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CHAPTER 11: VLAN REGISTRATION OVER GARP VLAN REGISTRATION OVER GARP
MULTILINK ML1200 MANAGED FIELD SWITCH – INSTRUCTION MANUAL 11–3
11. Port 2 receives advertisement of VID 3. (Port 2 was already statically
configured for VIDs 1, 2, 3).
If a static VLAN is configured on at least one port of a switch, and that port has established
a link with another device, then all other ports of that switch will send advertisements for
In the following figure, tagged VLAN ports on switch “A” and switch “C” advertise VLANs 22
and 33 to ports on other GVRP-enabled switches that can dynamically join the VLANs. A
port can learn of a dynamic VLAN through devices that are not aware of GVRP (Switch “B”).
FIGURE 11–2: VLAN assignment in GVRP enabled switches
An “unknown VLAN” is a VLAN that the switch learns of by GVRP. For example, suppose that
port 1 on switch “A” is connected to port 5 on switch “C”. Because switch “A” has VLAN 22
statically configured, while switch “C” does not have this VLAN statically configured, VLAN
22 is handled as an “Unknown VLAN” on port 5 in switch “C”. Conversely, if VLAN 22 was
statically configured on switch C, but port 5 was not a member, port 5 would become a
member when advertisements for VLAN 22 were received from switch “A”. GVRP provides a
per-port join-request option which can be configured.
VLANs must be disabled in GVRP-unaware devices to allow tagged packets to pass
through. A GVRP-aware port receiving advertisements has these options:
• If there is no static VLAN with the advertised VID on the receiving port, then
dynamically create a VLAN with the same VID as in the advertisement, and allow
that VLAN's traffic
• If the switch already has a static VLAN with the same VID as in the advertisement,
and the port is configured to learn for that VLAN, then the port will dynamically join
the VLAN and allow that VLAN's traffic.
• Ignore the advertisement for that VID and drop all GVRP traffic with that VID
• Don't participate in that VLAN
• A port belonging to a tagged or untagged static VLAN has these configurable
Port5dynamicallyjoinedVL AN 22
Port2dynamicallyjoinedVL AN 33
Port3dynamicallyjoinedVL AN 33