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CSMA/CA

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Carrier Sense Multiple Access with Collision Avoidance Carrier sense multiple access with collision avoidance (CSMA/CA) was invented for wireless networks. Collisions are avoided through the use of CSMA/CA’s three strategies: the interframe space, the contention window, and acknowledgments, Interframe Space (IFS)   First, collisions are avoided by deferring transmission even if the channel is found idle. When an idle channel is found, the station does not send immediately. It waits for a period of time called the interframe space or IFS. Even though the channel may appear idle when it is sensed, a distant station may have already started transmitting. The distant station’s signal has not yet reached this station. The IFS time allows the front of the transmitted signal by the distant station to reach this station. After waiting an IFS time, if the channel is still idle, the station can send, but it still needs to wait a time equal to the contention window. The IFS vari...
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CSMA/CD

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Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Carrier sense multiple access with collision detection (CSMA/CD) augments the algorithm to handle the collision. CSMA/CD method, a station monitors the medium after it sends a frame to see if the transmission was successful. If so, the station is finished. If, however, there is a collision, the frame is sent again. To better understand CSMA/CD, let us look at the first bits transmitted by the two stations involved in the collision. Although each station continues to send bits in the frame until it detects the collision, we show what happens as the first bits collide. In below figure stations A and C are involved in the collision. At time t1, station A has executed its persistence procedure and starts sending the bits of its frame. At time t2, station C has not yet sensed the first bit sent by A. Station C executes its persistence procedure and starts sending the bits in its frame, which propagate bo...
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IPV4 Address

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IPV4 Addresses The IP layer of the TCP/IP protocol suite to identify the connection of each device to the Internet is called the Internet address or IP address. An IPv4 address is a 32-bit address that uniquely and universally defines the connection of a host or a router to the Internet. IPv4 addresses are unique in the sense that each address defines one, and only one, connection to the Internet. If a device has two connections to the Internet, via two networks, it has two IPv4 addresses. IPv4 addresses are universal in the sense that the addressing system must be accepted by any host that wants to be connected to the Internet. Address Space An address space is the total number of addresses used by the protocol. If a protocol uses b bits to define an address, the address space is 2 b because each bit can have two different values (0 or 1). IPv4 uses 32-bit addresses, which means that the address space is 2 32 or 4,294,967,296 (more than four billion devices could be ...
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