ENGI 2453 Computer Communications and Networking
Assignment 5 — 2018
1. Suppose 12780 bytes of data is to be transferred from server to client over a TCP connection
over a point-to-point line using Ethernet frames (total overhead = 34 bytes, including an 8-byte
interframe gap). The line bit rate is 1 Gbps, distance is 6 km with $v = 2.5 \times 10^8$ m/s.
The connection parameters are the following: MSS=1420 for both ends, initial sequence number
for client is 332 and for server is 1856. The server initiates the disconnection right after finishing
data transmission by sending the FIN flag and client replies by sending the FIN flag. Assume the
window size is 2840 bytes on both sides and no options in IP and TCP headers. Also assume one
ACK segment is sent for each data segment.
(a) Show a diagram of a data frame and a control frame (ACK, SYN, etc). Show how many
bytes in each field: Eth header, payload, trailer. Assume padding is used for Ethernet frames
with a data length less than 46 bytes.
(b) Calculate the time to transmit each type of frame and the delay in the line.
(c) Draw a diagram showing connection setup. Indicate ACK, SYN, FIN flag values, SEQ and
ACK numbers.
(d) Draw a diagram showing the disconnection exchange. Indicate ACK, SYN, FIN flag values,
SEQ and ACK numbers.
(e) How many data frames are sent from server to client? How many data frames are sent from
client to server?
(f) What is the time elapsed until the connection is closed?