A Bit History of Internet/Chapter 3 : Internet Edge
Author/Editor: Loh Boon Pin/Lim Weng Kai/Lee Ming Yue/Lim Wai Chun/Lee Lih Horng
Internet Edge Introduction
What is internet edge? Internet edge is considered a edge of a network and look at the electronic components with what we are using including computers,personal digital assistants(PDAs),cellphones,smartphones,tablets ,and other devices that we use on our daily lives.The computers and other electronic devices that connected to the Internet are often known as end systems.The reason why they are called as end systems because they are situated at the edge of the Internet.
The end-to-end principle is a classic design principle of computer networking which states that application specific functions ought to reside in the end hosts of a network rather than in intermediary nodes, provided they can be implemented "completely and correctly" in the end hosts. First explicitly articulated in a 1981 conference paper by Saltzer, Reed, and Clark,it has inspired and informed many subsequent debates on the proper distribution of functions in the Internet and communication networks more generally.
The Internet's end systems include desktop computers(e.g.,desktop personal computers(PCs),Macs,and Linux boxes),servers(e.g.,Web and e-mail servers),and mobile computers(e.g.,portable computers,PDAs, and phones with wireless Internet connections). With the accelerating rate at which technology is advancing today, gaming consoles (such as PlayStation 2/3 and XBOX360)as well as digital cameras are all being connected to the Internet as end systems. They allow users to interact directly with the Internet to send and receive data.Other end systems are not accessed directly by users, but do facilitate Internet communications. This includes servers for data such as email and web pages. Users connect with such end systems through their own computers, which contact the server to access and transfer information.The end user always interacts with the end systems.The Internet’s end systems include some computers with which the end user does not interact.
End system are also referred as hosts as they host application programs such as a Web browser program.Hosts or end systems usually are further categorized into two groups which are clients and servers. For your information,clients tend to be desktop and mobile PCs, PDAs, and so on, whereas servers tend to be more powerful machines that store and distribute Web page, stream video, replay e-mail, and so on.
Advantages of intelligent at the edge
Nowadays, to have a better throughput performance, intelligence at the network's edge is needed. There are several advantages to show that the important of intelligence at network’s edge.
Since wireless controller is now becoming the bottleneck for throughput and security enforcement as throughput needs rise. By using the 11n access points, distributed intelligence allows more of the on-site data flow to be routed internally on the edge of the network without sending that data to the wireless controller and back. The ability of the "spokes" to communicate directly with one another along an optimal path is increases, even prioritizing more critical data while providing full security and mobility services.
Furthermore, remote troubleshooting and advanced self-healing are greatly facilitate by the access points that distribute intelligence throughout the network. During outages access points can also serve a bridging function to reduce latencies. Since security is as important to the organization as solid network coverage and availability, it is important to make sure that any distributed architecture has enough application awareness to be self-healing without dropping VoIP calls and that it is able to deliver the same firewall capabilities as hub-and-spoke to avoid compromising QoS. This helps maintain network services throughout outages, ensuring the organization and its assets continue to benefit from continued local QoS prioritization, authentication, security policies and direct routing as well as backhaul failover to 3G.
With distributed traffic management, a single controller can oversee up to eight times the number of access points. This frees up controllers to focus on large scale network and policy management as well as other services, resulting in a more efficient architecture. Access points with built-in sensors for security and troubleshooting can also eliminate extra installation and power costs that would come with a separate sensor network.
Furthermore, access edge switches are tasked with providing intelligence at the edges of your network. The modular design of these switches enables network administrators to first classify traffic, and then decide what action to take with that classified traffic. Traffic can be classified based on criteria such as: source/destination port, source/destination MAC address, Virtual Local Area Network (VLAN) ID, protocol, IP source/destination address, IP source/destination network, Type of Service (ToS)/Differentiated Services Code Point (DSCP), TCP/UDP source/destination port, or TCP flags.
Classifiers can also be associated with a QoS policy to allow per-port or per-flow traffic shaping. This lets classified traffic be shaped in 64 kbps increments based on individual users or applications. This is especially popular in university housing scenarios, where traffic shaping on a per-port basis allows differentiated service and/or better control of bandwidth requirements at the edge of the network.
Moreover, greater intelligence at the edge of the network can also make IT budgets go further, offering advantages in both capital and operational expenditures. Adding 802.11n access points to the network can be less expensive than adding more controllers, and can actually result in significant savings since access points with greater intelligence can reduce the number of controllers needed.
In short, the advantages of having intelligence at network edge is obviously important and greatly providing better throughput to user and clients without compromising security or quality of service and driving up cost.
