Shared Flashcard Set

Details

Cisco 1 - Chapter 2
CCNA Cisco 1 Network Fundamentals Chapter 2
97
Computer Networking
09/05/2010

Additional Computer Networking Flashcards

 


 

Cards

Term
Channel
Definition
A communication path over a medium used to transport information from a sender to a receiver. Multiple channels can be multiplexed over a single cable.

A channel consists fo the media that provides the pathway over which the message can travel from source to destination.
Term
Segmentation
Definition
In TCP, the process of taking a large chunk of data and breaking it into small-enough pieces to fit within a TCP segment without breaking any rules about the maximum amount of data allowed in a segment.

The answer to this problem (dedicated circuits) is a process called segmentation, in which all messages are broken into smaller pieces that can be easily transported together across a medium.
Term
Multiplexing
Definition
A process where multiple digital data streams are combined into one signal.

Multiplexing occurs when the segments of two or more messages can shuffle into each other and share the medium.
Term
Switch
Definition
In Ethernet, a Layer 2 device that receives an electrical signal in one port, interprets the bits, and makes a filtering or forwarding decision about the frame. If it forwards, it sends a regenerated signal. Switches typically have many physical ports, oftentimes RJ-45 jacks, whereas bridges traditionally have two ports.
Term
End Device
Definition
A device such as a desktop or mobile device that is used by an end user.

An end device refers to apiece of equipment that is either the source or the destination of a message on a network.
Term
Host
Definition
A network device that has an IPv4 address assigned to it to communicate over a network.

Another generic term for an end device that sends or receives messages is a host.
Term
Client
Definition
A network device that accesses a service on another computer remotely by accessing the network.

Clients request information and services, like e-mail and web pages, from servers, and servers reply with the request information if they recognize the client.
Term
Host Address
Definition
A network device that has an IPv4 address assigned to it to communicate over a network.

The host address is a unique physical address used by hosts inside a local-area network (LAN), and when a host sends a message to another host, it uses the physical address of the destination device.
Term
Physical Address
Definition
A data link layer address, for example, a MAC address.
Term
Intermediary Device
Definition
A device that connects end devices to the network or interconnects different networks. A router is an example of an intermediary device.

Intermediary devices connect the individual hosts tot he network and can connect multiple individual networks to form an internetowrk.
Term
Encoding
Definition
Encoding messages refers to the way data is converted to patterns of electrical, light, or electromagnetic energy and carried on the medium.

Encode - To change the energy levels transmitted over some networking medium to transmit bits over that medium.
Term
Local-area Network (LAN)
Definition
A network created for devices located in a limited geographic area, through which the company owning the LAN has the right to run cables.

A local-area network (LAN) is a group of end devices and users under the control of a common administration.
Term
Internet Service Provider (ISP)
Definition
A company that helps create the Internet by providing connectivity to enterprises and individuals, as well as interconnecteing to other ISPs to create connectivity to all other ISPs

Internet service providers (ISP), which are often also telecommunication service providers (TSP), connect their customers to the Internet.
Term
Protocols
Definition

Protocol - A written specification that defines what tasks a service or device should perform. Each protocol defines messages, often in the form of headers, plus the rules and processes by which these messages are used to achieve some stated purpose.

 

All communication, whether face-to-face or over a network, is governed by predetermined rules called protocols.

Term
Protocol Suite
Definition

A delineation of networking protocols and standards into different categories, called layers, along with definitions of which sets of standards and protocols need to be implemented to create products that can be used to create a working network.

 

Theses rules, or protocols, that work together to ensure successful communication are grouped into what is known as a protocol suite.

Term
Institute of Electrical and Electronics Engineers (IEEE)
Definition

An international, nonprofit organization for the advancement of technology related to electricity. IEEE maintains the standards of defining many LAN protocols.

 

The organizations that standardize networking protoocls are the Institute of Electrical and Electronics Engineers (IEEE) and the Internet Engineering Task Force (IETF)

Term
Internet Engineering Task Force (IETF)
Definition
The standards body responsible for the development and approval of TCP/IP standards.
Term
Layered Models
Definition

A model that consists of various layers that enable the development and explanation of technology to be done on a modular basis. This allows interoperability among different technologies among the different layers.

 

The IT industry uses layered models to describe the complex process of network communication.

Term
TCP/IP
Definition

Transmission Control Protocol/Internet Protocol - A network model defined by the IETF that has been implemented on most computers and network devices in the world.

 

The TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols within the TCP/IP suite.

Term
Encapsulation
Definition

The process by which a device adds networking headers and trailers to data from an application for the eventual transmission of the data onto a transmission medium.

