Wired LANs: Ethernet Study Notes

  • Ethernet is the most widely used local area network protocoL
  • The IEEE 802.3 Standard defines I-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 CSMAlCD access method and framing.
  • Each station on an Ethernet network has a unique 48-bit address imprinted on its network interface card (NIC).
  • The minimum frame length for lO-Mbps Ethernet is 64 bytes; the maximum is 1518 bytes.
  • The common implementations of lO-Mbps Ethernet are lOBase5 (thick Ethernet), 10Base2 (thin Ethernet), lOBase-T (twisted-pair Ethernet), and lOBase-F (fiber Ethernet).
  • The 10Base5 implementation of Ethernet uses thick coaxial cable. lOBase2 uses thin coaxial cable. lOBase-T uses four twisted-pair cables that connect each station to a common hub. lOBase-F uses fiber-optic cable.
  • A bridge can increase 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 removes the need for the CSMAlCD 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 common Fast Ethernet implementations are 1OOBase-TX (two pairs of twistedpair cable), lOOBase-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 mode using traditional CSMAI CD (not common) and full-duplex mode (most popular method).
  • The common Gigabit Ethernet implementations are 1000Base-SX (two optical fibers and a short-wave laser source), 1000Base-LX (two optical fibers and a long-wave laser source), and 1000Base-T (four twisted pairs).
  • The latest Ethernet standard is Ten-Gigabit Ethernet that operates at 10 Gbps. The three common implementations are lOGBase-S, 10GBase-L, and 10GBase-E. These implementations use fiber-optic cables in full-duplex mode.


Try Now – Data Communication and Networking MCQs
Practice Now – Data Communication and Networking Online Tests
Practice Now – Ethernet & WAN Technologies Online Test