Network Connectivity and Mobility BSAD 141 Dave Novak Topics Covered Lecture is structured based on the five elements of creating a connected world from the text book (with additional content) 1. Network Categories 2. Network Providers 3. Network Access Technologies 4. Network Standards and Protocols 5. Network Convergence A Connected World Five elements creating a connected world Communication Network Business perspective sharing information between people within and outside an organization How is this information managed? What is shared and how? Security? Information accuracy and integrity? Timeliness? Network Services File and print services Allow sharing of data files and printers Communications services Such as mail services Coordination and storage of email Internet services WWW, FTP, some security Access services Allow remote users to connect to network Login (authorization / authentication) Network Management Services Traffic monitoring, load balancing, diagnostics Communication Network Information sharing depends on a combination of networking technologies, protocols, and standards Be familiar with common networking terminology 1
Terminology to know Communication channel Network medium Signal Transmission Data transfer rate (bit rate) Bandwidth versus throughput Shared versus dedicated Public versus private Terminology Communication channel any pathway over which data are transmitted Can be a physical wire, radio wave, or any radiated source of energy (even if it has no physical presence) Transmitted information has a source (sender) and a destination (receiver) Terminology Data some entity that has meaning or conveys some type of information Signal an electromagnetic representation of data Transmission moving data from source to destination through the use of signals How do Computers Communicate? At a very basic level computers use binary digits (bits) to represent information Bits are transmitted over some medium Electrical current over copper cable Pulses of light over fiber optic cable Bit rate or data transfer rate number bits transmitted per sec Background Electromagnetic radiation is the basis for all data transmission Electromagnetic radiation propagates (moves, spreads, disseminates) along different media (copper wire, fiber, etc.) and in free space (air) in different ways Background Different parts of the electromagnetic frequency spectrum can be used for data transmission Specifics depend on medium used and communications standards followed Specific standards/media properties affect: Bandwidth Attenuation Noise Distortion 2
Terminology The network medium is the physical channel used to transmit data across a network Copper wires, fiber optics, radio waves Communication Networks and Road Networks Communications medium is a highway Cars are the packets of data traveling along the highway So the wider the road, the more cars can travel on it (greater bandwidth) the maximum capacity of the highway Latency is how long it takes to get from Point A to Point B (including stops, traffic and rerouting ) Throughput is how many cars actually go from Point A to Point B in a given amount of time Protocols - Rules Transportation Network has: Motor Vehicle Rules Lights, windshield, steering wheel on left side, safety belts.. Road Rules Width, Yellow line, white line, paved, bumps, incline Sign Rules Reflection, Color, Size, Position Driving Rules Speed limit, right side of the road, blinker.. Vehicle Specific Rules Motorcycles, Big Rigs, Armored Vehicles, Wide Loads, Passenger Vans Protocols - Rules Data Networks have Rules for how data packets are built, tracked, managed, directed, moved and more.. These rules are called protocols Network Terminology When a provider uses the term broadband what do they mean? 3
Broadband Broadband systems transmit multiple signals over many different channels simultaneously Each channel uses a different frequency band to transmit Cable TV uses broadband signaling Broadband Carry multiple signals on a single medium at one time Medium split into multiple channels Different signals are multiplexed, or combined in different ways and then transmitted Network Standards and Protocols Protocol - a formal set of steps and rules that specifies the format of data as well as the rules to be followed during transmission (TCP, IP, HTTP, DHCP, ) Standard agreed upon sets of guidelines and definitions to allow different products and services from different manufacturers to work together (ANSI SQL, IEEE 802.3, ) Network Categories 1) LAN (local area network): a group of computers sharing a common media usually in a small geographic area such as a building 2) MAN (metropolitan area network): network larger than a LAN connects computers over a larger geographic area 3) WAN (wide area network): largest network that connects various LANs and MANs throughout the world Differences LANs utilize high-speed, lower-cost shared networking technologies such as Ethernet and WiFi MANs connect a group of LANs to various network providers such cable TV providers, local ISPs, telecom providers WANs utilize very different networking technologies than LANs point-to-point, higher-cost technologies that function across large geographic areas 4
Differences LAN WAN Networking Layers Data transfer rate High speed( 1000 mbps) Lower speed ( 155 mbps) OSI Model TCP/IP Model Network technology Components Fault tolerance Ownership Tend to primarily use technologies that are easy to set up and designed to operate over short distances such as Ethernet and WiFi Generally consist of layer 2 devices like switches, bridges. To a lesser extent layer1 devices like hubs & repeaters LANs tend to have fewer problems associated with them, as there are a smaller number of systems to deal with. Typically owned, controlled, and managed by a single organization WANs tend to use more advanced technologies designed to operate over large distances such as MPLS, ATM, Frame Relay & X.25 Layer 3 (+) devices such as routers, multi-layer switches and technology specific devices like ATM or Frame-relay Switches etc. WANs tend to be less fault tolerant. as they consist of a many different