 

The process of adding control information as it passes through the layered model is called encapsulation.

Term
Decapsulation
Definition

A process by which an end device, after it receives data over some transmission medium, examines the headers and trailers at each successive higher layer, eventually handing the data to the correct application. Sometimes called deencapsulation.

 

Decapsulation is the process of removing the extra information and sending only the original application data up to the destination application layer.

Term
Protocol Data Unit (PDU)
Definition

A generic term from OSI that refers to the data, headers, and trailers about which a particular networking layer is concerned.

 

The generic term for data at each level is protocol data unit (PDU), but a PDU is different at each layer.

Term
Segment
Definition
1. A collision domain that is a section of a LAN that is bound by bridges, routers, or switches. 2. In a LAN using a bus topology, a segment is a continuous electrical circuit that is often connected to other such segments with repeaters. 3. When used with TCP, the term segment (verb) refers to the work TCP does to accept a large piece of data from an application and break it into smaller pieces. Again with TCP, used as a noun, segment refers to one of those smaller pieces.
Term
Frame
Definition
The Layer 2 PDU that has been encoded by a data link layer protocol for digital transmission. Some different kinds of frames are Ethernet frames and PPP frames.
Term
Open Systems Interconnection (OSI)
Definition

International standardization program created by ISO and ITU-T to develop standards for data networking that facilitate multivendor equipment interoperability.

 

The OSI model describes the entire communication process in detail, and the TCP/IP model describes the communication process in terms of the TCP/IP protocol suite and the way it functions.

 

Know the details of the OSI model to understand the entire network communication process

 

Know the TCP/IP model to understand how the process is implemented in current networks

 

The Open Systems Interconnections (OSI) model, known as the OSI model, provides an abstract description of the network communication process.

Term
Internation Standards for Organization (ISO)
Definition

An international standards body that defines many networking standards. Also, the standards body that created the OSI model.

 

[OSI] Developed by the International Organization for Standardization (ISO) to provide a road map for nonproprietary protocol development, the OSI model did not evolve as readily as the TCP/IP model.

Term
Port
Definition

In networking, this term is used in several ways. With Ethernet hub and switch hardware, port is simply another name for interface, which is a physical connector in the switch into which a cable can be connected. With TCP and UDP, a port is a software function that uniquely identifies a software process on a computer that uses TCP or UDP. With PCs, a port can be a physical connector on the PC, like a parallel or USB port.

 

This is because the transport layer adds port numbers to its segment header information to ensure that the destination host knows which application process is to receive the packet.  

Term
The Elements of Communication
Definition
Message source, or sender
Destination, or receiver of the message
Term
Primary Benefits of Segmentation
Definition
Multiplexing
Increased efficiency of network communications
Term
Basis of network communication between computers
Definition
The model of sending a message through a channel to the recevier
Term
Downside of Segmentation
Definition
Added complexity
Increased overhead (breaking the message down and reassembling it, sequencing, etc).
Term
Components of the Network
Definition
Hardware - laptop, pc, switch, cabling, the air for wireless communications

Services and processes - communication programs (software)

Network Service - provides information in response to a request (email, web)
Term
Examples of Hosts and End Devices
Definition
Computers including workstations, laptops, and servers connected to a network

Network printers

Voice over Internet Protocol (VoIP) phones

Cameras on a network, including webcams and security cameras

Handheld devices such as PDAs and handheld scanners

Remote Monitoring stations for weather observation
Term
End user
Definition
An end user is a person or group using an end device.
Term
Network access devices
Definition
Connect end users to their network. Examples are hubs, switches, and wireless access points.
Term
Internetwork devices
Definition
Connect one network to one or more other networks. Routers are the main example.
Term
Communication Servers
Definition
Route services such as IPTV and wireless broadband.
Term
Modems
Definition
Connect users to servers and networks through telephone or cable.
Term
Security Devices
Definition
Secure the network with devices such as firewalls that analyze traffic exiting and entering networks.
Term
Intermediary Devices
Definition
Role - management of data as it flows through the network

Intermediary devices connect the individual hosts to the network and can connect multiple individual networks to form an internetwork.

use the destination host address with information about the network interconnections to determine the path messages should take
Term
Intermediary Device Processes
Definition
Regenerate and retransmit data signals

Maintain information about what pathways exist through the network and internetwork

Notify other devices of errors and communication failures

Direct data along alternate pathways when there is a link failure

Classify and direct messages according to quality of service (WoS) priorities

Permit or deny the flow of data, based on security settings
Term
Three main types of network media
Definition
Copper
Fiber-optic cable
Wireless
Term
Media - Copper
Definition
Twisted-pair cable usually used as LAN media

