Allied Telesis AT-S62 - Manual (Page 61)

AT-S62 Web Browser Interface User’s Guide
Section I: Basic Operations 61
HOL Blocking
For a definition of Head of Line Blocking, refer to the AT-S62 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 queue. 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.
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.
Broadcast Filter
Most frames on an Ethernet network are usually unicast frames. A
unicast frame is a frame that is sent to a single destination. A node
sending a unicast frame intends the frame for a particular node on
the network. For example, when a node sends a file to a network
server for storage, the node sends the file in unicast Ethernet
frames containing the destination address of the server where the
file is to be stored.
Broadcast frames are different. Broadcast frames are directed to
all nodes on the network or all nodes within a particular virtual
LAN. Broadcast packets can perform a variety of functions. For
example, some network operating systems use broadcast frames
to announce the presence of devices on a network.
The problem with broadcast frames is that too many of them
traversing a network can impact network performance. The more
bandwidth consumed by broadcast frames, the less available for
unicast frames.
Should the performance of your network be impacted by heavy
broadcast traffic, you can use this parameter to limit the number
of broadcast frames forwarded by the switch and so limit the
number of broadcast frames on your network.