Thread: Wireless LANs
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Old 18-03-2011, 06:32 PM
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Default Wireless LANs
Wireless LANs


* Ethernet is the most widely used local area network protocol.
* The IEEE 802.3 standard defines 1-persistent CSMA/CD as the access method for first-generation 10-Mbps Ethernet.
* The data link layer of Ethernet consists of the LLC sublayer and the MAC sublayer.
* The MAC sublayer is responsible for the operation of the CSMA/CD access method.
* Each station on an Ethernet network has a unique 48-bit address imprinted on its network interface card (NIC).
* The minimum frame length for 10-Mbps Ethernet is 64 bytes; the maximum is 1518 bytes.
* The physical layer of 10-Mbps Ethernet can be composed of four sublayers: the physical layer signaling (PLS) sublayer, the attachment unit interface (AUI) sublayer, the medium attachment unit (MAU) sublayer, and the medium-dependent interface (MDI) sublayer.
* The common baseband implementations of 10-Mbps Ethernet are 10Base5 (thick Ethernet), 10Base2 (thin Ethernet), 10Base-T (twisted-pair Ethernet), and 10Base-FL (fiber link Ethernet).
* The 10Base5 implementation of Ethernet uses thick coaxial cable. The 10Base2 implementation of Ethernet uses thin coaxial cable. The 10Base-T implementation of Ethernet uses twisted-pair cable that connects each station to a port in a hub. The 10Base-FL implementation of Ethernet uses fiber-optic cable.
* A bridge can raise the bandwidth and separate the collision domains on an Ethernet LAN.
* A switch allows each station on an Ethernet LAN to have the entire capacity of the network to itself.
* Full-duplex mode doubles the capacity of each domain and deletes the need for the CSMA/CD method.
* Fast Ethernet has a data rate of 100 Mbps.
* In Fast Ethernet, autonegotiation allows two devices to negotiate the mode or data rate of operation.
* The Fast Ethernet reconciliation sublayer is responsible for the passing of data in 4-bit format to the MII.
* The Fast Ethernet MII is an interface that can be used with both a 10- and a 100-Mbps interface.
* The Fast Ethernet PHY sublayer is responsible for encoding and decoding.
* The common Fast Ethernet implementations are 100Base-TX (two pairs of twisted-pair cable), 100Base-FX (two fiber-optic cables), and 100Base-T4 (four pairs of voice-grade, or higher, twisted-pair cable).
* Gigabit Ethernet has a data rate of 1000 Mbps.
* Gigabit Ethernet access methods include half-duplex using traditional CSMA/CD (not common) and full-duplex (most popular method).
* The Gigabit Ethernet reconciliation sublayer is responsible for sending 8-bit parallel data to the PHY sublayer via a GMII interface.
* The Gigabit Ethernet GMII defines how the reconciliation sublayer is to be connected to the PHY sublayer.
* The Gigabit Ethernet PHY sublayer is responsible for encoding and decoding.
* The common Gigabit Ethernet implementations are 1000Base-SX (two optical fibers and a shortwave laser source), 100Base-LX (two optical fibers and a long-wave laser source), and 100Base-T (four twisted pairs).
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