[e2e] UDP length field

Joe Touch touch at ISI.EDU
Wed Apr 11 11:53:57 PDT 2001

Bill Sommerfeld wrote:
> >       Why does UDP have a length field?
> Same reason tcp does: to preserve an end-to-end length in the presence
> of fragmentation.
> The ip packet length is the length of a particular fragment, and may
> have been set by a router which fragmented the packet.
> The udp length appears only in the first fragment and describes the
> fully assembled datagram.

The reassembled packet should have had the IP packet length restored
during reassembly.


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