IT Infra Exam 1

4 Tech Milestones

Telegraph, Multiplexing, Switching, Packet Switching

Telegraph

Patented by Samuel Morse, sent coded messages with lines and dots over wires. Sent by connecting and releasing a switch as needed

Multiplexing

ability to combine multiple channels of information on a common transmission medium

Switching

Transmitting data between selected points in a circuit

Packet Switching

process of routing data using addressed packets so a channel is occupied only during the transmission of the packet. all users are connected.

Circuit Switching

establishes circuits between senders and receivers

Circuit

electronic closed loop path between 2+ points for signal transfer

Routers

device used to interconnect 2+ networks, packet switches between networks

Packetization

process of breaking down user data into small segments and packaging them appropriately so they can be delivered and reassembled

Reasons for packet switching

Aggregate Network Traffic, Moore’s Law

Aggregate Network Traffic

technique to smooth traffic bc different users have different traffic patterns

Burstiness

short periods where large volumes of data are uploaded or downloaded followed by long periods of minimal activity. circuit switching is inefficient for this

Layering

arranging functionality of components in a system in a hierarchical manner so lower layers provide functions that support the higher layers

top most layer of the stack

computer applications

bottom later of the stack

computer hardwarre

Hop

jumps from one router to another

Steps for packetization

1- specify user commands, 2- segmentation and reassembly of packets, 3- identify and locate destination on network, 4- error control, 5- signaling

Application

Top layer of stack, user needs, user commands

Transport

4th layer of stack, segmentation and reassembly of packets, sequence numbers

Network

3rd layer of stack, identifying and locating destination, address

Datalink

2nd layer of stack, error control, error check

Physical Layeer

1st layer of stack, signaling

What layer of the stack is TCP in?

4th

What layer of the stack is IP in?

3rd

OSI Model

logical structure for communication networks, standardized by the International Organization for Standardization

Physical Layer Functions

Signaling, sending data as signals over physical medium

Signal

change that can be detected at the receiving end , must be easily detectable, good at resisting noise, efficient at using bandwidth, and easy to be multiplexed

How is the physical layer different from the others?

Doesnt need a header, only layer that interacts with nature.

Physical Medium

transmission path a signal propagates over, can be wireless

Which material has the most common transmission media?

Copper, higher twist = higher category

Registered Jack

Connects copper wire to router

Unshielded Twisted Pair

4 pairs of copper wire twisted for information eexchange

Balanced Line

2 wires in each pair carry signals that are the opposites of each other

Optical Fiber

thin strand of glass that guides light along length. Benefits = data rates, distance, installation, and costs

Digital Signals

signals where discrete steps are used to represent information

Analog Signals

signals that have a continuous nature rather than a pulsed or discrete nature. made by sine waves

Properties of sine waves

Amplitude, Frequence, Phase

Carrier Wave

Sine wave with information

Modulation

changing the sine wave with info to extract data

Bit Period

amount of time required to transmit one bit of data

Bit

Unit of info that designates 1 of 2 possible states of anything that conveys info

Byte

sequence of 8 continuous bits

Hertz

speed at something happens repeatedly

Frequency Division Multiplexing

signals from one channel are sent through one frequency, signals for the other one is sent at a diff frequence

Data-Link Layer Functions

Addressing, Error Detection

Ethernet

technology for low cost, high speed communication in small networks. no privacy

Frame/Overhead/Header

includes data and all info needed for data

Packet Header

where all overhead is

Broadcasting

transmission of signals that may be simultaneously received by stations that usually make no acknowledgement. good for small networks, bad for big ones

Collision

when 2 or more demands are made simultaneously on a system that can only handle one demand at a given instance

Medium Access Control

method used to determine who gets to send data over a shared medium. required by ethernet

Carrier Sense Multiple Access with Collision Detection (CSMA/CD)

MAC control part of the ethernet

Multiple Access

scheme that gives more than 1 computer access to the network to transmit information

Collision Detection

requirement that a transmitting computer that detects another signal while transmitting data stops transmitting that data

Random Back-Off

each computer that detects a collision waits a random amount of time before sensing the medium again

CRC

error checking algorithm that reviews data integrity by computing a polynomial algorithm-based checksum. data-link layer

Frame-Check Sequence (FCS)

ending result of a CRC error detection, does math to the bits to see if tis correct or has an error

Preamble

well defined sequence of 7 bytes that help identify data for receiver

Start of Frame Delimiter (SFD)

at end of preamble, 1 more byte is sent to alert the receiver about the beginning of the frame

Destination Address

helps computers on network determine whether the frame is addressed to them

Source Address

tells the receiver who to send to

Spanning Tree Protocol

helps eliminate loops through the Ethernet

Function of Network Layer

Routing

Routing

process of selecting a path on internet that can be used to deliver data to a destination

Octet

set of 8 binary numbers.

IP Address have how many Octets

4 octets, 32 binary numbers

Address

unique label that helps locate an entity on a network

IP addressees

identifiers used as addresses of computer resources on Internet. no end-to-end reliability. provides best effort delivery

Best Effort Delivery

network service in which network doesnt provide any guarantee that data will be delivered. postal service

1st Octet of IP Address

identify where network is

2nd Octet of IP Address

identifies computer

Multipart Addresses

combines different address components into a single field

Class A IP address

the first 8 bits identified the network ID and the remaining 24 bits identified hosts within the network

Class B IP Address

the first 16 bits identified the network ID and the remaining 16 bits identified hosts within the network

Class C IP Address

the first 24 bits identified the network ID and the remaining 8 bits identified hosts within the network

CIDR

address allocation scheme that eliminates the concept of address classes and allows address blocks oof arbitrary length. allows nay length of network ID

\n Internet Assigned Numbers Authority (IANA)

responsible for managing all available IP addresses

Transport Layer

segmentation, reliability, mulitplexing, Flow Control

TCP

highly reliable host-to-host transport layer protocol over packet-switched networks

User Diagram protocol (UDP)

simpler transport layer protocol. eliminates all computational processing associated with TCP

Datagrams

segments, TCP assigns number on segmentation

Reliability

resolves issues from network layer

Port Numbers

identifiers assigned to each application process by transport layer. gate numbers at airport

Flow Control

control oof the rate at which data is transmitted from a terminal so data can be received by another terminal. drinking water as a kid vs as an adult

Sliding-Window Flow Control

uses variable length window that allows a sender to transmit a specified number of data units before ACK is received

Common Establishment

generating initial sequence number (ISN) for connections from a continuously advancing number generator

3 way handshake

each side has to inform the other side of the initial sequence number it will use for the connection

Packetization is the process of

breaking down user data into small segments

the transport layer in the TCP/IP stack is responsible for

segmentation and reassembly of packets

Each and every piece ("packet") of data traveling across the Internet is labeled with its destination known as an IP address

True

Business Data Communications refers to the movement of data from

One computer application on a computer to another computer application on another computer.

Signals in copper wire are transmitted as

Electrical signals.

All of the following are examples of using broadcasting to transmit data, except

Mail

A computer knows that it is the intended receiver of a data packet by looking at

\

The destination address of the packet

The functions of the Data link layer include

Local addressing and error-detection

The "time to live" field of an IP packet (it is also called a hop limit in IPV6) indicates

The remaining life of the packet in network hops

IP provides

best-effort delivery

When you use Google Maps to navigate to the destination, the intermediate exit numbers along the route are analogous to the

MAC address of a frame

When you use Google Maps to navigate to your destination, the street address of the final destination is analogous to the

IP address of a packet

In your Economist reading, the big networking concern with Internet-of-Things (iOT) smart devices is likely to be...

Having too many protocols