an ethernet metropolitan area network provides connectivity to one or more customer premises to packet - bases services , such as atm , frame relay , or ip while advantageously providing a mechanism for assuring security and regulation of customer traffic . upon receipt of each customer - generated information frame , an ingress multi - service platform “ tags ” the frame with a customer descriptor that specifically identifies the recipient customer . in practice , the msp tags each frame by overwriting the virtual local area network identifier with the routing descriptor . using the customer descriptor in each frame , a recipient provider edge router or atm switch can map the information as appropriate to direct the information to the specific customer . in addition , the customer descriptor may also include quality of service allowing the recipient provider edge router or atm switch to vary the qos level accordingly .