HP 6125G Configuration Manual page 152

A GARP participant sends Join messages when it wishes to declare its attribute values or receives
Join messages from other GARP participants.
Join messages fall into JoinEmpty and JoinIn. A GARP participant sends JoinEmpty messages to
declare attribute values that it has not registered. It sends JoinIn messages to declare attribute
values that it has registered.
Leave messages
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A GARP participant sends Leave messages when it wishes to withdraw declarations of its attribute
values (because, for example, it has deregistered its attribute values), or receives Leave messages
from other participants.
Leave messages fall into LeaveEmpty and LeaveIn. A GARP participant sends LeaveEmpty
messages to withdraw declarations of the attribute values that it has not registered. It sends LeaveIn
messages to withdraw declarations of the attribute values that it has registered.
LeaveAll messages
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A GARP participant sends a LeaveAll message when it declares that it is deregistering all attribute
values or receives LeaveAll messages from other participants. If any participants want to maintain
the registration for a particular attribute value, they must send a Join message.
GARP timers
HP's implementation of GARP uses the following timers to control GARP message transmission:
• 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 send 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.
• Join timer
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.
Because all attributes of a GARP participant share the same Join timer, you must set the Join timer
long enough so that all attributes can be sent out in one declaration.
Leave timer
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A GARP participant starts a Leave timer when it receives a Leave message for an attribute value.
If the GARP participant receives no Join message for the attribute value before the timer expires, it
deregisters the attribute value.
LeaveAll timer
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When a GARP application is enabled, a LeaveAll timer starts. The GARP participant sends a
LeaveAll message when the timer expires. Then, the LeaveAll timer restarts to begin a new cycle.
The LeaveAll timer and all other GARP timers also restart when the GARP participant receives a
LeaveAll message.
When you configure GARP timers, follow these guidelines:
The settings of GARP timers apply to all GARP applications, such as GVRP, on a LAN.
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