I want to develop a program in c using pjsip for peer to peer file transfer. As pjsip uses ice and in ICE UDP is used, so do I need to handle the packet delivery assurance.
And as I would be sending the file by breaking it into several parts and them re assemble all the parts at the receiver's end, so do I have to maintain the sequence of the packets or can i assume that packets are delivered in the correct sequence??
With UDP you can neither assume that packets are delivered in order nor that they are delivered exactly once nor that they are delivered at all! So you need to come up with a protocol that does a lot of things which normally TCP would take care of. It has to reassemble the original data stream and handle the things I listed above.
Additionally, with UDP you can have the problem that you cause congestion. TCP can avoid that with its congestion avoidance algorithms, with UDP you can easily send packets too fast causing them to drop at the overloaded router.
All these are non trivial problems to solve so I suggest you read up on the topic. I'd start with a good book about TCP.
