Networks

CAN: A campus area network (CAN) is a network of multiple interconnected local area networks (LAN) in a limited geographical area. A CAN is smaller than a wide area network (WAN) or metropolitan area network (MAN). A CAN is also known as a corporate area network (CAN).

LAN: (Local Area Network as listed in our computer terms page) A group of computers that share a common connection and are usually in a small area or even in the same building. For example an office or home network. They are usually connected by Ethernet cables and have high speed connections. If it was a wireless setup it would be called a WLAN, which would have a lower connection speed. 

MAN: (Metropolitan Area Network) This is a larger network that connects computer users in a particular  geographic area or region. For example a large university may have a network so large that it may be classified as a MAN. The MAN network usually exist to provide connectivity to local ISPs, cable tv, or large corporations. It is far larger than a LAN and smaller than a WAN. Also large cities like London and Sydney, Australia have metropolitan area networks.

WAN: (Wide Area Network) This is the largest network and can interconnect networks throughout the world and is not restricted to a geographical location. The Internet is an example of a worldwide public WAN. Most WANs exist to connect LANs that are not in the same geographical area. This technology is high speed and very expensive to setup.

Next Gen NBN

The Next Generation Nationwide Broadband Network (Next Gen NBN) is the wired network of the Next Generation National Infocomm Infrastructure (Next Gen NII), which seeks to transform Singapore into an intelligent nation and a global city, powered by infocomm. It will provide ultra-high speed broadband access of 1Gbps and more, delivering a slew of next generation services at all physical addresses including homes, schools, government buildings, businesses and hospitals.

Besides enabling Singapore to exploit new economic opportunities and enhancing the vibrancy of the infocomm sector, the network will also offer effective open access to retail service providers to bring about a more competitive broadband market. This is expected to spark off the creation of a wider range of next generation services for end-users. A competitive and globally recognised infrastructure, coupled with a high level of adoption by the nation, will result in greater productivity gains and enable new possibilities to transform the way we live, learn, work and interact.

SIngapore Internet Exchange (SGIX)

SGIX provides a central point for the ISPs to exchange traffic with one another directly instead of routing through international carriers before reaching a local ISP. In addition, this arrangement enables customers of the ISPs to access local contents  from other ISPs even during cable outages which occur on the international network, such as those caused by earthquakes,. Using a local exchange like SGIX will help to cut connectivity cost and improve the resiliency of their networks. It will ultimately also improve the speeds their customers can experience when accessing local content.

Singapore’s proximity to regional markets and extensive global connectivity allows SGIX to be well-positioned as a central traffic exchange in the region to serve international carriers and content service providers. Carriers around the world can exchange traffic effectively without having to establish multiple international connections across the region.  This provides a good opportunity for them to aggregate their international traffic from the region, resulting in greater cost-savings.

Content providers can also leverage on SGIX as a gateway to reach out to the growing market in the region without the need to establish multiple connectivity links or presence across the region.

References:

Mitz. (n.d.). What is the difference between network lan, wan, and man. Retrieved from http://tips4pc.com/articles/networking tips/what_is_the_difference_between_networks_lan_wan_man_.htm

Cory , J. (n.d.). Campus area network (can). Retrieved from http://www.techopedia.com/definition/25931/campus-area-network-can

(n.d.) What is Next Gen NBN, http://www.ida.gov.sg/Infocomm-Landscape/Infrastructure/Wired/What-is-Next-Gen-NBN.aspx#.ULHhQofqmyl

(March, 2011), Singapore Internet Exchange, http://www.ida.gov.sg/~/media/Files/Archive/Infrastructure/Infrastructure_Level2/20090708173942/SGIX_FactSheet.pdf



Done by: Tan Ting Hwee (TT01)

Future of Internet

IPv4 
IPv4 uses a 32-bit address scheme allowing for a total of 2^32 addresses (just over 4 billion addresses).  With the growth of the Internet it is expected that the number of unused IPv4 addresses will eventually run out because every device -- including computers, smartphones and game consoles -- that connects to the Internet requires an address.

