W90N740CD WINBOND [Winbond], W90N740CD Datasheet - Page 104

• Manufacturer Part Number: W90N740CD
• Description: 32-Bit ARM7TDMI-Based Micro-Controller
• Manufacturer: WINBOND [Winbond]

6.6.1
1. The IP address in the IP header is replaced with new inside or outside IP address
2. The port number in the TCP/UDP header is replaced with new port number
3. Recalculate the IP checksum
4. Recalculate the TCP/UDP checksum
NAT Process Flow
While EMC port get valid MAC packets and store them in
memory, it check if {IP, port} hit, and update descriptors
Rx: Look up NAT table process :
1. parsing IP address
2. according IP header length jump to TCP/UDP header
3. parsing TCP/UDP port number
4. compare {IP address, port number} with NAT table content
NATA begins IP address (or Port number) replacement process :
Replace MAC 0 and MAC 1 address in the MAC header
NATA do MAC address replacement process :
Hit or not, hit message in descriptor
(if Rx interrupt is enabled)
NATA exit NAT process
NAT Process Flow
Rx send interrupt
Rx triggers NAT
processing
NAT hit?
Yes
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W90N740CD/W90N740CDG
Publication Release Date: September. 19, 2005
No
No NAT processing
Revision A7