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?
2. Despite its conceptual elegance, RPC (Remote Procedure Call) has a few problems. Discuss any 3 of those in brief.
3. Why is timestamping needed in real-time applications? This is in the context of Real-time Transport Protocol (RTP).
4. Why does UDP exist? Would it not have been enough to just let user processes send raw IP packets?
5. Explain how QUIC eliminates a couple of RTTs usually needed at the start of a secure web connection.

Answer 1

a)Assuming standard 1500 byte Ethernet max pay loads: we need two fragments of IPv4 to transfer 2000 bytes of user data with single UDP send. The 2000 will split as follows:

20 bytes for IP header.

8 bytes for UDP header.

1500 bytes of data, which contain both IP & UDP header, remaining 1472 bytes of user data.

528 bytes of user data without IP&UDP header.

b)RPC- Remote Procedure Call have few problems. Some of them are discussed below.

The first problem i would discuss about is it does not have the ability to deal with unexpected messages like if a client wants to send a important message to the server but the server is already working on a problem , then the server immediately terminates the existing problem and take up the client given message.

The second problem is that the in RPC, the servers are not allowed to take up any other request until the existing user or client responds to exit the task. For example, If the client is not responding to the server, then it has to wait until the client responds ,only then it has to take other requests.

The third problem is that the 2-sided RPC cannot understand or able to tell when the process is over if the network is unreliable.

c) Time stamping of data is needed to allow the user to play the data back at a particular time. This works by transport of Real-Time. It enable the user to determine the timing relationship of the received data. Real-Time applications need to store the playback buffer as there might be some disturbance during the transmission of data.

d)UDP allows us to transfer the IP enclosed data without any connection which is a way better than TCP or we can simply say overhead of TCP.

UDP allows you to multiplex or de-multiplex on variety of source/destination ports when simply send raw packets.

e)QUIC refers Quick UDP Internet Connections generally exchange the setup keys and protocols that are supported in the initial handshake process whereas HTTP demands the TLS. As soon as the client access a connection, the response packets will have the data which is needed for future packets that are used for encryption. This eliminates the need to setup the TCP connection and can negotiate the security protocols through additional packets. In such cases QUIC eliminates the initial RTT allowing data delivery from the very first packet. and the second and may be even third RTT are eliminated for negotiating the security protocols( TLS encryption).