Intel Intel Gigabit Ethernet Controllers, PCI-X Source Port Destination Port Length Checksum

Receive and Transmit Description

TCP Length = Payload + HDRLEN - TUCSS

“Payload” is normally MSS except for the last packet where it represents the remainder of the payload.

0 31

IP Source Address

IP Destination Address

Zero

Layer 4 Protocol

ID

TCP Length

Figure 3-13. TCP Pseudo Header Content (Traditional Representation)

IP Source Address

IP Destination Address

Upper Layer Packet Length

Zero

Next Header

Figure 3-14. TCP PseudoHeader Content for IPv6

Note: The IP Destination address is the final destination of the packet. Therefore, if a routing header is used, the last address in the route list is used in this calculation. The upper-layer packet length is the length of the TCP header and the TCP payload.

The UDP header is always 8 bytes in size with no options.

										1									2									3
0	1	2	3	4	5	6	7	8	9	0	1 2	3	4	5	6	7	8	9	0	1	2	3	4	5	6 7	8	9	0	1
Source Port															Destination Port
Length															Checksum

Figure 3-15. UDP Header (Traditional Representation)

Byte3

Byte2

Byte1

Byte0

0	1	2	3	4	5	6	7	0	1	2	3	4	5	6	7	0	1	2	3	4	5	6	7	0	1	2	3	4	5	6	7
						Destination Port																	Source Port
							Checksum																	Length

Figure 3-16. UDP Header (Little-Endian Order)

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