Intro to Networks v5

Chapter 1:Exploring the Network

Introduction to Networks

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Networks in Our Past and Daily Lives

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Clients and Servers

The advantages of Client/Server networks:

• Can provide services simultaneously to one or many clients.

• Can run multiple types of software and services

• Add security

The disadvantages of Client/Server networks:

• More Devices

• More complex

• Single point of failure

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Peer-to-Peer

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Components of a Network

There are three categories of network components:

Devices

Media

Services

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Components of a Network End Devices

Some examples of end devices are:

• Computers (work stations, laptops, file servers, web servers)

• Network printers

• VoIP phones

• TelePresence endpoint

• Security cameras

• Mobile handheld devices (such as smartphones, tablets, PDAs, and wireless debit / credit card readers and barcode scanners)

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Network Infrastructure Devices

Examples of intermediary network devices are:

• Network Access Devices (switches, and wireless access points)

• Internetworking Devices (routers)

• Security Devices (firewalls)

Functions of intermediary devices on a network:

• They direct data along alternate pathways when there is a link failure

• They filter the flow of data, based on security settings

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Network Media

Criteria used to help select network media:

•The distance the media can successfully carry a signal

•The environment where the media is to be installed

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Topology Diagrams

Logical Topologies

Naming scheme

IP addressing

Physical Topologies

Physical locations

Layout of devices and hosts

Length of cables

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Types of Networks

The two most common types of network infrastructures are:

•Local Area Network (LAN)

•Wide Area Network (WAN).

Other types of networks include:

•Metropolitan Area Network (MAN)

•Wireless LAN (WLAN)

•Storage Area Network (SAN)

•Network Area Storage (NOS)

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Local Area Networks (LAN)

A LAN is considered a small geographical area.

Servers a home, building, or campus.

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Wide Area Networks (WAN)

A WAN is considered a large geographic area.

WANs connect LANs at slower speed bandwidth than LANs connect their internal end devices.

WANs are typically operated through multiple ISPs, but LANs are typically operated by single organizations or individuals.

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The Internet, Extranet, and Intranet

The Internet is used to access the world, like surfing the web, online shopping, or watching a video (WAN).

The Extranet is used from the Internet to access resources inside a private company.

The Intranet is used to access private resources from inside a company (LAN).

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Internet Access Technologies

Instant messaging – real-time communication between two or more people.

Social media – interactive website there people create and share user-generated content with friends and family.

Wiki – web pages that groups people can edit and use together.

Podcast – an audio basedmedium that allows peopleto deliver their recordingto a wide audience.

Weblog (blog) - a discussion or informational site published on the web and consisting of discrete entries called posts.

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Connecting to the Internet

Require physical cables to be run to the building:

• DSL – splits the access into three signals (always-on, high-bandwidth connection)

• Cable – coaxial (always-on, high-bandwidth connection)

• Dialup (very low bandwidth)

• Dedicated leased line

Do NOT require physical cables:

• Cellular

• Satellite (must have line-of-sight)

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Converged Networks

A converged network is a single network channel capable of delivering multiple communication forms.

Multiple services running on multiple networks.

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Reliable Network

Supporting Network Architecture

As networks evolve, we are discovering that there are four basic characteristics that the underlying architectures need to address in order to meet user expectations:

•Fault Tolerance

•Scalability

•Quality of Service (QoS)

•Security

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Circuit-Switched Networks

A characteristic of circuit-switched networks is that If all circuits are busy, a new call cannot be placed.

There is a finite number of circuits. During peak periods, some calls may be denied.

The circuits stays active, even if no one is speaking.

No fault tolerance.

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Packet-Switched Networks

The term congestion defines a state where the demand on the network resources exceeds the available capacity.

During peak periods, communications may be delayed, but not denied.

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Scalable Networks

Tier 1 – Can reach every other network on the Internet without buying anything

Tier 2 – buys from Tier 1 – but can resell. Can do that with some networks, but still buys to go some places on the Internet

Tier 3 - Probably also buy from Tier 3’s, but more on the retail market, and for a specific area. Much lower in price.

Tier-3 ISPs are the local providers of services directly to end users.

Tier-3 ISPs are usually connected to Tier-2 ISPs and pay Tier-2 providers for internet access.

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Quality of Service (QoS)

Examples of priority decisions for an organization might include:

• Time-sensitive communication - increase priority for services like telephony or video distribution.

• Non time-sensitive communication - decrease priority for web page retrieval or email.

• High importance to organization - increase priority for production control or business transaction data.

• Undesirable communication - decrease priority or block unwanted activity, like peer-to-peer file sharing or live entertainment

The network provides predictable levels of service to different types of traffic.

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Network Security

Requiring strong, complex passwords is a practice that ensures data confidentiality. Only the intended recipients can access and read the data.

Maintaining integrity ensures that the information has not been altered during transmission.

Ensuring availability provides the assurance of timely and reliable access to data.

These tools provide the minimum required security protection for home users:

• Antivirus software

• Antispyware software

• A firewall

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Security Threats

The most common external threats to networks include:

• Viruses, worms, and Trojan horses

• Spyware and adware

• Zero-day attacks, also called zero-hour attacks

• Hacker attacks

• Denial of service attacks

• Data interception and theft

• Identity theft

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Security Solutions

Network security components often include:

•Antivirus and antispyware

•Firewall filtering

•Dedicated firewall systems

•Access control lists (ACL)

• Intrusion prevention systems (IPS)

•Virtual Private Networks (VPNs)

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Network Trends

Some of the top trends include:

•Bring Your Own Device (BYOD)

•Online collaboration

•Video

•Cloud computing

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Bring Your Own Device (BYOD)

The acronym BYOD refers to the trend of end users being able to use their personal devices to access business/campus networks and resources.

Many wireless LANs are having to be redesign as a direct result of many students bringing their own tablets and smartphones to school to access school resources.

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Online Collaboration

TelePresence provides real-time video and audio communication over the Internet so that businesses can conduct corporate meetings with participants from several remote locations.

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Video Communication

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Cloud Computing

Cloud computing provides applications accessed over the Internet through a subscription.

There are four primary types of clouds:

•Public clouds

•Private clouds

•Custom clouds

•Hybrid clouds

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Data Centers

A data center is a facility used to house computer systems and associated components including:

• Redundant data communications connections

• High-speed virtual servers (sometimes referred to as server farms or server clusters)

• Redundant storage systems (typically uses SAN technology)

• Redundant or backup power supplies

• Environmental controls (e.g., air conditioning, fire suppression)

• Security devices

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