Enterasys Networks 2200 - Manual (Page 313)

Generic Attribute Registration Protocol (GARP) A-1
A
Generic Attribute Registration Protocol
(GARP)
This appendix describes the switch operation when its ports are configured to operate under the
Generic Attribute Registration Protocol (GARP) applications – GARP VLAN Registration
Protocol (GVRP) and/or GARP Multicast Registration Protocol (GMRP).
A.1 GARP SWITCH OPERATION
Some or all ports on the switch may be activated to operate under the GARP applications, GVRP
and/or GMRP. A description of how GVRP and GMRP handle frames under GARP is described in
Section A.1.1 and Section A.1.2 .
A.1.1 GARP VLAN Registration Protocol (GVRP)
The process of the forwarding decision and tagging frames is the same as for 802.1Q as described
in
Chapter 12 . However, the GVRP protocol frames will not have a tag even when transmitted out
a 1Q Trunk Port.
The purpose of GVRP is to dynamically create VLANs across a switched network. When a VLAN
is declared, the information is transmitted out GVRP configured ports on the switch in a GARP
formatted frame using the GVRP multicast MAC address. A switch that receives this frame,
examines the frame, and extracts the VLAN IDs. GVRP then creates the VLANs and adds the
receiving port to its tagged member list for the extracted VLAN ID(s). The information is then
transmitted out the other GVRP configured ports of the switch.
Figure A-1 shows an example of
how VLAN blue from end station A would be propagated across a switch network.