3Com 4007, Implementation Manual, Page: 197 / 684

GARP VLAN Registration Protocol (GVRP) 197
GARP VLAN
Registration
Protocol (GVRP)
To activate GVRP on a Multilayer Switching Module, you enable the GARP
VLAN Registration Protocol (GVRP) first on the bridge and then on
individual bridge ports. On a port-by-port basis, GVRP allows the module
to automatically learn the presence of and updates to 802.1Q VLANs.
GVRP simplifies the management of IEEE 802.1Q VLAN configurations in
large networks by making aspects of VLAN configuration dynamic.
GVRP maintains a database of VLAN member ports as the bridge learns
about them. Specifically, GVRP tracks which ports are added to and
removed from each VLAN and communicates this information to other
GVRP-aware bridges. The bridges then determine active topologies for
the network and for each VLAN using STP to prevent network loops.
GVRP operates only on ports that are in the STP forwarding state. If GVRP
is enabled, a port that changes to the STP forwarding state automatically
begins to participate in GVRP. A port that changes to an STP state other
than forwarding no longer participates in GVRP.
Important
Considerations
To use GVRP, consider the following:
■
GVRP updates are not sent out to any blocked STP ports. GVRP
operates only on ports that are in the STP forwarding state. If GVRP is
enabled, a port that changes to the STP forwarding state
automatically begins to participate in GVRP. A port that changes to an
STP state other than forwarding no longer participates in GVRP.
■
GVRP is disabled by default on the bridge and on all bridge ports.
■
Enabling GVRP determines whether the VLAN origin for a port-based
VLAN is dynamic (GVRP enabled) or static (GVRP disabled).
■
To maximize the effectiveness of GVRP, it should be supported in as
many end stations and network devices as possible.
■
Based on updates from GVRP-enabled devices, GVRP allows the
module to dynamically create a port-based VLAN (unspecified
protocol) with a specific VLAN ID and a specific port.
■
On a port-by-port basis, GVRP allows the module to learn about GVRP
updates to an existing port-based, protocol-based, or network-based
VLAN with that VLAN ID and IEEE 802.1Q tagging.
■
VLANs that are created dynamically with GVRP exist only as long as a
GVRP-enabled device is sending updates — if the devices no longer