CCNA Chapter 4

What factors influence throughput?

A. Amount of traffic B. Type of traffic C. Latency created by the number of network devices device encouraged between source and destination

List the three types of network media commonly used.

A. Copper cable: The signals are patterns of electrical pulses. B. Fiber-optic cable: The signals are patterns of light. C. Wireless: The signals are patterns of microwave transmissions.

List and explain each of the three physical layer standards functional areas.

A. Physical Components: The physical components are the electronic hardware devices, media, and other connectors that transmit and carry the signals to represent the bits. Hardware components such as NICs, interfaces and connectors, cable materials, and cable designs are all specified in standards associated with the physical layer. The various ports and interfaces on a Cisco 1941 router are also examples of physical components with specific connectors and pinouts resulting from standards. B. Encoding: Encoding or line encoding is a method of converting a stream of data bits into a predefined "code". Codes are groupings of bits used to provide a predictable pattern that can be recognized by both the sender and the receiver. In other words, encoding is the method or pattern used to represent digital information. Similar to how Morse code encodes a message using a series of dots and dashes. For example, Manchester encoding represents a 0 bit by a high to low voltage transition, and a 1 bit is represented as a low to high voltage transition. An example of Manchester encoding is illustrated in Figure 1. The transition occurs at the middle of each bit period. This type of encoding is used in 10 b/s Ethernet. Faster data rates require more complex encoding. Manchester encoding is used in older Ethernet standards such as 10BASE-T. Ethernet 100BASE-X family uses 4B/5B encoding and 1000BASE-X uses 8B/10B encoding. C. Signaling: The physical layer must generate the electrical, optical, or wireless signals that represent the "1" and "0" on the media. The method of representing the bits is called the signaling method. The physical layer standards must define what type of signal represents a "1" and what type of signal represents a "0". This can be as simple as a change in the level of an electrical signal or optical pulse. For example, a long pulse might represent a 1 whereas a short pulse represents a 0. This is similar to the signaling method used in Morse code, which may use a series of on-off tones, lights, or clicks to send text over telephone wires or between ships at sea. There are many ways to transmit signals. A common method to send data is using modulation techniques. Modulation is the process by which the characteristic of one wave (the signal) modifies another wave (the carrier). The nature of the actual signals representing the bits on the media will depend on the signaling method in use.

The practical bandwidth of a network is determined b what combination of factors?

A. Properties of the physical media B. Technologies chosen for signaling and detecting network signals

Explain in detail the process that data undergoes from a source node to a destination node.

A. The user data is segmented by the transport layer, placed into packets by the network layer, and further encapsulated into frames by the data link layer. B. The physical layer encodes the frames and creates the electrical, optical, or radio wave signals that represent the bits in each frame. C. These signals are then sent on the media, one at a time. D. The destination node physical layer retrieves these individual signals from the media, restores them to their bit representations, and passes the bits up to the data link layer as a complete frame.

List the defined standards for copper media are:

A. Type of copper cabling B. Bandwidth of the communication C. Type of connectors used D. Pinout and color codes of connectors to the media E. Maximum distance of the media

Define latency?

Amount of time, to include delays, for data to travel from one given point to another

Why do networks use copper media?

Because it is inexpensive, easy to install, and has low resistance to electrical current.

What is copped media limited by?

By distance and signal interference

Which home device incorporates both types of physical connections?

Integrated service routers (ISR)

Explain what Goodput is.

Is a measure of usable data transferred over a given period of time.

What is bandwidth?

Is the capacity of a medium to carry data.

Does a wired device need to share its access to the network with other devices?

No

What type of cabling is the most common

UTP (unshielded twisted pair)

What is throughput?

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

What are two types of physical connections?

wired connection - cable wireless connection - radio waves