Enterasys Networks 2200 - Manual (Page 314)

GARP Switch Operation
A-2 Generic Attribute Registration Protocol (GARP)
In Figure A-1 , Switch 4, port 1 is registered as being a member of VLAN Blue and then declares
this fact out all its ports (2 and 3) to Switch 1 and Switch 2. These two switches register this in the
Port VLAN Lists of the ports (Switch 1, port 1 and Switch 2, port 1) that received the frames with
the information. Switch 2, which is connected to Switch 3 and Switch 5 declares the same
information to those two switches and the Port VLAN List of each port is updated with the new
information, accordingly.
Figure A-1 Example of VLAN Propagation via GVRP
Configuring a VLAN on an 802.1Q switch creates a static GVRP entry. The entry will always
remain registered and will not time out. However, dynamic entries will time-out and their
registrations are removed from the member list if the end station A is removed. This ensures that if
switches are disconnected, or if end stations are removed, the registered information remains
accurate.
The end result is that the Port VLAN List of a port is updated with information about VLANs that
reside off that port, even if the actual station on the VLAN is several hops away.
D
End
Station A
Switch 1 Switch 2 Switch 3
Switch 4 Switch 5
R
R R
R
D
D
D
= Port registered as a member of VLAN Blue
= Port declaring VLAN Blue
D
R
30691_77
1
1
1 1
1
2
2
3
3
R