HP 5820X Series

150
A GARP participant sends Join messages when it wants to register with other participants its attributes
(including manually configured attributes), and when it receives Join messages from other participants.
There are two types of Join messages, 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.
2. Leave messages
A GARP participant sends Leave messages to have its attributes deregistered on other participants. It also
sends Leave messages when it deregisters attributes after receiving Leave messages from other GARP
participants, and when attributes are manually deregistered on it. There are two types of Leave messages:
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.
3. LeaveAll messages
Each GARP participant starts a LeaveAll timer upon startup. Upon the expiration of the LeaveAll timer, a
GARP participant sends LeaveAll messages to deregister all attributes so that all attributes can be re-
registered on the other GARP participants.
GARP timers
GARP defines four 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
information, see Table 21.
1. Hold timer
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.
2. Join timer
A GARP participant may 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 share the same Join timer on a GARP participant. Set the Join timer long enough so that all
attributes can be sent out in one declaration.
3. Leave timer
A GARP participant starts a Leave timer when it receives a Leave message for an attribute value. If the
GARP participant has not received a Join message for the attribute value before the timer expires, it
deregisters the attribute value.