Administrator Guide

Layer 2 Switching Commands 288
MAC Address Table Commands
Dell Networking N1500/N2000/N3000/N4000 Series Switches
Dell Networking switches implement a MAC Learning Bridge is compliance
with IEEE 802.1Q. The switches implement independent VLAN learning
(IVL). Dynamically learned MAC addresses are used to filter the set of ports
on which a frame is forwarded within a VLAN, that is, the destination MAC
address and ingress VLAN for a frame entering the switch is looked up in the
MAC address table and, if a match is found, the frame is forwarded out the
matching port(s). If no match is found, the frame is flooded out all ports in
the VLAN except for the ingress port.
When a frame is received on a port, the source MAC address (and VLAN) is
looked up in the MAC address table. If no matching entry is found, a new
entry is added to the MAC address table assciated with the source port. If a
matching entry is found, the matching entry timestamp is refreshed such
that it will continue to remain in the MAC address table. Dynamic MAC
address entries for which no frames have been received within the aging
period are removed out of the MAC address table. The administrator can
globally configure the MAC address aging timer.
Administrators can configure static MAC address entries. Static MAC entries
are treated in the same manner as dynamic MAC address entries for the
purposes of frame forwarding. Static MAC addresses never age out of the
MAC address database and can only be removed by administrator action.
Port security allows the administrator to disable learning of MAC addresses
on selected interfaces. Dynamically learned MAC addresses are flushed on an
interface at the time port security is enabled. The interface then dynamically
learns MAC addresses up to the configured limit and no more. The
administrator may configure a limit of 0 in order to disable MAC learning on
the interface entirely. In this configuration, it is advisable to configure static
MAC entries on the interface in order to facilitate forwarding.
2CSNXXX_SWUM204.book Page 288 Monday, January 25, 2016 1:25 PM