Packet Format

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

Figure 1 GARP packet format

The following table describes the fields in a GARP packet.

Field	Description	Value
Protocol ID	Indicates the protocol ID.	1
Message	Indicates the messages in the packet. Each message consists of the Attribute Type and Attribute List fields.	-
Attribute Type	Indicates an attribute type, which is defined by the GARP application.	0x01 for GVRP, indicating that the attribute value is a VLAN ID
Attribute List	Indicates the attribute list of a message, which consists of multiple attributes.	-
Attribute	Indicates an attribute, which consists of the Attribute Length, Attribute Event, and Attribute Value fields.	-
Attribute Length	Indicates the length of an attribute.	2 to 255, in bytes
Attribute Event	Indicates the 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	Indicates the value of an attribute.	VLAN ID for GVRP This field is invalid in a LeaveAll attribute.
End Mark	Indicates the end of a GARP PDU.	0x00