 If an application uses UDP and delivery guarantees are needed, in which layer
(of the 5 layer model that we studied) is this achieved?
b. Design a modification to RPC that uses UDP but guarantees that a remote
procedure call is only invoked once if packets go missing. Your modification should be able 
to cope with the case where the request is not delivered and the case where the response is 
not delivered.
Hint: your solution could add a request sequence number which is embedded in the UDP 
request packet. Write exactly 4 paragraphs each separated with two new lines answering this question. The 3rd paragraph must start with "contact".
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