotiation should always be used to establish a connection over any
1000BASE-T port or trunk. If not used, the success of the link process
cannot be guaranteed when connecting to other types of switches.
EXAMPLE
Port>mode 5 100hdx
Port>mode 5
Port Mode Link
---- ------ ----
5 100hdx Down
Port>
port flow control This command displays or sets the flow control mode.
SYNTAX
port flow control [port-list] [enable | disable]
port-list - A specific port or a range of ports. (Range: 1-28, or all)
enable - Enables flow control.
disable - Disables flow control.
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.
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