IS 3413 Telcom & Net Midterm 1 Flashcards

The layers of the OSI model from top to bottom are

HINT: People Don't Need To See People's A**

1. Physical

2. Data Link

3. Network

4. Transport

5. Session

6. Presentation

7. Application

The Layers of the Internet Model are

HINT: It combines 3 layers to = the Application Layer

1. Physical

2. Data Link

3. Network

4. Transport

5. Application

Types of Servers

1. File Server: stores data and software that can be used by computers on the network

2. Web Server: store documents and graphics to be accessed from any Web browser

3. Mail Server: handles and delivers emails over to the network

Network Standards

The Primary reason for standards is to ensure that hardware and software produced by different vendors can work together, no standards = chaos

What is layer 8?

Layer 8 is the user/people

Physical Layer

Physical Connection between the sender and the receiver, i.e. network cable connecting your computer to the rest of the network

Five Key Benefits of Digital over Analog

1. Fewer Errors

2. Higher Maximum Transmission Rates

3. More Efficient

4. More Secure

5. Integration is simpler

Point-to-Point Circuit

Each Computer has its own dedicated server; can get very expensive

Multipoint Circuit

Many computers are connected to the same circuit/server; more efficient and less expensive

Simplex transmission

One way transmission

Example: Radio

Half Duplex Transmission

Two-way transmission in only one direction at a time

Example: Walkie Talkies

Full Duplex Transmission

Two-way transmission at all times/both directions at same time

Example: Phone Call

Ethernet Cable is made of...

4 pairs of twisted wires = 8 wires

Telephone Cable is made of...

2 pairs of twisted wires = 4 wires

Factors in Media Selection

1. Type of Network

2. Cost

3. Transmission Distance

4. Transmission Speed

5. Security

6. Error Rates

Serial Transmission

Sends 8 bits 1 at a time; much slower

Parallel Transmission

Sends 8 bits at the same time; much faster

Modulation

Manipulates sound wave shape to represent a value (0 or 1) (AM, FM, PM)

The Capacity of a Circuit is equal to the...

bandwidth!

top value - bottom value = bandwidth

Voice over Internet Protocol (VoIP)

Used to transmit phone conversations over digital networks using a codec built-in phone

Advantage = lower cost

Disadvantage = Dependent on internet Provider (Outages)

Data Link Layer

Uses a protocol called Ethernet to connect to the internet. Responsible for sending and receiving messages to and from other computers

Sublayers of Data Link Layer

1. Logical Link Control (LLC)- Data link's layer's connection to the network layer

2. Media Access Control(MAC) - controls physical hardware

**MAC Address = Hardware Address**

Contention

With contention, computers wait until circuit is free and then transmits data; commonly used in shared Ethernet LANs

3 Functions of the Data Link Protocol (MEM)

1. Media Access Control- controls when computers transmit

2. Error Control- detects and corrects transmission errors

3. Message Delineation- identifies start and end of message by using PDU

Asynchronous Transmission

Transmits each character one at a time

Synchronous Transmission

Transmits lots of characters at the same time as a block of data (frame); is more efficient

Ethernet has a ____ address which specifies the receiver and a ____ address which specifies the sender

Destination Address

Source Address

Ethernet

a LAN protocol that uses a contention media access protocol

Information Bits

used to convey the user's meaning

Overhead Bits

used for error checking and marking the start and end of characters and packets

Transmission Efficiency =

total information bits divided by total bits in transmission

Throughput =

total number of information bits received per second, taking into account overhead bits and need to retransmit frames

MAC Address

1. Has 12 Characters

2. First 6 Characters are the Vendor Code

3. Last 6 Characters are unique to the device

4. There is no such thing as a duplicate MAC Address

5. Uses Hexadecimal Numbers

Application Layer

Is the User's access to the network via an application, translates the user's message into HTTP

Example: Email; using a web browser to click on a link

Host Based Architectures

Server (mainframe computer) performs all functions and processes all messages

Example: IBM Mainframe

Client-Based Architectures

Client performs most functions; server and client are both personal computers

Example: Using Word to access a document on the server

Client Server Architectures

Both Client and Server have balanced and equal processing of work; mostly used today

Example: Accessing a Webpage

Advantages: Most reliable, cheapest, and enables cloud computing

Peer to Peer Architecture

Example: Napster (Music Sharing App)

Cloud-Based Architecture

Example: Zoom

Software as a Service (SaaS)

Outsources the entire application to the cloud provider

Example: Gmail, Netflix, Zoom, Dropbox

Platform as a Service (PaaS)

User can build their own application and manage their own data; hardware and software are rented from a cloud provider

Example: Windows Azure, Google App Engine

Infrastructure as a Service (IaaS)

Cloud provider manages the hardware

Example: IBM Cloud, Amazon Web Services

The Web and/or HTTP is a ___ Tier __________-_______ architecture

The Web and/or HTTP is a two-tier client-server architecture

HTTP Response Meanings

200 = successful

400 = unsuccessful (webpage not found)

Standards used for emails

SMTP =

POP & IMAP =

SMTP = used to send

POP & IMAP = used to retrieve

Network Layer

Performs routing; uses a protocol called IP (internet protocol)

Transport Layer

Transport layer maintains end-to-end connections and ensures packets are received

Transmission Control Protocol (TCP)

A protocol for sending packets that does error-checking to ensure all packets are received and properly ordered; PDU = segments

TCP Destination Port

Tells the destination which program the packet should be sent (where it's going)

TCP Source Port

Tell the receiver which program the packet is from (where it's from)

User Datagram Protocol (UDP)

Used to send short messages called datagrams; PDU = datagrams

Internet Protocol (IP)

IPV4: 32 bits, 4 octets, and 8 bits in each octet

IPV6 : 128 bits

Highest value in an IP address is 255

TCP uses ________ - ________ messaging

TCP uses connection-oriented messaging for sessions(conversations) between two computers. This method transmits segments in sequences until the conversation is over then the sender ends the session

UDP uses _________ messaging

UDP uses connectionless messaging which is used to send a short message and move on

You must be assigned an ___ Address, but a ______ Address is already assigned

You must be assigned an IP Address, but a MAC Address is already assigned

Network Adress

If the 4th octet ends with .0

Example: 128.192.56.0

Broadcast Address

If the 4th octet ends with a .255

Example: 128.192.56.255

Any Subnet Mask (first three octets) that is the same for any two IP Addresses is on the ____ network

Any Subnet Mask that is the same for any two IP Addresses is on the same network

Hosts =

2^n - 2 = Hosts

n = host bits

In a 32-bit IPV4 address you have ___ host bits and ___ subnet bits

8 host bits and 24 subnet bits

A 24 bit network has how many hosts?

2^8 - 2 = 256 -2 = 254 hosts

Routing

every router has a routing table which specifies how messages travel through the network, kind of like a roadmap; most routers have multiple interfaces

Static Routing

manual; each computer or routers in the network make their own routing decisions following a formal routing protocol

Dynamic Routing

learned and adaptable

downside: router requires more processing and wastes network capacity

4 elements given to a PC when it's installed to operate on a TCP/IP network

1. Its IP Address

2. A subnet mask

3. The IP address of a DNS Server

4. The IP address of an IP gateway (router)

Broadcast Message

sent to all computers on a specific LAN or subnet

Multicast Message

used to send the same message to a group of computers