Chapter 4
Ethernet Straight-through
Ethernet 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.
Multimode fiber (MMF)
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, as shown in the figure. 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. A orange (or aqua) jacket is for multimode fiber cables.
Electromagnetic interference (EMI) or radio frequency interference (RFI)
EMI and RFI signals can distort and corrupt the data signals being carried by copper media. Potential sources of EMI and RFI include radio waves and electromagnetic devices, such as fluorescent lights or electric motors.
Which procedure is used to reduce the effect of crosstalk in copper cables?
In copper cables, crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire interfering with the signal in an adjacent wire. Twisting opposing circuit wire pairs together can effectively cancel the crosstalk. The other options are effective measures to counter the negative effects of EMI and RFI, but not crosstalk.
Terms used to measure the quality of bandwidth include:
Latency Throughput Goodput
The physical layer standards address three functional areas:
Physical Components Encoding Signaling
There are three main types of copper media used in networking.
Unshielded Twisted Pair (UTP) cable. Shielded twisted-pair (STP) cable Coaxial Cable
The difference between DCE and DTE cables in packet tracer is just which side you click first:
With the DCE cable, (red zigzag with clock) the side you click first will be the DCE, the second will be DTE With the DTE cable (red zigzag no clock) the side you click first will be DTE, the second will be DCE
Which of the following wireless standards is best suited for industrial and IoT environments?
Zigbee Zigbee is intended for applications that require short-range, low data-rates, and long battery life, making it well suited for industrial and IoT applications.
What is the definition of bandwidth?
the amount of data that can flow from one place to another in a given amount of time Bandwidth is the measure of the capacity of a network medium to carry data. It is the amount of data that can move between two points on the network over a specific period of time, typically one second.
Which of these is the name for the capacity of a medium to carry data? Latency Throughput Goodput
Bandwidth is the capacity of a network medium to carry data.
Which of the following wireless standards is used for Personal Area Networks (PANs) and allows devices to communicate over distances of 1 to 100 meters?
Bluetooht This wireless standard is used for Personal Area Networks (PANs) and allows devices to communicate over distances of 1 to 100 meters.
Crosstalk
Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire. In telephone circuits, crosstalk can result in hearing part of another voice conversation from an adjacent circuit. Specifically, when an electrical current flows through a wire, it creates a small, circular magnetic field around the wire, which can be picked up by an adjacent wire.
Which statement correctly describes frame encoding?
It converst bits into a predefined conde in order to provide a predicatable pattern to help distinguish data bit from control bits. Frame encoding converts a stream of data bits into a predefined code that is recognized by both the sender and receiver. These codes are used for a variety of purposes, such as distinguishing data bits from control bits, and identifying the beginning and end of a frame.
Latency
Latency refers to the amount of time, including delays, for data to travel from one given point to another. In an internetwork, or a network with multiple segments, throughput cannot be faster than the slowest link in the path from source to destination. Even if all, or most, of the segments have high bandwidth, it will only take one segment in the path with low throughput to create a bottleneck in the throughput of the entire network.
Single-mode fiber (SMF)
SMF consists of a very small core and uses expensive laser technology to send a single ray of light, as shown in the figure. SMF is popular in long-distance situations spanning hundreds of kilometers, such as those required in long haul telephony and cable TV applications. A yellow jacket is for single-mode fiber cables
Fiber-optic cables are broadly classified into two types:
Single-mode fiber (SMF) Multimode fiber (MMF)
What is the purpose of the OSI physical layer?
The physical layer is responsible for transmitting the actual signals across the physical media as bits. Exchanging frames, controlling media access, and performing error detection are all functions of the data link layer. controlling media access, and performing error detection are all functions of the data link layer.
Which of these is a measure of the transfer of bits across the media? Latency Throughput Goodput
The transfer of bits across the network media over a period of time is known as throughput.
Goodput
There is a third measurement to assess the transfer of usable data; it is known as goodput. 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. Goodput is always lower than throughput, which is generally lower than the bandwidth.
Bluetooth (IEEE 802.15)
This is a wireless personal area network (WPAN) standard, commonly known as "Bluetooth." It uses a device pairing process to communicate over distances from 1 to 100 meters.
These are the wireless standards:
Wi-Fi (IEEE 802.11) Bluetooth (IEEE 802.15) WiMAX (IEEE 802:16) Zigbee (IEEE 802.15.4) Note: Other wireless technologies such as cellular and satellite communications can also provide data network connectivity. However, these wireless technologies are out of scope for this module.
