multiple access
- 1. 12.1 Multiple Access Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 2. 12.2 Data link layer divided into two functionality-oriented sublayers
- 3. 12.3 Taxonomy of multiple-access protocols discussed in this chapter
- 4. 12.4 RANDOM ACCESSRANDOM ACCESS InIn random accessrandom access oror contentioncontention methods, no station ismethods, no station is superior to another station and none is assigned thesuperior to another station and none is assigned the control over another. No station permits, or does notcontrol over another. No station permits, or does not permit, another station to send. At each instance, apermit, another station to send. At each instance, a station that has data to send uses a procedure definedstation that has data to send uses a procedure defined by the protocol to make a decision on whether or notby the protocol to make a decision on whether or not to send.to send. ALOHA Carrier Sense Multiple Access Carrier Sense Multiple Access with Collision Detection Carrier Sense Multiple Access with Collision Avoidance Topics discussed in this section:Topics discussed in this section:
- 5. 12.5 To avoid access conflict or to resolve it when itTo avoid access conflict or to resolve it when it happens, each station follows a procedure that answerhappens, each station follows a procedure that answer the following questions:the following questions: When can the station access the medium.When can the station access the medium. What can the station do if the medium is busy.What can the station do if the medium is busy. How can the station determine the success or failureHow can the station determine the success or failure of the transmission.of the transmission. What can the station do if there is an access conflict.What can the station do if there is an access conflict.
- 6. 12.6 ALOHA ALOHA, the earliest random access method, was developed at the University of Hawaii in early 1970. It was designed for a radio (wireless) LAN, but it can be used on any shared medium. Pure ALOHA Slotted ALOHA
- 7. 12.7 Frames in a pure ALOHA network
- 8. 12.8 Procedure for pure ALOHA protocol
- 9. 12.9 Vulnerable time for pure ALOHA protocol The Vulnerable time, in which there is possibility of collision
- 11. 12.11 Frames in a slotted ALOHA network
- 12. 12.12 Figure 12.7 Vulnerable time for slotted ALOHA protocol
- 13. 12.13 CSMA Carrier Sense Multiple Access
- 14. 12.14 Space/time model of the collision in CSMA
- 15. 12.15 Figure 12.9 Vulnerable time in CSMA
- 16. 12.16 Persistence Method What Should a station do if the channel is busy. What should a station do if the channel is idle. 1-Persistence Method Non Persistence Method p-Persistence Method
- 17. 12.17 Behavior of three persistence methods
- 18. 12.18 Flow diagram for three persistence methods
- 19. 12.19 Collision of the first bit in CSMA/CD
- 20. 12.20 Collision and abortion in CSMA/CD
- 21. 12.21 Flow diagram for the CSMA/CD
- 22. 12.22 Figure 12.15 Energy level during transmission, idleness, or collision
- 23. 12.23 Figure 12.16 Timing in CSMA/CA Interframe Space (IFS)
- 24. 12.24 In CSMA/CA, the IFS can also be used to define the priority of a station or a frame. Note
- 25. 12.25 In CSMA/CA, if the station finds the channel busy, it does not restart the timer of the contention window; it stops the timer and restarts it when the channel becomes idle. Note
- 26. 12.26 Figure 12.17 Flow diagram for CSMA/CA
- 27. 12.27 CONTROLLED ACCESSCONTROLLED ACCESS InIn controlled accesscontrolled access, the stations consult one another, the stations consult one another to find which station has the right to send. A stationto find which station has the right to send. A station cannot send unless it has been authorized by othercannot send unless it has been authorized by other stations. We discuss three popular controlled-accessstations. We discuss three popular controlled-access methods.methods. Reservation Polling Token Passing Topics discussed in this section:Topics discussed in this section:
- 28. 12.28 Logical ring and physical topology in token-passing access method
- 29. Computer Science & Engineering Assignment Semester- VI (I & II) Branch: CSE Subject with Code: Computer Networks (IT-305-F) ----------------------------------------------------------------------------------------------- Q:1 Explain Lacal Area Network. Q:2 Explain IEEE 802 standards in Detail.