Reference of Networking

http://en.wikipedia.org/wiki/IPv6 --> IPv6

http://en.wikipedia.org/wiki/IPv4 --> IPv4

http://en.wikipedia.org/wiki/Network_address_translation --> Network Address Translation

http://darojatun.blogsome.com/2008/06/29/
nat-internet-sharing-di-linux-dengan-iptables-dalam-4-langkah/

http://en.wikipedia.org/wiki/Virtual_private_network

http://id.wikipedia.org/wiki/Routing

Read More...

What is the difference between IPv4 and IPv6?

IPv4 means Internet Protocol version 4, whereas IPv6 means Internet Protocol version 6.

IPv4 is 32 bits IP address that we use commonly, it can be 192.168.8.1, 10.3.4.5 or other 32 bits IP addresses. IPv4 can support up to 2³² addresses, however the 32 bits IPv4 addresses are finishing to be used in near future, so IPv6 is developed as a replacement.

IPv6 is 128 bits, can support up to 2¹²⁸ addresses to fulfill future needs with better security and network related features. Here are some examples of IPv6 address:

1050:0:0:0:5:600:300c:326b
ff06::c3
0:0:0:0:0:0:192.1.56.10


source : http://www.home-network-help.com/ipv4-ipv6.html

Read More...

IPv4

Internet Protocol version 4 (IPv4) is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be widely deployed. IPv4 is the dominant network layer protocol on the Internet and apart from IPv6 it is the only standard internetwork-layer protocol used on the Internet.

It is described in IETF RFC 791 (September 1981) which made obsolete RFC 760 (January 1980). The United States Department of Defense also standardized it as MIL-STD-1777.

IPv4 is a data-oriented protocol to be used on a packet switched internetwork (e.g., Ethernet). It is a best effort protocol in that it does not guarantee delivery. It does not make any guarantees on the correctness of the data; this may result in duplicated packets or packets delivered out of order. These aspects are addressed by an upper layer protocol (e.g. TCP, and partly by UDP).

IPv4 uses 32-bit (four-byte) addresses, which limits the address space to 4,294,967,296 (2³²) possible unique addresses. However, some are reserved for special purposes such as private networks (~18 million addresses) or multicast addresses (~16 million addresses). This reduces the number of addresses that can be allocated as public Internet addresses. As the number of addresses available are consumed, an IPv4 address shortage appears to be inevitable, however Network Address Translation (NAT) has significantly delayed this inevitability.

This limitation has helped stimulate the push towards IPv6, which is currently in the early stages of deployment and is currently the only contender to replace IPv4.

source : http://en.wikipedia.org/wiki/IPv4

Read More...

What is IP Address?

An IP (Internet Protocol) address is a unique identifier for a node or host connection on an IP network. An IP address is a 32 bit binary number usually represented as 4 decimal values, each representing 8 bits, in the range 0 to 255 (known as octets) separated by decimal points. This is known as "dotted decimal" notation.

Example: 140.179.220.200

It is sometimes useful to view the values in their binary form.

140     .179     .220     .200
10001100.10110011.11011100.11001000

Every IP address consists of two parts, one identifying the network and one identifying the node. The Class of the address and the subnet mask determine which part belongs to the network address and which part belongs to the node address.

Address Classes

There are 5 different address classes. You can determine which class any IP address is in by examining the first 4 bits of the IP address.

• Class A addresses begin with 0xxx, or 1 to 126 decimal.
• Class B addresses begin with 10xx, or 128 to 191 decimal.
• Class C addresses begin with 110x, or 192 to 223 decimal.
• Class D addresses begin with 1110, or 224 to 239 decimal.
• Class E addresses begin with 1111, or 240 to 254 decimal.

Addresses beginning with 01111111, or 127 decimal, are reserved for loopback and for internal testing on a local machine; [You can test this: you should always be able to ping 127.0.0.1, which points to yourself] Class D addresses are reserved for multicasting; Class E addresses are reserved for future use. They should not be used for host addresses.

Now we can see how the Class determines, by default, which part of the IP address belongs to the network (N, in blue) and which part belongs to the node (n, in red).

• Class A -- NNNNNNNN.nnnnnnnn.nnnnnnnn.nnnnnnnn
• Class B -- NNNNNNNN.NNNNNNNN.nnnnnnnn.nnnnnnnn
• Class C -- NNNNNNNN.NNNNNNNN.NNNNNNNN.nnnnnnnn

In the example, 140.179.220.200 is a Class B address so by default the Network part of the address (also known as the Network Address) is defined by the first two octets (140.179.x.x) and the node part is defined by the last 2 octets (x.x.220.200).

