H3C Technologies H3C S12500 Series Switches - Manual (Page 185)

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de-registration of attribute information. As a GARP application, GVRP also uses GARP messages for
information exchange.
1. Join messages
A GARP participant sends Join messages when it wishes to declare its attribute values or receives
Join messages from other GARP 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 when it wishes to withdraw declarations of its attribute
values, or receives Leave messages from other participants. 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
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
GARP defines the following timers to control the sending of GARP messages:
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 can 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.
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.
4. LeaveAll timer
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.