Free CCNA | Interfaces and Cables | Day 2 | CCNA 200-301 Complete Course

Introduction

In this section, the instructor introduces the course and explains that it is a complete course for the CCNA, including everything needed to pass the exam.

Course Introduction

• The course is a complete course for the CCNA.

• The goal of the course is to provide everything needed to pass the exam.

• The course is 100% free.

Interfaces and Cables

In this section, the instructor discusses interfaces and cables used in networks.

Connecting Devices with Cables

• Switches have lots of interfaces to connect end hosts like PCs and servers.

• Ports are Auto-MDIX.

• RJ stands for Registered Jack.

• RJ-45 connectors are used on copper Ethernet cables.

Ethernet Standards

• Ethernet is a collection of network protocols and standards.

• Ethernet isn't one single thing, making it difficult to define exactly what it is.

• For this lesson, we will focus on types of cabling as defined by Ethernet standards.

Network Protocols and Standards

• Network protocols serve as an agreed-upon system of communicating between devices in a network.

• Standards like Ethernet exist because there needs to be agreement between vendors on physical standards like connectors and cables as well as logical standards like IP, the internet protocol.

Speed Measurements

• Speeds are measured in bits per second (bps).

• A bit is a value represented by either a 0 or a 1.

• A byte consists of 8 bits.

• Data on hard drives is measured in bytes.

• A gigabyte (GB) is actually 8 times larger than a gigabit (Gb).

Units of Measurement

In this section, the instructor discusses units of measurement used for network speed.

Units of Measurement

• Speed is measured in bits per second (bps).

• 1 kilobit (Kb) is equal to 1,000 bits.

• 1 megabit (Mb) is equal to 1 million bits.

• 1 gigabit (Gb) is equal to 1 billion bits.

• Beyond terabits there are petabits, exabits, zettabits, yottabits, and more.

Understanding Ethernet Cables

In this section, we will learn about different types of Ethernet cables and their speeds. We will also understand the meaning of base and T in 10base-T, 100base-T, 1000base-T, and 10gbase-t.

Types of Ethernet Cables

• There are four common network cable speeds - 10 megabits per second, 100 megabits per second, 1 gigabit per second, and 10 gigabits per second.

• The next column lists the common names used when talking about different network interfaces and cables.

• The official IEEE standard in which they are defined is listed in the next column.

• Informal standard names given to each standard are listed in the last column.

• Base refers to baseband signaling while T refers to twisted pair cabling.

• The maximum cable length for all twisted pair cables as defined in Ethernet is 100 meters.

Understanding UTP Cables

• Copper cables used in Ethernet standards are Unshielded Twisted Pair (UTP) cables.

• Unshielded means that the wires have no metallic shield which can make them vulnerable to electrical interference.

• Twisted pairs help protect against electromagnetic interference (EMI).

• There are four pairs of wires twisted together making eight wires in total.

Connecting Devices with FastEthernet Connection

• FastEthernet or 100BASE-T connection uses two pairs or four wires.

• Pins at positions one and two on a switch's network interface receive data while pins at positions three and six transmit data.

• A PC transmits data on pins one and two while it receives data on pins three and six.

• Full-duplex transmission allows both devices to send data at the same time with no issues.

Connecting a Router to a Switch

• A router transmits data on pins one and two while it receives data on pins three and six, which is the same as a PC.

• Pins one and two receive data while pins three and six transmit data on a switch's network interface.

• FastEthernet or 100BASE-T connection uses two pairs or four wires.

Connecting Devices with Copper UTP Cables

In this section, we learn about connecting devices using copper UTP cables. We explore the challenges of connecting routers to other routers, switches to other switches, and PCs to other PCs. We also learn about straight-through and crossover cables and how they are used to connect different types of devices.

Connecting Routers, Switches, and PCs

• When connecting a router to another router or a switch to another switch or PC to PC, communication between them doesn't happen because they transmit data on pins 1 and 2 of their interface.

