WEEKS 9_ internet infrastructure

(1) INTERNET INFRASTRUKTUR

With the growth of the Internet for personal use (e.g. Facebook, Amazon, Google, Gmail) and business purposes (i.e. file storage, web applications, collaboration and communication, VOIP) I thought it would be useful to talk about what actually powers all these things.

What mean by ‘Internet Infrastructure’. All the hardware and services required to make this web page appear in your browser, or an RSS feed download into your reader, or VOIP calls / emails get to your desktop. All the underlying technologies that are unseen, but ‘make the Internet go’.

Internet Infrastructure consisting of a ‘Top 5′ areas:

• Data Centres
• Network Connectivity
• Computer Equipment
• Storage Services
• Server Applications

Data Centre
The Data Centre is the home for Internet Infrastructure. It is the central point of aggregation and distribution of data and network services. These facilities tend to include:

Ø 24 x 7 Staffed Operations Centre (typically called a NOC, the staff monitor all activities of the Data Centre and ensure smooth operation as well as deal with equipment issues).

Ø Building Management System (the BMS normally monitors and alerts on temperature zones, power and cooling usage, outside temp., access control and CCTV).

Ø Secure Access Controls (i.e. biometrics on all entry and DC floor doors). Fire Alarm and Suppression (i.e. VESDA for detection and Inergen gas for suppression)

Network

Possibly to most important foundation block of Internet Infrastructure is the Network. Without a network connection no data can pass between Data Centres, over the Internet, and ultimately onto your Desktop, Laptop or Mobile Handset.

For the purpose of this post, let’s talk about the network infrastructure in a Data Centre, where data passed in to computer equipment, is processed and/or stored, and passed back out of the DC.

So you would expect at least N+1 network connectivity into a Data Centre in the form of at least 2 Fibre Cables from telecommunications providers on diverse rings.

Therefore if one had service cut, the Data Centre’s network connection would not be affected. Some data centres (Hosting365′s is one) are Carrier Neutral – which means a number of carriers have a Point-Of-Presence in the facility, so the Data Centre is not affected by any commercial or technical issues of a single carrier.

Computer Equipment

Now that the two basics of Internet Infrastructure are in place – the ability to power your equipment and the ability to connect it to the Internet, the next thing is the computer hardware that uses this to process and store the applications and data.

By computer equipment, for this basic post, I really mean Servers. A Server is a more complex and high-end version of a desktop PC.

An average server might consist of 2 power supplies (for redundancy), 8-12 RAM slots, anything from 2-10 hard drive bays and multiple processors (not just multi-core!).

Servers are housed in Racks in a DC which are typically 42u in height. (1U is 1-unit and a low-end server takes up just 1 of these units, other servers scale within these racks to multiple ‘U’).

Racks are normally powered by 2 PDU (Power Distribution Units) which connect to (if available) multiple power supply units in the server.

The unit of measure for Servers is Processor Power and RAM. Although there is a lot more to selecting a server such as expandability, reliability, network ports, BUS speed, Cache size and speed.

Personally I would like the unit of measure in Servers to change, I think for buyers and users it should be rated in ‘MIPS’ – which is ‘Millions of Instructions Per Second’ which is effectively all that matters, and how today’s Mainframe computers (IBM BlueGene is a high end Mainframe) are measured.

Storage Services

Data Storage is a huge part of Internet Infrastructure. All those emails accessible online, all the web pages on your favourite web site, all those photos on Facebook … are all stored on a hard drive in a DC somewhere.

The basic level of storage is on-server storage, which means the hard drives in the computer server.

This can cause not just performance and capacity issues, but also redundancy ones – local storage is inherently as prone to failure as the server it is in.

A Storage Area Network may be shared among many services, applications, servers and customers.

Server Applications

The final piece of underlying Internet Infrastructure is the server applications themselves. In order for an web application to be delivered from a server, that server requires an Operation System (typically Windows or Linux), a Web Server application (like Apache or Microsoft IIS), and a Database (such as MySQL, MS-SQL or Oracle).

There any many more variations here, but the basic web server has these 3 things. From here you can install blog software, an ecommerce site, your new web 2.0 application, or any Internet capable piece of software (more include – Instant Messaging Server, File Storage Server, Message Board)

More complex applications tend to have dedicated servers, or pools or servers, for specific things – like a cluster of Database Servers, or a pool of Web Server to serve those ‘www.’ page requests. 

   HIERARCHY OF NETWORKS :

1     From a single computer to LAN

2.            From LAN to ISP ( Internet Service Provider)

3.           From ISP to WWW. .... ( worldwide)

Connect yourself:

§  Computer

§  Web browser

§  Internet access

(2) INTERNET PROTOCOL

The Internet Protocol (IP) is the principal communications protocol used for relaying datagram’s (also known as network packets) across an internetwork using the Internet Protocol Suite.

Responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet.

IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering datagram’s from the source host to the destination host solely based on the addresses.

For this purpose, IP defines datagram structures that encapsulate the data to be delivered. It also defines addressing methods that are used to label the datagram source and destination.

