Allied Telesis AT-S62 - Manual (Page 428)

Chapter 21: GARP VLAN Registration Protocol
Section V: Virtual LANs 428
An instance of GID consists of the set of state machines that define the
current registration and declaration state of all attribute values
associated with the GARP Participant. Separate state machines exist for
the Applicant and Registrar. This is shown in Figure 136.
Figure 136 GID Architecture
GARP registers and de-registers 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
(de-registering 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 re-declare
(rejoin) after anyone withdraws a declaration (leaves).
Attribute ... state:
Attribute C state:
Attribute A state:
Applicant
State Registrar
State
Attribute B state:
GID