Network and OSI Models

How do Networks restrict the amount of data and why?

Because all the data sent by one NIC is read by every other NIC on the network, only one system may speak at a time. Networks use frames to restrict the amount of data a NIC can send at once, giving all NICs a chance to send data over the network in a reasonable span of time.

What is the Logical Addressing method?

It is a method, like a postal code or telephone numbering scheme, that ignores the hardware and enables you to break up the entire large network into smaller networks called subnets.

How is the IP address configured?

It is configured using software.

What does the NIC do?

It serves as the interface between the PC and the network. Usually looks like a circuit board, and are now built into the motherboard. Older ones were literally a separate card.

NICs encapsulate data into a(n) ____ for sending that data over a network.

frame

How much data can a frame hold?

1500 bytes

How much data can a typical frame contain?

1500 bytes

Which of the following is most likely to be a MAC address assigned to a NIC?

23.4F.17.8A.4C.10

Central Box

A key piece of hardware, like the UTP, that that handles the flow of data from each computer to every other computer. Each system on the network has its own cable that runs to the central box.

What is an FCS?

A Frame Check Sequence (FCS). The FCS uses a type of binary math called a Cyclic Redundancy Check (CRC) that the receiving NIC uses to verify that the data arrived intact.

What is a router?

A box that connects each of the subnets. Routers use the IP address, not the MAC address, to forward data.

What is a UTP?

A cable that usually contains four paris of wires that can transmit and receive data.

What is a TCP segment?

A chunk of data that ensures the data gets to its destination in good order.

Which of the following best describes an IP address?

A dotted decimal notation assigned to a NIC by software.

What is a packet?

A inner container of the frame which includes the Destination IP address, source IP address, and data.

What is a Network Protocol?

A special software that moves past the physical MAC addresses to start using logical addressing.

What is a MAC address?

A unique identifier with 48-bit value on the firmware of the NIC.

How does a frame work within the Network?

All networks transmit data by breaking whatever is moving across the Physical layer into discrete chunks, which are Frames. There are a lot of different frame types, but all NICs on the end networks use the same frame type, so they can communicate.

What is an IP address?

An IP address is known as a logical address to distinguish it from the physical address (MAC address).

Subnets

An identifiable separate part of an organization's network.

Layer 7

Application

Which TCP/IP layer includes layers 5-7 from the OSI seven-layer model?

Application

What is an API?

Application Programming Interface. Using an API is a way programmers can make their programs network aware.

What 4 layers make up the TC/IP model?

Application, Transport, Internet, Link/Network Interface

Which components work at Layer 1 of the OSI seven-layer model? (Select two.)

Cables / Hub

How is binary represented physically?

Charge = 1. No Charge = 0.

What are segments or datagrams?

Chunks of data that the transport protocol breaks the data into. Each segment has some type of sequence number.

What is the difference between connection-oriented vs. connectionless communication?

Connection-oriented: checks that they have a good connection before a message is sent. Connectionless communication: protocols simply send data without first waiting to verify that the receiving system is ready.

What happens in the Network layer?

Containers called packets get created and addressed so they can go from one network to another.

What is the fourth layer of the TCP/IP model?

Controls how to initiate, control, and disconnect from a remote system. Similar to the application, presentation, and session layers of the OSI model.

Layer 2

Data Link

The ______ provides the key interface between the Physical and Network layers.

Data link layer

What is a UDP datagram include?

Destination port, source port, length, checksum, data

What is a TCP segment made of?

Destination port, source port, sequence number, checksum, flags, acknowledgment, data.

What is modular design in networking?

Each layer has as little to do with the operation of the other layers.

What does the router do with the frame before it reaches its desination?

Each router strips off the incoming frame, determines where to send the data according to the IP address in the packet, creates a new frame, and then sends the packet within a frame on its way. The new frame type will be the appropriate technology for whatever connection technology connects to the next router. The IP packet, on the other hand, remains unchanged.

If a sending system does not know the MAC address of the intended recipient system, it sends a broadcast frame with what MAC address?

FF-FF-FF-FF-FF-FF

How does a frame get from one system to another?

First, the sending system's operating system hands some data to its NIC. The NIC builds a frame to transport that data to the receiving NIC. After the NIC creates the frame, it adds the FCS, and then dumps it and the data into the frame. Next, the NIC puts both the destination MAC address and its own MAC address onto the frame. It waits until no other NIC is using the cable, and then sends the frame through the cable to the network. The frame propagates down the wire into the central box, which creates copies of the frame and sends it to every other system on the network. Every NIC receives the frame and checks the MAC address. If a NIC finds that a frame is addressed to it, it processes the frame; if the frame is not addressed to it, the NIC erases it.

