GVRP PDU Structure

GARP PDUs are encapsulated in the IEEE 802.3 Ethernet format, as shown in Figure 1.

Figure 1 GARP PDU

Each field is described as follows.

Field	Description	Value
Protocol ID	GARP protocol ID	1
Message	GARP message, consisting of Attribute Type and Attribute List	-
Attribute Type	Attribute type, defined by specific GARP applications	The value is 0x01 for GVRP, indicating that the attribute value is a VLAN ID
Attribute List	Attribute list, consisting of multiple attributes	-
Attribute	An attribute, consisting of Attribute Length, Attribute Event, and Attribute Value	-
Attribute Length	Length of an attribute	2–255, in bytes
Attribute Event	Event that an attribute describes	0: LeaveAll Event 1: JoinEmpty Event 2: JoinIn Event 3: LeaveEmpty Event 4: LeaveIn Event 5: Empty Event
Attribute Value	Value of an attribute	The value is a VLAN ID for GVRP. This field is invalid for a LeaveAll attribute.
End Mark	End of a GARP PDU	0x00