3Com Switch 8800 Advanced Software V5 Configuration Guide

Introduction to GVRP 141
GARP message format
The following figure illustrates the format of GARP messages, which are carried in
GARP PDUs.
Figure 37 Figure 11-1 GARP message format
The following table describes the GARP message fields.
Tab le 15 Table 11-1 Description on the GARP message fields
Field Description Value
Protocol ID Protocol identifier for GARP 1
Message Each message contains an
attribute type and an attribute
list
--
Attribute Type Defined by the concerned
GARP application
0x01 for GVRP, indicating the
VLAN ID attribute
Attribute List Contains one or multiple
attributes
--
Attribute Consists of an Attribute
Length, an Attribute Event,
and an Attribute Value
--
Attribute Length Number of octets occupied by
an attribute, inclusive of the
attribute length field
2 to 255 in bytes
Attribute Event Event described by the
attribute
0: LeaveAll
1: JoinEmpty
2: JoinIn
3: LeaveEmpty
4: LeaveIn
5: Empty
Attribute Value Attribute value VLAN ID for GVRP
If the Attribute Event is
LeaveAll, Attribute Value is
omitted.
End Mark Indicates the end of PDU --
GARP PDU structure
Message structure
Attribute List structure
Attribute structure
Protocol ID Message N End Mark...
Attribute 1 End Mark...
Attribute Type
Attribute Length Attribute Event Attribute Vlaue
1
1
1
1
3
3
2
2
N
N
N
N
Message 1
Attribute List
Attribute N