An architecture for a line card in a network routing device is provided. The line card architecture provides a bi-directional interface between the routing device and a network, both receiving packets from the network and transmitting the packets to the network through one or more connecting ports of a network interface. A high priority buffer and a low priority buffer can be assigned to each port of the network interface. The network interface can perform packet prioritization through buffer selection based on priority. High priority packets will be transmitted to an ingress packet processor before low priority packets for a given port.