Garp Overview; Gvrp Overview - Alcatel-Lucent OmniSwitch 6850-48 Network Configuration Manual

Configuring GVRP

GARP Overview

GARP was introduced to avoid manual configuration of devices and applications in a large network. It
enables dynamic configuration of devices and applications in a network. It also provides a generic
framework whereby devices in a bridged LAN can register and de-register attribute values, such as VLAN
identifiers, with each other. These attributes are propagated through devices in the bridged LAN. GARP
consists of:
GARP Information Declaration (GID)—The part of GARP that generates data from the switch.
GARP Information Propagation (GIP)—The part of GARP that distributes data to different switches.
A GARP applicant may or may not choose to actively participate in declaring and registering an attribute
value. By declaring an attribute, a GARP applicant indicates to other applicants that it is either associated
with the attribute or it is interested to know about the other applicants associated with that attribute. A
GARP applicant that declares attributes is referred to as an active member. A passive member is an appli-
cant interested in an attribute but will not initiate GARP PDUs when it is aware that other applicants have
also registered the attribute.
The following messages are used in GARP:
JoinIn and JoinEmpty—Used by an applicant (including itself) associated with an attribute. Receiving
JoinIn messages from other applicants or transmitting JoinEmpty messages enables an applicant to regis-
ter the attribute.
LeaveIn and LeaveEmpty—Used by an applicant to withdraw its declaration when it is no more associ-
ated with an attribute.
LeaveAll—Used for periodic declarations and registration maintenance. An applicant periodically sends
LeaveAll messages, which enable other applicants to indicate their attributes' registered states.
These messages indicate the current state of the sender applicant device to other GARP applicant devices.
With this information, these GARP applicant devices can modify their behavior associated with the
attribute (declare and withdraw).

GVRP Overview

GVRP, an application of GARP, is designed to propagate VLAN information from device to device. With
GVRP, a single switch is manually configured with all the desired VLANs for the network, and all the
other switches on the network learn those VLANs dynamically. An end station can be plugged into a
switch and be connected to its desired VLAN. However, end stations need GVRP-aware Network Inter-
face Cards (NIC) to make use of GVRP.
GVRP sends information encapsulated in an Ethernet frame to a specific MAC address
(01:80:C2:00:00:21). Based on the received registration information (Join message of GARP), VLAN
information is learned on a system. GVRP enables new dynamic VLANs on a device or dynamically
registers a port to an existing VLAN. In effect, based on the received registration information of a VLAN,
the port becomes associated with that VLAN. Similarly, whenever de-registration information is received
for a VLAN (Leave message of GARP) on a particular port, the association of that VLAN with the port
may get deleted.
A GVRP-enabled port sends GVRP PDUs advertising the VLAN. Other GVRP-aware ports receiving
advertisements over a link can dynamically join the advertised VLAN. All ports of a dynamic VLAN
operate as tagged ports for that VLAN. Also, a GVRP-enabled port can forward an advertisement for a
OmniSwitch AOS Release 6 Network Configuration Guide September 2009
GARP Overview
page 5-3