Chapter 2 Network+

Front 1

OSI model has 7 hierarchical layers

Back 1

developed to enable different networks to communicate reliably between disparate systems; created by international organization for standardization

Front 2

encapsulation

Back 2

is the process of encoding data as it goes down the OSI stack

Front 3

binding

Back 3

only being concerned with one layers protocols because the layers are independent of each other

Front 4

OSI advantages

Back 4

1. divides network communication processes into smaller and simpler components, thus aiding component development, design, and troubleshooting

2. it allows multiple vendor development through the standardization of network components

3. it encourages industry standardization by defining the specific functions that occur at each layer of the model.

4. it allows various types of network hardware and software to communicate

5. it prevents changes in one layer from affecting other layers, facilitating development, and making application programming much easier

Front 5

Layer 7 - Application

Back 5

file, print, message, database, and application services

provides a user interface

Front 6

Layer 6 - Presentation

Back 6

data encryption, compression, and translation services

presents data, handles processing such as encryption

Front 7

Layer 5 - Session

Back 7

dialog control

keeps different applications' data separate

Front 8

Layer 4 - Transport

Back 8

end to end connection

provides reliable or unreliable delivery, performs error correction before retransmit

Front 9

Layer 3 - Network

Back 9

routing

provides logical addressing, which routers use for path determination

Front 10

Layer 2 - Data link

Back 10

framing

combines packets into bytes and bytes into frames, provides access to media using MAC address, performs error detection, not correction

Front 11

Layer 1 - Physical

Back 11

physical topology

moves bits between devices, specifies voltage, wire speed, and pin out of cables

Front 12

OSI is not a physical model

Back 12

it's conceptual and comprehensive yet fluid; utilized to create and implement applications; provides a framework for creating and implementing networking standards, devices, and internetworking schemes

Front 13

upper layers

Back 13

application, presentation, session

Front 14

lower layers

Back 14

transport, networking, data link, physical

Front 15

bottom layers job

Back 15

networking and network addresses; define how data is transferred through physical media, switches, and routers

Front 16

application layer (7)

Back 16

where users actually communicate with the network stack through applications and interfaces; chooses and determines the availability of communicating partners along with the resources necessary to make their required connections; acts as an interface between the application program; identifying and establishing the availability of the intended communication partner and determining whether sufficient resources for the requested communication exist

Front 17

presentation layer (6)

Back 17

presents data to the application layer and is responsible for data translation and code formatting; ensures that the data transferred from one system's application layer can be read and understood by the application layer on another's; data compression, decompression, encryption, and decryption

Front 18

session layer (5)

Back 18

responsible for setting up, managing, and tearing down sessions between presentation layer entities; dialog control between devices or nodes; coordinates communication between systems and servers to organize communication; 3 different modes: simplex, half duplex, and full duplex

Front 19

transport layer (4)

Back 19

reassembles data into a data stream; handles data from upper and unite it onto the same data stream; provide end-to-end data transport services and can establish a logical connection between the sending host and destination host on an internetwork; provides the mechanisms for multiplexing upper applications, establishing virtual connections, and tearing down virtual circuits; hides many and sundry details of any network dependent info from the higher layers

Front 20

TCP and UDP work at

Back 20

the transport layer

TCP is reliable (connection-oriented), UDP is not (connectionless)

Front 21

encapsulation

Back 21

data is wrapped with protocol info at each layer of the OSI model steps

Front 22

Upper level data encapsulation from application layer down

Back 22

sent to session layer for TCP header>IP header, segement in the transport layer>LLC Header, packet in the networking layer>MAC Header, packet in the data link layer> into binary code at the physical layer

Front 23

PDU

Back 23

transport = segment

network= packet

datalink = frame

physical = bits

8 bits in a byte

Front 24

modulation

Back 24

is the process of varying one or more properties of a waveform, called the carrier signal

Front 25

modems

Back 25

modulator is a device that performs modulation of a signal

demodulation is a device that performs demodulation

the purpose is to transfer a digital bit stream over an analog bandpass channel

Front 26

TDM - time division multiplexing

Back 26

is a method of transmitting and receiving many independent signals over a common signal path by means of synchronized network devices at each end of the transmission line so that each signal appears on the line only a fraction of time in an alternating pattern

Front 27

virtual circuit is a connection-oriented type of communication

Back 27

before a transmitting host starts to send segments down the model, the sender's TCP process contacts the destination's TCP process to establish a connection

Front 28

During the initial handshake of a virtual circuit

Back 28

the two TCP processes agree on the amount of information that will be sent in either direction before the respective recipient's TCP sends back an acknowledgement.

