Module 4 – Physical Layer

Network Interface Cards

connect a device to the network.

Ethernet NIC

A type of network interface card that uses Ethernet standards to connect devices to a wired network like a network printer.

WLAN NIC

A type of network interface card that allows devices to connect to a wireless local area network (WLAN).

physical layer

consists of electronic circuitry, media, and connectors developed by engineers.

Physical components

are the electronic hardware devices, media, and other connectors that transmit the signals that represent the bits.

Encoding or line encoding

is a method of converting a stream of data bits into a predefined “code”.

Latency

refers to the amount of time, including delays, for data to travel from one given point to another.

Throughput

is the measure of the transfer of bits across the media over a given period of time.

Goodput

is the measure of usable data transferred over a given period of time

Goodput

is throughput minus traffic overhead for establishing sessions, acknowledgments, encapsulation, and retransmitted bits.

lower

Goodput is always ____ than throughput, which is generally lower than the bandwidth.

Copper cabling

is the most common type of cabling used in networks today.

signal attenuation

the farther the signal travels, the more it deteriorates

copper

a medium that media must follow strict distance limitations as specified by the guiding standards.

Electromagnetic interference (EMI) or radio frequency interference (RFI)

can distort and corrupt the data signals being carried by copper media.

Crosstalk

is a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire.

metallic shielding

is a protective layer used to prevent interference from external electromagnetic signals, enhancing signal quality in copper and other wired media.

Unshielded twisted-pair (UTP) cabling

is the most common networking media

UTP cable

consists of four pairs of color-coded wires that have been twisted together and then encased in a flexible plastic sheath that protects from minor physical damage.

twisting of wires

helps protect against signal interference from other wires.

Shielded twisted-pair (STP)

provides better noise protection than UTP cabling but more expensive and difficult to install

foil

this features distinguishes UTP to STP

coax

a short term for coaxial cable

coaxial

its name from the fact that there are two conductors that share the same axis

Institute of Electrical and Electronics Engineers (IEEE)

The electrical characteristics of copper cabling are defined by the_______

higher categories

type of wire that is designed and constructed to support higher data rates

Straight-through

The most common type of networking cable. It is commonly used to interconnect a host to a switch and a switch to a router.

Crossover

A cable used to interconnect similar devices. For example, to connect a switch to a switch, a host to a host, or a router to a router.

rollover

is Cisco proprietary. It is used to connect a workstation to a router or switch console port. This cable type is used for connecting devices like terminals to network equipment for configuration and management.

Optical fiber cable

transmits data over longer distances and at higher bandwidths than any other networking media.

Single-mode fiber (SMF)

consists of a very small core and uses expensive laser technology to send a single ray of light, as shown in the figure

Single-mode fiber (SMF)

popular in long-distance situations spanning hundreds of kilometers, such as those required in long haul telephony and cable TV applications.

Multimode fiber (MMF)

consists of a larger core and uses LED emitters to send light pulses. Specifically, light from an LED enters the multimode fiber at different angles

Multimode fiber (MMF)

Popular in LANs because they can be powered by low-cost LEDs. It provides bandwidth up to 10 Gb/s over link lengths of up to 550 meters.

Dispersion

refers to the spreading out of a light pulse over time

MMF

the one that has a higher dispersion among the two types of fiber optics

straight tip

connectors were one of the first connector types used. The connector locks securely with a “Twist-on/twist-off” bayonet-style mechanism.

subscriber connector

connectors are sometimes referred to as square connector or standard connector

subscriber connector

are a widely-adopted LAN and WAN connector that uses a push-pull mechanism to ensure positive insertion. This connector type is used with multimode and single-mode fiber.

lucent connector simplex connector

smaller version of the SC connector

lucent connector simplex connector

are sometimes called little or local connectors and are quickly growing in popularity due to their smaller size.

duplex multimode LC connector

is similar to a LC simplex connector, but uses a duplex connector.

Wireless Access Point (AP)

These concentrate the wireless signals from users and connect to the existing copper-based network infrastructure, such as Ethernet.

Wireless NIC adapterer

These provide wireless communication capability to network hosts.