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AT-S63 Management Software Features Guide
Section VI: Virtual LANs 271
Figure 37. GID Architecture
GARP registers and deregisters attribute values through GARP messages
sent at the GID level. A GARP participant that wishes to make a
declaration (an applicant registering an attribute value) sends a JoinIn or
JoinEmpty message. An applicant that wishes to withdraw a declaration
(deregistering an attribute value) sends a LeaveEmpty or LeaveIn
message. Following the de-registration of an attribute value, the applicant
sends a number of Empty messages. The purpose of the Empty message
is to prompt other applicants to send JoinIn/JoinEmpty messages. For the
GARP protocol to be resilient against multiple lost messages, a LeaveAll
message is available. Timers are used in the state machines to generate
events and control state transitions.
The job of the applicant is twofold:
To ensure that this participant’s declarations are registered by other
participants’ registrars
To ensure that other participants have a chance to redeclare (rejoin)
after anyone withdraws a declaration (leaves).
The applicant is therefore looking after the interests of all would-be
participants. This allows the registrar to be very simple.
The job of the registrar is to record whether an attribute is registered, in the
process of being deregistered, or is not registered for an instance of GID.
Attribute ... state:
Attribute C state:
Attribute A state:
Applicant
State
Registrar
State
Attribute B state:
GID