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.
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.
NOTE:
•
Because a LeaveAll message deregisters all attributes in the entire network, do not set the LeaveAll timer
too short. At a minimum, the LeaveAll timer must be at least longer than the Leave timer.
•
On a GARP-enabled network, a switch can send LeaveAll messages at the interval set by its LeaveAll
timer or the LeaveAll timer of another device on the network, whichever is smaller. This is because each
time a switch on the network receives a LeaveAll message, it resets its LeaveAll timer.
GARP message format
Figure 39
GARP message format
As shown in
, GARP messages use the IEEE 802.3 Ethernet frame format.
Table 18
Descriptions of the GARP message fields
Field Description
Value
GARP PDU
GARP Protocol Data Unit
––
Protocol ID
Protocol identifier for GARP PDU
0x0001
Message
One or multiple messages, each of
which contains an attribute type
and an attribute list
––
End mark
Indicates the end of a GARP PDU
0x00
Attribute type
Defined by the GARP application
0x01 for GVRP, which indicates
the VLAN ID attribute
Attribute list
Contains one or multiple attributes
––
127