What are the details of an IP address?

IP uses a dotted-octet numbering system based on four 8-bit numbers. Each 8-bit number ranges from 0 to 255, and the four numbers are separated by periods.

What is a hub?

In the early days of networking, the central box was a hub.

What does ISO stand for?

International Organization for Standardization

Which layer of the TCP/IP Model involves routing?

Internet

What does IP stand for?

Internet Protocol

The ____ is an example of software that creates packets for moving data across networks.

Internet Protocol (IP)

Which protocol creates the final IP packet?

Internet Protocol (IP)

What does the sequence number that is embedded into the data of the packet allow?

It allows the receiving the system to know both the total number of segments and how to put them back together.

What does a UDP do?

It also gets data from the Application layer and adds port and length numbers plus a checksum to create a container called a UDP datagram.

Define the Physical Layer.

Layer 1. Handles moving data between computers. Doesn't care what data goes through, it just moves it. Includes cabling, central box, copper cabling, fiber optics, radio waves.

Name the seven OSI layers?

Layer 7: Application, Layer 6: Presentation, Layer 5: Session, Layer 4: Transport, Layer 3: Network, Layer 2: Data Link, Layer 1: Physical.

What are the two jobs that the network performs to keep data moving?

Logical Link Control (LLC) and Media Access Control(MAC)

Every NIC has a hard-coded identifier called a(n) ____

MAC address

What component of Layer 2 of the OSI model creates and addresses for the frame?

MAC sublayer

What does MAC stand for?

Media Access Control Address

Layer 3

Network

What does NIC stand for?

Network Interface Card

Most often, the ____ provides the physical connection between the PC and the network.

Network Interface Card (NIC)

What does OSI work for compared to TCP/IP?

OSI works for almost every type of network, even extremely old and long-obsolete ones. TCP/IP only works for networks that use the now-dominant TCP/IP protocol suite.

Andalyn says complete 48-bit MAC addresses are allocated to NIC manufacturers from the IEEE. Buster says the IEEE only assigns the first 24 bitys to manufacturers. Carlos says the IEEE assigns only the last 24 bits to manufacturers. Who is correct?

Only Buster is correct.

What does OSI stand for?

Open Systems Interconnection

What does OUI stand for?

Organizationally Unique Identifier - first 6 digits of the MAC Address

Layer 1

Physical

Which of the following OSI layers converts the ones and zeroes to electrical signals and places these signals on the cable?

Physical

Acronym for the OSI model?

Please Do Not Throw Sausage Pizza Away

Layer 6

Presentation

Which layer of the OSI Model makes sure the data is in a readable format for the application layer?

Presentation

From the options that follow, select the one that best describes the contents of a typical (simplified) network frame.

Recipient's MAC Address, Sender's MAC address, data, FCS.

Layer 5

Session

What is session software?

Session software handles connecting applications to applications.

What does Protocol stand for?

Sets of clearly defined rules, regulations, standards, and procedures that enable hardware and software developers to make devices and applications that function properly at a particular level.

What is a protocol suite?

Several network protocols designed to work together.

What layer is the NIC part of?

Sometimes it is defined as layer 1, and sometimes as layer 2.

What is a switch and how does it work?

The "central box". The switch only sends the frame to the recipient MAC address.

What is Layer 7?

The Application Layer. What the user sees. Refers to the code built into all operating systems that enables network-aware applications.

What is IP?

The Internet Protocol is the primary logical addressing protocol for TCP/IP. IP makes sure that a piece of data gets to where it needs to go on the network. It does this by giving each device on the network a unique numeric identifier called an IP address.

What is the second layer of TCP/IP?

The Internet layer. "IP packet" layer. Any device or protocol that deals with pure IP packets--getting an IP packet to its destination--sits in the Internet layer. IP addressing itself is also part of the Internet layer, as are routers. Equivalent to the Network layer on the OSI model.

What does the LLC do?

The LLC is the aspect of the NIC that talks to the system's operating system. The LLC handles multiple network protocols and provides flow control.

What is the first layer of the TCP/IP model?

The Link layer and Network Interface layer. (Combination of the physical and data link layer of the OSI model). Includes cabling, hubs, physical addresses, and NICs.

