Niveo Professional NGSME16T2H - Manual (Page 68)

Chapter 3: Featuring Configuration – Web UI
Featuring Configuration – Web UI
NGSME16T2H User Manual | 68
System Configuration
Mode
Indicates if Limit Control is globally enabled or disabled on the switch. If globally
disabled, other modules may still use the underlying functionality, but limit checks
and corresponding actions are disabled.
Aging Enabled
If checked, secured MAC addresses are subject to aging as discussed under Aging
Period.
Aging Period
If Aging Period is checked, then the aging period is controlled with this input. If other
modules are using the underlying port security for securing MAC addresses, they
may have other requirements to the aging period. The underlying port security will
use the shorter requested aging period of all modules that use the functionality.
The Aging Period can be set to a number between 10 and 10,000,000 seconds.
To understand why aging may be desired, consider the following scenario: Suppose
an end-host is connected to a 3rd party switch or hub, which in turn is connected to a
port on this switch on which Limit Control is enabled. The end-host will be allowed to
forward if the limit is not exceeded. Now suppose that the end-host logs off or
powers down. If it wasn't for aging, the end-host would still take up resources on this
switch and will be allowed to forward. To overcome this situation, enable aging. With
aging enabled, a timer is started once the end-host gets secured. When the timer
expires, the switch starts looking for frames from the end-host, and if such frames
are not seen within the next Aging Period, the end-host is assumed to be
disconnected, and the corresponding resources are freed on the switch.