3Com Switch 7750 Configuration Guide Guide

Introduction to GARP and GVRP 147
The protocol packets of GARP entity use specific multicast MAC addresses as their
destination MAC addresses. When receiving these packets, the switch
distinguishes them by their destination MAC addresses and delivers them to
different GARP application (for example, GVRP) for further processing.
GVRP Packet Format The GVRP packets are in the following format:
Figure 37 Format of GVRP packets
The following table describes the fields of a GVRP packet.
Table 85 Description of GVRP 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
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
The attribute value of GVRP is
the VID.