GVRP reduces
the chance of errors in VLAN configuration
by automatically providing VLAN ID
(VID) consistency across the network. In addition, you can use GVRP to dynamically enable port
membership in static VLANs configured
on a switch. Once GVRP creates
a dynamic VLAN, you can use the
CLI to convert it to a static VLAN. GVRP can also reduce unnecessary
broadcast traffic and unicast traffic.
Keep the following
considerations in mind when configuring GVRP:
- A dynamic VLAN must be converted
to a static VLAN before it can
have an IP address.
- The total number of VLANs
on the switch (static and dynamic combined) cannot exceed the current Maximum VLANs setting. For example, in
the factory default state, the switch supports eight VLANs. Thus, when four static VLANs are configured on the switch,
the switch can accept up to four additional VLANs
in any combination of static and dynamic. Any additional VLANs advertised to the switch
will not be added unless you first increase the maximum VLANs setting.
- Converting a dynamic VLAN to
a static VLAN and then executing
the write memory command saves the VLAN in
the startup configuration file and makes it a permanent part of
the switch’s VLAN configuration.
- Within the same broadcast domain, a dynamic VLAN can pass through a device
that is not GVRP-aware. This
is because a hub or a switch that is not GVRP-aware
will flood the GVRP (multicast)
advertisement packets out all ports.
- GVRP assigns dynamic VLANs as Tagged VLANs. To configure the VLAN as Untagged, you must first convert
it to a static VLAN.
- Rebooting a switch on which a dynamic VLAN exists
deletes that VLAN. However, the
dynamic VLAN reappears after
the reboot if GVRP is enabled
and the switch again receives advertisements for that VLAN through a port configured
to add dynamic VLANs.
- By receiving advertisements from other devices running GVRP, the switch learns of static VLANs on those other devices and
automatically creates tagged VLANs
on the links to the advertising devices. Similarly, the switch advertises
its static VLANs to other GVRP-aware devices, as well as
the dynamic VLANs the switch has learned.
- A GVRP-enabled switch does
not advertise any GVRP-learned VLANs out of the port(s) on which
it originally learned of those VLANs.
- While GVRP is enabled on
the switch, you cannot apply any access control lists ( ACL)s to VLANs configured
on the same switch.
By default, GVRP is
enabled globally and can be enabled/disabled on a per-port basis.