All-Ethernet metro networks pose many scalability and reliability challenges. The following are some of the issues that arise with an all-Ethernet control plane:
Restrictions on the number of customers
Scaling the L2 backbone
Interworking with legacy deployments
The following sections describe each of these challenges.
The Ethernet control plane restricts the carrier to 4096 customers, because the 802.1Q defines 12 bits that can be used as a VLAN ID, which restricts the number of VLANs to 212 = 4096. Remember that although Q-in-Q allows the customer VLANs (CE-VLANs) to be hidden from the carrier network, the carrier is still ...