A technique for managing traffic in a multiport network node involves establishing customer-specific VLANs within the multiport network node that are identified by a combination of a VLAN ID and a customer ID. Traffic received at the multiport network node is mapped to a customer-specific VLAN and then broadcast to ports that are included in the customer-specific VLAN. Because customer-specific VLANs are identified by a combination of a VLAN ID and customer ID, a service provider can establish and maintain private broadcast domains on a per-customer ID basis. This enables the service provider to expand the number of unique VLAN IDs within the Service Provider Edge Device beyond the 4,096 limitation set by the IEEE 802.1Q standard while maintaining interoperability with the IEEE 802.1Q standard for incoming and outgoing traffic.