Question 1 [4 marks]
Briefly explain key advantages and disadvantages of using Fibre Optics versus Copper Wire.
Question 2 [4 marks]
(1) How can you increase the bit rate of a 1200KHz line from X bit/s to 3X bit/s without
changing the frequency?
(2) Consider a telephone line that is bandwidth limited to 4kHz. If we use 32 levels, what is
the bit rate achieved to transmit data?
Question 3 [2 marks]
(1) The following data fragment occurs in the middle of a data stream for which the byte
stuffing algorithm described in the lectures is to be applied:
A B ESC D FLAG FLAG ESC C
Show the output data stream after the byte-stuffing algorithm has been applied.
(2) What is the maximum overhead in the byte-stuffing algorithm in general and when does
Question 4 [2 marks]
Briefly explain the difference in operation and philosophy of two approaches to error
handling on the data link layer, error-correcting and error-detecting.
Question 5 [2 marks]
If a LAN is under high load, would it be more efficient to use a contention protocol or a
collision free protocol in the MAC sublayer? Briefly explain your answer.
Question 6 [3 marks]
Give the name of one sliding window protocols and briefly explain how that protocol works
at Data Link Layer when a transmission error occurs.
Question 7 [4 marks]
A router has built the following routing table. The router can directly deliver packets over
Interface 0 and Interface 1 or it can forward to routers R2, R3 and R4.
Describe what the router does if a packet addressed to each of the following destinations is
本网站支持 Alipay WeChatPay PayPal等支付方式
E-mail: firstname.lastname@example.org 微信号:vipnxx