Data Sheet

Ethernet Controller I210 —Packet Types
870
A TCP or UDP frame uses a 16 bit wide one's complement checksum. The checksum word is computed
on the outgoing TCP or UDP header and payload, and on the pseudo header. Details on checksum
computations are provided in Section 7.2.4.
Note: TCP and UDP over IPv6 requires the use of checksum, where it is optional for UDP over IPv4.
The TCP header is first shown in the traditional (such as RFC 793) representation, and
because byte and bit ordering is confusing in that representation, the TCP header is also
shown in little endian format. The actual data is fetched from memory in little endian format.
Table A-4. IPv6 Header (Little Endian Order)
Byte3 Byte2 Byte1 Byte0
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Flow Label Version Priority
Hop Limit Next Header Type
LSB Payload Length MSB
Source Address
Destination Address
Extensions
Table A-5. TCP Header (Traditional Representation)
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
Sequence Number
Acknowledgement Number
TCP Header
Length
Reserved
U
R
G
A
C
K
P
S
H
R
S
T
S
Y
N
FI
N
Window
Checksum Urgent Pointer
Options
Table A-6. TCP Header (Little Endian)
Byte3 Byte2 Byte1 Byte0
7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0 7 6 5 4 3 2 1 0
Destination Port Source Port
LSB Sequence Number MSB
Acknowledgement Number
Window RE S
U
R
G
A
C
K
PS
H
R
ST
SY
N
FIN
TCP Header
Length
Reserved
Urgent Pointer
Checksum
Options