H3C Technologies H3C S10500 Series Switches - Manual (Page 175)

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Field Description Value
Attribute
Consists of an attribute length, an attribute
event, and an attribute value
––
Attribute length
Length of an attribute, inclusive of the
attribute length field
2 to 255 (in bytes)
Attribute event Event that the attribute describes
• 0x00: LeaveAll event
• 0x01: JoinEmpty event
• 0x02: JoinIn event
• 0x03: LeaveEmpty event
• 0x04: LeaveIn event
• 0x05: Empty event
Attribute value Attribute value
VLAN ID for GVRP
If the value of the attribute event field is
0x00 (LeaveAll event), the attribute value
field is invalid.
The destination MAC addresses of GARP messages are multicast MAC addresses, and vary with GARP
applications. For example, the destination MAC address of GVRP is 01-80-C2-00-00-21.
GVRP
GVRP overview
As a GARP application, GVRP uses the operating mechanism of GARP to maintain and propagate
dynamic VLAN registrations throughout a switched LAN.
In a switched LAN, each GVRP-enabled switch sends and receives VLAN declarations and withdrawals
from other GVRP-enabled switches, and dynamically updates its local database, including active VLAN
members and through which port each VLAN member can be reached. This ensures that all
GVRP-enabled switches in a LAN maintain the same VLAN information.
The VLAN information propagated by GVRP includes not only manually configured static VLAN
information but also dynamic VLAN information from other switches.
GVRP registration modes
GVRP is available on trunk ports. It provides the following registration modes:
• Normal mode—Performs dynamic VLAN registrations and deregistrations on the trunk port, and
sends declarations and withdrawals for dynamic and static VLANs. VLANs manually configured
are called static VLANs, and VLANs created by GVRP are called dynamic VLANs.
• Fixed mode—Disables the trunk port to register or withdraw dynamic VLAN information, but allows
the port to send declarations for static VLANs. A trunk port in this mode carries only static VLANs,
even if it has been assigned to all VLANs.
• Forbidden mode—Disables the trunk port to register or withdraw dynamic VLAN information, and
allows the port to send declarations only for VLAN 1. A trunk port in this mode carries only VLAN
1 even if it has been assigned to any other VLANs.
Protocols and standards
• IEEE 802.1Q, Virtual Bridged Local Area Networks