The receive address filtering function accepts or rejects received frames by examining the destination address field . Part of this function is carried out in the TEMAC component and part is carried out based on the bit settings in the Control register (Reset and Address Filter Register). Using the Address Filters shows the address filtering flow.
The decisions shown in white are made in the TEMAC component while the decisions shown in gray are made based on the Control register settings. The filtering functions includes:
TEMAC Component Functions
- Programmable unicast destination address matching
- Four programmable multicast address matching
- Broadcast address recognition (0xFFFF_FFFF_FFFF)
- Optional pass through mode with address filter disabled (promiscuous mode)
- Pause control frame address recognition (0x0100 00C2 8001)
Control Register Enabled Functions
- Enable or reject received multicast frames
- Enable or reject received broadcast frames
Receive address filtering eliminates the software overhead required to process frames that are not relevant to a particular Ethernet interface by checking the Destination Address (DA) field of the received frame.
The unicast address and multicast addresses are programmed in software through the AXI4-Lite bus as are the Address Filter enable bit, Multicast Address enable bit, and Broadcast Address enable bit. The pause frame address and broadcast address are predefined and do not need programming. See the footnote in Interrupt Status Register for a more detailed description on the conditions that can cause the receive reject interrupt to be set.