HP ProCurve series 2500 Management And Configuration Manual page 275

Table 9-8. Options for Handling "Unknown VLAN" Advertisements:
Unknown VLAN Operation
Mode
Learn Enables the port to dynamically join any VLAN for which it receives an
(the Default) advertisement, and allows the port to forward advertisements it receives.
Block Prevents the port from dynamically joining a VLAN that is not statically
configured on the switch. The port will still forward advertisements that
were received by the switch on other ports. Block should typically be used
on ports in unsecure networks, where there is exposure to "attacks", such
as ports where intruders can connect.
Disable Causes the port to ignore and drop all advertisements it receives from any
source.
The CLI show gvrp command and the menu interface VLAN Support screen
show a switch's current GVRP configuration, including the Unknown VLAN
settings.
Figure 9-59. Example of GVRP Unknown VLAN Settings
The above options also influence GVRP operation on ports where static
VLANs are configured. (See the next section.)
Configuring Advanced Features
GVRP
GVRP Enabled
(Required for Unknown
VLAN operation.)
Unknown VLAN Settings
Learn
Default:
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