Wi-Fi (IEEE 802.11)
Wireless LAN (WLAN) technology, commonly referred to as Wi-Fi. WLAN uses a contention-based protocol known as carrier sense multiple access/collision avoidance (CSMA/CA). The wireless NIC must first listen before transmitting to determine if the radio channel is clear. If another wireless device is transmitting, then the NIC must wait until the channel is clear. Wi-Fi is a trademark of the Wi-Fi Alliance. Wi-Fi is used with certified WLAN devices based on the IEEE 802.11 standards.
Zigbee (IEEE 802.15.4)
Zigbee is a specification used for low-data rate, low-power communications. It is intended for applications that require short-range, low data-rates and long battery life. Zigbee is typically used for industrial and Internet of Things (IoT) environments such as wireless light switches and medical device data collection.
Which characteristic describes crosstalk?
the distortion of the transmitted massage from signals carried adjscent wires EMI and RFI can distort network signals because of interference from fluorescent lights or electric motors. Attenuation results in deterioration of the network signal as it travels along copper cabling. Wireless devices can experience loss of signals because of excessive distances from a access point, but this is not crosstalk. Crosstalk is the disturbance caused by the electric or magnetic fields of the signal carried on an adjacent wire within the same cable.
deteriorate attenuation dispersion
verschlechtern Dämpfung Abschwächung Streuung Verteilung
Category 5 and 5e Category 6 Category 7 Category 8
Category 5 and 5e is used for data transmission. Category 5 supports 100Mbps and Category 5e supports 1000 Mbps Category 6 has an added separator between each wire pair to support higher speeds. Category 6 supports up to 10 Gbps. Category 7 also supports 10 Gbps. Category 8 supports 40 Gbps.
WiMAX (IEEE 802:16)
Commonly known as Worldwide Interoperability for Microware Access (WiMAX), this wireless standard uses a point-to-multipoint topology to provide wireless broadband access.
Ethernet Crossover
Ethernet 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. However, crossover cables are now considered legacy as NICs use medium-dependent interface crossover (auto-MDIX) to automatically detect the cable type and make the internal connection.
Which standards organization oversees development of wireless LAN standards?
IEEE IANA oversees the management of IP address allocation and domain names. ISO is the largest developer of international networking standards and is famous for the Open Systems Interconnection (OSI) model. TIA focuses on communication standards. The IEEE 802 standards are many, but the ones that affect an entry-level network professional are Ethernet (802.3), wireless LANs (802.11), and wireless PANs (802.15).
Which type of UTP cable is used to connect a PC to a switch port?
Streight throught A rollover cable is a Cisco proprietary cable used to connect to a router or switch console port. A straight-through (also called patch) cable is usually used to interconnect a host to a switch and a switch to a router. A crossover cable is used to interconnect similar devices together, for example, between two switches, two routers, and two hosts.
Throughput
Throughput is the measure of the transfer of bits across the media over a given period of time. Due to a number of factors, throughput usually does not match the specified bandwidth in physical layer implementations. Throughput is usually lower than the bandwidth. There are many factors that influence throughput: The amount of traffic The type of traffic The latency created by the number of network devices encountered between source and destination
Why are two strands of fiber used for a single fiber optic connection?
To allow full-duplex connectivity Light can only travel in one direction down a single strand of fiber. In order to allow for full-duplex communication two strands of fiber must be connected between each device.
What is a characteristic of UTP cabling?
cancellation Cladding and immunization from electrical hazards are characteristics for fiber-optic cabling. A woven copper braid or metallic foil is used as a shield for the inner coaxial cable conductor. Cancellation is a property of UTP cabling where two wires are located adjacent to one another so each magnetic field cancels out the adjacent magnetic field.
True or false? When a frame is encoded by the physical layer, all bits are sent over the media at the same time.
false When encoded, the bits making up a frame are transmitted over the media one at a time.
What is indicated by the term throughput?
the measure of the bits trannsfered across the media over a given period of time Throughput is the measure of the transfer of bits across the media over a given period of time. Throughput is affected by a number of factors such as, EMI and latency, so it rarely matches the specified bandwidth for a network medium. The throughput measurement includes user data bits and other data bits, such as overhead, acknowledging, and encapsulation. The measure of the usable data transferred across the media is called goodput.