Access network referred to the physical links that connect an end system to the first router (edge router). Local telco referred to the local wired telephone infrastructure provided by a local telephone provider such as Telekom Malaysia and Digi Service Center in Malaysia. Central Office (CO) is a building where the telco switch located and each residence or customer will link to its nearest telco switch.
Dial-up Internet access is set up when the PC is attached to a dial-up modem, which is in turn attached to the home’s analog phone line. Users dial an ISP’s phone number and make a traditional phone connection with the Internet Service Provider (ISP) modem. Dial-up internet access has two major drawbacks. It is very slow with a maximum rate of 56kbps. User can only choose either surf the Web or receive and make an ordinary phone call over the phone line at the same instant time.
Digital Subscriber Line (DSL) internet access is obtained from the wired local phone access (i.e., the local telco). A telephone call and an Internet connection can share the DSL link at the same time because the single DSL link is separated into 3 channels (high-speed downstream, medium-speed upstream, ordinary two-way telephone). DSL has two major advantages over dial-up internet access. It can transmit and receive data at much higher rates. Besides that, users can simultaneously talk on the phone and access the Internet.
Cable Internet access makes use the cable television company’s existing cable television infrastructure. It is known as hybrid fiber-coaxial (HFC) access network because both fiber and coaxial cable are used in this system. Cable internet access is a shared broadcast medium. Therefore the transmission rate will be lower when there are several users download a video file simultaneously.
Some local telcos provide high-speed Internet access over optical fibers which are known as Fiber-To-The-Home (FTTH)or Fiber-To-The-Premise (FTTP). Direct fiber is the simplest optical distribution network for one optical fiber link from the CO to each home so that user receives high bandwidth. Actually, each fiber leaving the central office is shared by many homes and it is split into individual customer-specific fibers when the fiber gets relatively close to the homes.
Ethernet is a local area network (LAN) used to connect an end system to the edge router in corporate and university campuses.
Wide-area wireless access
Wide-area wireless access networks enable users to roam internet on the beach, on a bus, or in your car. For such wide-area access, a base station is used over the cellular phone infrastructure within a few tens of kilometers.
WiFi is a wireless LAN access based on IEEE 802.11 technology which installed at everywhere such as universities, business office, cafés, airports, homes and even in airplanes. Wireless users must be within a few tens of meters of an access point that in turn is connected to the wired Internet.
WiMAX, also known as IEEE 802.16, operates independently of the cellular network and provides speeds of 5 to 10 Mbps or higher over distances of tens of kilometers.
Last mile evolution and problems
The 'last mile' refers to the final connection, reaching the user, which enables the user to actually connect their computer to the Internet. In the year 1989, the first commercial dial-up ISP, “The World” started their business in United States; at the time, the only means of internet access for the general public was dial-up, by telephone line. In the early 2000s, this was followed by ADSL internet connections, which allowed the users to surf the internet at a higher speed. FTTH is the latest internet connection service provided by local ISP to their network. What are the differences between dial-up connection, ADSL connection, FTTH and others type of internet connection currently available?
From the word “Dialup”, users know they need to dial a number to make an internet connection to the outside world. Modern dial-up modems normally transfer at 56Kbps unless the ISP use compression techniques to exceed 56Kbps speed limit. During the dial-up process, we can hear an "handshake" noise.The noise takes place to established connection and information exchange with the local remote server. Several problems occur in dial-up connection; phone line during dial-up connection for voice service would be disturbed; only a computer can connect to the internet by using dial-up connection per phone line; it has low speed internet connection compared to the new ADSL connection.
Asymmetric Digital Subscriber Line (ADSL) is a type of Digital Subscriber Line technology (DSL). The term “Asymmetric” in ADSL connection means the upload band and download band is unequal bandwidth. Normally ISP will allocate more bandwidth for the download band rather than the upload band because the clients usually browse web pages, download files, read email etc, which require the server to send data to their clients. ADSL or DSL has a connection speed ranging from 256Kbps to 20Mbps. ADSL also use the same infrastructure as dial-up connection. The unused bandwidth in the twin-pair copper wire phone line can be used simultaneously for transmission of data (internet) and voice or fax services at the same line. There are few problems associated with ADSL connection. Firstly, not every phone line is equipped for ADSL service and it maybe not be available for some rural areas. Secondly, it requires static IP address to send or receive data. This is the main problem that causes the run out of IPv4 address and the static IPs have high internet security risk. Finally, the ADSL has been replaced by optical fiber connection to counter the limitation of the ADSL bandwidth.
Fiber to the Home (FTTH)has become popular in the city area in which it provide high speed internet access, IPTV and phone call services. Some ISP companies in Hong Kong, US and South Korea provide 1Gbps Internet connection to their network. FTTH connections are using optical fiber to replace the usual metal local loop used for the last mile telecommunications. FTTH lets their users experience same upload and download bandwidths. This means the FTTH internet connection is good for certain network applications especially P2P type file sharing. Until now, optical fiber connection still is the fastest internet connection between point-to-points. Unless scientists discover a new technology that can defeat the speed of the light.
