1. Assuming standard 1500 byte Ethernet max payloads: how many IPv4 fragments wi
ID: 3918543 • Letter: 1
Question
1. Assuming standard 1500 byte Ethernet max payloads: how many IPv4 fragments will be needed to transfer 2000 bytes of user data with a single UDP send? And, how do the 2000 bytes get split over the frags?
Part B
Despite its conceptual elegance, RPC (Remote Procedure Call) has a few problems. Discuss any 3 of those in brief.
Part C
Why is timestamping needed in real-time applications? This is in the context of Real-time Transport Protocol (RTP).
Part D
Why does UDP exist? Would it not have been enough to just let user processes send raw IP packets?
Part E
Explain how QUIC eliminates a couple of RTTs usually needed at the start of a secure web connection.
Explanation / Answer
1. Assuming standard 1500 byte Ethernet max payloads: how many IPv4 fragments will be needed to transfer 2000 bytes of user data with a single UDP send? And, how do the 2000 bytes get split over the frags?
Answer:
we first need to factor in the space needed for the IP header, which is20 bytes, and the UDP header, which is 8 bytes. This is a total of 28 bytes that need to be factored inimmediately, which leaves a total of 1472 bytes for data (PCVR.NL, N.D.). This allows us to figure thenumber of fragments that will be needed for 2000 bytes of date, which is 2. The first fragment willcontain a total of 1500 bytes of data, which will include the 20 bytes for the IP header, the 8 bytes forthe UDP header, and 1472 bytes of user data. The remaining 528 bytes of user data will be the totalamount of data in the second fragment, as it will not include either the IP header or UDP header
Despite its conceptual elegance, RPC (Remote Procedure Call) has a few problems. Discuss any 3 of those in brief.
Answer:
->The first issue is Marshalling: RPC frameworks have a stub for the functions involved. Before sending the message the stub has to Marshall the parameters so they can be sent across the network. Parameters consist of simple types and compound types. Due to each type having its own representation, the types of the various parameters must be known to the modules that actually do the conversion. Without that knowledge, conversations can’tstart.
?The second issue is Lack of Streaming:This problem deals with the fact that when the server is building the response it must build it entirely and the client is then idle for that period.
?The third issue is Single Threaded Servers: RCP favors the use of multi-threaded servers instead of single threaded ones. This is due to the RPC model not allowing the server to return without serving a response to the client.
Why does UDP exist? Would it not have been enough to just let user processes send raw IP packets?
Answer:
By using UDP, a segment will be delivered correctly to the specified application because UDP uses source and destination ports while raw IP packet does not include ports. That is, a segment cannot be delivered to a specified application as a raw IP packet.
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