3Com Switch 8800 Configuration Guide Chapter 9 GARP/GVRP Configuration
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Chapter 9 GARP/GVRP Configuration 9.1 Configuring GARP
9.1.1 GARP Overview
Generic attribute registration protocol (GARP) offers a mechanism that is used by the
members in the same switching network to distribute, propagate and register such
information as VLAN and multicast addresses.
GARP dose not exist in a switch as an entity. A GARP participant is called GARP
application. The main GARP applications at present are GVRP (GARP VLAN
registration protocol) and GMRP. For details, refer to section 9.2 “Configuring GVRP”
and section ”Configuring Multicast”. When a GARP participant is on a port of the switch,
this port corresponds to a GARP participant.
The GARP mechanism enables the configuration information on one GARP member to
be propagated rapidly across the whole switching network. A GARP member can be a
terminal workstation or a bridge. The GARP member can notify other members to
register or remove its attribute information by sending declarations or withdrawing
declarations. It can also register or remove the attribute information of other GARP
members according to the received declarations/withdrawn declarations.
GARP members exchange information by sending messages. There are mainly three
types of GARP messages, Join, Leave, and LeaveAll. When a GARP participant wants
to register its attribute information with other switches, it sends the Join message
outward. When it wants to remove some attribute information from other switches, it
sends the Leave message. The LeaveAll timer is started simultaneously when each
GARP participant is enabled and the LeaveAll message is sent upon expiration. The
Join and Leave messages cooperate to ensure the logout and the re-registration of a
message. The message exchange enables all the to-be-registered attribute information
to be propagated to all the switches across the same switching network.
The destination MAC addresses of the packets of the GARP participants are specific
multicast MAC addresses. A GARP-supporting switch classifies the packets received
from the GARP participants and processes them with corresponding GARP
applications (GVRP or GMRP).
GARP and GMRP are described in details in the IEEE 802.1P standard (which has
been added to the IEEE802.1D standard). Quidway series switches fully support the
GARP compliant with the IEEE standards.
The following section describes the GARP configuration task:
z Setting the GARP Timer