Network Connectivity and Mobility Part 2 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 From last time Communication channel Network medium, signal, transmission Data transfer rate (bit rate) Bandwidth versus throughput Shared versus dedicated Public versus private Client / server architecture Network providers Internet versus WWW From last time Five elements creating a connected world Questions from last time Who sets standards? LAN versus WAN Relationships between different types of providers Clarify broadband Who develops networking standards? IEEE (Institute of Electrical and Electronics Engineers) EIA (Electronic Industries Alliance / Association) TIA (Telecommunications Industry Association) ANSI (American National Standards Institute) 1
LAN versus WAN LAN and WAN are generic, universal terms Networks are hierarchical in nature LAN versus WAN LANs designed to span relatively small geographic areas Typically rely on shared media Different devices attached to network must coordinate use of the network WANs designed to span large geographic areas Utilize different technologies, protocols, and standards than LANs LAN versus WAN Create a WiFi network in your apartment Can scale up by adding functionality and services At some point, the networking technologies you are using must change how much traffic is being carried? Distance covered? Right-of-way? LAN versus WAN LANs are typically privately owned networks WANs connect smaller networks and can use a variety of service providers such as telecom, cable TV, satellites, national providers Network Devices 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 Providers Point where physical communication facilities owned by one organization connect to or interface with another organization 2
Providers Broadband? Two definitions Your service provider refers to internet broadband as a fast connection to the internet that is always on and supports multiple services (TV, phone, internet) over a single medium The medium can be coaxial, fiber, twisted pair, radio Technically, broadband signaling supports a wide range or band of frequencies The wider or broader the bandwidth, the more information can be carried Broadband? Today Five elements creating a connected world Today 1. Network Access Technologies Focus on LAN access 2. Network Standards and Protocols Focus on TCP/IP protocol stack 3. Network Convergence 3
Network Access Technology Simply stated which technology or group of technologies are used to gain access to or connect to a particular network? Network technology - a standards-based combination of hardware, software, and protocols Network Access Technology There are MANY different networking technologies different for both for LANs and WANs Ethernet WiFi Asynchronous Transfer Mode (ATM) The following IEEE 802.11 standards exist or are in development to support the creation of technologies for wireless local area networking: 802.11a - 54 Mbps standard, 5 GHz signaling (ratified 1999) 802.11b - 11 Mbps standard, 2.4 GHz signaling (1999) 802.11c - operation of bridge connections (moved to 802.1D) 802.11d - worldwide compliance with regulations for use of wireless signal spectrum (2001) 802.11e - Quality of Service (QoS) support (not yet ratified) 802.11F - Inter-Access Point Protocol recommendation for communication between access points to support roaming clients (2003) 802.11g - 54 Mbps standard, 2.4 GHz signaling (2003) 802.11h - enhanced version of 802.11a to support European regulatory requirements (2003) 802.11i - security improvements for the 802.11 family (2004) 802.11j - enhancements to 5 GHz signaling to support Japan regulatory requirements (2004) 802.11k - WLAN system management 802.11l - skipped to avoid confusion with 802.11i 802.11m - maintenance of 802.11 family documentation 802.11n - 100+ Mbps standard improvements over 802.11g (2009) 802.11o - skipped 802.11p - Wireless Access for the Vehicular Environment 802.11q - skipped 802.11r - fast roaming support via Basic Service Set transitions 802.11s - ESS mesh networking for access points 802.11T - Wireless Performance Prediction - recommendation for testing standards and metrics 802.11u - internetworking with 3G / cellular and other forms of external networks 802.11v - wireless network management / device configuration 802.11w - Protected Management Frames security enhancement 802.11x - skipped (generic name for the 802.11 family) 802.11y - Contention Based Protocol for interference avoidance Network Access Technology The network access technology is directly tied to the media and type/level of network provider Phone network? Cable TV network? Data network Not nearly as big a difference now as it was 10 years ago Networking Technology Ethernet is the most popular and widely used wired LAN networking technology There are many different Ethernet standards that use different media (different types of cabling), different topologies and support different data transfer rates 4
Networking Technology WiFi is a commonly used wireless technology used on LANs that provides relatively high-speed, but short range connectivity Networking Technology What is the difference between WiFi and the general term wireless? Networking Technology Is Bluetooth an access technology? Source: http://retailtechnologytrends.com/2010/11/05/2010-45-whats-the-difference-between-wifi-and-wireless/ Network Access Technologies Corporate connectivity options 1) Point-to-point leased lines 2) Public Telephone Network (PSTN) 3) Home connectivity options 1) Dialup modem 2) DSL modem 3) Cable modem How does WiFi fit in? 5
Relies on public / shared network service but provides users with increased security and private access to their organization s network Idea is to leverage the low cost of a public / shared network (i.e. the internet) with the security of a private network Security using shared leased lines at a fraction of the cost of a private, dedicated line Accomplished by installing VPN client-side software and having client computers connect directly to the VPN server on the organization s home network Uses special tunneling protocols to encrypt data at the sending end and decrypt the data at the receiving end Essentially masks or hides the private information VPN requires special software for each user and at the home network site Allows only secure communication between remote host and VPN server protects from unauthorized access Users connect through via dialup or another access method User establishes connection with her organization s Network Access Server using VPN client-side software and provides A/A credentials Uses tunneling protocols (such as PPTP, L2TP) to encapsulate data before sent across network What is a frame / packet? Networking Layers OSI Model TCP/IP Model Application = layer 7 Presentation = layer 6 Session = layer 5 Transport = layer 4 Network = layer 3 Data link = layer 2 Application = layer 4 Transport = layer 3 Internet = layer 2 Link = layer 1 Physical = layer 1 6
