Modern Ethernet–The Physical Network–NETWORKING, SECURITY, & MORE ESSENTIALS—CompTIA Network+ (N10-007) NETWORK-PLUS Certification Prep Course Notes

Modern Ethernet

• 100Base-T
  • Full-duplex mode allows both sides of a conversation to occur at the same time.
  • Half-duplex, you can “talk” or “listen” but not at the same time.
  • 100BaseT (aka 100BaseTX) runs at 100 Mbps up to 100 meters.
  • 100BaseFX, a fiber solution, runs at 100 Mbps up to 2 kilometers.

• Connecting Switches
  • (Note: Connecting switches in a tree structure is common when networks are larger & more spread out, into clusters.)
  • Straight-through cables have identical ends, such as 568B.
  • Crossover cables have different ends–568A and 568B.
  • Connect switches directly with crossover cables.

• Gigabit Ethernet & 10-Gigabit Ethernet
  • Know your 1000Base types: names, distances, node numbers, etc.
  • Know your 10GBase types: names, distances, cable types, etc.
  • Know these 4 Gigabit Ethernet standards!:
    1. ex’s: 1000BaseCX–old, weird standard; uses a coaxial cable called “Twinax”
       • 25 meters max allowed between switch & nodes
    2. 1000BaseSX–multimode fiberoptic cable; 500 meters
    3. 1000BaseLX–single-mode fiberoptic cable; 5 kilometers
    4. 1000BaseT–use Cat6; U.T.P.; 100 meters;

• 10 GB Ethernet—
  • 10 GB Ethernet uses standards designed for LAN, & designed to work with SONET (a different type of networking technology & backbone of the internet.
  • 10GBaseT–on Cat6–55meters; on Cat6a–100meters;
  • 10GBaseSR–multimode; 26meters-400meters;
  • 10GBaseLR (long range)–single-mode on 1310 nanometer cable; 10 kilometers;
  • 10GBaseER–single-mode on 1550 nm cable; 40 kilometers.
  • SONET standards are the same but end with:
    • 10GBaseSR –> SW
    • 10GBaseER –> EW
    • 10GBase LR –> LW

• Transceivers
  • Fiber-optic cable supports multple connection types from various vender MSA’s (Multi-source Agreement)
  • SFP & SFP+ are small form-factor transceivers.
  • QSFP is designed for 40 Gbps Ethernet.
  • GBIC (Gigabit interface converter) (more for ST & SC connectors).
  • SFP (Small form-factor pluggable)
  • SFP+ (Enhanced small form-factor pluggable) (more common than SFP)
  • QSFP (Quad small form-factor pluggable) Transceiver for 40 gigabit ethernet!
  • bidi–Bidirectional

• Connecting Ethernet Scenarios
  • Proper switch configuration will avoid bridging loops.
  • Match switch speeds to network speeds to avoid a slowdown due to speed mismatch.
  • Most current switches autodetect, eliminating crossover & uplink cable requirements.