Network+ Chapter 2

MAC Address

A 12-character string that uniquely identifies a network node. The manufacturer hard codes the MAC address into the NIC. This address is composed of the block ID and device ID.

Fragmentation

A Network Layer service that subdivides segments it receives from the Transport Layer into smaller packets.

Session

A connection for data exchange between two parties.

IP (Internet Protocol)

A core protocol in the TCP/IP suite that operates in the Network Layer and provides information about how and where data should be delivered. IP is the subprotocol that enables TCP/IP to internetwork.

Router

A device that connects network segments and directs data based on information contained in the data packet.

Terminal

A device with little (if any) of its own processing or disk capacity that depends on a host to supply it with applications and data-processing services.

Checksum

A method of error checking that determines if the contents of an arriving data unit match the contents of the data unit sent by the source.

Flow Control

A method of gauging the appropriate rate of data transmission based on how fast the recipient can accept data.

Token Ring

A networking technology developed by IBM in the 1980s. It relies upon direct links between nodes and a ring topology, using tokens to allow nodes to transmit data.

Frame

A package for data that includes not only the raw data or payload, but also the sender's and recipient's addressing and control information.

ACK (acknowledgment)

A response generated at the Transport layer of the OSI model that confirms to a sender that its frame was received.

API (Application Program Interface)

A set of routines that make up part of a software application.

Token

A special control frame that indicates to the rest of the network that a particular node has the right to transmit data.

Connection Oriented

A type of Transport Layer protocol that requires the establishment of a connection between communicating nodes before it will transmit data.

Connectionless

A type of Transport Layer protocol that services a request without requiring a verified session and without guaranteeing delivery of data.

Network Address

A unique identifying number for a network node that follows a hierarchical addressing scheme and can be assigned through operating system software. Network addresses are added to data packets and interpreted by protocols at the Network Layer of the OSI model.

PDU (protocol data unit)

A unit of data at any layer of the OSI model

Segment

A unit of data that results from subdividing a larger protocol data unit.

List the different standards organisations.

ANSI - American National Standards Institute IEEE - Institute of Electrical and Electronics Engineers ISO - International Organization for Standardization ISOC - Internet Society

What is the main function of the Presentation Layer of the OSI Model

Allows hosts and applications to use a common language, performs data formatting, encryption, and congestion

HTTP (Hypertext Transfer Protocol)

An Application Layer protocol that formulates and interprets requests between Web clients and servers.

CRC (Cyclic Redundancy Check)

An algorithm used to verify the accurace of data contained in a data frame.

802.16

Broadband wireless metropolitan area networks: The IEEE standard for the atmospheric interface and related functions associated with broadband wireless connectivity, also known as WiMax

Name two different Transport Layer Protocols

Connection Oriented Protocols Connectionless Protocols

What is the main function of the Transport Layer of the OSI Model

Ensures accurate delivery of data through flow control, segmentation and reassembly, error correction, and acknowledgement

What is the main function of the Network Layer of the OSI Model

Establishes network connections, translates network addresses into their physical counterparts and determines routing

What is the main function of the Session Layer of the OSI Model

Establishes, maintains, and terminates user connections

802.3

Ethernet LAN: The IEEE standard for Ethernet networking devices and data handling (using the CSMACD access method

Which technology does the IEEE 802.3 specification describe?

Ethernet LANs

Where are frames generated?

Frames are generated at the Data Link Layer and issues to the network at the Physical Layer.

Give an example of the protocol you will find in the Application Layer of the OSI model

HTTP (Hypertext Transfer Protocol)

Who developed the OSI model?

ISO

802.1

Internetworking: The IEEE standard for routing, bridging, and network to network communication

List some of the functions performed by the Session Layer

Keeping alive the communications link for the duration of the session Keeping the communication secure Synchronizing the dialog between the two nodes Figuring out when to restart communication if it has been cut off Monitors the identification of session participants, ensuring only authorized nodes can access the session

Name the two sublayers of the Data Link Layer

LLC: Logical Link Control MAC: Media Access Control

802.2

Logical Link Control: The IEEE standard for error and flow control in data frames

You have just installed a new NIC in your computer and see the following stamped on it: 000A5E1A8DA2. This unique identifier is an example of what kind of address?

