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Transmission Control
Protocol (TCP) Header Format
| bit |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
Byte 0
Byte 1 |
Source
Port Number |
Byte 2
Byte 3 |
Destination
Port Number |
Byte 4
Byte 5
Byte 6
Byte 7 |
Sequence
Number |
Byte 8
Byte 9
Byte 10
Byte 11 |
Acknowledgement
Number |
| Byte 12 |
Header
Length |
|
| Byte 13 |
|
URG |
ACK |
PSH |
RST |
SYN |
FIN |
Byte 14
Byte 15 |
Window
Size |
Byte 16
Byte 17 |
TCP
Checksum |
Byte 18
Byte 19 |
Urgent
Pointer |
placement in the OSI model
| Layer |
Name |
Protocols / Terms |
Devices that operate in this layer |
Addresses are called... |
| 4 |
Transport |
TCP/UDP |
OS application protocols |
local addresses |
| 3 |
Network |
IP, IPX, AppleTalk |
Routers |
Network Addresses |
| 2 |
Datalink |
Ethernet, Token Ring, PPP, SLIP, HDLC |
Bridges, Switches, Repeaters, Hubs |
Datalink, or MAC* addresses |
| 1 |
Physical |
Unshielded Twisted Pair, Shielded Twisted Pair, Coax, Twinax, Serial cable |
Modems, CSU/DSUs |
N/A (cables don't have addresses) |
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