In order to specify the network address for a given IP address, the node section is set to all "0"s. In our example, 140.179.0.0 specifies the network address for 140.179.220.200. When the node section is set to all "1"s, it specifies a broadcast that is sent to all hosts on the network. 140.179.255.255 specifies the example broadcast address. Note that this is true regardless of the length of the node section.

Private Subnets

There are three IP network addresses reserved for private networks. The addresses are 10.0.0.0, Subnet Mask 255.0.0.0, 172.16.0.0, Subnet Mask 255.240.0.0, and 192.168.0.0, Subnet Mask 255.255.0.0. These addresses are also notated 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16; this notation will be explained later in this tutorial. They can be used by anyone setting up internal IP networks, such as a lab or home LAN behind a NAT or proxy server or a router. It is always safe to use these because routers on the Internet by default will never forward packets coming from these addresses. These addresses are defined in RFC 1918.


source : http://www.ralphb.net/IPSubnet/ipaddr.html

Read More...

Internet Protocol

The Internet Protocol (IP) is the method or protocol by which data is sent from one computer to another on the Internet. Each computer (known as a host) on the Internet has at least one IP address that uniquely identifies it from all other computers on the Internet. When you send or receive data (for example, an e-mail note or a Web page), the message gets divided into little chunks called packets. Each of these packets contains both the sender's Internet address and the receiver's address. Any packet is sent first to a gateway computer that understands a small part of the Internet. The gateway computer reads the destination address and forwards the packet to an adjacent gateway that in turn reads the destination address and so forth across the Internet until one gateway recognizes the packet as belonging to a computer within its immediate neighborhood or domain. That gateway then forwards the packet directly to the computer whose address is specified.

Because a message is divided into a number of packets, each packet can, if necessary, be sent by a different route across the Internet. Packets can arrive in a different order than the order they were sent in. The Internet Protocol just delivers them. It's up to another protocol, the Transmission Control Protocol (TCP) to put them back in the right order.

IP is a connectionless protocol, which means that there is no continuing connection between the end points that are communicating. Each packet that travels through the Internet is treated as an independent unit of data without any relation to any other unit of data. (The reason the packets do get put in the right order is because of TCP, the connection-oriented protocol that keeps track of the packet sequence in a message.) In the Open Systems Interconnection (OSI) communication model, IP is in layer 3, the Networking Layer.

The most widely used version of IP today is Internet Protocol Version 4 (IPv4). However, IP Version 6 (IPv6) is also beginning to be supported. IPv6 provides for much longer addresses and therefore for the possibility of many more Internet users. IPv6 includes the capabilities of IPv4 and any server that can support IPv6 packets can also support IPv4 packets.

source : http://searchunifiedcommunications.techtarget.com/sDefinition/0,,sid186_gci214031,00.html#

reference : http://en.wikipedia.org/wiki/Internet_Protocol

Read More...

Enterprise Resource Planning (ERP)

Enterprise resource planning (ERP) is the planning of how business resources (materials, employees, customers etc.) are acquired and moved from one state to another.

An ERP system is a business support system that maintains in a single database the data needed for a variety of business functions such as Manufacturing, Supply Chain Management, Financials, Projects, Human Resources and Customer Relationship Management.

An ERP system is based on a common database and a modular software design. The common database can allow every department of a business to store and retrieve information in real-time. The information should be reliable, accessible, and easily shared. The modular software design should mean a business can select the modules they need, mix and match modules from different vendors, and add new modules of their own to improve business performance.

Ideally, the data for the various business functions are integrated. In practice the ERP system may comprise a set of discrete applications, each maintaining a discrete data store within one physical database.

Origin of the term

MRP vs. ERP-ENTERPRISE RECOURCE PLANNING — Manufacturing management systems have evolved in stages over the past 30 years from a simple means of calculating materials requirements to the automation of an entire enterprise. Around 1980, over-frequent changes in sales forecasts, entailing continual readjustments in production, as well as inflexible fixed system parameters, led MRP (Material Requirement Planning) to evolve into a new concept : Manufacturing Resource Planning (or MRP2) and finally the generic concept Enterprise Resource Planning (ERP)^[1]

The initials ERP originated as an extension of MRP (material requirements planning then manufacturing resource planning) and CIM (computer-integrated manufacturing) and was introduced by research and analysis firm Gartner. ERP systems now attempt to cover all basic functions of an enterprise, regardless of the organization's business or charter. Non-manufacturing businesses, non-profit organizations and governments now all use ERP systems.

