A GARP participant sends Join messages when it must register its attributes (including manually
configured attributes) with other participants, and when it receives Join messages from other participants.
The types of Join messages are JoinEmpty and JoinIn.
A GARP participant sends a JoinEmpty message to declare an attribute not registered on it.
A GARP participant sends a JoinIn message to declare an attribute registered on it.
A GARP participant sends Leave messages to have its attributes deregistered on other participants. It also
sends Leave messages when it deregisters attributes after it receives Leave messages from other GARP
participants, and when attributes are manually deregistered on it. The types of Leave messages are
LeaveEmpty and LeaveIn.
A GARP participant sends a LeaveEmpty message to deregister an attribute not registered on it.
A GARP participant sends a LeaveIn message to deregister an attribute registered on it.
Each GARP participant starts a LeaveAll timer upon startup. When the LeaveAll timer expires, a GARP
participant sends LeaveAll messages to deregister all attributes so that all attributes can be re-registered
on the other GARP participants.
GARP defines timers to control the sending of GARP messages.
The settings of GARP timers apply to all GARP applications, such as GVRP, on a LAN.
On a GARP-enabled network, each port of a switch maintains its own Hold, Join, and Leave timers, but
only one LeaveAll timer is maintained on each switch globally.
The value ranges for the Hold, Join, Leave, and LeaveAll timers are dependent on one another. For more
The Hold timer sets the delay that a GARP participant waits before sending a Join or Leave message.
When an attribute value changes or a Join or Leave message arrives, the GARP participant does not
sends the message immediately. Rather, it assembles Join and Leave messages in the least number of
GARP PDUs, and sends them out when the Hold timer expires. This timer reduces the number of GARP
PDUs and saves bandwidth.
A GARP participant might declare an attribute twice to ensure reliable transmission. The Join timer sets
the interval between the two declarations.
A GARP participant starts a Join timer when it declares an attribute value or receives a JoinIn message
for the attribute value. If the GARP participant does not receive any declaration for the attribute value
when the Join timer expires, it re-declares the attribute value.
All attributes of a GARP participant share the same Join timer. Set the Join timer long enough so that all
attributes can be sent in one declaration.