CSMA/CD, CSMA/CA and Token Passing
CSMA/CD (Carrier Sense Multiple Access/Collision Detection)
In CSMA/CD (Carrier Sense Multiple Access/Collision Detection) Access Method, every host has equal access to the wire and can place data on the wire when the wire is free from traffic. When a host want to place data on the wire, it will “sense” the wire to find whether there is a signal already on the wire. If there is traffic already in the medium, the host will wait and if there is no traffic, it will place the data in the medium. But, if two systems place data on the medium at the same instance, they will collide with each other, destroying the data. If the data is destroyed during transmission, the data will need to be retransmitted. After collision, each host will wait for a small interval of time and again the data will be retransmitted, to avoid collision again.
CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance)
In CSMA/CA, before a host sends real data on the wire it will “sense” the wire to check if the wire is free. If the wire is free, it will send a piece of “dummy” data on the wire to see whether it collides with any other data. If it does not collide, the host will assume that the real data also will not collide.
Token Passing
In CSMA/CD and CSMA/CA the chances of collisions are there. As the number of hosts in the network increases, the chances of collisions also will become more. In token passing, when a host want to transmit data, it should hold the token, which is an empty packet. The token is circling the network in a very high speed. If any workstation wants to send data, it should wait for the token. When the token has reached the workstation, the workstation can take the token from the network, fill it with data, mark the token as being used and place the token back to the network.
Chapter 1 :- Introduction to Computer Networking
Chapter 2 :- What is a Computer Network
Chapter 3 :- Why we need computer networks
Chapter 4 :- Client Operating Systems
Chapter 5 :- Common Network Application Software
Chapter 6 :- LAN and WAN
Chapter 7 :- CAN and MAN
Chapter 8 :- Peer-to-Peer networks and Client-Server networks
Chapter 9 :- Centralized and Distributed Computer Networks
Chapter 10 :- Internetworks, Internet, Intranet and Extranet
Chapter 11 :- What is a Network Protocol
Chapter 12 :- Difference between Proprietary and Standard Protocols
Chapter 13 :- What are RFCs
Chapter 14 :- Organizations which control Internet
Chapter 15 :- Bus Topology
Chapter 16 :- Star Topology
Chapter 17 :- Mesh, Ring and Hybrid Topologies
Chapter 18 :- Network Infrastructure Devices and Icons
Chapter 19 :- Network Hub
Chapter 20 :- Network Bridge
Chapter 21 :- What is a Router
Chapter 21 :- What is a Firewall
Chapter 22 :- Office Networks
Chapter 23 :- Hub-and-spoke WAN topology
Chapter 24 :- Partial-Mesh WAN topology
Chapter 25 :- Full-mesh Site-to-site WAN topology
Chapter 26 :- What is NIC
Chapter 27 :- Common Network Cable types
Chapter 28 :- Difference between Baseband and Broadband
Chapter 29 :- CSMA/CD, CSMA/CA and Token Passing
Chapter 30 :- LAN Technologies Ethernet
Chapter 31 :- Ethernet Media Standards
Chapter 32 :- What is Token Ring
Chapter 33 :- What is FDDI
Chapter 34 :- IEEE 802 Standards
Networking Interview Questions :- 1
Networking Interview Questions :- 2
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