Advanced Networking

Routing & Switching:

Introduction to Networks

Chapter 1: Exploring the Network

Hacklab Cosenza / Centro di Ricerca su Tecnologia e Innovazione

Internet of Things (IoT)

IoT: How on earth did we get here?

• We used to go to the connected device. Think PCs.
• Now we bring our own device with us, and it connects us. Think Smartphones, tablets.
• Soon you won't feel any difference, because everything will be a connected device.
• And then? Cisco thinks everything and everyone, material and asbtract, will be connected, and calls this Internet of Everything.

Beware: Cisco has its own term for anything. No, seriously.

The Human Network

Think for 1 minute about how much just the first 25 years of the Internet have changed, and then for another minute about what the impact of the next 25 years could possibly be.

Cisco calls the study of such an impact networks can make on people, businesses, ideas, the Human Network.

You were warned about Cisco and terminology, weren't you?

Impact on how we learn

This would be you, by the way.

First of all, just look at the sheer amount of material: it's self-learning paradise.

We have grown out of textbook, schedule, teachers: audio, video and interactivity mean we can learn about anything, anywhere, on our own pace, and reach any level we want to.

No fixed roles, you can contribute back: the only thing stopping you from sharing your knowledge with the same effectiveness, is an internet connection.

MOOC: Massive Open Online Course

or: Let's graduate at MIT for free!. Kind of.

Impact on how we communicate

There's been a switch on the Internet, that is long completed: from Web 1.0 (the content is provided to us) to Web 2.0 (User Generated Content, UCG).

Some of the keywords for the Web 2.0: Social Media, Istant Messaging, Podcasting, File Sharing, Blog, RSS.

Impact on how we work

An ever increasing number of people can work from home thanks to the improved capabilities of networks and the quality of the tool at their disposal.

For many tasks, you went from needing several tools, persons and facilities, to just one: a network connection.

Impact on how we're entertained

More videos of cute cats and dogs than you need in a lifetime.

It's also worth mentioning:

• Throw your destination at your phone and see what happens.
• 5D Graphics are worthless if you can't do online gaming / multiplaying.
• Any niche market, no matter how small, can prosper with eCommerce and online payments.

All sizes of Networks

• Small networks: think about your home.
• Small Office/Home Office (SOHO): centralized resourced and dedicated devices.
• Medium Networks: think about the Unical island.
• Large Networks: let's talk about GARR.
• World Wide Networks: well, the Internet.

Internet is literally Network of Networks. It's the largest network there is.

Client-Server

• Host: generic name for a device that participates in a network's communications.
• Server: hosts that provide information through server software.
• Client: hosts that request and display this information through client software.

Client-Server: no clear-cut

• One host can be both a client and a server.
• Multiple kinds of informations provided or requested at the same time.
• Server functions are usually logically grouped, while clients are general purpose.

Peer to Peer (P2P)

A network where hosts acts simultaneously as client and server for a specific type of information is called a Peer to Peer network.

This is much more a software distinction.

Peer to Peer (P2P)

Advantages

• Easy configuration
• Less complexity
• Lower cost, doesn't need dedicated devices
• Better for simple tasks

Disadvantages

• No centralized administration
• Security
• Scalability
• Slow performances of devices.

Network Components

Every network infrastructures has components that falls in one of these 3 categories:

• Devices
• Media
• Services

Even the smaller one has them all. Let's say: this very room!

(End) Devices

An (end) host device is a device that can be the source or the destination of a network communication.

End devices can be distinguished and reached on a network by their addresses

Examples?

Intermediary Devices

Intermediary devices carry the task to ensure data flows through the network to reach end devices, connecting them.

Network Access (switches, AP, hubs), Internetworking (routers), Security (firewalls) devices are all intermediary devices.

Functions of Intermediary Devices

• Regenerate and retransmit signals
• Maintain information about pathways
• Notify communication errors and failures
• Direct data along alternate pathways
• Classify and direct messages according to Quality of Service (QoS) priorities
• Permit or deny the flow of data, based on security settings

Network Media

The medium is the physical object that carries the signal from one point of the network to the other.

There are mostly 3 types of media:

• Metallic wires/cables
• Glass/Plastic fibers
• Wireless

Signal must be encoded in a way that is appropriate to each media.

How do you choose a media?

Different media have different features, PROs and CONs. The most common criteria for choosing a media are:

• Distance that can be covered by the media
• Environment in which the media will be operating.
• Amount of data and requires speed of tranmission.
• Costs, of media itself and its installation.

