Hard Processor System Technical Reference Manual: Agilex™ 5 SoCs

ID 814346
Date 11/27/2024
Public

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5.1.7.12. Setting up VLAN Filtering on Receive

Use the following steps to set up the extended VLAN filtering.

  1. Program the MAC_VLAN_Tag register for the following bits to select the filtering method:
    1. ETV: Enable 12 bits VLAN tag comparison or 16 bits VLAN tag comparison.
    2. VTHM: VLAN tag hash table match enable.
    3. ERIVLT: Enable inner VLAN Tag or outer VLAN Tag (to enable the inner or outer VLAN tag filtering, Double VLAN processing must be enabled by setting EDVLP)
    4. ERSVLM: Enable receive S-VLAN match or C-VLAN match (for S-VLAN processing to be enabled, set ESVL).
    5. DOVLTC: Ignores VLAN type for tag match.
    6. VTIM: To enable VLAN tag inverse match instead of the normal VLAN tag matching.
  2. Program VL of MAC_VLAN_Tag register for the 12 bits or 16 bits VLAN tag.
  3. If hash filtering of VLAN tag is enabled, program the MAC_VLAN_Hash_Table register. The upper four bits of the calculated CRC are used to index the contents of the VLAN hash table. For example, a hash value of 4’b1000 selects bit 8 of the VLAN hash table.