Ch.1 Terms and Acronyms

MAC Address

(Media Access Control) -12 digits first 6 are manufacturer number, last 6 is device ID -each device has it's own unique one

TCP/IP Model

(Transmission Control Protocol/Internet Protocol) application(layer7-5 OSI), transport(4), internet(3), network access(2-1)

What is an example of a physical address?

A MAC address

NIC

A Network Interface Card is a piece of hardware that allows a computer to connect to a network.

The Link Layer (TCP/IP Model)

A combination of layers 1 & 2 from the OSI model

Frame

A container for a chunk of data moving across a network

Switch

A device that sends a message to the device with the right MAC address

Hub

A device that sends the same message out to all devices connected to it. That message is only accepted by the device with the corresponding MAC address

Subnet

A larger network split up into smaller networks

API

Application Programming Interface

Packet

Basic component of communication over a network. Group of bits of fixed maximum size and well-defined format that is switched and transmitted as a single entity through a network. Contains source and destination address, data, and control information.

EUI

Extended Unique Identifier. EUI-48 means that same thing as MAC-48. That the MAC Address has 48 bits

FCS

Frame Check Sequence allows for error checking -Think of it as the bank tube system

ISO

International Organization for Standardization (isos in greek means equal, which is where the acronym came from)

IMAP

Internet Message Authentication Protocol.

Application Layer (Layer 7)

Involves programs that respond to a users request as well as the responses to that request to use the network for applications such as email and file transfer. Gateway communication devices handle Layer 7

Media Access Control (MAC)

It adds the NIC's own MAC address and attaches MAC addresses to the frames. The MAC sublayer adds or checks the FCS. It also checks to make sure that the frames are sent along to the network cabling

De-encapsulation

Stripping all the extra header information out as the data goes up the stack.

What is an example of a descriptive model (a tight protocol-to-integration layer)?

TCP/IP Model

Physical Layer (Layer 1)

responsible for movements of individual bits from one hop (node) to the next. Physical link between sender and receiver Dumb layer - does not attach header and trailer, no extra info

What is an example of a logical address?

An IP Address

Unicast Frame

Any frame addressed specifically to another device's MAC address

Application Layer (TCP/IP Model)

Combines layers 5-7 of the OSI model. Every application, especially connection-oriented applications, must know how to initiate, control and disconnect from a remote system. No single method exists for doing this. Each TCP/IP application uses its own method

Segmentation

Chopping up requested data into chunks that will fit into a packet (and eventually a NIC's frame), organize the packets for the benefit of the receiving system, and hand them to the NIC for sending

Transport Layer (TCP/IP Model)

Combines layers 4, 5 and part of 7 from the OSI model. Deals with segmentation and reassembly of data. It also defines two other functions, such as the connection-oriented and the connectionless communication. The connection-oriented protocol is TCP (Transmission Control Protocol) and the connectionless communication protocol is the UDP (User Datagram Protocol)

Router

Connects subnets together. They use IP address and not MAC addresses

Network Protocol

Creates a unique identifier for each system, and also creates a set of communication rules for issues like how to handle data chopped up into multiple packets and how to ensure those packets get from one subnet to another

CRC

Cyclical Redundancy Check. Checks to see if the message has any errors or not

Presentation Layer (Layer 6)

OSI Layer: Converts data intended for or received from the application layer into other formats. For example graphics, text, and sound/video data. Only layer that can modify application data. Transfers data between applications. Also handles encryption.

Session Layer (Layer 5)

OSI Layer: Handles all the sessions for a system. Initiates sessions, accepts incoming sessions, and opens and closes existing sessions

Network Layer (Layer 3)

OSI Layer: Primary responsibility is providing mechanisms for routing. Functionality provided through routing protocols which are responsible for route selection on a network. Packet describes logical grouping of data at this layer. CAN - Campus Area Network MAN - Metropolitan Area Network WAN - Wide Area Network inter - between intra - within

Data Link Layer (Layer 2)

OSI Layer: gets data to physical layer so it can transmit over network. Responsible for error detection, error correction, and hardware addressing. Frame describes a logical grouping of data at this layer. Does segmentation, by breaking up big chunks of data into smaller pieces Two Sublayers: Media Access Control (MAC) layer and Logical Link Control Layer (LLC - for errors and flow control).

What is an example of a prescriptive model?

OSI seven-layer model

OUI

Organizationally Unique Identifier - first 6 digits of a MAC address. Tells you what manufacturer it came from

PDU

Protocol data unit. An OSI term to refer generically to a grouping of information by a particular layer of the OSI model. Some PDU's have given names: Application Layer is called Message Transport Layer is called Segment Network Layer is called Packet Data Layer is called Frame

Logical Link Control (LLC)

The aspect of the NIC that talks to the operating system (usually via device drivers). The LLC handles multiple network protocols and provides flow control

Encapsulation

The entire process of preparing data to go onto a network

Unicast Addressing

The one-to-one addressing scheme

Transport Layer (Layer 4)

The transport layer, acts as a dividing line between the upper layers and lower layers of the OSI model. Specifically, messages are taken from upper layers (Layers 5-7) and are encapsulated into segments for transmission to the lower layers (Layers 1-3). Similarly, data streams coming from lower layers are decapsulated and sent to Layer 5 (the session layer), or some other upper layer, depending on the protocol. The Transport Layer is associated with TCP/UDP Windowing Buffering The basic function of the transport layer is to provide mechanisms to transport data between network devices. Primarily it does this in three ways: Error checking, Service addressing, Segmentation

The Internet Layer (TCP/IP Model)

This is layer 2 from the TCP/IP model. Deals with anything regarding with IP packets (getting an IP packet to its destination). IP addressing itself is also part of the Internet Layer, as are routers and the magic they perform to get IP packets to the next router.

TCP Segment

This is what you get when you take away the IP address from an IP packet. You are left with a chunk of data in another container

UTP

Unshielded twisted pair. Cable type used in networks that do not have any concerns over EMI, RFI, or cross talk. If these are a concern, STP is used.

OSI Model

a.k.a Open Systems Interconnection Model -Model describes how data is transferred across the network -does NOT how to connect components Application, Presentation, Session, Transport, Network, Data Link, Physical (Layer 7-1) Layer 1-4= Data Transport Layer 5-7= Application Mnemonic: All People Seem To Need Data Processing