MACsec Intel® FPGA IP User Guide

ID 736108
Date 6/26/2023
Public

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5.1.9. Controlled/Uncontrolled Port Muxing

The diagram below shows the arbitration mux between the Controlled and Uncontrolled ports on the Tx encryption lane. The Uncontrolled port traffic is directly taken from the user while the Controlled port traffic is output from the Encryption Deframer block.
Figure 23. Controlled/Uncontrolled Port Muxing


The Encryption Deframer output can interleave 64-byte words from different streams. The Uncontrolled port traffic requirements are specified below.

Table 39.  Uncontrolled Port Traffic Requirement
Cycle 0 1 2 3 4 5 6
Stream 0 0 3 3 4 7 7
Data[127:0] SOP EOP SOP Data SOP SOP Data
Data[255:128] Data IDLE Data Data Data Data EOP
Data[383:256] Data IDLE Data Data Data Data IDLE
Data[511:384] Data IDLE Data EOP EOP Data IDLE
  • Packet based per stream
  • Single Packet Mode only
  • No interleaving of packets with different stream packet
  • The arbitration between the Uncontrolled and Controlled ports follows the following criteria.
  • Priority is for the controlled port following these rules:
    • Traffic from the Uncontrolled port is not granted when the Controlled port has incoming traffic.
    • Traffic from the Uncontrolled port is not granted when the Controlled port traffic targeting the same stream as the Uncontrolled Port is not reaching EOP.
    • Traffic from the Uncontrolled port is not granted when the Controlled port traffic targeting the same stream as the Uncontrolled port is reaching EOP but there is another SOP within the same cycle.
    • Traffic from the Uncontrolled port is granted when the Controlled port traffic reaches EOP and none of the above is met.
  • For use cases where both the controlled port and the uncontrolled port are required to be active, neither port meets the line rate.
  • The E- or F-tile Ethernet IP requires that tvalid be continuously asserted between the assertions of the "start-of-packet" and "end-of-packet" signals for the same packet. This places a restriction that the port demux be in "store and forward" (STFD) mode. For small packets (of the order of the minimum packet size), STFD may introduce a performance limitation because two packets in the same line (multi-packet scenario) should be read out on different clock cycles (making it a single-packet scenario).