To be considered an ERP system, a software package must provide the function of at least two systems. For example, a software package that provides both payroll and accounting functions could technically be considered an ERP software package.

However, the term is typically reserved for larger, more broadly based applications. The introduction of an ERP system to replace two or more independent applications eliminates the need for external interfaces previously required between systems, and provides additional benefits ranging from standardization and lower maintenance (one system instead of two or more) to easier and/or greater reporting capabilities (as all data is typically kept in one database).

Examples of modules in an ERP which formerly would have been stand-alone applications include: Manufacturing, Supply Chain, Financials, Customer Relationship Management (CRM), Human Resources, Warehouse Management and Decision Support System.

Overview

Some organizations — typically those with sufficient in-house IT skills to integrate multiple software products — choose to implement only portions of an ERP system and develop an external interface to other ERP or stand-alone systems for their other application needs. For example, one may choose to use human resource management system from one vendor, and the financial systems from another, and perform the integration between the systems themselves.

This is very common in the retail sector^{[citation needed]}, where even a mid-sized retailer will have a discrete Point-of-Sale (POS) product and financials application, then a series of specialized applications to handle business requirements such as warehouse management, staff rostering, merchandising and logistics.

Ideally, ERP delivers a single database that contains all data for the software modules, which would include:

Manufacturing

Engineering, Bills of Material, Scheduling, Capacity, Workflow Management, Quality Control, Cost Management, Manufacturing Process, Manufacturing Projects, Manufacturing Flow

Supply Chain Management

Inventory, Order Entry, Purchasing, Product Configurator, Supply Chain Planning, Supplier Scheduling, Inspection of goods, Claim Processing, Commission Calculation

Financials

General Ledger, Cash Management, Accounts Payable, Accounts Receivable, Fixed Assets

Projects

Costing, Billing, Time and Expense, Activity Management

Human Resources

Human Resources, Payroll, Training, Time & Attendance, Rostering, Benefits

Customer Relationship Management

Sales and Marketing, Commissions, Service, Customer Contact and Call Center support

Data Warehouse

and various Self-Service interfaces for Customers, Suppliers, and Employees

Enterprise Resource Planning is a term originally derived from manufacturing resource planning (MRP II) that followed material requirements planning (MRP).^[2] MRP evolved into ERP when "routings" became a major part of the software architecture and a company's capacity planning activity also became a part of the standard software activity.^{[citation needed]} ERP systems typically handle the manufacturing, logistics, distribution, inventory, shipping, invoicing, and accounting for a company. Enterprise Resource Planning or ERP software can aid in the control of many business activities, like sales, marketing, delivery, billing, production, inventory management, quality management, and human resource management.

ERP systems saw a large boost in sales in the 1990s as companies faced the Y2K problem in their legacy systems. Many companies took this opportunity to replace their legacy information systems with ERP systems. This rapid growth in sales was followed by a slump in 1999, at which time most companies had already implemented their Y2K solution.^[3]

ERPs are often incorrectly called back office systems indicating that customers and the general public are not directly involved. This is contrasted with front office systems like customer relationship management (CRM) systems that deal directly with the customers, or the eBusiness systems such as eCommerce, eGovernment, eTelecom, and eFinance, or supplier relationship management (SRM) systems.

ERPs are cross-functional and enterprise wide. All functional departments that are involved in operations or production are integrated in one system. In addition to manufacturing, warehousing, logistics, and information technology, this would include accounting, human resources, marketing, and strategic management.

ERP II means open ERP architecture of components. The older, monolithic ERP systems became component oriented.^{[citation needed]}

EAS — Enterprise Application Suite is a new name for formerly developed ERP systems which include (almost) all segments of business, using ordinary Internet browsers as thin clients.^{[citation needed]}

Advantages

In the absence of an ERP system, a large manufacturer may find itself with many software applications that do not talk to each other and do not effectively interface. Tasks that need to interface with one another may involve:

• design engineering (how to best make the product)
• order tracking from acceptance through fulfillment
• the revenue cycle from invoice through cash receipt
• managing interdependencies of complex Bill of Materials
• tracking the 3-way match between Purchase orders (what was ordered), Inventory receipts (what arrived), and Costing (what the vendor invoiced)
• the Accounting for all of these tasks, tracking the Revenue, Cost and Profit on a granular level.

