Question

1. What is TCP three-step handshake? What happens if the handshake is not successfully completed?
2. What technological development led to the CSMA/CD protocols becoming obsolete?
3. Give an example of a networking protocol that we have discussed in class that utilizes UDP over TCP. Provide two pros and two cons to switiching the protocol over to tcp

Answer 1

Solution

Part 1

TCP three-step handshake is a process which is used in a TCP/IP network to make a connection between the server and client.

Step 1

In the first step the client establishes a connection with a server by sending a segment with SYN packet.The client sends a Synchronize Sequence Number data packet over an IP network to a server and informs the server to start the communication, and with what should be its sequence number.

This SYN packet is a random sequence number that the client wants to use for the communication (Example, Y).

Step 2

On receiving the SYN packet from the client node ,server responds with a SYN-ACK packet (Acknowledgement Sequence Number). This packet includes two sequence numbers.

ACK is  set by the server to one more than the sequence number it received from the client (i.e Y+1).

SYN is a random sequence number (i.e Z).

Step 3

This is the final step in which the client acknowledges the response of the server by sending ACK and stable connection is established between client and server.

If the handshake fails the connection is not establised and the 2 way communication will not be possible between the client and server.

Part 2

CSMA/CD was used in now-obsolete shared media Ethernet variants and also in the early versions of twisted-pair Ethernet. Modern Ethernet networks are built with switches and full-duplex connections so CSMA/CD is no longer used.

Part 3

UDP is used in Trivial File Transfer Protocol (TFTP), Real Time Streaming Protocol (RTSP) and Simple Network Management Protocol (SNMP)

Though TCP offers resilience through error recovery but TFTP uses the User Data Protocol (UDP) because of the “trivial” nature of its file transfers.

Similarly  UDP is unreliable protocol whileTCP is reliable but has overhead. SNMP doesn’t require reliability for simplicity ,because each request generates a response. In case  SNMP application does not receive a response, simply the request is reissued.

Part 4

TCP is a reliable protocol as the delievery of data to the destination router is guaranteed by TCP. Retransmission of lost packets is possible in TCP.

TCP provides flow and error control and hence extensive error checking mechanisms.

TCP is slower as compared to User Datagram Protocol.

TCP does not support broadcasting, while UDP supports broadcasting.