(CISCO) Intro to Networks - Chapter 1

Physical Port

A connector or outlet on a networking device where the media connects to an end device or another networking device.

A Scalable Network

Expands quickly to support new users and applications. It does this without degrading the performance of services that are being accessed by existing users.

IP Address (Internet Protocol Address)

Identifies the host and the network to which the host is attached. Numeric address of a computer connected to the internet.

Logical Topology Diagrams

Illustrate devices, ports, and the addressing scheme of the network. *Lets you see which end devices are connected to which intermediary devices and what media is being used.

Organizations that were developed to help maintain the structure and standardization of internet protocols and processes:

These organizations include the Internet Engineering Task Force (IETF), Internet Corporation for Assigned Names and Numbers (ICANN), and the Internet Architecture Board (IAB), plus many others.

Metro Ethernet

This is sometimes known as Ethernet WAN. Metro ethernets extend LAN access technology into the WAN.

The advantages of peer-to-peer networking:

- Easy to set up - Less complex - Lower cost because network devices and dedicated servers may not be required - Can be used for simple tasks such as transferring files and sharing printers

WANs have specific characteristics:

- Interconnect LANs over wide geographical areas such as between cities, states, provinces, countries, or continents. - Usually administered by multiple service providers. - Provide slower speed links between LANs. * WANs can connect through copper wires, fiber-optic cables, and wireless transmissions.

LANs have specific characteristics:

- Interconnect end devices in a limited area such as a home, school, office building, or campus. - Usually administered by a single organization or individual. Administrative control is enforced at the network level and governs the security and access control policies. - Provide high-speed bandwidth to internal end devices and intermediary devices.

The disadvantages of peer-to-peer networking:

- No centralized administration - Not as secure - Not scalable - All devices may act as both clients and servers which can slow their performance

Intermediary network devices perform some or all of these functions:

- Regenerate and retransmit communication signals. - Maintain information about what pathways exist through the network and internetwork. - Notify other devices of errors and communication failures. - Direct data along alternate pathways when there is a link failure. - Classify and direct messages according to priorities - Permit or deny the flow of data, based on security settings.

Criteria to consider when choosing network media:

- What is the maximum distance that the media can successfully carry a signal? - What is the environment in which the media will be installed? - What is the amount of data and at what speed must it be transmitted? - What is the amount of data and at what speed must it be transmitted? * Different types of network media have different features and benefits. Not all network media have the same characteristics, nor are they all appropriate for the same purpose.

In order to achieve the goals of network security, there are three primary requirements.

1. Confidentiality 2. Integrity 3. Availability

Requirements of Security

1. Confidentiality 2. Integrity 3. Availability

Three (3) common types of server software

1. Email - The email server runs email server software. Clients use mail client software, such as Microsoft Outlook, to access email on the server. 2. Web - The web server runs web server software. Clients use browser software, such as Windows Internet Explorer, to access web pages on the server. 3. File - The file server stores corporate and user files in a central location. The client devices access these files with client software such as the Windows File Explorer.

Modern networks primarily use three (3) types of media to interconnect devices:

1. Metal wires within cables - Data is encoded into electrical impulses. 2. Glass or plastic fibers within cables (fiber-optic cable) - Data is encoded into pulses of light. 3. Wireless transmission - Data is encoded via modulation of specific frequencies of electromagnetic waves.

Wide Area Networks (WANs)

A WAN is a network infrastructure that provides access to other networks over a wide/large geographical area, which is typically owned and managed by a larger corporation or a telecommunications service provider. Typically managed by service providers (SPs) or Internet Service Providers (ISPs).

What is the name for all computers connected to a network that participate directly in network communication?

Hosts

Local Area Networks (LANs)

A network infrastructure that provides access to users and end devices in a small geographical area. Typically used in a department within an enterprise, a home, or a small business network. A network serving a home, small building, or a small campus.

Intranet

A private connection of LANs and WANs that belongs to an organization. Designed to be accessible only by the organization's members, employees, or others with authorization.

Network Interface Card (NIC)

A specialized port on a networking device that connects to individual networks.

Clients

A type of host. They have software for requesting and displaying the information obtained from the server. Computer program that uses the services of another computer program. Also, a software that extracts information from a server. A machine that accesses shared resources on a server. An example of client software is a web browser, like Chrome or FireFox. A single computer can also run multiple types of client software. For example, a user can check email and view a web page while instant messaging and listening to an audio stream.

