Chapter 7

Ethernet AVB Endpoint Reception

Rx Splitter

The input to the Rx splitter (see Figure 5-1) is connected directly to the client Receive (Rx) interface of the connected Ethernet MAC. Received data from an AVB network can be of three types:

Precise Timing Protocol (PTP) Packets. Routed to the dedicated hardware “Rx PTP Packet Buffer” which can be accessed by the “Software Drivers.” PTP packets are identified by searching for a specific MAC Destination Address.

AV Traffic. Routed to the “Rx AV Traffic I/F”of the core. These packets are identified by searching for MAC packets containing a MAC VLAN field with one of two possible configurable VLAN priority values (see “Rx Filtering Control Register”).

Legacy Traffic:. Routed to the“Rx Legacy Traffic I/F” of the core. All packet types which are not identified as PTP or AV Traffic will be considered legacy traffic.

Rx Legacy Traffic I/F

The signals forming the Rx Legacy Traffic I/F are defined in Table 5-3. All signals are synchronous to the Tri-Mode Ethernet MAC receiver clock, rx_clk, which must always be qualified by the corresponding clock enable, rx_clk_en (see Table 5-1).

This interface is intentionally identical to the client receiver interface of the supported Xilinx Tri-Mode Ethernet MAC core (there is a one-to-one correspondence between signal names of the block-level wrapper from the Tri-Mode Ethernet MAC example design, after the legacy_ prefix is removed). This provides backward compatibility–all existing MAC client-side designs which use the clock enable should be able to connect to the legacy Ethernet port unmodified.

Operation of the Rx Legacy Traffic Interface is closely connected with the frame header match results of the “Legacy MAC Header Filters.” If the filters are enabled and do not obtain a match, the frame data does not appear on this interface (legacy_rx_data_valid and legacy_rx_frame_good/legacy_rx_frame_bad are not asserted). When a match is obtained these signals are asserted as described in the following sections.

Ethernet AVB Endpoint User Guide

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UG492 July 23, 2010

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Xilinx UG492 manual Ethernet AVB Endpoint Reception, Rx Splitter, Rx Legacy Traffic I/F