Why No Source and Destination IPs in UDP Datagram?

Question

In literature, I see UDP datagram format as following: enter image description here

I cannot understand why it does not include source and destination IP addresses?

A packet contains IP source and destination, a segment contains protocol information. — HAL, Mar 6 '14 at 21:57

Ricky · Accepted Answer · 2014-03-06 18:39:11Z

17

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.

answered Mar 6 '14 at 18:39

Ricky

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Why are we having the source and destination ports in UDP Datagram in that case? – Curious Coder Jan 18 '20 at 0:58

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Community · Accepted Answer · 2017-05-23 12:37:19Z

2

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.

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answered Mar 6 '14 at 15:29

HAL

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2

The pseudoheader is only used for calculating checksums, it is never actually transmitted. – Peter Green Feb 3 '17 at 12:15

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2 Answers 2