IPv6
IPv6 has an address space size of 2¹²⁸ and a standard subnet size of 2⁶⁴ 
So 2 to the power of 128 ends up being 340,282,366,920,938,000,000,000,000,000,000,000,000 unique IP addresses.

Issues of moving from IPv4 to IPv6


1. Infrastructure Issues:
The TCP/IP suite must be redesigned to support the new address format. e.g. the DNS has defined AAAA resource record for IPv6 (128 bit) but it has defined A resource record for IPv4 (32 bit). The other protocols must be redesigned to support IPv6 including DHCP, OSPF, RIP, BGP, ARP etc.

B. Tunnelling Issues:
Without changing the applications, IPv6 can be implemented in an existing network by using IPv6 over IPv4  tunnelling for connecting the IPv4 nodes to the backbone network. But  tunnelling has very less throughput and it needs network managers to configure the tunnel end points information, which is a time consuming process.  

C. Financial Issues:
Migrating from IPv4 to IPv6 means, purchasing new network devices (which supports IPv6) such as switches, routers etc. which is a kind of additional investment.

D. Security Issues:
The IPv6 is not used in wide scale till now and it is not tested properly. So no one is very sure about the security level of IPv6.

iDA in helping Singapore to move from IPv4 to IPv6

With the depletion of IPv4 addresses, the Internet community will be moving towards adopting IPv6 technologies. In view of this, IDA sees the need to develop a local pool of IPv6 competent workforce, to support IPv6 adoption.

IDA recently called for a tender to identify a training provider to deliver IPv6 knowledge and skills training to two key target groups - the current workforce of ICT professionals, and the future workforce which comprises students from institutes of higher learning (IHLs) such as the universities, polytechnics and Institutes of Technical Education.

For the current workforce which includes network planners, network administrators and other ICT professionals, the aim is to provide certified IPv6 training courses to ensure that they are equipped with the necessary IPv6 skills to handle IPv6 related tasks such as administration, IPv6 implementation and operational tasks. The courses will cover topics such as IPv6 packet generation and detection, network configuration, IPv6 routing protocols, and steps to migrate to IPv6. Each training programme will include theory, a hands-on component, and an examination.

In addition to this cohort, IDA is also targeting to train ICT professionals to become IPv6-certified trainers who will, in turn, be able to conduct IPv6 courses to train more ICT professionals with IPv6 skills and to develop their own courseware if required.

For the second target group - the students - IDA's main aim is to ensure that they are equipped with IPv6 knowledge prior to joining the IT workforce. This target group will be able to handle IPv6-related tasks and job requirements upon graduation. To deliver this, the training provider will have to develop an IPv6 training programme consisting of IPv6 course modules and an evaluation quiz to be offered to the IHLs.

"We would like to see the training provider establish strong collaborations with the various IHLs and to deliver IPv6 training using various mechanisms, for example, incorporating IPv6 modules into the existing school curriculum, conducting IPv6 workshops or organising industry-sharing sessions on IPv6 implementation experiences," said Mr Eddy Leong, Manager, IPv6 task force at IDA.

Students targeted will be drawn mainly from second and third-year polytechnic students, especially those pursuing diplomas in information technology or network systems, as well as university students doing relevant networking or ICT modules under Electrical and Electronic Engineering and Computer Engineering.

How IPv6 look like?

As previously mentioned, IPv6 addresses are 128 bits long. This number of bits generates very high decimal numbers with up to 39 digits:

2^128-1: 340282366920938463463374607431768211455

Such numbers are not really addresses that can be memorized. Also the IPv6 address schema is bitwise orientated (just like IPv4, but that's not often recognized). Therefore a better notation of such big numbers is hexadecimal. In hexadecimal, 4 bits (also known as “nibble”) are represented by a digit or character from 0-9 and a-f (10-15). This format reduces the length of the IPv6 address to 32 characters.

