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Classes of Routing Protocols Classification of Routing Algorithms Controlled Access Protocols in Computer Networks Differences between IPv4 and IPv6 Fixed and Flooding Routing Algorithms Advantages and Disadvantages of Fibre Optics Cable APIPA Difference between Active and Passive FTP Fiber Optics and its Types Method of Joining and Fusion of Fiber Optic Cable Define Framing in Computer Network Disadvantages of Computer Network Mesh Topology Diagram in Computer Network Ring Topology in Computer Network Star Topology in Computer Networks 4G Mobile Communication Technology Advantages and Disadvantages of LAN Advantages and Disadvantages of MAN Advantages and Disadvantages of WAN Application Layer in OSI Model Cyclic Redundancy Check Example Data link layer in OSI model Difference between Transport and Network Layer Hamming Code Example Network Layer in OSI Model Session Layer in OSI Model Transport Layer in OSI Model Two Port Network in Computer Networks Uses of Computer Networks What is Computer Network What is Framing in a Computer Network Advantages and Disadvantages of Bus Topology Difference between Star Topology and Bus Topology Subnetting in Computer Network Subnetting Questions and Answers What is Bus Topology What is Network Topology and Types in Computer Networks Access Control in Networking Basic Characteristics of Computer Network Benefits of SOCKS5 Proxy in Computer Networks Computer Network viva Questions Difference between BOOTP and RARP Difference Between Network Topologies and Network Protocols Difference between NFC and RFID Difference Between Point-to-Point Link and star Topology Network Differences Between MSS and MTU Differences Between Trunk Port and Access Port Different Modes of Communication in Computer Networks MIME Protocol in Computer Networks Modes of Communication in Computer Networks Network Attack in Computer Network Port Address in Networking Simplest Protocol in Computer Network Sliding Window Protocol in Computer Network Stop And Wait Protocol in Computer Networks TCP 3-Way Handshake Process in Computer Networks What is a Proxy Server What is APPN What is ICMP Protocol What is Point-to-Point Protocol What is Port Address in Networking What is the HDLC Protocol What is VRRP Protocol Difference Between Analog and Digital Signals Difference Between Hub and Repeater Difference between Repeater and Switch Difference Between Transparent Bridge and Source Routing Bridge Source Routing Bridge in Computer Networks Transparent Bridge in Computer Networks Transport Protocol in Computer Networks Types of CSMA in Computer Networks What is Wired and Wireless Networking Network Security in Computer Network Disadvantages of Extranet Difference Between TELNET and FTP Define Protocol in Computer Networks Guided Transmission Media in Computer Network What is a Gateway in a Computer Network IGMP in Computer Networks LAN Protocols in Computer Networks MAN Meaning in Computer Modulation Techniques in Computer Networks Switching in DCN TCP/IP Applications What is IGMP? What is Modem in Networking What is Non-Persistent CSMA Difference between Cell Splitting and Cell Sectoring Forouzen Computer Network Open Loop and Closed Loop Congestion Control Types of Cluster Computing WAP-Wireless Access Point What are the elements of the Transport Protocol Difference between Gateway and Switch Flow Control in Data Link Layer Body Area Network Flooding in Computer Network Token Ring in Computer Networks VoIP in Computer Networks What is Infrared Transmission Congestion Control Techniques Forward Error Correction (FEC) Switching Techniques What is Telnet in Computer Network What are the Types of IPv4 Addresses IEEE 802.6 (DQDB) IEEE 802.15.4 Technology What is HDLC (High-level Data Link Control)? What is SMS Hubbing in Telecom? Circuit Switching in Computer Networks Communication Satellites in Computer Networks Features of HTTP Protocol IMAP4 (Internet Message Access Protocol) Internet Services How to Set up a Wireless Router Internetwork Routing in Computer Networks Distributed Computing System Features of GSM The 802.11 MAC Sublayer Protocol What is IEEE 802.3? What are Hubs and Switches in Computer Networks? What is Modem in a Computer Network? What is multicasting in Computer Networks? GSM -The Mobile Station What is Network Server? Slotted Aloha in Computer Network What is Ethernet in Computer Networks What is Arpanet?

