ST.MOTHER THERESA ENGINEERING COLLEGE

Transcription

1 ST.MOTHER CHETTINAD COLLEGE OF ENGINEERING THERESA & TECHNOLOGY ENGINEERING COLLEGE DEPARTMENT OF ELECTRONICS AND COMMUNICATION ENGINEERING SUBJECT CODE: CS 2060 SEM/YEAR: VII/IV SUBJECT NAME: HIGH SPEED NETWORKS PART - A (2 Marks) UNIT-1 HIGH SPEED NETWORKS 1. List and explain the types of frame relay messages. Setup Connect Release Complete 2. Give some examples of ATM application. In real time services, Video conferencing Interactive audio Audio/Video distribution In Non real time services, LAN inter connection Remote terminal 3. Define asynchronous transfer mode. ATM is a relay which is used to improve the packet switching network. It involves the transfer of data in discrete chunks. It is also allow multiple logical connections to be multiplexed over a single physical interface. 4. List the function provided by AAL 3/4 layer. AAL 3/4 provides its data transfer service by accepting block of data from the next higher layer and transmitting each to a destination AAL user. A block of data from a higher layer such as PDU is encapsulated into a PDU at the CPU sub layer.

2 5. Difference between frame relaying and X.25 packet switching service. FRAME RELAY X.25 End to End flow and error control HOP by HOP flow and error control Multiplexing and Switching done in layer 2 Common channel signaling Data rate 2 Mbps Multiplexing and Switching operation are carrier out of layer 3 In Band signaling Data rate 64 Kbps 6. State the data link control function provided by LAPF protocol. Congestion control function Detection of transmission error Frame multiplexing/ Demultiplexing Frame delimiting, alignment and transparency 7. Give few examples for High Speed Network. Fast Ethernet Gigabit Ethernet Fiber Channel Wireless LANs 8. Draw the ATM cell structures.

3 9. State the advantages of frame relay. Stream lined communication process Lower delay and higher throughput Effective utilization of network Frame relay speed up to 2 Mbps 10. Is CSMA/CD used in gigabit LANs? Justify Yes, CSMA/CD is used in gigabit LANs with CSMA/CD a station wishing to transmit forced listen to the medium to determine of another transmission is in progress. If the medium is idle the station may transmit. With CD if collision is occurred the data from both transmission will be grabbled and not receive successfully. 11. What is the need for AAL? The use of ATM creates the needs for an adaptation layer to support information transfer protocol but not based on ATM. Example: PCM voice, LAPF 12. What are the data link control functions that are provided by LAPF core? While frame delimiting, alignment and transparency. Frame multiplexing. Detection of transmission errors. Congestion control function. Inspection of frame to ensure that is neither too long nor too short. 13. What are the uses of wireless LAN? It saves cost of installation of LAN cabling and Uses the task of location and other modification to network structure. It provides an effective and more attractive alternative in stock exchanging warehouse etc. It is also used in Adhoc networks. 14. What is the access method used by wireless LAN? The accessing method used in wireless LAN is CSMA/CD and CSMA/CA. CSMA/CD: Carrier Sense Multiple Access/ Collision Detection. CSMA/CA: Carrier Sense Multiple Access/ Collision Avoidance.

4 15. Distinguish between frame relay and ATM. (or) Differentiate ATM bearer service from other bearer service. FRAME RELAY Variable cell size 2 Mbps Speed Less efficient ATM Fixed cell size Mbps Speed Compared frame relay ATM is efficient 16. What is the difference between Class A and Class C service offered by ATM? CLASS A CLASS B Constant bit rate Variable bit rate ATM adaption layer ATM adaption layer protocol used AAL Mention four important feature of frame relay network. End to end error control and flow control. Lower delay and higher throughput. Effective utilization of networks. Stream lined communication process. 18. What is meant by virtual circuit? Virtual circuit, A virtual circuit is a bidirectional path through the network that is defined in software. Both frame relay network and ATM uses virtual circuit concept there are two types of virtual circuit, PVC (Permanent Virtual Circuit) SVC (Switched Virtual Circuit) PVC is manually configured path through a network that does not change unless manually reconfigured. SVC is dynamically established when needed and dynamically to run down when no longer needed.

5 19. What is need for High speed LANs? Many new applications have the large capacity of data. So with that new application such as CAD, Image processing real time audio and video being implemented on LAN There is a need for a high speed LAN with a data rate higher than 10 Mbps. Fast Ethernet with 100 Mbps and Gigabit Ethernet with 1 Gbps are the high speed LANs. 20. Mention the advantage and disadvantage of wireless LAN? Advantage: It is easier to add or move work station. It has more flexibility within ratio coverage, nodes can communicate without further restriction. It has robustness ie, Wireless network survive disasters. Disadvantages: It typically offers lower QOS Implementation cost is very high. It has very less security and safety. 21. State the use of CLP bit in the header an ATM cell. It provides guidance to the network in the event of congestion. A value of 0 indicates a cell of relatively higher priority which should not be discarded unless no other alternatives is available. A value of 1 indicated that this cell is subjected to discard within the network. 22. What are the requirement of High speed LAN? Throughput Number of nodes Connection to backbone Service area Hand off/ Roaming Dynamic configuration

6 23. Give the frame format of frame relay. Implemented by end system but not network Not network LAPF CORE Implemented by end system and network LAPF CORE PHYSICAL LAYER By network