2^128-1: 0xffffffffffffffffffffffffffffffff

This representation is still not very convenient (possible mix-up or loss of single hexadecimal digits), so the designers of IPv6 chose a hexadecimal format with a colon as separator after each block of 16 bits. In addition, the leading "0x" (a signifier for hexadecimal values used in programming languages) is removed:

2^128-1: ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff

A usable address (see address types later) is e.g.:

2001:0db8:0100:f101:0210:a4ff:fee3:9566

For simplifications, leading zeros of each 16 bit block can be omitted:

2001:0db8:0100:f101:0210:a4ff:fee3:9566 -> ¬ 2001:db8:100:f101:210:a4ff:fee3:9566

References:

Vangie , B. (2011, January 1). What is the difference between ipv6 and ipv4?. Retrieved from http://www.webopedia.com/DidYouKnow/Internet/ipv6_ipv4_difference.html

How many ip addresses does ipv6 support?. (2008, March 25). Retrieved from http://geekswithblogs.net/devdevin/archive/2008/03/25/120750.aspx

Issues in ipv4 to ipv6 migration. (2011, March). Retrieved from 
http://www.caesjournals.org/uploads/IJCAES-CSE-2011-19.pdf

Ida steps up effort to develop ipv6 manpower pool. (2011, August 31). Retrieved from http://www.ida.gov.sg/Infocomm-Landscape/Technology/IPv6/Resources/Latest-IPv6-News/IDA-Steps-Up-Effort-to-Develop-IPv6-Manpower-Pool.aspx

2.3. what do ipv6 addresses look like?. (n.d.). Retrieved from http://tldp.org/HOWTO/Linux IPv6-HOWTO/x422.html



Done by: Tan Ting Hwee (TT01)

Internet Applications

RTP

Short for Real-Time Transport Protocol, an Internet protocol for transmitting real-time data such as audio and video. RTCP itself does not guarantee real-time delivery of data, but it does provide mechanisms for the sending and receiving applications to support streaming data. Typically, RTCP runs on top of the UDP protocol, although the specification is general enough to support other transport protocols.

UDP

UDP (User Datagram Protocol) is a simple OSI transport layer protocol for client/server network applications based on Internet Protocol (IP). UDP is the main alternative to TCP and one of the oldest network protocols in existence, introduced in 1980.

UDP is often used in videoconferencing applications or computer games specially tuned for real-time performance. To achieve higher performance, the protocol allows individual packets to be dropped (with no retries) and UDP packets to be received in a different order than they were sent as dictated by the application.

RTCP

It’s a companion protocol to RTP – the one used to send and receive most media over IP these days. It gives it a lightweight control mechanism that provides feedback to the sender about the quality of the data it is sending 

RTSP

Real Time Streaming Protocol (RTSP) is an application-level protocol for the transfer of real-time media data. The protocol is used to establish and control media sessions between end points by serving as a network-remote-control for time-synchronized streams of continuous media such as audio and video.

SMTP

Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server.

POP3

POP3, which is an abbreviation for Post Office Protocol 3, is the third version of a widespread method of receiving email. Much like the physical version of a post office clerk, POP3 receives and holds email for an individual until they pick it up. And, much as the post office does not make copies of the mail it receives, in previous versions of POP3, when an individual downloaded email from the server into their email program, there were no more copies of the email on the server; POP automatically deleted them.

IMAP4

IMAP (Internet Message Access Protocol) is richer in functionality than POP and is designed to allow clients to access and manage mailboxes on the server as if they were local. IMAP is a much more complex protocol than POP, with less client support. IMAP4 is the latest implementation of IMAP.

Difference between IMAP4 & POP3

The main difference between IMAP4 and POP3 is that with POP3 the messages are only stored temporarily on the mail server until they are downloaded to the email client where the messages are stored, manipulated, searched etc. With IMAP4 the messages are stored permanently on the server, and they are manipulated, searched etc on the mail server.