• A straight-through cable connects pin 1 to pin 1, pin 2 to pin 2, etc., while a crossover cable reverses the pairs on each end.

• The wires in a crossover cable are 'crossed over' each other so that the transmit pins on one side are connected to the receive pins on the other side.

• Routers and firewalls transmit data on Pins 1 and 2 and receive data on pins 3 and 6. PCs also transmit data on Pins 1 and 2 but receive data on pins 3 and 6. Switches are different as they transmit data on pins 3 and 6 but receive data on pins 1 and 2.

Auto MDI-X

• Newer networking devices include a feature called Auto MDI-X that allows devices to automatically detect which pins their neighbor is transmitting data on.

• Auto MDI-X then adjusts which pins it uses for transmitting or receiving data so that two devices can exchange data normally without worrying about straight-through or crossover cables.

Higher Speed Copper Ethernet Cables

• For gigabit ethernet (1000BASE-T)and10 gigabit ethernet (10GBASE-T), all eight wires are used with pairs reversed at each end.

• In 1000BASE-T and 10GBASE-T, each pair is bidirectional, meaning each pair isn't dedicated specifically to transmitting data or receiving data.

SFP Transceiver

• Copper UTP wiring can be used for up to 100 meters, which is usually enough within a LAN.

• For larger networks, an SFP transceiver is inserted into the device's interface.

Understanding Fiber-Optic Cables

In this section, we will learn about the structure of fiber-optic cables and their characteristics. We will also compare fiber-optic cabling to copper UTP cabling.

Structure of Fiber-Optic Cables

• Fiber-optic cables use separate cables to transmit and receive data.

• The cable has four numbered parts: fiberglass core, cladding, protective buffer, and outer jacket.

• Multimode fiber allows multiple angles of lightwaves to enter the glass fiber core due to its wider core diameter.

• Single-mode fiber has a narrower core diameter than multimode fiber, allowing light waves to travel straight down the core.

Standards for Fiber-Optic Cables

• 1000BASE-LX is a standard for 1 gigabit ethernet over fiber that can be used over single-mode or multimode fibers with different maximum cable lengths.

• 10GBASE-SR uses multimode fibers and supports cable lengths up to 400 meters.

• 10GBASE-LR uses single-mode fibers and supports cable lengths up to 10 kilometers.

• 10GBASE-ER supports even longer distances than 10GBASE-LR with distances up to 30 kilometers possible over a standard connection.

Comparing UTP Cabling and Fiber-optic Cabling

• Copper UTP cables are cheaper than fiber-optic cables but have shorter maximum cable distances (about 100 meters).

• UTP cables can be vulnerable to electromagnetic interface (EMI) and emit a faint signal outside of the cable, posing a possible security risk.

• Fiber-optic cables are more expensive than UTP cables but support longer distances and do not emit any signal outside of the cable, eliminating security risks.

Quiz Questions and Answers

This section covers quiz questions and their answers related to network cables, including straight-through cables, crossover cables, UTP, single-mode fiber, and multimode fiber.

Straight-Through vs. Crossover Cable

• A straight-through cable is necessary to connect old devices without Auto MDI-X.

• A crossover cable would likely fix the issue of connecting two routers that transmit data on pins 1 and 2.

• Auto MDI-X allows devices to detect which pins and wires their neighbors are using to transmit and receive data.

• The best answer for connecting two old routers is a straight-through cable.

Choosing the Right Cable for Different Distances

• Multimode fiber is the best choice for connecting switches in two separate buildings that are about 150 meters apart.

• Single-mode fiber is the best choice for connecting two offices that are about 3 kilometers apart.

Connecting Switches with Identical Ports

• Two switches with identical ports connected by a straight-through cable would operate normally because the ports are Auto MDI-X enabled.

Choosing the Right Cable for End Host Connections

• UTP cables are the standard for wired connections to switches when connecting many end hosts in a wiring cabinet on the same office floor as the hosts.