Protocol Interaction What is a frame / packet? Secure connection established over the internet via a protocol like PPTP Connection established between remote host and NAS / VPN server Data are encapsulated Great!! low cost + secure why wouldn t you do this? Design and implementation is complex Reliability can be an issue and depends on the network service provider It is expensive As you scale up, compatibility issues may arise Security issues if wireless is employed Mini Summary Network access technologies Ethernet WiFi VPN Packets Network layers Encapsulation 7
Network Protocols Data Networks have Rules for how data packets are built, tracked, managed, directed, moved and more.. These rules are called protocols Network Protocols Computers use MANY protocols even during simple data exchanges Protocols enable communication between Different computers Different hardware within the computer Different software within the computer Hardware and software within the computer Protocols specify how communication occurs and the form it takes Network Protocols IP and TCP UDP vs. TCP SSL and HTTPS? Network Protocols Transmission control protocol/internet protocol (TCP/IP) - provides the technical foundation for the internet as well as for large numbers of private networks TCP/IP referred to as the Internet Protocol Stack There are many more protocols that comprise the TCP/IP stack these two are the foundational protocols All protocols have different jobs TCP/IP on Your Computer What does IP do? Figure CE10-4 Copyright 2010 Pearson Education, Inc. Publishing as Prentice Hall CE10-47 Provides a generic address understood by all devices on the Internet Independent of specific networking technologies Routes all IP datagrams independently No guarantee that packets will travel on same route to destination Allows for fragmentation and reassembly of datagrams Can subdivide datagrams to fit in any frame payload 8
What does TCP do? Provides reliable service Address out of order delivery Address packet loss Adjust routing based on network conditions (congestion control) Adjust how many packets are sent in a given time period (flow control) Establish an explicit connection between sender and receiver Address corrupt data TCP vs. UDP http://www.diffen.com/difference/tcp_vs_udp What does HTTP do? Hyper Text Transfer Protocol (HTTP) The de facto set of rules for transferring all files (text, image, video, graphics, etc.) on the Web When using a browser, you indirectly begin using HTTP as part of the TCP/IP suite What does HTTP do? By default, when you connect to a website, your browser looks up the IP address associated with that website and automatically assumes that you are connected to the correct web server All data transfer is unencrypted clear text You would never want to transmit sensitive information using HTTP What does HTTPS do? Hyper Text Transfer Protocol Secure What does HTTPS do? When connecting to an HTTPS-enabled server, your clear text HTTP request will automatically be redirected to HTTPS Your browser checks the security certificate of the remote website and verifies that the certificate is legitimate Your bank s HTTPS-enabled web server sends information to your computer that verifies that you are indeed connected to the web server that you want to connect to 9
What does HTTPS do? Then uses one of two encryption protocols Secure Socket Layer (SSL) is the most widely used What does SSL do? Encryption protocol widely used for webbased (browser) communication SSL certificate is basically a small piece of code that provides security through encryption Strength of encryption depends on browser, web server, client OS Security mini summary SSL Certificate - An electronic document that confirms the identity of a website or server and verifies that a public key belongs to a trustworthy individual or company Secure hypertext transfer protocol (SHTTP or HTTPS) - A combination of HTTP and SSL to provide encryption and secure identification of an Internet server Network Convergence The movement toward the combination of different services such as voice, video, and data on a single network infrastructure One physical network handles multiple services instead of voice over telephone networks and data over data networks Why are we even bringing this up? Network Convergence Problem: different physical networks utilize different networking technologies The individual technologies are not designed to communicate with one another Different technologies are better for certain types of services TCP/IP allows heterogeneous or different types of networks to communicate 10
Network Convergence Network Convergence Network infrastructure is not free and is mostly owned by private organizations Networking infrastructure is expensive and organizations do not casually build new networks explicitly for the good of humanity Make a profit or at least recover costs But this means that some people can t afford access Network convergence - The efficient coexistence of telephone, video, and data communication within a single network, offering convenience and flexibility not possible with separate infrastructures Net Neutrality? General assumption that you can share and access information of your choosing without interference Example of what would constitute interference? A network provider (i.e. Sprint, AT&T, Comcast, Verizon, Burlington Telecom, etc.) speeds up or slows down (or even blocks) data transmission rate associated with certain content, applications, or websites Net Neutrality? ISPs Must be transparent about how they handle congestion Prohibited from blocking streaming applications / services such as Skype and Netflix on wired networks Outlaws unreasonable discrimination such as migrating these services to reduced bandwidth channels Net Neutrality? Who cares? Example streaming video and music consumes a lot of available bandwidth on the provider s physical network (fact) Maybe the provider should charge companies like Netflix a premium to carry their data? How large a premium? Maybe the provider should reduce the transmission speed for all Netflix data so that your service suffers until Netflix pays up Net Neutrality? Internet currently operates under net neutrality to a large degree There are priority applications and data Net Neutrality does not apply to private networks! Administration of private networks can generally engage in whatever types of traffic shaping they deem appropriate 11
Digital divide? Gap between those that have access to information and modern communications technologies and those who don t With respect to internet connectivity, typically used to describe broadband services Dialup is not considered a broadband technology Digital divide? Urban versus rural Educated versus uneducated Wealthy versus poor Developed versus undeveloped Summary 1. Network Access Technologies Focus on LAN access 2. Network Standards and Protocols Focus on TCP/IP protocol stack HTTP, HTTPS, SSL 3. Network Convergence 12