MNS-BB
Software User Guide
-93-
Note:
To understand and use GVRP you must have a working knowledge of 802.1Q
VLAN tagging. (See “Tag-Based Virtual LANs (Static VLANs)” ). GVRP uses “GVRP Bridge
Protocol Data Units” (“GVRP BPDUs”) to “advertise” static VLANs. In this manual, a GVRP BPDU
is termed an
advertisement
.
GVRP enables the LE2425A and LEV2525A Switch to dynamically create 802.1Q-compliant
VLANs on links with other devices running GVRP. This enables the switch to automatically create
VLAN links between GVRP-aware devices. (A GVRP link can include intermediate devices that are
not GVRP-aware.) This operation reduces the chances for errors in VLAN configuration by
automatically providing VLAN ID (VID) consistency across the network. That is, you can use GVRP
to propagate VLANs to other GVRP-aware devices instead of manually having to set up VLANs
across your network. After the switch creates a dynamic, you can also use GVRP to dynamically
enable port membership in static VLANs configured on a switch.
Note:
There must be one common VLAN (that is, one common VID) connecting all of the GVRP-
aware devices in the network to carry GVRP packets. Blackbox recommends the default VLAN
(DEFAULT_VLAN; VID = 1), which is automatically enabled and configured as untagged on every
port of the LE2425A and LEV2525A switches). That is, on ports used for GVRP links, leave the
default VLAN set to
Untagged
and configure other static VLANs on the same ports as either
Tagged
,
Forbid
. (
Forbid
option described under “Per-Port Options for Dynamic VLAN Advertising
and Joining”.
17.2 General
Operation
A GVRP-enabled port with a Tagged or Untagged static VLAN sends advertisements (BPDUs, or
Bridge Protocol Data Units) advertising the VLAN (actually, its VID). Another GVRP-aware port
receiving the advertisements over a link can dynamically join the advertised VLAN.
All dynamic
VLANs operate as Tagged VLANs
. Also, a GVRP-enabled port can forward an advertisement for a
VLAN it learned about from other ports on the same switch. However, the forwarding port will not
itself join that VLAN until an advertisement for that VLAN is received on that specific port.
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.
2.
Port 1 receives advertisement of VIDs 1, 2, & 3 AND becomes a member of VIDs 1, 2, & 3.
3.
Port 3 advertises VIDs 1, 2, & 3, but port 3 is NOT a member of VIDs 1, 2, & 3 at this point.
4.
Port 4 receives advertisement of VIDs 1, 2, & 3 AND becomes a member of VIDs 1, 2, & 3.
5.
Port 5 advertises VIDs 1, 2,& 3, but port 5 is NOT a member of VIDs 1, 2, & 3 at this point.
Port 6 is statically configured to be a member of VID 3.
6.
Port 6 advertises VID 3.
7.
Port 5 receives advertisement
8.
Port 4 advertises VID 3.
9.
Port 3 receives advertisement of VID 3 AND becomes a member of VID 3. (Still not a member of
VIDs 1 & 2.)
10.
Port 1 advertises VID 3 of VID 3 AND becomes a member of VID 3. (Still not a member of VIDs
1 & 2.)
11.
Port 2 receives advertisement of VID 3. (Port 2 is already statically configured for VID 3.