Encoding - Electrical pulses
Term
Fiber-optic Media
Definition
Glass or plastic fibers ina vinyl coating usually used for long runs in a LAN and as a trunk

Encoding - Light pulses
Term
Wireless Media
Definition
Connects local users through the air

Encoding - Electromagnetic waves
Term
Consider the following when choosing network media:
Definition
The distance the media can carry the signal

The environment in which the media works

The bandwidth requirements for users

The cost of installation

The cost of connectors and compatible equipment
Term
Basic differences between networks
Definition
Size of the area covered

The number of users connected

The number and types of services available
Term
Wide Area Network (WAN)
Definition
A network that is used to connect LANs that are located geographically far apart.

Typically does not have users.
Term
Network interface card (NIC)
Definition
A NIC, or LAN adapter, provides the physical connection to the network at the PC or other host device. The media connecting the PC to the networking device plugs directly into the NIC. Each NIC has a unique physical address that identifies it on the LAN.
Term
Physical port
Definition
A physical port is a connector or outlet on a networking device where the media is connected to a host or other networking device. You can assume that all network host devices used in this book have a physical port that allows a connection to the network.
Term
Interface
Definition
The term interface refers to how the device can allow two different networks to communicate.  Routers connect to different networks, and the specialized NICs on routers are simple called interfaces.  the interface on a router device has a unique physical address and appears as a host on the local network.
Term
Protocols Define the Following
Definition

The format of the message, such as how much data to put into each segment

 

The way intermediary devices share information about the path to the destination

 

The method to handle update messages between intermediary devices

 

The process to initiate and terminate communications between hosts

Term

HTTP

Hypertext Transfer Protocol

Definition
HTTP is a common protocol that governs the way that a web server and a web client interact.  HTTP defines the content and formatting of the requests and responses exchanged between the client and server.  Both the client and the web server software implement HTTP as part of the application.  The HTTP protocol relies on other protocols to govern how the messages are transported between client and server.
Term

TCP

Transport Protocol

Definition
Transmission Control Protocol (TCP) is the transport protocol that manages the individual conversations between web servers and web clients.  TCP divides the HTTP messages into smaller pieces, called segments, to be sent to the destination client.  It is also responsible for controlling the size and rate at which messages are exchanged between the server and the client.
Term

IP

Internetwork Protocol

 

Definition
The most common internetwork protocol is Internet  Protocol (IP).  IP is responsible for taking the formatted segments from TCP, encapsulating them into packets, assigning the appropriate addresses, and selecting the best path to the destination host.
Term
Network access protocols
Definition
Network access protocols describe two primary functions: data-link management and the physical transmission of data on the media
Term
Benefits of a Layered Model
Definition

Defines common terms that describe the network functions to those working in the industry and allows greater understanding and cooperation

 

Segments the process to allow technologies performing one function to evolve independently of technologies performing other functions

 

Fosters competition because products from different vendors can work together

 

Provides a common language to describe networking functions and capabilities

 

Assists in protocol design, because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below

Term
Protocol Models
Definition

A protocol model provides a model that closely matches the structure of a particular protocol suite

 

The hierarchical set of related protocols in a suite typically represents all the functionality required to interface the human network with the data network

Term
Reference Models
Definition

provides a common reference for maintaining consistency within all types of network protocols and services

 

not intended to be an implementation specification or to provide a sufficient level of detail to define precisely the services of the network architecture

 

Primary purpose of a reference model is to aid in clearer understanding of the functions and process involved

 

The Open Systems Interconnection (OSI) model is the most widely know internetwork reference model

Term
TCP/IP Model
Definition

defines the four communication functions that protocols perform

 

is an open standard

Term
TCP/IP Model Application Layer
Definition
Represents application data to the user.  For example, the HTTP presents data to the user in a web browser application like Internet Explorer.
Term
TCP/IP Transport Layer
Definition
Supports communication between devices and performs error correction
Term
TCP/IP Internet Layer
Definition
Finds the best path through the network
Term
TCP/IP Network Access Layer
Definition
Controls hardware devices and media.
Term
A complete communication process includes these steps:
Definition

1.  Creation of data at the application layer of the originating source end device

 

2.  Segmentation and encapsulation of data as it passes down the protocol stack in the source end device.

 

3.  Generation of the data onto the media at the network access layer of the stack.

 

4.  Transportation of the data through the internetwork, which consists of media and any intermediary devices.

 

5.  Reception of the data at the network access layer of the destination end device

 

6.  Decapsulation and reassembly of the data as it passes up the stack in the destination device.  you learn more about the encapsulation and decapsulation processes in the next section

 

7.  Passing this data to the destination application at the application layer of the destination end device.

 

Term
Protocol Data Unit (PDU) Naming Conventions
Definition

Data -> Application layer PDU

 

Segment -> Transport layer PDU

 

Packet -> Internetwork layer PDU

 

Frame -> Network access layer PDU

 

Bits-> PDU used for the physical transmission of binary data over media.

