GVRP
Introduction
General Operation
When GVRP is enabled on a switch, the VID for any static VLANs configured
on the switch is advertised (using BPDUs—Bridge Protocol Data Units) out
all ports, regardless of whether a port is up or assigned to any particular VLAN.
A GVRP-aware port on another device that receives the advertisements over
a link can dynamically join the advertised VLAN.
A dynamic VLAN (that is, a VLAN learned through GVRP) is tagged on the port
on which it was learned. Also, a GVRP-enabled port can forward an advertise-
ment for a VLAN it learned about from other ports on the same switch (internal
source), but the forwarding port will not itself join that VLAN until an adver-
tisement for that VLAN is received through a link from another device (exter-
nal source) on that specific port
Operating Note: When a GVRP-aware port on a switch learns a VID through GVRP from another device, the switch begins
advertising that VID out all of its ports except the port on which the VID was learned.
2. Port 1 receives advertise- 4. Port 4 receives advertise-
ment of VIDs 1, 2, & 3 AND ment of VIDs 1, 2, & 3 AND
becomes a member of VIDs becomes a member of VIDs
1, 2, & 3. 1, 2, & 3.
3. Port 3 advertises VIDs 1, 2, 5. Port 5 advertises VIDs 1, 2,
& 3, but port 3 is NOT a & 3, but port 5 is NOT a
member of VIDs 1, 2, & 3 at member of VIDs 1, 2, & 3 at
Port 6 is statically configured
this point. this point.
to be a member of VID 3.
Static VLAN con-
figured End Device
Switch 2 Switch 3
GVRP On GVRP On
(NIC or switch) with
GVRP On
1
3
4 5
6
Core switch with static
VLANs (VID= 1, 2, & 3). Port 2
is a member of VIDs 1, 2, & 3.
1. Port 2 advertises VIDs 1, 2,
& 3.
Switch 1
GVRP On
2
11. Port 2 receives 9. Port 3 receives advertise- 7. Port 5 receives advertise- 6. Port 6 advertises VID 3.
advertisement of VID 3. (Port ment of VID 3 AND becomes ment of VID 3 AND becomes
2 is already statically a member of VID 3. (Still not a member of VID 3. (Still not
configured for VID 3.) a member of VIDs 1 & 2.) a member of VIDs 1 & 2.)
10. Port 1 advertises VID 3. 8. Port 4 advertises VID 3.
Figure 3-1. Example of Forwarding Advertisements and Dynamic Joining
3-4
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