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Module : LAN Cabling & CSMA/CD

Objectives Describe the LAN physical layer implementations Describe the main connectivity recommendations for implementing Ethernet in the campus Identify different types of connectors specified for Ethernet use Describe the different connection media for an Ethernet LAN Describe UTP cables and connectors in an Ethernet LAN Lesson Aim <Enter lesson aim here.>

LAN Physical Layer Implementation LLC Sublayer IEEE 802.2 MAC Sublayer Ethernet 10BASE-2 10BASE-5 10BASE-T 10BASE-F 10BASE-TX 10BASE-FX 10BASE-T4 10BASE-T 10BASE-CX Physical Layer Lesson Aim <Enter lesson aim here.> DIX Standard 802.3 Specifications for 10-Mbps Ethernet 802.3u Specifications for 100-Mbps (Fast) Ethernet 802.3u Specifications for 1000-Mbps (Gigabit) Ethernet Physical layer implementations vary. Some implementations support multiple physical media.

Ethernet Connectivity Recommendations Ethernet 10 BASE-T Positions Fast Ethernet Position Gigabit Ethernet Position Provides connectivity between the end-user device and the user-level switch. Gives high-performance PC workstations 100 Mpbs access to the servers. — Provides connectivity between end user and workgroup. Provides connectivity from the workgroup to backbone. Provides connectivity from the server block to the backbone layer. Lesson Aim <Enter lesson aim here.> — — Provides inter-switch connectivity. Provides backbone and inter-switch connectivity. —

Ethernet Protocol Description 100BASE-FX LAN speed 100 Mbps Indicates type of cable and maximum length. If a number, maximum length = No. x 100m Lesson Aim <Enter lesson aim here.> BASE = Baseband Broad = Broadband

Comparing Ethernet Media Requirements 10 BASE-2 10 BASE-5 10 BASE-T 100 BASE-TX 100 BASE-FX 1000 BASE-CX 1000 BASE-T 1000 BASE-SX 1000 BASE-LX EIA/TIA Category 3, 4, 5 UTP 2 pair EIA/TIA Category 5 UTP 2 pair 62.5/125 micro multimode fiber EIA/TIA Category 5 UTP 4 pair 62.5/50 micro multimode fiber 9 micron single-mode fiber 50-ohm coaxial (Thinnet) 50-ohm coaxial (Thicknet) Media STP Maximum Segment Length 3-10 km (1.86-6.2 miles) 185 m (606.94 ft) 500 m (1640.4 ft) 100 m (328 ft) 100 m (328 ft) 400 m (1312.3 ft) 25 m (82 ft) 100 m (328 ft) 260 m (853 ft) Lesson Aim <Enter lesson aim here.> Point to Point Topology Bus Bus Star Star — — — — Duplex media interface connector (MIC) ST Attachment unit interface (AUI) ISO 8877 (RJ-45) ISO 8877 (RJ-45) ISO 8877 (RJ-45) ISO 8877 (RJ-45) Connector AUI — —

Differentiating Between Connections Lesson Aim <Enter lesson aim here.>

GigaStack GBIC Gigabit Interface Converters (GBICs) Lesson Aim <Enter lesson aim here.> Gigabit Interface Converters (GBICs)

Cisco WS-X2931 Gigabit Ethernet Module with GBIC Out Lesson Aim <Enter lesson aim here.>

RJ-45 Connector Lesson Aim <Enter lesson aim here.>

RJ-45 Jack Lesson Aim <Enter lesson aim here.>

UTP Implementation (Straight-Through) Cable 10BASE-T/ 100BASE-TX Straight-Through Straight-Through Cable Hub/Switch Server/Router Pin Label Pin Label Lesson Aim <Enter lesson aim here.> 1 2 3 4 5 6 7 8 TX+ TX- RX+ NC RX- 1 2 3 4 5 6 7 8 TX+ TX- RX+ NC RX- Wires on cable ends are in same order.

UTP Implementation (Crossover) Cable 10BASE-T/ 100BASE-TX Straight-Through Crossover Cable Hub/Switch Server/Router Pin Label Pin Label Lesson Aim <Enter lesson aim here.> 1 2 3 4 5 6 7 8 TX+ TX- RX+ NC RX- 1 2 3 4 5 6 7 8 TX+ TX- RX+ NC RX- Some wires on cable ends are crossed.

UTP Implementation – Straight-Through vs. Crossover Lesson Aim <Enter lesson aim here.>

Cabling the Campus Lesson Aim <Enter lesson aim here.> 1000-Mbps Category 5 Crossover 10-Mbps Category 3, 4, 5 Crossover 10-Mbps Category 3, 4, 5 Straight-Through Lesson Aim <Enter lesson aim here.> 10-Mbps Category 3, 4, 5 Straight-Through 100-Mbps Category 5 Straight-Through

Carrier sense multiple access collision detect (CSMA/CD) B C D Carrier Sense A B C D Multiple Access A B C D Lesson Aim <Enter lesson aim here.> Collision Collision A B C D Collision Detection (Backoff Algorithm) JAM JAM JAM JAM JAM JAM Carrier sense multiple access collision detect (CSMA/CD)

CSMA/CD Process Host wants to transmit Is carrier sensed? 1 Is carrier sensed? Yes 2 Assemble frame No Start transmitting 3 Is a collision detected? Keep transmitting 4 Is the transmission done? Yes Transmission completed 5 Lesson Aim <Enter lesson aim here.> 9 Broadcast jam signal No 6 10 Attempts = Attempts + 1 Attempts > Too many ? No No 7 11 13 Too many collisions; abort transmission Yes Yes Algorithm calculates backoff 8 12 14 Wait for t microseconds

Summary The three principle LAN implementation categories are Ethernet, Fast Ethernet, and Gigabit Ethernet. There are several connection media used for Ethernet, including RJ-45, AUI, and GBIC. A Gigabit Interface Converter (GBIC) is a hot-swappable input/output device that plugs into a Gigabit Ethernet port. A crossover cable is used to connect between similar devices (such as switch to switch, router to router, PC to PC, and hub to hub). A straight-through cable is used to connect between dissimilar devices (such as switch to router, switch to PC, hub to router, and hub to PC).