Change how a product is made, in the engineering details, and that is how it will now be made. Effective dates can be used to control when the switch over will occur from an old version to the next one, both the date that some ingredients go into effect, and date that some are discontinued. Part of the change can include labeling to identify version numbers.

Some security features are included within an ERP system to protect against both outsider crime, such as industrial espionage, and insider crime, such as embezzlement. A data tampering scenario might involve a disgruntled employee intentionally modifying prices to below the breakeven point in order to attempt to take down the company, or other sabotage. ERP systems typically provide functionality for implementing internal controls to prevent actions of this kind. ERP vendors are also moving toward better integration with other kinds of information security tools.^[12]

Disadvantages

Problems with ERP systems are mainly due to inadequate investment in ongoing training for involved personnel, including those implementing and testing changes, as well as a lack of corporate policy protecting the integrity of the data in the ERP systems and how it is used.

Disadvantages

• Customization of the ERP software is limited.
• Re-engineering of business processes to fit the "industry standard" prescribed by the ERP system may lead to a loss of competitive advantage.
• ERP systems can be very expensive leading to a new category of "ERP light" solutions
• ERPs are often seen as too rigid and too difficult to adapt to the specific workflow and business process of some companies—this is cited as one of the main causes of their failure.
• Many of the integrated links need high accuracy in other applications to work effectively. A company can achieve minimum standards, then over time "dirty data" will reduce the reliability of some applications.
• Once a system is established, switching costs are very high for any one of the partners (reducing flexibility and strategic control at the corporate level).
• The blurring of company boundaries can cause problems in accountability, lines of responsibility, and employee morale.
• Resistance in sharing sensitive internal information between departments can reduce the effectiveness of the software.
• Some large organizations may have multiple departments with separate, independent resources, missions, chains-of-command, etc, and consolidation into a single enterprise may yield limited benefits.
• The system may be too complex measured the actual needs of the customer.

* source : http://en.wikipedia.org/wiki/Enterprise_resource_planning, 07/15/2008

Read More...

Data Flow Diagram (DFD) Sistem Informasi Penjualan Tiket Pesawat Online

Sebuah perusahaan penerbangan ”Colombus” ingin membangun sebuah Sistem Informasi Penjualan Tiket Pesawat Online (Web). Adapun prosedur penjualan tiket pesawat online yang akan diterapkan adalah sebagai berikut :

- Setiap customer yang akan melakukan pembelian tiket harus terlebih dahulu melakukan pendaftaran customer, karena setiap transaksi penjualan yang akan dilakukan harus melewati proses login terlebih dahulu.

- Apabila customer sudah melakukan pendaftaran, maka sistem akan memberikan login dan password supaya customer dapat melakukan pembelian tiket secara online.

- Untuk melihat jadwal penerbangan, customer dapat memilih menu schedule dan memasukkan data tujuan penerbangan (dari dan tujuan penerbangan) untuk mengetahui ketersediaan dan jam penerbangan tersebut.

- Apabila schedule telah didapatkan, customer dapat memilih menu e-booking availability untuk melakukan cek seat penerbangan.

- Apabila seat penumpang masih ada, maka customer dapat melakukan pembelian tiket pesawat dengan cara meng-click jadwal yang sesuai, dan sistem akan memberikan sebuah kode yang dipakai untuk melakukan pembayaran beserta nomer rekening untuk pembayaran tersebut.

- Kode yang diterima oleh customer akan dipakai untuk pembayaran lewat sebuah ATM dengan cara transfer ke nomer rekening yang telah disebutkan di web.

- ATM akan mengeluarkan sebuah slip yang didalamnya terdapat pin sepanjang 12 digit. Pin tersebut akan digunakan oleh customer untuk dimasukkan ke dalam menu Reconfirm yang ada pada halaman web, untuk membuktikan bahwa customer telah melakukan pembayaran.

- Slip yang didapat dari pembayaran di ATM harus disimpan oleh customer untuk ditukarkan dengan tiket pesawat di loket bandara saat akan melakukan penerbangan.

Dari cerita di atas, anda sebagai seorang tim pengembang sistem informasi, diminta untuk membuat Data Flow Diagram (DFD) mulai dari context diagram sampai dengan break down level detail sesuai dengan analisis anda.

Jawaban :

Context Diagram

DFD Level 1

DFD Level 2

1. Pendaftaran Customer

2. Pemesanan

Read More...