3G & Wimax 4G
3rd generation mobile telecommunication (3G) is a mobile telecommunication services that fulfill the International Mobile Telecommunication-2000 (IMT-2000) standard. 3G and 4G Wimax are the evolution of 2G GSM network. Below are few examples of 2G networks until 4G networks:
2G- Fully digital 2G networks replaced 1G (analog) in the 1980s.
2.5G- known as General Packet Radio Service (GPRS),used for data transfer. Data transfer speeds up to 114Kbps
2.75G- known as Enhanced Data GSM Environment (EDGE), used for data transfer such as pictures sharing or browse internet. Data transfer speeds up to 384Kbps.
3G – speeds up to 2Mbps for stationary or walking users and 384kbps in moving vehicle. Provide better security than 2G network. Used for mobile TV, Videoconferencing and Video on demand.
3.5G – known as High Speed Downlink Packet Access (HSDPA), evolution for mobile telephone data transmission. Speed up to 7.2Mbps.
4G – known as Worldwide Interoperability for Microwave Access (Wimax). Offers speeds of up to 75Mbps, but in reality the speed needs to be split among the users.
The biggest problem that occurs in the wireless channel is that the bandwidth needs to be shared among the users, leading to competition for bandwidth as a scarce resource. More simultaneous users lead to smaller shares of the bandwidth pie for all, and thus poorer service. Local ISPs usually attempt to contain the problem with fair usage policies; these set (and thereby cap) a quota of data usage for each user. Such measures are unpopular, and some ISPs are trying to provide (and advertise) solutions without such capping.
Conclusion/Summary of Internet Edge
Internet edge is considered as an edge of a network. Desktop computers, servers, and mobile computers are included as the Internet’s end systems because they are at the edge of a network. End systems run (host) application programs such as Web browser program, therefore they are also referred to as hosts. Hosts are divided into two categories which are clients and servers. The client-server model of Internet application is a distributed application because client program running on one end system (one computer) and server program running on another end system (another computer). Client components initiate requests for services, which provided by server components to one or many clients.
There are several advantages of intelligence at network’s edge. By using the 11n access points, the ability of on-site data flow is increased and prioritizing more critical data while providing full security and mobility services. Moreover, the access points also greatly facilitate remote troubleshooting and advanced self-healing. During outages, it can also serve a bridging function to reduce latencies. Furthermore, access edge switches are designed to enable network administrators to classify traffic first, and then decide what action to take with that classified traffic. Classified traffic is shaped in 64 kbps increments based on individual users or applications. This traffic shaping on a per-port basis allows differentiated service and/or better control of bandwidth requirements at the edge of the network. Additionally, it is less expensive by adding 802.11n access points to the network than adding more controllers and access points with greater intelligence can reduce the number of controllers needed. In short, intelligence at network edge is greatly providing better throughput to user and clients without compromising security or quality of service and driving up cost.
Access network referred to the physical links that connect an end system to the first router (edge router). Local telco referred to the local wired telephone infrastructure provided by a local telephone provider. Central Office (CO) is a building where the telco switch located and each residence or customer will link to its nearest telco switch. There are some ways to share the access network such as dial-up which is using the phone line to connect network, DSL which obtained from the wired local phone access, cable which is using both fiber and coaxial cable, FTTH which is provided high-speed internet access over optical distribution and Ethernet which is LAN used to connect an end system to the edge router. Besides that, other ways also enable to access the network like WiFi which is a wireless LAN access based on IEEE 802.11 technology, Wide-area wireless access networks which is enable users to roam internet in outdoor and WiMAX which operates independently of the cellular network in higher speed or distances.
In dialup connection, phone line for voice service can be disturbed; only one computer can connect to the internet by using per phone line; the internet connection speed is low compared to ADSL connection. For ADSL connection, not every phone line is equipped for ADSL service, it maybe not available for some rural area and it required static IP address to send or receive data. While users experience same upload and download bandwidths with FTTH. It is the fastest internet connection between point-to-point using optical fiber. Problem for wireless channel is the bandwidth need to be shared among the users. The speed is low when more users use the network at the same time. References： 1)"PUSHING INTELLIGENCE TO THE EDG"E Dec 1, 2005 12:00 PM, By James Gompers；"LIVING AT THE EDGE" BY M. THIYAGARAJAN; "INTELLIGENCE AT THE EDGE" BY ALLIED TELESYN. 2)James F. Kurose and Keith W. Ross, "Computer Network:A Top-Down Approach,"1.2The Internet edge,5th ed.,2009,pp 9-12.