Altera Low Latency 40-Gbps Ethernet MAC and PHY MegaCore Function - Manual (Page 61)

Low Latency 40-100GbE IP Core RX Datapath
The Low Latency 40-100GbE RX MAC receives Ethernet frames from the PHY and forwards the payload
with relevant header bytes to the client after performing some MAC functions on header bytes.
Figure 3-12: Flow of Frame Through the MAC RX Without Preamble Pass-Through
Illustrates the typical flow of frame through the MAC RX when the preamble pass-through feature is
turned off. In this figure,
is payload size (0–1500 bytes), and is the number of pad bytes (0–46
bytes).
Client - MAC Rx Interface
Client Frame
MAC Frame
Destination
Addr[47:0] Source
Addr[47:0]
Type/
Length[15:0]
Payload
[:0]
Destination
Addr[47:0]
SFD[7:0]
Preamble
[47:0]
CRC32
[31:0]
PAD [-1:0]
Source
Addr[47:0]
Start[7:0] EFD[7:0]
Figure 3-13: Flow of Frame Through the MAC RX With Preamble Pass-Through Turned On
Illustrates the typical flow of frame through the MAC RX when the preamble pass-through feature is
turned on. In this figure,
is payload size (0–1500 bytes), and is the number of pad bytes (0–46
bytes).
Client - MAC Rx Interface
Client Frame
MAC Frame
Destination
Addr[47:0] Source
Addr[47:0]
Type/
Length[15:0]
Payload
[:0]
Destination
Addr[47:0]
SFD[7:0]
Preamble
[47:0]
CRC32
[31:0]
PAD [-1:0]
Source
Addr[47:0]
Start[7:0]
SFD[7:0]
Preamble
[47:0]
Start[7:0]
EFD[7:0]
The following sections describe the functions performed by the RX MAC:
Low Latency 40-100GbE IP Core RX Filtering on page 3-17
40-100GbE IP Core Preamble Processing on page 3-17
40-100GbE IP Core FCS (CRC-32) Removal on page 3-17
40-100GbE IP Core CRC Checking on page 3-17
LL 40-100GbE IP Core Malformed Packet Handling on page 3-17
RX CRC Forwarding on page 3-18
Inter-Packet Gap on page 3-18
Pause Ignore on page 3-18
Control Frame Identification on page 3-19
3-16 Low Latency 40-100GbE IP Core RX Datapath
UG-01172
2015.05.04
Altera Corporation Functional Description
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