Front 29

three-way handshake

Back 29

connection agreement is requested for synchronization

acknowledgment of request and establishment of connection parameters between hosts

acknowledgement, notifies the destination host that the connection agreement has been accepted and that the connection has been established

Front 30

flow control

Back 30

provides a means for the receiver to govern the amount of data sent by the sender

prevents a sending host on one side of the connection from overflowing the buffers in the receiving host

Front 31

data integrity

Back 31

is ensured at the transport layer by maintaining flow control and by allowing users to request reliable data transport between systems

Front 32

reliable data

Back 32

transport employs a connection oriented communications session between systems, and the protocols involved ensure that the following will be achieved p.35

Front 33

connection oriented characteristics

Back 33

a virtual circuit is set up - 3 way handshake

it uses sequencing

it uses acknowledgments

it uses flow control

Front 34

window

Back 34

the quantity of data segments that the transmitting machine is allowed to send without receiving an acknowledgement

Front 35

positive acknowledgment with re-transmission

Back 35

a technique that requires a receiving machine to communicate with the transmitting source by sending an acknowledgment message back to the sender when it receives data

Front 36

network devices that operate at all seven layers of the OSI model

Back 36

network management stations, web and application servers, gateways, network hosts

Front 37

devices that operate primarily at the physical layer

Back 37

network interface cards, transceivers, repeaters, and hubs

Front 38

Network layer (3)

Back 38

manages logical device addressing, tracks the location of devices on the network, and determines the best way to move data; must transport traffic between devices that aren't locally atached

Front 39

routers

Back 39

layer 3 devices that are specified at the network layer and provide the routing services within an internetwork

Front 40

data packets

Back 40

used to transport user data through the internetwork

Front 41

routed protocols

Back 41

used to support data traffic

Front 42

routed protocols

Back 42

Internet Protocol - IP

Internet Protocol version 6 - IPv6

Front 43

route-update packets

Back 43

used to update neighboring routers about the networks connected to all routers within the internetwork

sender are Routing Information protocol - RIP

RIPv2

Enhanced Interior Gateway Routing Protocol - EIGRP

open shortest path first - OSPF

Front 44

hop count

Back 44

the number of routers a packet passes through en route to a remote network

Front 45

routers break up

Back 45

broadcast domains, collision domains (layer 2 switches can also break collision domains)

Front 46

each interface in a router

Back 46

represents a separate network, it must be assigned unique network identification numbers, and each host on the network connected to that router must use the same network number

Front 47

key point on routers

Back 47

routers, won't forward any broadcast or multicast packets

routers use the logical address in a network layer header to determine the next hop router to forward the packet to

routers can use access lists, created by an administrator, to control security on the types of packets that are allowed to enter or exit an interface

routers can provide layer 2 bridging functions if needed and can simultaneously route through the same interface

layer 3 devices provide connections between virtual LANs

routers can provide quality of service for specific types of network traffic

Front 48

data link layer (2)

Back 48

provides the physical transmission of the data and handles error notification, network topology, and flow control

ensures that messages are delivered to the proper device on a LAN using hardware addresses and translates messages from the network layer into bits for the physical layer to transmit

Front 49

data link formats the message into pieces

Back 49

called a data frame, and adds a customized header containing the destination and source hardware address

Front 50

data link layer is responsible for

Back 50

the unique identification of each device that resides on a local network

Front 51

data link layer uses hardware addressing

Back 51

for a host to send packets to individual hosts on a local network as well as transmit packets between routers

Front 52

each time a packet is sent between routers

Back 52

its framed with control information at the data link layer

Front 53

IEEE

Back 53

institute of electrical and electronics engineers

Front 54

IEEE has two sublayers

Back 54

medica access control (MAC) - defines how packets are placed on the media, first come, first serve access, physical addressing is defined here, as are logical topologies

logical link control (LLC) - responsible for identifying network layer protocols and then encapsulating them, an llc header tells the data link layer what to do with a packet once a frame is received.

Front 55

802.3

Back 55

calls out anything having to do with ethernet

Front 56

802.11

Back 56

calls out to anything wireless

Front 57

Physical Layer (1)

Back 57

it sends bits and receives bits

specifies the electrical, mechanical, procedural, and functional requirements for activating, maintaining, and deactivating a physical link between end systems

also the layer you identify the interface between the data terminal equipment and the data communication equipment

specifies the layout of the transmission media, otherwise known as its topology

Front 58

bits come only in values of

Back 58

1 and 0

Front 59

state transitions

Back 59

changes in voltage from high to low and low to high