User guide

Q-in-Q DVLAN (Double-VLAN) Tagging
(802.1AD)
Engineering VLANs
170
pmp-0229 (Mar 2013)
Figure 54 Q-in-Q network diagram
In this diagram, we have four example PMP SM endpoints and a BH pair that are using VLAN
configurations involving Q-in-Q. For Multipoint and Point-to-Point systems, the VLAN Port type can
be configured to be one of two modes: Q or Q-in-Q.
• For Q mode, this means the port will operate just like today’s existing VLAN implementation. It
will not add a second layer S-Tag, but it will add and remove the regular Q-Tag.
• For Q-in-Q mode, there is a difference between the multipoint mode and the point to point mode.
For Multipoint, an SM will be able to add 2 layers of tags to an untagged packet. It will also be
able to just add the single outer S-Tag to an already-tagged 802.1Q packet.