Intel® Agilex™ Hard Processor System Technical Reference Manual

ID 683567
Date 11/11/2022
Public

A newer version of this document is available. Customers should click here to go to the newest version.

Document Table of Contents

17.6.8.1.1. Unicast Destination Address Filter

Up to 128 MAC addresses for unicast perfect filtering are supported. The filter compares all 48 bits of the received unicast address with the programmed MAC address for any match. Default MacAddr0 is always enabled, other addresses MacAddr1–MacAddr127 are selected with an individual enable bit. For MacAddr1–MacAddr31 addresses, you can mask each byte during comparison with the corresponding received DA byte. This enables group address filtering for the DA. The MacAddr32‑MacAddr127 addresses do not have mask control and all six bytes of the MAC address are compared with the received six bytes of DA.

In hash filtering mode, the filter performs imperfect filtering for unicast addresses using a 256‑bit hash table. It uses the upper ten bits of the CRC of the received destination address to index the content of the hash table. A value of 0 selects Bit 0 of the selected register, and a value of 111111 binary selects Bit 63 of the Hash Table register. If the corresponding bit is set to one, the unicast frame is said to have passed the hash filter; otherwise, the frame has failed the hash filter.