
The simple way to resolve the second problem is to stack another VLAN tag,
called service VLAN tag (or S-tag), on top of the customer VLAN tag (or C-tag) as
shown in Figure 9.21. This techniq ue is also called Q-tag-in-Q-tag, or QiQ, and is
standardized as IEEE 802.1ad Provider Bridges [32]. The QiQ technique nested
customer VLANs (C-VLANs) inside service VLANs (S-VLANs) to achieve
C-VLAN transparency from a customer point of view.
9.5 CARRIER ETHERNET
The cost advantage of Ethernet and the convergence of voice, data, and video
services on packet-oriented network infrastructure made Ethernet services the fastest
growing services in the telecommunicat ...