Log In
1 vote
Why does UDP exist? Would it not have been enough to just let user processes send
raw IP packets
in Computer Networks 92 views

1 Answer

0 votes

why do we need UDP when we could just send IP packets with the same payload?

  1. IP packets have no end-to-end error detection mechanism. IPv4 has a checksum that covers only its header, so the data is protected only by the layer 2 error detection, which isn't end-to-end. Both UDP and TCP use a checksum to check the data for errors end-to-end.

  2. Once the destination machine receives such an IP packet, which application should it pass it to? We need a way of identifying the destination app (socket actually, but never mind) of a specific message. UDP and TCP do that with port numbers. Having no port number is similar to sending a postal package to an apartment building without specifying which apartment it should be given to.


Related questions

0 votes
1 answer
Both UDP and TCP use port numbers to identify the destination entity when delivering a message. Give two reasons why these protocols invented a new abstract ID (port numbers), instead of using process IDs, which already existed when these protocols were designed.
asked Mar 18, 2019 in Computer Networks ajaysoni1924 252 views
0 votes
0 answers
Consider a simple application-level protocol built on top of UDP that allows a client to retrieve a file from a remote server residing at a well-known address. The client first sends a request with a file name, and the server responds with a sequence ... . Ignoring the obvious performance issue, do you see a problem with this protocol? Think carefully about the possibility of processes crashing.
asked Mar 18, 2019 in Computer Networks ajaysoni1924 256 views
0 votes
0 answers
Some other policies for fairness in congestion control are Additive Increase Additive Decrease (AIAD), Multiplicative Increase Additive Decrease (MIAD), and Multiplicative Increase Multiplicative Decrease (MIMD). Discuss these three policies in terms of convergence and stability.
asked Mar 18, 2019 in Computer Networks ajaysoni1924 193 views
0 votes
0 answers
Imagine that a two-way handshake rather than a three-way handshake were used to set up connections. In other words, the third message was not required. Are deadlocks now possible? Give an example or show that none exist.
asked Mar 18, 2019 in Computer Networks ajaysoni1924 58 views