VLAN C
ONFIGURATION

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hosts, and core switches in the network, enable GVRP on the links
between these devices. You should also determine security
boundaries in the network and disable GVRP on ports to prevent
advertisements being propagated, or forbid ports from joining
restricted VLANs.
Note: If you have host devices that do not support GVRP, you
must configure static VLANs for the switch ports connected
to these devices. You also still need to enable GVRP on
these edge switches, as well as on the core switches in the
network.

Forwarding Tagged/Untagged Frames

If you want to create a small port-based VLAN for devices attached
directly to a single switch, you can assign ports to the same
untagged VLAN. However, to participate in a VLAN group that
crosses several switches, you need to create a VLAN for that group
and enable tagging on all ports.
Ports can be assigned to multiple tagged or untagged VLANs. Each
port on the switch is therefore capable of passing tagged or
untagged frames. When forwarding a frame from this switch along
a path that contains any VLAN-aware devices, the switch should
include VLAN tags. When forwarding a frame from this switch
along a path that does not contain any VLAN-aware devices
(including the destination host), the switch must first strip off the
VLAN tag before forwarding the frame. When the switch receives a
tagged frame, it will pass this frame onto the VLAN(s) indicated by
the frame tag. However, when this switch receives an untagged
frame from a VLAN-unaware device, it first decides where to
forward the frame, and then inserts a VLAN tag reflecting the
ingress port’s default VID.
b_mgmt.book Page 73 Tuesday, July 8, 2003 5:24 PM