The Internet

A worldwide collection of interconnected networks (internetworks, or internet for short). * The internet is not owned by any individual or group. Ensuring effective communication across this diverse infrastructure requires the application of consistent and commonly recognized technologies and standards as well as the cooperation of many network administration agencies.

Host / End Devices / Clients

All computers that are connected to a network and participate directly in network communication. However, the term hosts specifically refers to devices on the network that are assigned a number for communication purposes. This number identifies the host within a particular network. This number is called the Internet Protocol (IP) address.

Redundant Connections

Allow for alternative paths if a device or a link fails. The user experience is unaffected.

Small Office and Home Office (SOHO) Networks

Allow people to work from home, or a remote office. Many self-employed workers use these types of networks to advertise and sell products, order supplies, and communicate with customers.

End Devices

An end device is either the source or destination of a message/packet transmitted over the network. To distinguish one end device from another, each end device on a network has an address. When an end device initiates communication, it uses the address of the destination end device to specify where to deliver the message.

Dial-Up Telephone

An inexpensive option that uses any phone line and a modem. The low bandwidth provided by a dial-up modem connection is not sufficient for large data transfer, although it is useful for mobile access while traveling.

Extranet

An organization may use to provide secure and safe access to individuals who work for a different organization but require access to the organization's data. Example: * A company that is providing access to outside suppliers and contractors. * A hospital that is providing a booking system to doctors so they can make appointments for their patients.

Topology Diagrams

Are mandatory documentation for anyone working with a network. They provide a visual map of how the network is connected. Two (2) types of topology diagrams: Physical and logical.

Business DSL

Available in various formats. A popular choice is Symmetric Digital Subscriber Line (SDSL) which is similar to the consumer version of DSL but provides uploads and downloads at the same high speeds.

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.

Cellular

Cellular internet access uses a cell phone network to connect. Wherever you can get a cellular signal, you can get cellular internet access. Performance is limited by the capabilities of the phone and the cell tower to which it is connected.

Servers

Computers with software that allow them to provide information, like email or web pages, to other end devices on the network. Computer can also share printers and files with other computers on a network. Each service requires separate server software. For example, a server requires web server software in order to provide web services to the network. A computer with server software can provide services simultaneously to many different clients.

Intermediary Devices

Connect the individual end devices to the network. They can connect multiple individual networks to form an internetwork. These intermediary devices provide connectivity and ensure that data flows across the network. Intermediary devices use the destination end device address, in conjunction with information about the network interconnections, to determine the path that messages should take through the network. * All intermediary devices perform the function of a repeater. Examples of the more common intermediary devices: - Wireless Router - LAN Switch - Router - Multilayer Switch - Firewall Appliance - Ethernet hub

Businesses Internet Connections

Corporate connection options differ from home user options. Businesses may require higher bandwidth, dedicated bandwidth, and managed services. Connection options that are available differ depending on the type of service providers located nearby. Common connection options for businesses: Dedicated Leased Lines Metro Ethernet Business DSL Satellite

Common Internet connection options for small office and home office users:

DSL Cable Cellular Internet Satellite Dial-Up Telephone * The choice of connection varies depending on geographical location and service provider availability.

Availability

Data availability assures users of timely and reliable access to data services for authorized users.

Confidentiality

Data confidentiality means that only the intended and authorized recipients can access and read data.

Integrity

Data integrity assures users that the information has not been altered in transmission, from origin to destination.

Metal wires within cables

Data is encoded into electrical impulses.

Wireless Transmission

Data is encoded via modulation of specific frequencies of electromagnetic waves.

Types of End Devices

Desktop Computer Laptop Printer IP Phone Wireless Tablet TelePresence EndPoint

As networks evolve, we have learned that there are four basic characteristics that network architects must address to meet user expectations:

Fault Tolerance Scalability Quality of Service (QoS) Security

When data is encoded as pulses of light, which media is being used to transmit the data?

Fiber-Optic Cable

Fiber-Optic Cable

Glass or plastic fibers within cables - Data is encoded into pulses of light.

Redundancy

Having multiple paths to a destination. Redundancy is an example a fault-tolerant network architecture.

