VLAN stacking, also known as double VLAN tagging or Q-in-Q, is a mechanism specified in IEEE standard 802.1ad (“Provider Bridges”) to extend the IEEE VLAN tagging standard (802.1Q). VLAN stacking allows service providers to assign service VLAN tags (S-VLAN) to Ethernet frames that are already marked with customer VLAN IDs (C-VLAN), resulting in hierarchical or “stacked” VLAN tags.
S-VLAN tags are added at the provider network’s edge, and then removed at the network egress in a process termed “VLAN stripping”. VLAN stacking supports C-VLAN preservation over metro area networks (MANs) and ensures complete separation between traffic from different user groups, as well as between user payload and management signals.
RAD’s Carrier Ethernet access solutions feature standard VLAN stacking capabilities, supplying carriers, enterprises and service providers with an essential tool for Carrier Ethernet transport and services. In addition to enabling users to transparently manage multiple C-VLANs over public networks, RAD’s Ethernet demarcation solutions increase the number of available VLAN tags by allowing service providers to use a single S-VLAN tag per customer over the metro network.