Historically, IP was the connectionless datagram service in the original Transmission Control Program introduced by Vint Cerf and Bob Kahn in 1974, the other being the connection-oriented Transmission Control Protocol (TCP). The Internet Protocol Suite is therefore often referred to as TCP/IP.

The first major version of IP, Internet Protocol Version 4 (IPv4), is the dominant protocol of the internet. Its successor is Internet Protocol Version 6 (IPv6), which is increasing in use.

IP CONSISTS 2 PART : 

• Identifying the node /host
• Identifying network

The four numbers in an IP address are used in different ways to identify a particular network and a host on that network.:

Class A Network
~ binary address start with 0
~ no. can be anywhere from 1-126
~ first octet is the identify network
~ eg : 108.187.212.206

Class B Network

~ binary address start with 10
~ no. can be anywhere from 128-191
~ first two octets is the identify network
~ 127 is reserved for loopback
~ eg : 187.202.226.212

Class C Network

~ binary address start with 110
~ no. can be anywhere from 129-223
~ first three octets is the identify network
~ eg : 212.167.203.224

Class D Network

~ binary address start with 1110
~ no. can be anywhere from 224-239
~ used to support multicasting

Class E Network
~ binary address start with 1111
~ no. can be anywhere from 240-255
~ used for experiment and never been documented

 

IAPS

Short for Internet Access Provider, a company that provides access to the Internet. IAPs generally provide dial-up access through a modem and PPP connection, though companies that offer Internet access with other devices, such as cable modems or wireless connections, could also be considered IAPs.

The terms IAPs and ISP (Internet Service Providers) are often used interchangeably, though some people consider IAPs to be a subset of ISPs.      

 Whereas IAPs offer only Internet access, ISPs may provide additional services, such as leased lines (T-1 or T-3) and Web development.   

(3) Gateway (telecommunications)

Juniper SRX210 service gateway

In telecommunications, the term gateway has the following meaning:

In a communications network, a network node equipped for interfacing with another network that uses different protocols.

A gateway may contain devices such as protocol translators, impedance matching devices, rate converters, fault isolators, or signal translators as necessary to provide system interoperability. It also requires the establishment of mutually acceptable administrative procedures between both networks.

Gateways, also called protocol converters, can operate at any network layer. The activities of a gateway are more complex than that of the router or switch as it communicates using more than one protocol.

1.       Internet-to-Orbit Gateway 2.      Cloud Gateway 3.       See also 4.      Sources 5.      References 6.     External links

(4) Domain Name System

The Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network

A Domain Name Service resolves queries for these names into IP addresses for the purpose of locating computer services and devices worldwide

An often-used analogy to explain the Domain Name System is that it serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses.

For example, the domain name www.example.com translates to the addresses 192.0.43.10 (IPv4) and 2620:0:2d0:200:: 10 (IPv6). Unlike a phone book, however, DNS can be quickly updated and these updates distributed, allowing a service's location on the network to change without affecting the end users, who continue to use the same hostname.

 Users take advantage of this when they recite meaningful Uniform Resource Locators (URLs) and e-mail addresses without having to know how the computer actually locates the services.

The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain.

Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains. This mechanism has made the DNS distributed and fault tolerant and has helped avoid the need for a single central register to be continually consulted and updated.

Additionally, the responsibility for maintaining and updating the master record for the domains is spread among many domain name registrars, who compete for the end-user's, domain-owner's, business. Domains can be moved from registrar to registrar at any time.

The Domain Name System also specifies the technical functionality of this database service. It defines the DNS protocol, a detailed specification of the data structures and communication.

(5) INTERNET SERVICE PROVIDER

An Internet service provider (ISP) is an organization that provides access to the Internet.

Internet service providers can be either community-owned and non-profit, or privately owned and for-profit.

Access ISPs directly connect clients to the Internet using copper wires, wireless or fiber-optic connections. Hosting ISPs lease server space for smaller businesses and other people (collocation). Transit ISPs provide large amounts of bandwidth for connecting hosting ISPs to access ISPs.

Internet connectivity options from end-user to Tier 3/2 ISPs

Classification

ACCESS PROVIDERS

ISPs employ a range of technologies to enable consumers to connect to their network.

For users and small businesses, traditional options include: dial-up, DSL (typically Asymmetric Digital Subscriber Line, ADSL), broadband wireless, cable modem, fiber to the premises (FTTH), and Integrated Services Digital Network (ISDN) (typically basic rate interface).

For customers with more demanding requirements, such as medium-to-large businesses, or other ISPs, DSL (often Single-Pair High-speed Digital Subscriber Line or ADSL), Ethernet, Metropolitan Ethernet, Gigabit Ethernet, Frame Relay, ISDN (B.R.I. or P.R.I.), ATM (Asynchronous Transfer Mode) and upload satellite Internet access. Sync-optical cabling (SONET) are more likely to be used.

HOSTING ISPS

Hosting ISPs routinely provide email, FTP, and web-hosting services. Other services include virtual machines, clouds, or entire physical servers where customers can run their own custom software.

Transit ISPs

Just as their customers pay them for Internet access, ISPs themselves pay upstream ISPs for Internet access. An upstream ISP usually has a larger network than the contracting ISP and/or is able to provide the contracting ISP with access to parts of the Internet the contracting ISP by itself has no access to.