Networks by Geograophic Scale

A network can be characterized by its physical capacities (size of the area, number of users) and also by the services it provides. The most commond types based on this parameters are:

• LAN: Local Area Network
• WAN: Wide Area Network
• MAN: Metropolitan Area Network
• WLAN: Wireless Local Area Network
• SAN: Storage Area Network

LAN: Local Area Networks

It's a network that covers a relatively small, limited geographical area. LANs share these characteristics:

• Devices participating in a LAN are located in a self-containing area, like a home, school, building.
• They are administered by a single entity that controls access, features and policies in general.
• Almost every time they provide the fastest bandwidth to end and intermediare devices, when compared to other type of networks.

WAN: Wide Area Networks

The textbook definition is: a computer network spanning cities, regions, countries, or even the world.

WAN are more generally referred to as a set of technologies for trasmitting datas over long distances, between more localized types of networks. Typically LANs.

Another common (but not mandatory) feature of WANs: they're built using leased lines (often multiple kinds of them).

Either they're slower than LANs, or much more expensive for the same bandwidth.

Managed by single entities, they can be meant for the private use of a single organization or for end users of service providers

Networks by scope:

Intranet and Extranet

Intranet is defined as the ensemble of private connections of LANs and WANs belonging and only accessible to a single entity.

Extranets are also under a single administration, but supports connection and (limited) access from specific external networks.

Networks by scope: The Internet

The Internet is a network formed by a staggering amount of interconnected networks.

How do you make a network composed of billions of different devices, users and medium, work flawlessly? Standards.

No single entity, government, organization owns The Internet. But it all works because of consistent, internationally recognized and available technologies and protocols.

There are many organizazions that were purposefully created to maintain and produce these standards.

Connecting to the Internet: Users

• DSL: Internet over telephone lines.
• Cable: Internet over TV cable (not italian stuff, really).
• Cellular: Internet over cell towers.
• Satellite: Internet over parabolic dishes.
• Dial-up: Internet over 20 years ago.

Connecting to the Internet: Businesses

• Dedicated Leased Lines: This is my circuit. There are many circuits like this, but this one is mine.
• Metro Ethernet: Ethernet over Copper or Fiber, from 10 Mb/s to 10 Gb/s.
• DSL: like the one before, but symmetrical and/or high speed.
• Satellite: like the one for the regular user, but you can upload stuff in space.

Converged Networks

Telephone, television, radio, data, are all examples of communications that used to require a dedicated, separate network for each one of them.

Digital age and the ubiquity of the Internet is changing all that, making it possible to deliver everything over a single network.

Cisco calls this the Converging Network

Cisco's 4 basic network features

• Fault Tolerance
• Scalability
• Quality of Service (QoS)
• Security

#1: Fault Tolerance

Fault Tolerance is the ability to limit the impact of a failure in a network and to quickly recover from it.

Networks achieve this by having multiple paths on which communication can occur.

This is called redundancy. redundancy. redundancy.

#2: Scalability

Scalability is the ability of a network to grow in users, devices, traffic, etc without affecting performance levels.

The Internet could grow this much precisely because its architecture is scalable technically and politically.

The Internet is structured in Network Tiers (1+2+3), exchanging peering or transit traffic between them.

Scalability without standards would be just too painful to achieve.

#4: Security

Not just physical security but also information security.

Security is a matter of 3 basic requirements:

• Confidentiality: data, processes, resources can only be accessed by authorized users. Authentication and Encryption to the rescue.
• Integrity: It's about ensuring the data haven't been altered during transmission, either by accident or maliciously. Checksum and signatures can be involved in this process.
• Availability: data and resources must be accessible to the legitimate users when they need them. Denial of Service (DoS) attacks can damage you without even breaking into your network.

Network Trends for Businesses

• BYOD (Bring Your Own Device) means that you can use any device, with any ownership, in any IT organization.
• Cloud Computing refers to the offloading of computing resources and data storage, then delivered as a service over a network.
• Benefits: usable anywhere, rapid deployment, reduced costs, refocused resourced, new business models.
• 4 primary types of clouds: Public, Private, Custom, Hybrid
• Virtualization is running a virtual version of something on a computer, like an entire hardware platform, an operating system, a single device, storage or networks.

Network Trends for Home Users

• Smart home technology integrates computing capabilities into every-day machinery, interconnecting and automating them.
• Powerline Networking uses electrical wiring to transfer data on a network; works very similarly to DSL.
• Wireless Internet Service Providers sell Internet access through wireless technology. The connection to the provider's backbone requires the installation of an antenna.

End of Lesson