5.1 GVRP Overview
This section explains the concept of Generic Attribute Registration Protocol (GARP) and GARP
VLAN Registration Protocol (GVRP), and how they relate to each another.
GVRP
GVRP is an application of GARP that maintains and propagates VLAN registration information
to other devices.
GARP
GARP enables member routers on a LAN to distribute, transmit, and register information such
as VLAN information and multicast addresses with one another.
GARP is not an entity on a device. GARP-compliant entities are called GARP participants.
GVRP is a GARP application. When a GARP application runs on an interface, the interface is
considered a GARP participant.
GARP members transmit VLAN registration information by exchanging GARP messages. The
three main GARP messages are Join, Leave, and LeaveAll.
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Join messages: When a GARP participant expects other devices to register its attributes, it
sends Join messages to other devices. When the GARP participant receives a Join message
from another participant or is statically configured with attributes, it also sends Join
messages to other devices for the devices to register the new attributes.
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Leave messages: When a GARP participant expects other devices to deregister its attributes,
it sends Leave messages to other devices. When the GARP participant receives a Leave
message from another participant or some of its attributes are statically deregistered, it also
sends Leave messages to other devices.
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LeaveAll messages: When a GARP participant is enabled, the LeaveAll timer is started.
When the LeaveAll timer expires, the GARP participant sends LeaveAll messages to
request other GARP participants to deregister all the attributes of the sender. Then other
participants can re-register the attributes.
The Join, Leave, and LeaveAll messages are used to control registration and deregistration of
attributes.
Through GARP messages, all attributes that need to be registered are sent to all the GARP-
enabled devices on the same LAN.
The intervals for sending GARP messages are controlled by GARP timers. GARP defines four
timers to control the intervals for sending GARP messages.
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Hold timer: When a GARP participant receives a registration message from another
participant, it does not send the registration message in a Join message to other participants
immediately. Instead, the participant starts the Hold timer. When the Hold timer expires,
the participant packs all the registration messages received within this period in a Join
message and sends the Join message to other participants. Hold timers help economize
bandwidth.
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Join timer: To ensure reliable transmission of Join messages, a participant can send each
Join message twice. If the participant does not receive a response after sending the Join
Huawei AR3200 Series Enterprise Routers
Configuration Guide - LAN
5 GVRP Configuration
Issue 02 (2012-03-30)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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