Allied Telesis AT-S39 - Manual (Page 152)

Section II: Local and Telnet Management
152
Broadcast Frame Control Overview
Most frames on an Ethernet network are unicast frames. A unicast frame
is sent to a single destination. That is, the node sending a unicast frame
intends the frame for a particular node on the network. For example,
when a node needs to send 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. When a node sends out a broadcast
frame, the frame is directed to all nodes on the network or all nodes
within a particular virtual LAN. Broadcast packets can perform a variety
of functions in an Ethernet network. For example, some network
operating systems use broadcast frames to announce the presence of
devices on the network.
The problem with broadcast frames is that too many of them traversing
the network can impact network performance. Should the performance
of your network has been diminished by heavy broadcast traffic, you can
use the AT-S39 management software to limit the number of broadcast
frames passing through the switch and so limit the number of broadcast
frames on your network.
In order to use this feature, you must set two values: the interval timer
and the maximum broadcast frame limit.
The interval timer defines the time period used in counting the number
of broadcast frames on a port. You can specify a different value for 10
Mbps, 100 Mbps and 1000 Mbps ports on the switch. A time interval
setting applies to all corresponding ports on the switch.
The timer interval for 10 and 100 Mbps ports is measured in
milliseconds. The timer interval for 1000 Mbps ports is measured in
microseconds.
The maximum broadcast frame limit specifies the maximum number of
broadcast frames the switch will allow on a port during the specified
timer interval. Broadcast frames received once the maximum has been
exceeded are discarded by the port and are not forwarded. You can
specify a different maximum for each port on the switch.