Receive Data Path
BCM5718 Programmer’s Guide
Broadcom
®
January 29, 2016 • 5718-PG108-R
Page 54
Receive Data Path
RX Engine
The receive engine (see
) activates whenever a packet arrives from the PHY.
Figure 3: Receive Data Path
The receive engine performs the following four functions:
• Moves the data from the PHY to an internal FIFO
• Moves the data from the FIFO to NIC internal memory
• Classifies the frame and checks it for rules matches
• Performs the offloaded checksum calculations
RX FIFO
The RX FIFO provides elasticity while data is read from PHY transceiver and written into internal memory. There
are no programmable settings for the RX FIFO. This FIFO’s operation is completely transparent to host
software.
RX
Engine
Rules Checker
Rx
FIFO
Fram e
Buffers
Em pty BD
N IC Standard RX Producer Ring
Host RX
Return
Ring
List
Initiator
Rx
R
etu
rn
B
D
Rx
R
etu
rn
B
D
Rx
R
etu
rn
B
D
Rx
R
etu
rn
B
D
Rx
R
etu
rn
B
D
Host Standard RX Producer
Ring
DM A
D M A
Full BD
Em pty BD
N IC Jum bo RX Producer Ring
D M A
H ost Jum bo RX Producer Ring