Term
Sending and Receiving Process -> Email
Definition

1. An end user, using an em-mail application, creates data.  The application layer coeds the data as e-mail and sends the data to the transport layer

 

2.  The message is segmented, or broken into pieces, for transport.  The transport layer adds control information in a header so that it can be assigned to the correct process and all segments put into proper order at the destination.  The segment is sent down to the internetwork layer.

 

3.  The internetwork layer adds IP addressing information in an IP header.  The segment is now an addressed packet that can be handled by routers en route to the destination.  The internetwork layer send the packet down to the network access layer.

 

4.   The network access layer creates an Ethernet frame with local network physical address information in the header.  This enables the packet to get to the local router and out to the web.  The frame also contains a trailer with error-checking information.  After the frame is created, it is encoded into bits and sent onto the media to the destination.

 

5.  At the destination host, the process is reversed.  The frame is decapsulated to a packet, then to a segment, and then the transport layer puts all segments into the proper order.

 

6.  When all data has arrived and is ready, it is sent to the application layer, and then the original application dta goes to the receiver's e-mail application.  The message is successful.

Term
OSI Communication Process
Definition
Begins at the application layer of the source, and data is passed down to each lower layer to be encapsulated with supporting data until it reaches the physical layer and is put out on the media.  When the data arrives at the destination, it is passed back up through layers and decapsulated by each layer.  Each layer provides data services to the layer directly above by preparing information coming down the model or going up.
Term
OSI Application Layer - 7
Definition
Performs services for the applications used by the end users.
Term
OSI Presentation Layer - 6
Definition
Provides data format information to the application.  For example, the presentation layer tells the application layer whether there is encryption or whether it is a .jpg picture.
Term
OSI Session Layer - 5
Definition
Manages sessions between users.  For example, the session layer will synchronize multiple web sessions and voice and video data in web conferences.
Term
OSI Transport Layer - 4
Definition
Defines data segments and numbers them at the source, transfers the data, and reassembles the data at the destination.
Term
OSI Network Layer - 3
Definition
Creates and addresses packets for end-to-end delivery through intermediary devices in other networks.
Term
OSI Data Link Layer - 2
Definition
Creates and addresses framers for host-to-host delivery on the local LANs and between WAN devices
Term
OSI Physical Layer - 1
Definition
Transmits binary data over media between devices.  Physical layer protocols define media specifications.
Term
Comparing the OSI and TCP/IP Model
Definition

[image]

 

When juxtaposed, you can see that the functions of the application, presentation, and seesion layers of the OSI model are combined into one application layer in the TCP/IP model.

 

The bulk of networking functions reside at the transport and the network layers, so they remain individual layers.  TCP operates at the transport layer, and IP operates at the INternet layer.

 

The data link and physical layers of the OSI model comibine to make the network access layer of the TCP/IP model.

Term
Addressing of Data
Definition

Addressing of data happens in three different layers of the OSI model.  The PDU at each layer adss address information for use by the peer layer at the destination.

 

Physical - Timing and Synchronization Bits

Data Link - Destination and Source Physical Addresses

Network -Destination and Source Logical Network Addresses

Transport - Destination and Source Process Number (Ports)

Upper Layers - Encoded Application Data

 

Term
Getting Data to the End Device
Definition

During encapsulation, address identifiers are added to the data as it travels down the protocol stack on the source host.

 

The first identifier, the host physical address, is contained in the header of the Layer 2 PDU, called a frame.

 

The Layer 2 address is unique on the local network and represents the address of the end device on the physical media.  This address comes from codes placed on the NIC by the manufacturer.

 

In Ethernet, this address is called the MAC address.

 

Physical address and MAC address are often used interchangeable.

 

After a frame is successfully received by the destination host, the Layer 2 address information is removed as the data is decapsulated and moved up the protocol stack to Layer 3.

Term
Getting Data through the Network
Definition

Layer 3 protocols are primarily designed to move data from one local network to another local network within an internetwork.

