3Com WX3000 Switch User Manual


 
1-3
Figure 1-1 Format of GARP packets
Ethernet Frame
PDUDA DA length DSAP CtrlSSAP
Protocol ID Message 1 Message N... End Mark
1
3
N
Attribute Type Attribute List
12N
Attribute 1 Attribute N... End Mark
1N
Attribute Length Attribute Event Attribute Vlaue
123N
GARP PDU structure
Message structure
Attribute List structure
Attribute structure
The following table describes the fields of a GARP packet.
Table 1-1 Description of GARP packet fields
Field Description Value
Protocol ID Protocol ID 1
Message
Each message consists of two parts:
Attribute Type and Attribute List.
Attribute Type
Defined by the specific GARP
application
The attribute type of GVRP is 0x01.
Attribute List It contains multiple attributes.
Attribute
Each general attribute consists of
three parts: Attribute Length,
Attribute Event, and Attribute Value.
Each LeaveAll attribute consists of
two parts: Attribute Length and
LeaveAll Event.
Attribute Length The length of the attribute 2 to 255 (in bytes)
Attribute Event The event described by the attribute
0: LeaveAll Event
1: JoinEmpty
2: JoinIn
3: LeaveEmpty
4: LeaveIn
5: Empty
Attribute Value The value of the attribute
For GVRP packets, the value of this
field is the VLAN ID; however, for
LeaveAll messages, this field is invalid.
End Mark End mark of an GARP PDU The value of this field is fixed to 0x00.