Tuesday, February 5, 2013

Hello Protocol

The hello protocol  is a fundamental protocol for wired and wireless networks. In mobile ad-hoc networks, a hello protocol helps nodes to establish a neighbor table for link detection. If nodes exchange position information in hello packets, then it also helps them in packet forwarding decisions. In ad-hoc networks, due to node mobility, neighbor relationships change frequently. To cope with mobility, and to have an up-to-date neighbor table, nodes advertise hello packets periodically. These hello packets create congestion, which may cause control and data packets to be dropped in the network.

The Hello Protocol works differently on broadcast networks, as compared to non-broadcast networks. On broadcast networks, each router advertises itself by periodically multicasting Hello Packets. This allows neighbors to be discovered dynamically. These Hello Packets contain the router's view of the Designated Router's identity, and the list of routers whose Hello Packets have been seen recently. On non-broadcast networks some configuration information is necessary for the operation of the Hello Protocol. Each router that may potentially become Designated Router has a list of all other routers attached to the network. A router, having Designated Router potential, sends Hello Packets to all other potential Designated Routers when its interface to the non- broadcast network first becomes operational. This is an attempt to find the Designated Router for the network. If the router itself is elected Designated Router, it begins sending Hello Packets to all other routers attached to the network.

Saturday, December 31, 2011

Cloud Computing in Simple Terms

Cloud computing is a technology that uses the internet and central remote servers to maintain data and applications. Cloud computing allows consumers and businesses to use applications without installation and access their personal files at any computer with internet access. This technology allows for much more efficient computing by centralizing storage, memory, processing and bandwidth.

A simple example of cloud computing is Yahoo email, Gmail, or Hotmail etc. You dont need a software or a server to use them. All a consumer would need is just an internet connection and you can start sending emails. The server and email management software is all on the cloud ( internet) and is totally managed by the cloud service provider Yaho , Google etc. The consumer gets to use the software alone and enjoy the benefits. 

The analogy is , 'If you need milk , would you buy a cow ?' All the users or consumers need is to get the benefits of using the software or hardware of the computer like sending emails etc. Just to get this benefit (milk) why should a consumer buy a (cow) software /hardware ? Cloud computing is broken down into three segments: "application" "storage" and "connectivity." Each segment serves a different purpose and offers different products for businesses and individuals around the world.

Tuesday, December 20, 2011


An Actuator is something that converts energy into motion. It also can be used to apply a force. An actuator typically is a mechanical device that takes energy, usually energy that is created by air, electricity or liquid, and converts it into some kind of motion. That motion can be in virtually any form, such as blocking, clamping, ejecting or many other types of motion.

In simple words, an actuator that generates linear motion or movement is called Linear Actuator. Most of these actuators are operated using hydraulic or mechanical actuation techniques and they are using non-linear motion as their input. Electric Linear Actuators are most suitable for the movement of final control elements which require linear movement. The rotary to linear conversion is done without any wear and thrust rod can transfer force directly to the final element. 

Many actuators are designed to be used in hazardous areas. They are operated by standard electronic units. Literally hundreds of actuators are available in the market. One needs to understand the required force, rated speed, maximum stroke range, and whether explosion protection is needed or not. Then one can select appropriate linear actuator for their needs. A standard linear actuator commonly has the motor as a separate cylinder attached to the side of the actuator, It is attached either in parallel way with the actuator or it sticks out to the side 90 degrees to the actuator. Motion control also plays an important role in the working of this device.The motor may also be attached to the back of the actuator. The drive motor has a solid drive shaft. This shaft is geared to the drive nut or drive screw.

Saturday, November 26, 2011

Google+ was never a comptetior to Facebook

The social web is a well reported topic within the media today, and for good reason. We are in a transitional change with how we communicate with each other online, how brands reach consumers and how organisations market to their audience. We are undoubtedly immersed in the technology age, and our lives, the way we 
interact with others, is changing totally.

The monumental success of Facebook, Mark Zuckerberg's world leading social platform, has enticed brands, consumers, investors alike, and the world is continually awaiting for that 'next big thing'. A likely reason therefore that the majority of news stories, magazine articles and blog posts on Google's latest foray into the social web repeatedly draw up comparisons to Zuckerberg's global giant.

Predicting the next big thing is often easier than some might think. You simply have to look at what is already out there, not at who's focusing on doing something different, but rather someone who's doing it better.
Take the iPod for example. Certainly not the first digital music player on the market, but Apple's cult status products have led the way in both design and function. Google was certainly not the first search engine. Remember the likes of Lycos, Hotbot and AltaVista? Google simply developed a product that was faster, cleaner, and easier to use than its rivals, and they now command a dominating portion of the search market.
Skype too was not the first online video chat service, but with successful brand building and fantastic integration with offline communication, it continues to be the world's favourite online audio/video communication tool.