This difference means that, whichever computer a user uses to access his or her mail, the mail is always accessible when using IMAP4. With POP3, the user would have to copy the email client mailboxes onto the new PC to have access to their old mail. This makes it easier to have 'hot desking' (people just picking a free desk when they arrive at work) with an IMAP4 server like VPOP3 Enterprise.

References:

RTP. (n.d.). Retrieved from http://www.webopedia.com/TERM/R/RTP.html

Bradley , M. (n.d.). Udp. Retrieved from http://compnetworking.about.com/od/networkprotocolsip/g/udp-user-datagram-protocol.htm

Tsahi, L. (2011, July 14). Why do we need rtcp anyway?. Retrieved from http://blog.radvision.com/voipsurvivor/2011/07/14/why-do-we-need-rtcp-anyway/

Margaret, R. (n.d.). Real time streaming protocol (rtsp). Retrieved from http://searchvirtualdesktop.techtarget.com/definition/Real-Time-Streaming-Protocol-RTSP

SMTP. (n.d.). Retrieved from http://www.webopedia.com/TERM/S/SMTP.html

What is a pop3?. (n.d.). Retrieved from http://whatismyipaddress.com/pop3

What is imap4?. (2002, September 18). Retrieved from http://www.gordano.com/kb.htm?q=1444

What is imap4. (n.d.). Retrieved from http://wiki.pscs.co.uk/what_is;imap4

Done by: Tan Ting Hwee (TT01)

Internet Topology & Internet Domains

Singnet Topology

SingNet Business ADSL (Dynamic IP) Internet access is a popular value-for-money Internet service for business use. Built on the latest ADSL technology, your broadband connection can be delivered from any telephone port on the wall.

SingNet ADSL service allows much greater speeds for downlink than uplink, which makes it ideal for surfing, downloading and sharing among multiple users online.

SingNet belongs to the Tier 1 network as it span national and international boundaries.

DNS

The Domain Name System (DNS) is a global database that translates domain names (such as www.internetsociety.org) to Internet addresses that are used by computers to talk to each other.

HTTP

Short for Hyper Text Transfer Protocol, the underlying protocol used by the World Wide Web. HTTP defines how messages are formatted and transmitted, and what actions Web servers and browsers should take in response to various commands.

FTP

FTP is an acronym for File Transfer Protocol. As the name suggests, FTP is used to transfer files between computers on a network. You can use FTP to exchange files between computer accounts, transfer files between an account and a desktop computer, or access online software archives.

Internet Domain

Domain names are used to identify one or more IP addresses. For example, the domain name microsoft.com represents about a dozen IP addresses. Domain names are used in URLs to identify particular Web pages. For example, in the URL http://www.pcwebopedia.com/index.html , the domain name is pcwebopedia.com.

Every domain name has a suffix that indicates which top level domain (TLD) it belongs to. There are only a limited number of such domains. For example:

gov - Government agencies

edu - Educational institutions

org - Organizations (nonprofit)

mil - Military

com - commercial business

net - Network organizations

ca - Canada

th - Thailand

Because the Internet is based on IP addresses, not domain names, every Web server requires a Domain Name System (DNS) server to translate domain names into IP addresses.

Example of a DNS Name Space 

www.google.com.sg

.sg represent the top domain, followed by .com and google.

References:

Business broadband. (n.d.). Retrieved from http://info.singtel.com/business/products-and-services/singnet-business-broadband

Dns. (n.d.). Retrieved from http://www.internetsociety.org/dns?gclid=CP3upPWN6bMCFUx66wod3kEA3A

Http. (n.d.). Retrieved from http://www.webopedia.com/TERM/H/HTTP.html

What is ftp, and how do i use it to transfer files?. (2010, January 27). Retrieved from http://kb.iu.edu/data/aerg.html

domain name. (n.d.). Retrieved from http://www.webopedia.com/TERM/D/domain_name.html

Done by: Tan Ting Hwee (TT01)