AutoTracker VLANs
Page 22-5

How Devices are Assigned to AutoTracker VLANs

When a broadcast frame, a multicast frame, or a unicast frame from an unknown device is
received at a switching module, the frame is forwarded to the MPX for processing. Source
learning logic on the MPX module examines the entire frame to determine the VLAN or VLANs
in which the originating device should be a member. If the frame matches any one policy
defined for a VLAN, the originating device (and the port to which it is connected) are made
members of that VLAN. If the frame does not match any VLAN policy, one of the following
occurs:
• If the defvl command is on, the source device is made a member of Default VLAN #1 in the
Group of which the source port is a member. The defvl command determines whether traf-
fic from devices that do not match any policies is assigned to the default VLAN or dropped.
(See “The defvl Command” below for more information on this command.)
• If the defvl command is off, all traffic from the source device is dropped.
Please Take Note
A broadcast or multicast frame is processed to
determine the source device’s VLAN membership
each time it is received. A unicast frame is
processed to determine the source device’s VLAN
membership only the first time it is received.
When the MPX module has determined the VLAN or VLANs in which the originating device
belongs, it relays this information to the switching module. The switching module updates a
VLAN membership flag attached to the frame’s source MAC address in the CAM (content-
addressable memory). The frame is then switched based on this membership flag.
Refer to Chapter 24, “AutoTracker VLAN Application Examples,” for information on
AutoTracker VLAN assignments in specific network situations.

The defvl Command

You can turn the defvl command on and off simply by entering defvl on or defvl off. If you
enter the command without any parameters, it displays the current setting for the Default
VLAN. For example, if source devices are automatically placed in the Default VLAN when they
do not match any VLAN policy rule, the following message would display:
membership in default vlan is currently on
If source devices are automatically dropped when they do not match any VLAN policy, the
following message would display:
membership in default vlan is currently off
The defvl command applies to all Groups in an Omni Switch/Router and it is only applicable
if there is at least one AutoTracker rule configured.