Types of computer networks:

Introduction:

 

As networks have grown in size and capabilities, they also have grown in terms of their importance to the organization. In many cases, the network – this encompasses the Internet, intranet sites, email, local area networks (LANs), wide. Area networks (WANs), virtual LANs (Vans), and wireless networks – is the company. It's where applications and Transactions are hosted; where internal and external users access, send, and share information; and where mission critical.

Customer, product, and business data are stored.

Network Types:

• Ethernet
  
• FDDI
  
• Token Ring
  
• ARCnet
  
• AppleTalk
  

Other Network Types:

• Fiber channel - Operates at 256 Mbps or 1Gbps. It was developed for peripheral devices like disk arrays, but is now used for point to point networking for full dupls. server to server communications. It is the lowest cost 1Gbps network.
  
• Gigabit Ethernet - This type of Ethernet places Ethernet packets in fiber channel packets. The fiber channel network works like an Ethernet bridge.
  

Ethernet:

The IEEE 802.3 standard defines Ethernet at the physical and data link layers of the OSI network model. Most Ethernet systems use the following:

• Carrier-sense multiple-access with collision detection (CSMA/CD) for controlling access to the network media.
  
• Use base band broadcasts
  
• A method for packing data into data packets called frames
  
• Transmit at 10Mbps, 100Mbps, and 1Gbps.
  
• The maximum distance a network segment could cover in hundreds of meters.
  

 

FDDI:

 

FDDI stands for Fiber Distributed Data Interface. The FDDI topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic. Connectors are specialized. The media access method is token passing. Multiple tokens may be used by the system. The maximum length is 100 kilometers. The maximum number of nodes on the network is 500.

Characteristics:

• Cable - Fiber.
  
• Speed - 100Mbps.
  
• Topology - Double ring
  

Token Ring:

Developed by IBM, Token Ring uses a star topology, but it is wired so the signal will travel from hub to hub in a logical ring. These networks use a data token passed from computer to computer around the ring to allow each computer to have network access. The token comes from the nearest active upstream neighbor (NAUN). When a computer receives a token, if it has no attached data and the computer has data for transmission, it attaches its data to the token then sends it to its nearest active downstream neighbor (NADN).

Maximum cable length is 45 meters. Topology is star-wired ring. Maximum nodes per network are 72 nodes. Speed is 4 or 16 Mps.

ARC net (Attached Resource Computer Network):

ARC net Topology is star and bus or a mixture. A network can use any combination of this media... It passes tokens passing for media access. Maximum segment length is 600 meters with and 30 meters from a passive hub. It may use active and passive hubs. It can have up to 255 nodes per network. The speed is 2.5 Mbps. ARCnet plus has operating speeds approaching 20Mbps.

Characteristics:

• Topology - star-bus.
  
• Cable - fiber.
  
• Speed - 2.5/20 Mbps.
  
• Media access - Token passing.
  

AppleTalk:

AppleTalk topology is bus. The connectors are specialized. Maximum segment and network length is 300 meters. The maximum number of connected segments is 8.Speed is 230.4Kbps. The cabling system used with AppleTalk is called Local Talk

Characteristics:

• Topology - Bus.
  
• Cable - STP.
  
• Speed - 230.4Kbps.
  
• Maximum segment length - 300 meters.
  
• Maximum network length - 300 meters
  

NETWORK MODEL:

Networks are all about sharing resources of computers, servers, printers, scanners etc to each other. There are two different types with which network between computers can be formed. Networking formation completely depends on the requirement of the organization scale and usability. We should always study requirements and needs before we decide to choose any type of network. Two types of networks are Peer to Peer networking also known to be p2p, the other one is Client and Server networks.

Peer to Peer (p2p):

P2p networking type is most commonly used computer networks. This type of network is very cost effective but supports lesser number of computers in network. Ten to fifteen computers can be connected to each other using p2p networking model without problem, more number of computers often create problems. All computers possesses same status within the network and no computer control any other

Computer but it self, this network does not have server to control and monitor. Security level is not towards higher side and each work station it self is responsible for security. Using p2p models files can be shared among computers. Files like, videos, audios, pictures, spreadsheets and all digital media can be sent or received with in the network. Printers, scanners and internet can be shared with in all computers.

Client and Server networks:

Choosing right kind of networking model is very important for organization. If you are using lesser number of computer and do not see any need to increase the numbers of computers to more than 15 then you are fine with peer to peer networking model, but if you are bigger organization or seeing growth in network, client and server model is designed for it

 

Servers are powerful machines when they are compared to normal desktop computers. They are meant to provide strength to computing power within the entire network. Controlling developed network can only be done by dedicated servers as they have higher specifications to support network. Servers can have better processing speed with multiple processors capability available. Server machine have higher RAM to load and execute software with ease.

 

 

 

 

POVERTY REDUCTION

Poverty Reduction Strategies (PRSs) are country-owned and participatory, taking into account the views of Parliament, line ministries, development partners, civil society and specifically the poor themselves. The PRSPs are comprehensive and recognize the multidimensional nature of the causes of poverty. They highlight strategies to alleviate poverty and acknowledge the need for a coherent macroeconomic framework to support them. The PRSPs also base themselves on both medium and long term perspectives, including appropriate monitoring indicators against which progress could be measured. The PRSP approach, thus, aims to provide the crucial link between national public actions, achievement of socio-economic outcomes, and assistance from development partners for the attainment of the United Nations' Millennium Development Goals (MDGs), agreed at the Millennium Summit (September, 2000), which are centered on halving poverty by 2015.

The PRSP formulation process took off in Pakistan with the finalization of the Interim Poverty Reduction Strategy Paper (I-PRSP) in November 2001, which after further refinement was evolved into the Poverty Reduction Strategy Paper (PRSP) in December 2003 for the period up till 2006. The PRSP since then has been the key strategy document of the government for social development of the country.

With the PRSP-I having successfully completed its three years of implementation in 2006, the next step in the ongoing process inevitably was the compilation of its successor – the PRSP-II. The PRSP-II draws upon lessons learnt from the implementation of the PRSP-I and takes into account recent political, economic and social events, both domestic and international, which have considerable development impacts for Pakistan.

The National PRSP Implementation Committee oversees PRSP policy reforms, evaluation of their impact, and appropriate adjustments (as required) in the policy regime. To assist this Committee, the government in 2000 established a PRSP Secretariat.