Computer Communication Network
Sheet 6
1- How does an NNI differ from UNI?
User-Network Interface (UNI) header
Network-to-Network Interface (NNI) header
GFC: 4 bits of generic flow control 2- What is the relationship between TPs, VPs, VCs? Vc is a part of Vp Vp ia a part of Tp
3- How is an ATM virtual connection identified? By a pair of numbers : VPI & VCI 4- How are ATM cells multiplexed? Asynchronous time-division multiplexing 5- Describe the format of an ATM cell. GFC: 4 bits of generic flow control VPI: Virtual Path Identifier VCI: Virtual Channel Identifier PT: Payload Type CLP: Cell Loss Priority
6- Draw a graph to show an ATM architecture. Fig P128
7- What are the advantage of using a small, fixed-size cells in ATM? - Reducing queuing delay for a high-priority cell - To be switched more efficiently which is important for high data rates of ATM. - It make it easier to implement the switching mechanism in hardware.
1/2
Computer Communication Network
Sheet 6
8- Name ATM layers. 1- Physical Layer 2- ATM layer 3- ATM Adaptation Layer (AALs) 9- Name the four ATM service classes? CBR: Constant Bit Rate. VBR: Variable Bit Rate. ABR: Available Bit Rate. UBR: Unspecified Bit Rate. 10- How is ATM used in WAN? Fig P128
11- What are the three technologies that determine the nature of a LAN? 1- CSMA/CD 2- Token bus 3- Token ring 12- Define and explain the data link layer in IEEE project 802. Page 132 ^ 13- What are the most important applications areas for LANs? Page 130 v 14- Compare between IEEE 802 reference model and OSI reference model. Page 131 v 15- List the IEEE 802 layers? Page 135 v 16- What are the common topologies for LANs? 1- Star
2- Bus
3- Ring
4- Mesh
17- Compare and contrast the SSAP and DSAP on the PDU with the source and destination address of the MAC frame. Page 139 ^ 18- Explain CSMA/CD and its use. What part of the 802 project uses CSMA/CD? Page 138 v 19- What types of transmission media are used in LANs? - Coaxial
- Twisted pair
- Optical Fiber
- Wireless
20- Compare the data transmission rates for traditional Ethernet, Fast Ethernet, and Gigabit Ethernet? Traditional Ethernet: Fast Ethernet: Gigabit Ethernet:
1 & 10 Megabyte 100 Megabyte 1000 Megabyte
2/2