MAC address

What is the main function of the Physical Layer of the OSI Model

Manages signalling to and from physical network connections

802.20

Mobile broadband wireless network: The IEEE standard for packet handling and other specifications for multi vendor, mobile high-speed wireless transmission

What does OSI stand for?

Open Systems Interconnection Model

What is the main function of the Data Link Layer of the OSI Model

Packages data in frames appropriate to network transmission method

List the seven layers of the OSI model.

Physical Layer Data Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer

In which OSI layer is data encryption and decryption managed?

Presentation Layer

What is the main function of the Application Layer in the OSI model?

Provides interface between software applications and network for interpreting applications requests and requirements

802.17

Resilient packet rings: The IEEE standard for access method, physical layer specifications, and management of shared packet-based transmission on resilient rings

What are standards?

Standards are documented agreements containing technical specification or other precise criteria that stipulate how a particular product or service should be designed or performed.

Which of the following standards organisations has established guidelines for installing network cables in commercial buildings? a. TIA / EIA b. ITU c. ANSI d. IEEE

TIA / EIA

IP address

The Network Layer address assigned to nodes to uniquely identify them on a TCP/IP network. IP addresses consist of 32 bits divided into four octets, or bytes.

What is the OSI model?

The OSI model is a theoretical representation of what happens between two nodes communicating on a network.

FCS (Frame Check Sequence)

The field in a frame responsible for ensuring that data carried by the frame arrives intact. It uses an algorithm, such as CRC, to accomplish this verification.

Block ID

The first set of six characters that make up the MAC address and that are unique to a particular manufacturer.

MTU (maximum transmission unit)

The largest data unit a network will accept for transmission.

Sequencing

The process of assigning a placeholder to each piece of a data block to allow the receiving node's Transport Layer to reassemble the data in the correct order.

Segmentation

The process of decreasing the size of data units when moving data from a network that can handle large data units to a network that can handle only smaller data units.

Reassembly

The process of reconstructing data units that have been segmented

Encapsulate

The process of wrapping one layer's PDU with protocol information so that it can be interpreted by a lower layer.

Device ID

The second set of six characters that make up a network device's MAC address. The device ID, which is added at the factory, is based on the device's model and manufacture date.

Why do the different industries make use of standards?

To ensure that products, processes and services suit their purposes; Without standards, it would be very difficult to design a network because you would not be certain that software or hardware from different manufacturers would work together.

802.5

Token Ring LAN: The IEEE standard for token ring networking devices and data handling

Under what circumstances would the transport layer use segmentation?

When the destination node cannot accept the size of the data blocks transmitted by the source node.

802.11

Wireless Networks: The IEEE standard for wireless networking for many different broadcast frequencies and usage techniques

802.15

Wireless personal area networks: The IEEE standard for the coexistence of wireless personal area networks \with other wireless devices in unlicensed frequency bands

802.22

Wireless regional area networks (WRAN): The IEEE standard for wireless broadcast style network to operate in the UHF / VHF frequency bands formerly used for TV channels

Which part of a MAC address is unique to each manufacturer?

block ID

Which layer of the OSI model encapsulates network layer packets?

data link layer

What type of address follows a hierarchical format?

network address

Suppose your network is connected to another network via arouter. Which OSI model layer provides the information necessary to direct data between the two networks?

network layer

In which two layers of the OSI model do NICs belong?

physical and data link layers

Which OSI model layer generates and detects voltage so as to transmit and receive signals carrying data?

physical layer

If the TCP protocol did not receive an acknowledgment for data it transmitted, what would it do?

retransmit the data to the recipient

Which OSI model layer is responsible for keeping open acommunications path between your computer and the server when you dial in to aremote access server?

session layer

Suppose that, at the receiving node, a frame's FCS doesn't match the FCS it was issued at the transmitting node. What happens as a result?

the receiving node's link layer requests a retransmission

What is the purpose of the trailer field added to a frame in the data link layer?

to mark the end of a frame

Which layer of the OSI model is responsible for issuing acknowledgments (ACKs)?

transport layer

Given an example where connection oriented protocols would be more efficient than connectionless protocols

when data integrity has to be ensured; when data has to arrive exactly as it was sent; when data delivery has to be ensured

Give an example where connectionless protocols would be more efficient than connection oriented protocols.

when data needs to be transferred quickly (i.e. video live streaming)