HP ProCurve 5300xl Series Management Manual page 40

Static Virtual LANs (VLANs)
Static VLAN Operation
2-10
overlap in this way, VLAN "tags" are used in the individual packets to distin­
guish between traffic from different VLANs. A VLAN tag includes the particu­
lar VLAN I.D. (VID) of the VLAN on which the packet was generated.
Figure 2-3. Example of Overlapping VLANs Using the Same Server
Similarly, using 802.1Q-compliant switches, you can connect multiple VLANs
through a single switch-to-switch link.
Red Server
Red
VLAN
Red
VLAN
Figure 2-4. Example of Connecting Multiple VLANs Through the Same Link
Introducing Tagged VLAN Technology into Networks Running Legacy
(Untagged) VLANs. You can introduce 802.1Q-compliant devices into net-
works that have built untagged VLANs based on earlier VLAN technology. The
fundamental rule is that legacy/untagged VLANs require a separate link for
each VLAN, while 802.1Q, or tagged VLANs can combine several VLANs in one
link. This means that on the 802.1Q-compliant device, separate ports (config­
ured as untagged) must be used to connect separate VLANs to non-802.1Q
devices.
ProCurve
Switch
802.1Q-Compliant
Server
The same link carries Red
Blue Server
VLAN and Blue VLAN traffic.
ProCurve
Switch
Blue
VLAN
Red
ProCurve
VLAN
Switch
Blue
VLAN