In literature, I see UDP datagram format as following:
I cannot understand why it does not include source and destination IP addresses?
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6Hmmm, no mac-address shown either. – Mike Pennington Mar 6 '14 at 14:21
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2What is the difference between a segment and a packet? – YLearn♦ Mar 6 '14 at 14:39
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A packet contains IP source and destination, a segment contains protocol information. – HAL Mar 6 '14 at 21:57
Because you're looking at the UDP Datagram, which is the payload in an IP Datagram. The IP Header has the src/dst IP addresses.
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Why are we having the source and destination ports in UDP Datagram in that case? – Curious Coder Jan 18 at 0:58
At transmission the psuedoheader is added for the destination and source IP addresses. This might clarify the process a bit more:
By itself, the UDP packet header only contains the source port and destination port of the client/target as well as a checksum and length.
This is a related question asked on StackOverflow:
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2The pseudoheader is only used for calculating checksums, it is never actually transmitted. – Peter Green Feb 3 '17 at 12:15
