1 EE555: Broadband Network Technologies HW #2, Due September 28 Read Chapters 5 and 10 Text Problems: William Stalling's Book: #5.4, #5.5, 10.2 Extra Problems: 1. A company has two branches that are connected by a trunk of capacity 128Kbps. This trunk can be configured as 0,1, or 2 voice lines at 64Kbps each and the remainder of the circuit is used for data. The voice traffic arrival rate is one call every 3 minutes and the average call holding time is 3 minutes. When a voice line is not available, the call is routed to the PSTN and costs $1.50 per call. a) Sketch the state diagram for the voice service (assuming that the state of the system is the number of lines available for voice services) b) Fill-in the following Table Number of Voice Lines Blocking Probability Cost per minute 0 1 2 Now consider the data traffic. Assume that the data traffic average arrival rate is 80Kbps and messages are broken into 1Kbit packets. The average packet delay (both waiting and being served) should be less than 0.1 seconds. The company has an arrangement with an external ISP to carry data traffic at a cost of $0.10 per 1000 Kbit (note that this is not for a rate of 1Kbps but for 1Kbit) and the ISP guarantees an average packet delay of 0.1 seconds per Kbit packet.2c) Fill-in the following Table Capacity Available for Data Amount of Data traffic sent to external ISP (in Kbps) to maintain 0.1 sec delay Cost per minute 0 64Kbps 128 Kbps 2. A user is connected to a FR network through a T-1 line. The Committed Information Rate (CIR) is 1 Mbps with a Committed Burst Size, Bc, of 5 Mbits each 5 seconds. The Excess Burst Size, Be, is 1 Mbits every 5 seconds. Answer the following questions: a) What is the access rate? b) What is the maximum data rate the user can use all of the time without worrying about frames being discarded? c) If the user wants to take a risk, what is the maximum data rate the user can be used with no chance of frames being discarded if there is no congestion? d) Can the user sends data at a constant bit rate of 1.4 Mbps all the time? e) The user sends data at a rate of 1.4 Mbps for 2 seconds and nothing for the next three seconds. Is there a danger of discarding if there is no congestion? Is there a danger of discarding if there is congestion? Explain 3. The purpose of HEC field is to protect against errors in the header of ATM cells. Assume bit errors occur at random and that the HEC can correct all single errors and can detect all double errors only. Assume that the bit error rate p = 10-6 • What is the probability that the cell will be delivered to the right destination? • What is the probability that the cell is misinserted? • What is the probability that the cell is dropped?34. The IP datagram for a TCP ACK message is 40 bytes long (20 bytes of TCP header, 20 bytes of IP header). Assume this ACK is traversing an ATM network that uses AAL5 to encapsulate IP packets. How many ATM cells are needed to carry the TCP ACK? 5. In your opinion, what are the main problems in deploying ATM in the Internet? Suppose you have a connection between host "A" and host "B". IP packets pass through an IP network, then through an ATM network and then back through an IP network. What happens during link failures (consider a link failure inside an IP network, a failure in the link connecting the IP network to the ATM network and finally a link failure inside the core ATM network) core ATM