Where are the IP address and MAC address stored?

The MAC address (the physical address) is burned into the chips on the NIC, and the IP address (the logical address) is simply stored in the system's software.

What does the MAC do?

The MACC creates and addresses the frame. It adds the NIC's own MAC address and attaches MAC addresses to the frames. Recall that each frame the LLC creates must include both the sender's and recipient's MAC addresses. The MAC sublayer adds or checks the FCS. The MAC also ensures that the frames, now complete with their MAC addresses, are then sent along the network.

How does the driver work with the packet?

The NIC driver knows how to communicate with the NIC to send and receive frames, but it can't do anything with the packet. Instead, the NIC driver hands the packet off to other programs that know how to deal with all the separate packets and turn them into web pages, e-mail messages, files, and so forth.

How does the NIC work?

The NIC sends and receives binary data as pulses of electricity, light, or radio waves.

What does a network do if it doesn't already know the MAC address?

The NIC sends out a broadcast onto the network to ask for it. The MAC address of FF-FF-FF-FF-FF-FF is the broadcast address--if a NIC sends a frame using the broadcast address, every single NIC on the network will process that frame. The broadcast frame's data will contain a request for a system's MAC address. Without knowing the MAC address to begin with, the requesting computer will use an IP address to pick the target computer out of the crowd.

What does the receiving NIC do with the packet?

The NIC strips away the Ethernet frame and passes the remaining packet off to the software. The networking software built into your operating system handles all the rest of the work.

What is the interconnection between the hardware and the software?

The NIC's driver software.

What is Layer 3?

The Network Layer. The last layer that deals directly with hardware.

What is Layer 6?

The Presentation layer. Translates data from lower layers into a format usable by the Application layer, and vice versa.

What is Layer 4?

The Transport Layer. It is the assembler/disassembler software. It also initializes requests for packets that weren't received in good order.

What is layer 3 of the tcp/ip model?

The Transport layer combines features of the OSI Transport and Session layers with a dash of Application layer. Involved with the assembly and disassembly of data, it also defines other functions, such as connection-oriented and connectionless communication.

What does a frame enable?

The data to move from one device to another.

Break down a MAC address.

The first six digits represent the number of the NIC Manufacturer. The last six digits are the manufacturers unique serial number, referred to as the deviceID.

What is the device ID?

The last six digits of the MAC address that stand for the manufacturers unique serial number.

When does the Link layer move into the Internet layer?

The moment the frame information is stripped away from an IP packet.

What happens when the packet reaches the destination router?

The router will strip off the incoming frame--no matter what type--look at the destination IP address, and then add a frame with the appropriate destination MAC address that matches the destination IP address.

What happens when the data to be sent is larger than the frame size?

The sending system's software must chop the data up into nice, frame-sized chunks, which it then hands to the NIC for sending.

What is Layer 5?

The session layer. This handles all the sessions for a system. It accepts incoming sessions, and opens and closes existing sessions.

Modeling is used for?

To understand and communicate with other techs about networks.

What does TCP stand for?

Transmission Control Protocol

What is a connection-oriented protocol called?

Transmission Control Protocol (TCP).

The______provides an excellent tool for conceptualizing how a TCP/IP network works. (Select the best answer.)

Transmission Control Protocol/Internet Protocol (TCP/IP) model

At which layer of the TCP/IP model are UDP datagrams created?

Transport

Layer 4

Transport

On a sending machine, data gets broken up at the ___ of the OSI seven-layer model.

Transport Layer

The term "unshielded twisted pair" describes which of the following network components?

cable

What does UTP stand for?

Unshielded twisted pair

What is a connectionless protocol called?

User Datagram Protocol (UDP)

How did a hub work?

When a hub received a frame, the hub made an exact copy of that frame, sending a copy of the original frame to every other system on the network. If the NICs saw the frame wasn't addressed to their MAC address, they would erase the frame.

Using the ___ enables a computer to send a packet that every other PC on the network will process.

broadcast address

Command to see the MAC address for your NIC?

ifconfig /all (windows) and ifconfig (linux)

You can connect two very different networks by using a(n) ____.

router

A(n) ____ enables multiple machines to connect over a network

switch

What does the physical address stand for in the command line?

the MAC address

What is included in a frame?

the Recipient's MAC address, the sender's MAC address, type(specific network technology of the frame), Data, FCS(frame check sequence)