In the simplest case, a single connection is established to an upstream ISP and is used to transmit data to or from areas of the Internet beyond the home network; this mode of interconnection is often cascaded multiple times until reaching a Tier 1 carrier. In reality, the situation is often more complex.

ISPs with more than one point of presence (PoP) may have separate connections to an upstream ISP at multiple PoPs, or they may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence.

VIRTUAL ISPS

A Virtual ISP (VISP) is an operation which purchases services from another ISP (sometimes called a "wholesale ISP" in this context)^[4] which allow the VISP's customers to access the Internet using services and infrastructure owned and operated by the wholesale ISP.

Free ISPs

Free ISPs are Internet Service Providers (ISPs) which provide service free of charge. Many free ISPs display advertisements while the user is connected; like commercial television, in a sense they are selling the users' attention to the advertiser. Other free ISPs, often called freenets, are run on a nonprofit basis, usually with volunteer staff. 

(6)HTTP

HTTP (HyperText Transfer Protocol) adalah protokol digunakan untuk memindahkan dokumen dalam World Wide Web (WWW).Protokol ini adalah berbentuk protokol yang ringan, tidak berstatus dan ianya umum yang boleh digunakan dengan berbagai macam jenis dokumen.

Perkembangan Http dikordinasikan oleh Konsortium World Wide Web (W3C) dan Pasukan Petugas Kejuruteraan Internet Engineering Task Force (IETF). RFC adalah satu siri pengendali http dan yang paling dikenali adalah RFC 2616, yang memberi penjelasan HTTP/1.1 iaitu versi HTTP yang digunakan oleh umum pada hari ini.

Mesej permintaan

Mesej permintaan terdiri daripada yang berikut:

• Baris permintaan, seperti GET /images/logo.gif HTTP/1.1 yang meminta sumber        bernama /images/logo.gif dari pelayan

• Pengepala, seperti Accept-Language: en

• Baris kosong

• Isi mesej (tidak wajib)

Baris permintaan dan pengepala mesti berakhir dengan (iaitu kembali pembawa diikuti suap baris). Baris kosong hanya terdiri daripada tanpa apa-apa ruang putih. Dalam protokol HTTP/1.1, semua pengepala kecuali Host tidak diwajibkan.

 Baris permintaan yang mengandungi nama laluan sahaja diterima oleh pelayan untuk memastikan keserasian dengan klien HTTP sebelum spesifikasi HTTP/1.0 dalam RFC1945

Kaedah permintaan
            Permintaan HTTP dengan telnet. Pengepala permintaan dan sambutan dan isi sambutan diserlahkan.

HTTP mentakrifkan lapan cara (atau “verb”) yang menandakan tindakan yang hendak dilakukan pada sumber yang dikenal pasti.

Apa yang diwakili oleh sumber ini, sama ada data yang sudah sedia ada atau data yang dijana secara dinamik, tertakluk pada pelaksanaan pelayan. Selalunya, sumber berhubung dengan fail atau output boleh laku yang terletak dalam pelayan.

HEAD
          Meminta sambutan yang seiras dengan yang akan berhubung dengan permintaan GET, cuma tanpa isi sambutan. Berguna untuk menerima meta-maklumat yang ditulis dalam pengepala sambutan, tanpa perlu mengangkut seluruh kandungan.

GET
          Meminta perwakilan sumber yang ditentukan. Perhatian: GET tidak wajar digunakan untuk operasi yang menimbulkan kesan sampingan, seperti menggunakannya untuk membuat tindakan dalam aplikasi web. Salah satu sebabnya adalah GET boleh digunakan sewenang-wenangnya oleh bot atau perangkak (crawler) yang tidak patut menimbangkan kesan sampingan yang boleh diakibatkan oleh sesebuah permintaan. (Lihat kaedah selamat di bawah.)

POST
          Menghantar data untuk diproses (cth., dari suatu bentuk HTML) ke sumber yang dikenal pasti. Data disertakan dalam isi permintaan, maka menghasilkan sumber baru atau mengemaskini sumber-sumber sedia ada, atau kedua-duanya sekali.

PUT
          Memuat naik perwakilan sumber yang ditentukan.

DELETE
          Memadam sumber yang ditentukan.

TRACE
          Menggema balik permintaan yang diterima, supaya klien boleh melihat apa yang ditambah atau diubah oleh pelayan perantaraan dalam permintaan.

OPTIONS
          Mengembalikan kaedah HTTP yang disokong oleh pelayan untuk URL tertentu. Boleh digunakan untuk memastikan keberkesanan pelayan web dengan meminta ‘*’ dan bukannya sumber yang tertentu.

CONNECT
          Menukar sambungan permintaan menjadi terowong TCP/IP lutsinar, biasanya untuk memudahkan komunikasi tersulit SSL (HTTPS) melalui proksi HTTP yang tidak disulitkan. Pelayan HTTP diperlukan untuk melaksanakan sekurang-kurangnya kaedah GET dan HEAD, dan juga kaedah OPTIONS jika boleh.