Basic Concepts
On a switch, each GVRP-enabled interface is a GVRP participant. A GVRP participant sends an attribute declaration or attribute reclaim declaration to request other GVRP participants to register or deregister its attributes. A GVRP participant can also register or deregister attributes of other GVRP participants when receiving attribute declarations or attribute reclaim declarations from other GVRP participants.
A manually configured VLAN is a static VLAN, and a VLAN learned through GVRP is a dynamic VLAN.
GVRP Messages
Type |
Function |
Description |
|---|---|---|
Join message |
When a GVRP participant is configured with VLANs and expects other devices to register its attributes, it sends Join messages to other devices. |
Join messages are classified into two types:
|
Leave message |
When a GVRP participant where static VLANs are deleted expects other devices to deregister its attributes, it sends Leave messages to other devices. |
Leave messages are classified into two types:
|
LeaveAll message |
A GVRP participant sends LeaveAll messages to deregister all VLAN attributes so that other GVRP participants can re-register attributes. LeaveAll messages are used to periodically delete useless attributes on a network. For example, an attribute of a GVRP participant is deleted. Due to a sudden power failure, the GVRP participant does not send Leave messages to request other participants to deregister the attribute. In this case, the attribute becomes useless, necessitating the use of a LeaveAll message. |
When an interface is enabled with GVRP, the LeaveAll timer is started. When the LeaveAll timer expires, the GVRP participant sends LeaveAll messages to other devices. |
Timer
Timer |
Function |
Description |
|---|---|---|
Join timer |
The Join timer controls the sending of Join messages. Each interface maintains an independent Join timer. |
After sending the first Join message, a GARP participant starts the Join timer. If the participant receives a JoinIn message before the Join timer expires, it does not send the second Join message. If the GARP participant does not receive any JoinIn message, it sends the second Join message when the Join timer expires. This ensures that the Join message can be reliably transmitted to other GARP participants. |
Hold timer |
The Hold timer controls the sending of Join and Leave messages. Each interface maintains an independent Hold timer. |
After a GARP participant is configured with an attribute or receives a Join or Leave message, it does not send the message to other GARP participants before the Hold timer expires. The GARP participant encapsulates messages received into a minimum number of packets within the Hold timer value, reducing the number of packets sent to other GARP participants. |
Leave timer |
The Leave timer controls the sending of Leave messages. Each interface maintains an independent Leave timer. |
A GARP participant starts the Leave timer after receiving a Leave or LeaveAll message. If the GARP participant does not receive any Join message of the corresponding attribute before the Leave timer expires, the GARP participant deregisters the attribute. |
LeaveAll timer |
The LeaveAll timer controls the sending of LeaveAll messages and restarts all timers including the LeaveAll timer itself. Each device maintains a global LeaveAll timer. |
When a GARP participant is enabled, the LeaveAll timer is started. When the LeaveAll timer expires, the GARP participant sends LeaveAll messages for other GARP participants to re-register its attributes. Then the LeaveAll timer started again. Devices on a network may use different LeaveAll timer values, but all the devices use the smallest LeaveAll timer value on the network. |
The relationship between four timers is as follows: LeaveAll timer > Leave timer > 2 x Join timer >= 4 x Hold timer |
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Registration Modes
- In normal mode, a GVRP interface can register and deregister VLANs as well as transmit dynamic and static VLAN registration information.
- In fixed mode, a GVRP interface is disabled from dynamically registering and deregistering VLANs and can only transmit static VLAN information. If the registration mode of a trunk interface is set to fixed, the interface allows only the manually configured VLANs even if it is configured to allow all the VLANs.
- In forbidden mode, a GVRP interface is disabled from dynamically registering and deregistering VLANs and can transmit only information about VLAN 1. If the registration mode of a trunk interface is set to forbidden, the interface allows only VLAN 1, even if the interface is configured to allow all the VLANs.
Registration Mode on SwitchA |
Registration Mode on SwitchB |
Result |
|---|---|---|
Normal |
Normal |
SwitchA learns dynamic VLAN 20 and SwitchB learns dynamic VLAN 10. |
Fixed |
SwitchA learns dynamic VLAN 20 and SwitchB does not learn dynamic VLAN 10. |
|
Forbidden |
SwitchA and SwitchB do not learn VLANs of each other. |
|
Fixed |
Fixed |
SwitchA and SwitchB do not learn VLANs of each other. |
Forbidden |
SwitchA and SwitchB do not learn VLANs of each other. |
|
Forbidden |
Forbidden |
SwitchA and SwitchB do not learn VLANs of each other. |