ZyXEL Communications MGS3600-24F User Manual page 307

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RONT ATTER
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.
Port Configuration
Port:

The port number to which the configuration below applies.
Mode:

Controls whether Limit Control is enabled on this port. Both this and the Global Mode must be set to Enabled for Limit Control to be in effect.
Notice that other modules may still use the underlying port security features without enabling Limit Control on a given port.
Limit:

The maximum number of MAC addresses that can be secured on this port. This number cannot exceed 1024. If the limit is exceeded, the
corresponding action is taken.
The switch is born with a total number of MAC addresses from which all ports draw whenever a new MAC address is seen on a Port Secu-
rity-enabled port. Since all ports draw from the same pool, it may happen that a configured maximum cannot be granted, if the remaining
ports have already used all available MAC addresses.
Action:

If Limit is reached, the switch can take one of the following actions:
None: Do not allow more than Limit MAC addresses on the port, but take no further action.

Trap: If Limit + 1 MAC addresses is seen on the port, send an SNMP trap. If Aging is disabled, only one SNMP trap will be sent, but with

Aging enabled, new SNMP traps will be sent every time the limit gets exceeded.
Shutdown: If Limit + 1 MAC addresses is seen on the port, shut down the port. This implies that all secured MAC addresses will be

removed from the port, and no new address will be learned. Even if the link is physically disconnected and reconnected on the port (by
disconnecting the cable), the port will remain shut down. There are three ways to re-open the port:
Boot the stack or elect a new master the switch,

Disable and re-enable Limit Control on the port or the stacks witch,

MGS3600-24F/XGS3600-26F/XGS3600-28F 8-34 U ' G
SER S UIDE