Quality of Service (QoS)

Is an increasing requirement of networks today. New applications available to users over networks, such as voice and live video transmissions, create higher expectations for the quality of the delivered services. As data, voice, and video content continue to converge onto the same network, QoS becomes a primary mechanism for managing congestion and ensuring reliable delivery of content to all users. * Managed by the router, ensures that priorities are matched with the type of communication and its importance to the organization. ***Means that a router will manage the flow of data and voice traffic, giving priority to voice communications.

A fault tolerant network

Is one that limits the number of affected devices during a failure. It is built to allow quick recovery when such a failure occurs. These networks depend on multiple paths between the source and destination of a message. If one path fails, the messages are instantly sent over a different link.

Dedicated Leased Line

Leased lines are reserved circuits within the service provider's network that connect geographically separated offices for private voice and/or data networking. The circuits are rented at a monthly or yearly rate.

Simple Home Networks

Let you share resources, such as printers, documents, pictures, and music, among a few local end devices.

Physical Topology Diagrams

Lets you see the actual location of intermediary devices and cable installation.

The two most common types of network infrastructures are:

Local Area Networks (LANs), and Wide Area Networks (WANs).

1. QoS

Means that a router will manage the flow of data and voice traffic, giving priority to voice communications.

Peer-To-Peer Network

Network in which each machine can act as both a client and a server. In small businesses and homes, many computers function as the servers and clients on the network.

Scalability

Occurs when designers follow accepted standards and protocols.

Congestion

Occurs when the demand for bandwidth exceeds the amount available. Network bandwidth is measured in the number of bits that can be transmitted in a single second, or bits per second (bps). When simultaneous communications are attempted across the network, the demand for network bandwidth can exceed its availability, creating network congestion. When the volume of traffic is greater than what can be transported across the network, devices will hold the packets in memory until resources become available to transmit them.

Securing the network infrastructure includes:

Physically securing devices that provide network connectivity and preventing unauthorized access to the management software that resides on them. Administrators can protect the network with software and hardware security and by preventing physical access to network devices. Security measures protect the network from unauthorized access. Network administrators must also protect the information contained within the packets being transmitted over the network, and the information stored on network attached devices.

DSL (Digital Subscriber Lines)

Provide high bandwidth, high availability, and an always-on connection to the internet. DSL runs over a telephone line. In general, small office and home office users connect using Asymmetrical DSL (ADSL), which means that the download speed is faster than the upload speed.

Diagram

Provides an easy way to understand how devices connect in a large network. This type of "picture" of a network is known as a topology diagram. The ability to recognize the logical representations of the physical networking components is critical to being able to visualize the organization and operation of a network. In addition to these representations, specialized terminology is used to describe how each of these devices and media connect to each other: * Network Interface Card (NIC) - A NIC physically connects the end device to the network. * Physical Port - A connector or outlet on a networking device where the media connects to an end device or another networking device. * Interface - Specialized ports on a networking device that connect to individual networks. Because routers connect networks, the ports on a router are referred to as network interfaces. Note: Often, the terms port and interface are used interchangeably.

The Media

Provides the channel over which the message travels from source to destination.

Repeaters

Regenerate and retransmit communication signals.

Satellite Service

Satellite service can provide a connection when a wired solution is not available.

Network infrastructures vary greatly in terms of:

Size of the area covered Number of users connected Number and types of services available Area of responsibility

Interface

Specialized ports on a networking device that connect to individual networks. Because routers connect networks, the ports on a router are referred to as network interfaces. * Physically connects the end device to the network.

Satellite

The availability of satellite internet access is a benefit in those areas that would otherwise have no internet connectivity at all. Satellite dishes require a clear line of sight to the satellite.

The internet

The largest network in existence. In fact, the term internet means a "network of networks," It is a collection of interconnected private and public networks.

Communication

Transmits across a network on media.

Cable

Typically offered by cable television service providers, the internet data signal transmits on the same cable that delivers cable television. It provides a high bandwidth, high availability, and an always-on connection to the internet.

Converged Networks

Unlike dedicated networks, converged networks are capable of delivering data, voice, and video between many different types of devices over the same network infrastructure. This network infrastructure uses the same set of rules, agreements, and implementation standards. Converged data networks carry multiple services on one network.

Client and server software

Usually run on separate computers, but it is also possible for one computer to be used for both roles at the same time.

Types of Network Media

Wireless Media LAN Media WAN Media

Types of Intermediary Devices

Wireless Router Router LAN Switch Multilayer Switch Firewall Appliance