systems managed by different organizations. There is a lower amount of fault tolerance. WANs are typically not owned by any one organization but exist under collective or distributed ownership and management over long distances Application = layer 7 Presentation = layer 6 Session = layer 5 Transport = layer 4 Network = layer 3 Data link = layer 2 Physical = layer 1 Application = layer 4 Transport = layer 3 Internet = layer 2 Link = layer 1 Costs Low High Networking Layers Protocol Stack A universal framework for guide and describe communication on ALL networks Defines relationships between various protocols, the specific services provided by the different protocols, and the layers where each of the protocols operate The collection of networking protocols that operate at the various layers are referred to as a protocol stack Protocols running on a networked computer work together to provide all services required by a particular application Services provided by the protocols are not redundant if a protocol at one layer provides a particular service, the protocols at the other layers do not provide the same service Protocol Interaction LAN LANs are categorized as smaller networks that used a shared medium to connect computers, printers, and other network devices Physical LANs are constrained geographically to small areas Buildings or floors of buildings This is a function of the type of networking technologies used 5
Shared medium on a LAN LANs typically rely on shared media Different devices attached to network must coordinate use of the network Coordination requires communication Communication requires time Time increases as distance between computers grows Shared media with long delay is inefficient Spend more time coordinating actions than sending data Shared versus Dedicated? Shared media / channel capacity is used jointly by multiple users or applications as needed Envision a typical toll road on a highway Dedicated media / channel capacity is used exclusively by a single user or application Envision a toll road where users pay to reserve their own lane and no one else can use that lane while occupied Public versus Private? Public users pay fees to use a shared network medium Often a pay-as-you-go approach Parts of the physical infrastructure network are available to the general public for sharing Private users pay fees to obtain a dedicated portion of the network Often a flat fee approach Parts of the physical infrastructure network are dedicated just for the private user LAN Computers and other devices such as printers connect to the LAN via switches and/or wireless access points Switches manage communication between different devices on a single LAN LANs connect to other larger networks (like MANs and WANs) via routers Routers manage communication between different networks (or LANs) WAN WANs are generally categorized as large networks that connect other LANs and MANs and operate across large geographical areas Groups of buildings, Cities or municipalities, regions of a country WAN WANs use different networking technologies and protocols than LANs specifically technologies that operate over large areas Messages that traverse a WAN are passed from one router to another Routing involves selecting the best path through a network 6
LAN WAN Differences Communication between the devices that belong to the same wired or wireless network or LAN does not require the use of a router Communication between devices on different networks (to another LAN), to WAN, or to the internet requires the use of a router Traffic cannot come into or leave the LAN unless some type of router is used to provide a communication gateway to another network Client / Server (CS) Distinguishes between client / server devices and applications Clients request specific services Servers respond to individual client requests for services Functionality implemented in software Client/Server (CS) Structured architecture with specific roles for devices using specific applications File server, printer server A managed network Typically has some type of administration CS is the most commonly observed architecture Most applications are designed to be used on CS architecture The internet used a CS architecture The Internet A global WAN connecting millions of individual computers and networks Allows different networks (LANs, MANs, WANs) that use different networking technologies to communicate as if they were operating on a single network Uses a client-server architecture 7
Universal Networking Concept the Internet Users perceive a seamless network Functions as though using all same technologies The Internet No one owns the Internet (per se) Different groups, organizations, or individuals may own or manage different physical infrastructure networks that are connected to, or comprise, the internet In reality: Many different, unrelated physical networks and technologies The Internet World Wide Web (WWW) WWW is NOT the same thing as the Internet Connect to the Web via a graphical browser such as IE, Safari, or Chrome Web browsers open a Uniform Resource Locator (URL) URL provides information about the location of things on the Web For example http://www.bsad.uvm.edu The internet is a global WAN that supports all types of different technologies Network Providers National service providers (NSPs) - Private companies that own and maintain the worldwide backbone that supports the Internet Backbone Regional service providers (RSPs) - Offer Internet service by connecting to NSPs, but they also can connect directly to each other Backhaul Internet service providers (RSPs) Residential and Commercial endpoint providers; the edge of the network Last Mile Network Providers Backbone large network medium or transmission lines that carry aggregated data from smaller lines that connect to it Backhaul intermediate transmission lines between ISP and NSP Last Mile refers to final or local transmission lines that directly connect end-users (you and me) to larger regional and national networks Network Providers Last Mile Backhaul Last Mile 8
Summary Terminology Network Categories: LAN, MAN, WAN Network Providers: NSP, RSP, ISP 9