Internet Packet

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This is how a typical 1500-byte data packet on the Internet (TCP/IP over Ethernet) looks like for IPv6:

  0     1     2     3     4     5     6     7     8     9     A     B     C     D     E     F  
Ethernet header 0 preamble
2
4
6
8 destination MAC
10
12
14 source MAC
16
18
20 type
IPv6 header 22 version traffic class flow ...
24 .. label
26 payload length
28 next header hop limit
30 source IP
32
34
36
38
40
42
44
46 destination IP
48
50
52
54
56
58
60
TCP header 62 Source port
64 Destination port
66 Sequence number
68
70 Acknowledgment number (if ACK set)
72
74 data offset reserved NS CWR ECE URG ACK PSH RST SYN FIN
76 Window size
78 Checksum
80 Urgent pointer (if URG set)
Application data 82 Application data (1440 bytes)
84
86
...
1556
1558
1560
Ethernet footer 1562 Checksum (CRC)
1564
Ethernet inter-frame gap 1566
1568
1570
1572
1574
1576

For IPv4, a typical 1500-byte data packet looks like:

  0     1     2     3     4     5     6     7     8     9     A     B     C     D     E     F  
Ethernet header 0 preamble
2
4
6
8 destination MAC
10
12
14 source MAC
16
18
20 type
IPv4 header 22 version header len DiffServ ECN
24 Total length
26 Identification
28 flags fragment offset
30 hop limit Protocol
32 header checksum
34 source IP
36
38 destination IP
40
TCP header 42 Source port
44 Destination port
46 Sequence number
48
50 Acknowledgment number (if ACK set)
52
54 data offset reserved NS CWR ECE URG ACK PSH RST SYN FIN
56 Window size
58 Checksum
60 Urgent pointer (if URG set)
Application data 62 Application data (1460 bytes)
64
66
...
1556
1558
1560
Ethernet footer 1562 Checksum (CRC)
1564
Ethernet inter-frame gap 1566
1568
1570
1572
1574
1576