ECS4110-28T_Management Guide

C HAPTER 25 | General Security Measures
Port Security
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COMMAND MODE
Interface Configuration (Ethernet)
COMMAND USAGE
◆ The default maximum number of MAC addresses allowed on a secure
port is zero (that is, port security is disabled). To use port security, you
must configure the maximum number of addresses allowed on a port
using the port security max-mac-count command.
◆ When port security is enabled using the port security command, or
the maximum number or allowed addresses is set to a value lower than
the current limit after port security has been enabled, the switch first
clears all dynamically learned entries from the address table. It then
starts learning new MAC addresses on the specified port, and stops
learning addresses when it reaches a configured maximum number.
Only incoming traffic with source addresses already stored in the
dynamic or static address table will be accepted.
◆ To configure the maximum number of address entries which can be
learned on a port, and then specify the maximum number of dynamic
addresses allowed. The switch will learn up to the maximum number of
allowed address pairs <source MAC address, VLAN> for frames
received on the port. (The specified maximum address count is
effective when port security is enabled or disabled.) Note that you can
manually add additional secure addresses to a port using the mac-
address-table static command. When the port has reached the
maximum number of MAC addresses, the port will stop learning new
addresses. The MAC addresses already in the address table will be
retained and will not be aged out.
◆ MAC addresses that port security has learned, can be saved in the
configuration file as static entries. See command port security
mac-address-as-permanent.
◆ If port security is enabled, and the maximum number of allowed
addresses are set to a non-zero value, any device not in the address
table that attempts to use the port will be prevented from accessing the
switch.
◆ If a port is disabled due to a security violation, it must be manually re-
enabled using the no shutdown command.
◆ A secure port has the following restrictions:
■
Cannot be connected to a network interconnection device.
■
Cannot be a trunk port.
■
RSPAN and port security are mutually exclusive functions. If port
security is enabled on a port, that port cannot be set as an RSPAN
uplink port, source port, or destination port. Also, when a port is
configured as an RSPAN uplink port, source port, or destination
port, port security cannot be enabled on that port.