 

Layer 3 addresses must include identifiers that enable intermediary network devices to locate hosts on different networks.

 

At the boundary of each local network, an intermediary network device, usually a router, decapsulates the frame to read the destination host address contained in the header of the packet, the Layer 3 PDU.  Routers use the network identifier portion of this address to determine which path to use to reach the destination host.  When the path is determined, the router encapsulates the packet in a new frame and sends it on its way toward the destination end device.  When the frame reaches its final destination, the frame and packet headers are removed and the data moved up to Layer 4.

Term
Getting Data to the Right Application
Definition

At Layer 4, information contained in the PDU header does not identify a destination host or a destination network.  What it does identify is the specific process or service running on the destination host device that will act on the data being delivered.

 

A user can send and receive many types of traffic over a single network interface, and using port numbers for each segment keeps traffic for web pages separate from em-mail traffic and so on.  The segment contains both source and destination ports in case the receiver needs to contact the sender.

Term

Question 1

 

Which OSI layer is associated with IP addressing?

Definition

C = 3

 

IP addressing is a concern of the OSI network layer (Layer3).  Physical addressing happens at OSI Layer 2

Term

Question 2

 

The elements of communication include a message source, a message destination, and a ___________, or medium to transport the message.

Definition
channel
Term

Question 3

 

Which type of addressing is found at the OSI Layer 2? (Choose two).

Definition

B = Physical

C = MAC 

 

A MAC address is the physcial address burned on to the OSI Layer 2 network interface card.  Logical addressing happens at OSI Layer 3.

Term

Question 4

 

When a server responds to a web request, what occurs next in the encapsulation process after the web page data is formatted and separated into TCP segments?

Definition

D = The server adds the source and destination IP address to each segment header to deliver the packets to the destination.

 

Encapsulating into TCP segments occurs at OSI Layer 4, so the next encapsulation is at OSI Layer 3, which includes adding source and destination IP addresses to the segment headers and converting them into packets.  Then the physical addressing is added and the data is converted to bits.

Term

Question 5

 

Which term describes a specific set of rules that determine the formatting of messages and the process of encapsulation used to forward data?

Definition

B =Protocol

 

A protocol describes a specific set of rules for communication, including message formatting and encapsulation.

Term

Question 6

 

A limited-use protocol owned by a company is considered to be _________________.

Definition
proprietary
Term

Question 7

 

Which one of the following is associated with Layer 4 of the OSI model?

Definition

B = TCP

 

TCP has control features pertaining to OSI Layer 4, FTP is an application (Layer 7), and IP and TFTP are network layer protocols (Layer 3).

Term

Question 8

 

The device that connects a device to the media is called a/an ______________.

Definition
NIC, or network interface card.
Term

Question 9

 

Which of the following terms defines dividing data streams into smaller pieces suitable for transmission?

Definition

C = Segmentation

 

Segmentation, which occurs at OSI Layer 4, is the correct answer.

Term

Question 10

 

A device that moves data between networks is a ________________________.

Definition
router
Term

Question 11

 

Which of the following is the process for interweaving multiple data streams onto one shared communication channel or network medium?

Definition

B = Multiplexing

 

Multiplexing is the correct term.

Term

Question 12

 

Which of the following is associated with the network layer?

Definition

A = IP address

 

IP addressing is an OSI Layer 3 fucntion.  All others are OSI Layer 2 functions.

Term

Question 13

 

Which of the following is the correct "top down" order of the OSI model?

Definition

B = Application, presentation, session, transport, network, data link, physical

 

The correct order is application, presentation, session, transport, network, data link, physical.

Term

Question 14

 

Question 14 Which layer of the OSI model is concerned with end-to-end message delivery over the network?

Definition

B = Transport

 

End-to-end message delivery is the concern of OSI Layer 4, the transport layer.

Term

Challenge Question 1

 

Which layers of the OSI model are combined into other layers of the TCP/IP model? (Choose all that apply)

Definition

B = Presentation

D = Data Link

F = Physical

G = Session

 

The OSI presentation and session layers are combined

into the application layer of the TCP/IP model. The OSI

data link and physical layers are combined into the

network access layer of TCP/IP. The transport and

network layers have parallell layers in TCP/IP.

Term

Challenge Question 2

 

Which of the following are true about LANs and WANs? (Choose two).

Definition

C = WANs connect groups of networks using TSPs

E =Hosts on a LAN use physical addressing to communicate.

 

LANs are connected by WANs.  WANs connect networks through telephone service providers (TSP).  Logical addressing is used between networks, and physical addressing, or MAC addresses, are used inside LANs.

Term
Definition