Packets Held in Packet Buffer
The RX packets are held in the packet buffer until the MAC receiver determines what to do with it. If a packet is corrupt or does not pass the RX filter criteria, the packet is discarded. This has several performance advantages:
- RX packets with errors can be discarded before propagating further, which saves system interconnect bandwidth and the need for the device driver to discard them
- Process the IP/TCP/UDP checksum generation offload
- Generate the checksum before determining the fate of the frame
Packet Buffer Overflow
The RX packet buffer can overflow with packets and generate an interrupt when data is received, but there is not enough room to store it. An overflow also occurs if the limit of 2048 packets is breached. The maximum usable size of the packet buffer is 32 KB.