Types of CSMA in Computer Networks

Carrier Sense Multiple Access (CSMA) is a networking protocol used to control access to shared communication channels. In a shared communication channel, multiple devices are connected to the same channel and can transmit data over it. In order to avoid collisions between data transmissions, CSMA protocols ensure that only one device is transmitting at a time.

The basic principle of CSMA is that before transmitting data, a device must first check whether the communication channels are idle, meaning that no other device is currently transmitting data. The device does this by sensing the carrier signal on the communication channel. If the channel is busy, the device waits for a random amount of time before retrying the transmission.

There are several variations of the CSMA protocol, including CSMA/CD, CSMA/CA, and CSMA/CR.

CSMA protocols help to ensure that communication channels are used efficiently and that data transmissions are successful. However, they do not guarantee that collisions will never occur, especially in high-traffic networks. Therefore, other protocols, such as error-correction and retransmission, are often used in conjunction with CSMA to improve the reliability of data transmission.

The Three Types of CSMA

  1. CSMA/CD (Carrier Sense Multiple Access with Collision Detection): This type of CSMA is used in Ethernet networks. Before transmitting data, a device senses the communication channel to ensure it is idle. If another device begins transmitting at the same time, a collision occurs, and both devices stop transmission and retry after a random delay.
  2. CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance): This type of CSMA is used in wireless networks such as Wi-Fi. Before transmitting data, a device senses the communication channel to ensure it is idle. If the channel is busy, the device waits for a random period before trying again.
  3. CSMA/CR (Carrier Sense Multiple Access with Collision Resolution): This type of CSMA is used in token ring networks. Instead of sensing the communication channel, devices wait to receive a token, which grants them permission to transmit data. Once a device has finished transmitting data, it passes the token on to the next device in the ring.

Working Principle of CSMA

The working principle of Carrier Sense Multiple Access (CSMA) is based on the idea of sharing a common communication channel between multiple devices, while avoiding collisions between data transmissions.

The basic steps involved in the CSMA protocol are:

  • Carrier Sense: Before transmitting data, a device first checks whether the communication channel is idle by sensing the carrier signal on the channel. If the channel is busy, the device waits for a random period of time before retrying the transmission.
  • Multiple Access: Once the channel is sensed to be idle, the device can start transmitting data. However, other devices on the network may also be attempting to transmit data at the same time. To prevent collisions, CSMA ensures that only one device transmits data at a time.
  • Collision Detection/Resolution: In CSMA/CD (used in Ethernet networks), if two devices transmit data at the same time, a collision occurs. The devices detect the collision and stop transmitting, then wait for a random period of time before retrying the transmission. In CSMA/CA (used in wireless networks), devices listen for an acknowledgement signal from the receiver before transmitting data, to reduce the likelihood of collisions.
  • Retransmission: If a data transmission is unsuccessful, the device will retry the transmission after a random delay. This helps to ensure that data is successfully transmitted, even in the presence of collisions.

Vulnerable Time in CSMA

The vulnerable time in Carrier Sense Multiple Access (CSMA) refers to the period of time during which a collision can occur between two or more devices attempting to transmit data on a shared communication channel.

In CSMA protocols, devices first sense the carrier signal on the communication channel to determine if it is idle before attempting to transmit data. However, due to the propagation delay of the signal, there is a finite period of time during which two devices may start transmitting simultaneously, leading to a collision.

The vulnerable time can be calculated as the time taken for a signal to propagate across the entire network, plus any processing time required by the devices to sense the channel and start transmitting data. The length of the vulnerable time depends on factors such as the physical distance between devices, the transmission speed, and the network topology.

In Ethernet networks that use CSMA/CD, the vulnerable time is the time taken for a signal to travel the length of the cable twice. This is because a device can detect a collision only after the signal has travelled the entire length of the cable and returned to the device. In wireless networks that use CSMA/CA, the vulnerable time is generally longer due to the greater propagation delay of signals in the air.

To reduce the vulnerable time and minimize the likelihood of collisions, CSMA protocols typically use randomized backoff algorithms that introduce a random delay before a device retries a transmission after a collision. The backoff algorithm helps to ensure that devices do not retry transmissions simultaneously, reducing the likelihood of another collision.