Controlling how individual ports handle advertisements for new VLANs

When GVRP is enabled on the switch, use this command to change the Unknown VLAN field for one or more ports.

Syntax:

interface <port-list> unknown-vlans [ learn | block | disable ]

Changes the Unknown VLAN field to control how one or more ports handle advertisements. Use at either the Manager or interface context level for a port.

Changing the Unknown VLAN field

In the following example, the first command changes the configuration to Block, the second command requests to show the new configuration:

switch(config)# interface 1-2 unknown-vlans block

switch(config)# show gvrp
 GVRP support
  Maximum VLANs to support [256] : 256
  Primary VLAN : DEFAULT_VLAN 
  GVRP Enabled [No] : Yes

  Port Type      | Unknown VLAN Join  Leave Leaveall
  ---- --------- + ------------ ----- ----- --------
  1    10/100TX  | Block        20    300   1000
  2    10/100TX  | Block        20    300   1000
  3    10/100TX  | Learn        20    300   1000
  4    10/100TX  | Learn        20    300   1000

When you enable GVRP on a switch, you have the per-port join-request options listed in the following table:

Options for handling unknown VLAN advertisements
Unknown VLAN Mode	Operation
`Learn` (the Default)	Enables the port to become a member of any unknown VLAN for which it receives an advertisement. Allows the port to advertise other VLANs that have at least one other port on the same switch as a member.
`Block`	Prevents the port from joining any new dynamic VLANs for which it receives an advertisement.Allows the port to advertise other VLANs that have at least one other port as a member.
`Disable`	Causes the port to ignore and drop all GVRP advertisements it receives and prevents the port from sending any GVRP advertisements.