145
3. Leave timer
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 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 45 GARP message format
Ethernet frame
Attribute length Attribute event Attribute value
DA SA Length DSAP SSAP Ctrl GARP PDU
Attribute listAttribute type
... Message nMessage 1Protocol ID End mark
...Attribute 1 Attribute n End mark
As shown in Figure 45, GARP messages use the IEEE 802.3 Ethernet frame format.
Table 18 Descriptions of the GARP message fields
Protocol identifier for GARP PDU
One or multiple messages, each
of which contains an attribute
type and an attribute list
Indicates the end of a GARP PDU
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