Contrary to popular belief, Google+ was never created to directly compete for people's time on the internet. A simple, ad free system, Google+ was launched to compete for users' personal data. Becoming the primary platform for social networking would simply be a bonus.
Speaking at the Monaco Media Forum recently, Nikesh Arora, Google's chief business officer said that Google+ is a platform that allows the bringing together of all the services and products that they currently offer. It was never 'just about getting people together on one site and calling it a social network'.
The real power behind what Google has created comes down to the integration of Google's products, meaning that as people are using the search engine, they are also logged into Google+. The combination of that user data and knowing when people are actively searching for something opens up the possibility of the most targeted advertising platform in history, and Google are very aware of the fact.
Contrary to popular belief, Google+ was never created to directly compete for people's time on the internet. A simple, ad free system, Google+ was launched to compete for users' personal data. Becoming the primary platform for social networking would simply be a bonus
Little over a week into taking the reigns as CEO, Larry Page prioritised the company's social media strategy, by directly linking the annual bonuses of over 25% of Google employees to the success or failure of their social products.

Friday, August 12, 2011

What is Subnet and Subnet Mask?

Subnet:A subnet (short for "subnetwork") is an identifiably separate part of an organization's network. Typically, a subnet may represent all the machines at one geographic location, in one building, or on the same local area network (LAN). Having an organization's network divided into subnets allows it to be connected to the Internet with a single shared network address. Without subnets, an organization could get multiple connections to the Internet, one for each of its physically separate subnetworks, but this would require an unnecessary use of the limited number of network numbers the Internet has to assign. It would also require that Internet routing tables on gateways outside the organization would need to know about and have to manage routing that could and should be handled within an organization.

A subnet is a also logical grouping of connected network devices. Nodes on a subnet tend to be located in close physical proximity to each other on a LAN. Network designers employ subnets as a way to partition networks into logical segments for greater ease of administration. When subnets are properly implemented, both the performance and security of networks can be improved.

Subnet Mask:
A mask used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. For example, consider the IP address Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network.

Subnetting enables the network administrator to further divide the host part of the address into two or more subnets. In this case, a part of the host address is reserved to identify the particular subnet. This is easier to see if we show the IP address in binary format. The full address is:


The Class B network part is:


and the host address is


If this network is divided into 14 subnets, however, then the first 4 bits of the host address (0001) are reserved for identifying the subnet.

The subnet mask is the network address plus the bits reserved for identifying the subnetwork. (By convention, the bits for the network address are all set to 1, though it would also work if the bits were set exactly as in the network address.) In this case, therefore, the subnet mask would be 11111111.11111111.11110000.00000000. It's called a mask because it can be used to identify the subnet to which an IP address belongs by performing a bitwise AND operation on the mask and the IP address. The result is the subnetwork address:
Subnet Mask 11111111.11111111.11110000.00000000
IP Address 10010110.11010111.00010001.00001001
Subnet Address 10010110.11010111.00010000.00000000

The subnet address, therefore, is

Hope you enjoyed !!!

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Hina Rabbani Khar

Wednesday, August 3, 2011


Unicast:Unicast traffic is traffic addressed to a single device on the network.Unicast packets are sent from host to host. The communication is from a single host to another single host. There is one device transmitting a message destined for one reciever.Unicast uses IP delivery methods such as Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), which are session-based protocols. When a Windows Media Player client connects using unicast to a Windows Media server, that client has a direct relationship to the server.

Multicast:Multicast is a special protocol for use with IP. Multicast enables a single device to communicate with a specific set of hosts, not defined by any standard IP address and mask combination. This allows for communication that resembles a conference call.Multicast is a true broadcast. The multicast source relies on multicast-enabled routers to forward the packets to all client subnets that have clients listening. There is no direct relationship between the clients and Windows Media server. The Windows Media server generates an .nsc (NetShow channel) file when the multicast station is first created. Typically, the .nsc file is delivered to the client from a Web server.

Broadcast:Broadcast is when a single device is transmitting a message to all other devices in a given address range. This broadcast could reach all hosts on the subnet, all subnets, or all hosts on all subnets. Broadcast packets have the host (and/or subnet) portion of the address set to all ones. By design, most modern routers will block IP broadcast traffic and restrict it to the local subnet.