UMN:CLI
User Manual
V8102
446
9.8
Generic Attribute Registration Protocol (GARP)
Generic Attribute Registration Protocol (GARP) is an industry-standard protocol described
in IEEE 802.1D and IEEE 802.1Q. Both GARP VLAN Registration Protocol (GVRP) and
Multicast Registration Protocol (GMRP) are one of the GARP applications that provide a
generic framework so bridges could register and deregister attribute values, such as
VLAN identifiers and multicast group membership. GARP makes the configurations to be
restricted to a few devices and applications and the remaining devices or applications
learn the required information dynamically.
A GARP applicant may or may not to actively involve in declaring or registering the attrib-
ute value. By declaring an attribute A, a GARP applicant indicates to the other applicants
that it is associated with attribute A or it is interested to know about other applicants asso-
ciation with the attribute A. By registering an attribute A, a GARP applicant already knows
that there are applicants associated with the attribute A.
A GARP applicant can be a member or an observer. A member actively declares attrib-
utes. However, an observer does not declare but receive the attribute information like
GVRP or GMRP protocol data unit (PDUs).
GARP applicants use GARP messages to declare or register its attribute.
GARP Messages
There are five types of GARP messages as shown below:
JoinEmpty & JoinIn
: These messages are used by an applicant to declare an attribute.
Reception of a JoinIn message from other applicants or transmission of Join messages
enables an applicant to register the attribute.
LeaveEmpty
& LeaveIn
: These messages are used by an applicant to withdraw its dec-
laration when it is no more associated with an attribute.
LeaveAll
: It is in charge of periodic declarations and registration maintenance. An appli-
cant periodically sends LeaveAll messages which enable other applicants to indicate their
attributes registered states.
The GARP supports the following two applications:
•
GARP VLAN Registration Protocol (GVRP)
It enables VLAN Bridges to dynamically learn their VLAN membership. The switch
can exchange VLAN configuration information with other GVRP switches. You can
configure the minimum VLAN configuration at a bridge. However, you should keep in
mind the following conditions to use GVRP.
–
Member ports are added as either tagged or untagged members based on the
confirmed reachability of VLAN aware/un-aware devices.
–
GVRP is enabled/disabled globally.
–
GVRP is enabled/disabled on the port.
–
Dynamic VLAN registration is enabled/disabled by processing the received GVRP
messages.
