Method and apparatus for scheduling packets for transmission

A network device, comprising:

• a plurality of network interfaces configured to transmit and receive via communication links communicatively coupled to the plurality of network interfaces, the plurality of network interfaces including a first network interface communicatively coupled to a first communication link among the communication links communicatively coupled to the plurality of network interfaces;
• a packet processor configured to process packets received via the plurality of network interfaces, including processing at least headers of the packets to determine a set of network interfaces, among the plurality of network interfaces, to which the packets are to be forwarded;
• a packet memory to store packet data corresponding to the packets received via the plurality of network interfaces while the packets are processed by the packet processor;
• a transmit data paths corresponding to the first network interfaces, the transmit data path configured to transfer first packet data, amongst the packet data stored in the packet memory, to the first network interface for transmission by the first network interface on the first communication link, the transmit data path including a memory buffer;
• and
• scheduling control circuitry configured to i) measure an amounts of time required for the first network interfaces to transmit a first set of the first packet data that is within the transmit data path including a subset of the first set of the packet data stored in the memory buffer, and ii) use the measured amount of time to determine when to start transfer of a second set of the first packet data from the packet memory to the first network interface via the transmit data path.