Information Technology Reference
In-Depth Information
32 bits
Source port
Destination port
Length
Checksum
DATA
Figure 24.2
UDP header format
32 bits
Source IP address
Destination IP address
IP
header
Protocol=
17
Zero
UDP length
Source port
UDP
header
Destination port
Length
Checksum
DATA
Figure 24.3
UDP/IP header format
24.4 TCP specification
TCP is made reliable with the following:
•
Sequence numbers - each TCP packet is sent with a sequence number. Theoretically,
each data byte is assigned a sequence number. The sequence number of the first data
byte in the segment is transmitted with that segment and is called the segment sequence
number (SSN).
