Wireshark-dev: Re: [Wireshark-dev] Query regarding UDP
From: Jeff Morriss <[email protected]>
Date: Mon, 20 Nov 2006 21:30:55 +0800

prashanth joshi wrote:
Hi,
We have written TCP Reasembly code for our GCDR (Prime) parsing.
Do we need to write a UDP Reassembly code also?
The ethereal seems to do a GTP packet parsing when ever it receives data on UDP port. Is not reassembly needed in case of UDP packets? If fragmentation is done in case of UDP then when will it be initiated and who does the fragmentation.
Regards,
Prashanth
FYI, by replying to an email from a different thread (this one was 
originally "Query regarding PDUs", not "Query regarding UDP") instead of 
composing a new email (and thus creating a new thread), your email gets 
lost in the old thread (for those of us who read this mailing list 
threaded).  Suggestion: don't Reply while changing the subject.  Instead 
compose a new email.
Anyway, UDP (the protocol) does not have fragmentation and reassembly. 
If an application sends more than an MTU's worth of data to UDP, UDP 
will happily hand that data (unfragmented) to IP and IP will have to 
fragment it.  If, on the other hand, the application/upper layer 
protocol fragments and reassembles the packets (while also taking care 
of retransmissions, timeouts, etc.) then of course a dissector for that 
application/ULP could do reassembly.