Chapter 7: Network Reference Models and Standards

Open Systems Interconnection (OSI) reference model

a frame of reference for understanding networks by dividing the process of network communication into seven layers.

International Organization for Standardization (ISO)

the international standards-setting body based in Geneva, Switzerland, that sets worldwide technology standards

Peer communication

each layer on one computer behaves as though it were communicating with its counterpart on the other computer.

Protocol data unit (PDU)

a unit of information passed as a self-contained data structure from one layer to another on its way up or down the network protocol stack

Application layer

the 7th layer in the OSI model which provides interfaces that enable applications to request and receive network services.

Presentation layer

The 6th layer of the OSI model at which data can be encrypted or compressed to facilitate delivery

Redirector

a software component that intercepts requests for service from the computer

Session layer

the 5th layer of the OSI model that is responsible for setting up, maintaining, and ending communication sequences across a network

Checkpointing

a synchronization process between two related streams of data that happens at the Session layer

Transport layer

the 4th layer of the OSI model which manages data transfer from one application to another across a network. It breaks long data streams into smaller segments

Maximum Transmission Unit (MTU)

The maximum frame size allowed to be transmitted across a network medium

Network Layer

the 3rd layer of the OSI model that handles logical addressing, translating logical network addresses into physical addresses, and performs best path selection and routing in an internetwork.

Access control

the process by which a router consults a list of rules before forwarding an incoming packet at the network layer

Data link layer

the 2nd layer of the OSI model that is responsible for managing access to the network medium and delivery of data frames from sender to receiver

Physical Layer

The first layer of the OSI model that converts bits into signals for outgoing messages and signals into bits for incoming messages.

Logical Link Control (LLC) sublayer

controls data-link communication and defines the use of logical interface points, called “service access points” that other computers can use to transfer information from this sublayer to the upper OSI layers.

Media Access Control (MAC) sublayer

manages access to the physical medium and therefore communicates with the physical layer.

Encapsulation

The addition of information to a PDU as it's passed from one layer to the next is called which of the following?

Peers

Layers acting as though they communicate directly with each other across the network are called which of the following?

Data Link

Which OSI layer creates and processes frames?

Transport

Which OSI layer handles flow control, data segmentation, and reliability?

Physical

Which OSI layer governs how a NIC is attached to the network medium?

3

Which OSI layer determines the route a packet takes from sender to receiver?

5

Which OSI layer is responsible for setting up, maintaining, and ending ongoing information exchanges across a network?

At the source and destination and at each intermediary device

When and how many times is a CRC calculated?

Data link

Which layer of the OSI model does Project 802 divide into two sublayers?

Deencapsulation

Which term refers to stripping header information as a PDU is passed from one layer to a higher layer?

802.3

Which IEEE 802 standard applies to Ethernet?

802.11

Which IEEE 802 standard applies to wireless LANs?

Segment

What is the PDU at the transport layer?

4

At which OSI layer does the PDU contain sequence and acknowledgment numbers?

Media Access Control (MAC)

At which Data Link sublayer does the physical address reside?

Signal errors caused by noise

Which of the following problems can occur at the Physical layer?