Allied Telesis AT-S63 - Manual (Page 478)

Chapter 21: GARP VLAN Registration Protocol
478 Section III: VLANs
the applicant and registrar. This is shown in Figure 148.
Figure 148. 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.
Attribute ... state:
Attribute C state:
Attribute A state:
Applicant
State Registrar
State
Attribute B state:
GID