Allied Telesis AT-S62 User Manual
Page 75
AT-S62 Management Software Web Browser Interface User’s Guide
Section I: Basic Operations
75
HOL Blocking
For a definition of Head of Line Blocking, refer to the AT-S62
Management Software Menus Interface User’s Guide.
This parameter can prevent Head of Line Blocking from occurring on a
port. The parameter sets a threshold on the utilization of a port’s
egress queues. When the threshold for a port is exceeded, the switch
signals other ports to discard packets to the oversubscribed port. The
number for this value represents cells. A cell is 64 bytes. The range is
1 to 61,440 cells. The default is 7,168.
Flow Control
Sets flow control on the port. This option applies only to ports operating
in full-duplex mode.
A switch port uses flow control to control the flow of ingress packets
from its end node.
A port using flow control issues a special frame, referred to as a
PAUSE frame, as specified in the IEEE 802.3x standard, to stop the
transmission of data from an end node. When a port needs to stop an
end node from transmitting data, it issues this frame. The frame
instructs the end node to cease transmission. The port continues to
issue PAUSE frames until it is ready again to receive data from the end
node.
Possible values are:
Disabled - No flow control on the port. This is the default setting.
Enabled - Flow control is activated.
Limit - Specifies the number of cells. A cell represents 64 bytes. The
range is 1 to 57,344 cells. The default is 57,344.
Status
You use this selection to enable or disable a port. When disabled, a
port will not accept or forward frames.
You might want to disable a port and prevent packets from being
forwarded if a problem occurs with the node or cable connected to the
port. Once the problem has been fixed, you can enable the port again
to resume normal operation.
You might also want to disable a port that is not being used to secure it
from unauthorized connections.
Possible settings for this parameter are:
Enabled
The port will receive and forward packets. This is the
default setting.
Disabled
The port will not receive or forward packets.