Tuesday, September 30, 2008

Classful Vs Classless Address

Hello friends in this post i am again going to tell you some more interesting concepts of networking.In this post i am going to tell you what is the difference between classfull and classless address.
Classful addressing:In the classful addressing system all the IP addresses that are available are divided into the five classes A,B,C,D and E, in which class A,B and C address are frequently used because class D is for Multicast and is rarely used and class E is reserved and is not currently used.Each of the IP address belongs to a particular class that's why they are classful addresses.Earlier this addressing system did not have any name,but when classless addressing system came into existence then it is named as Classful addressing system.The main disadvantage of classful addressing is that it limited the flexibility and number of addresses that can be assigned to any device.One of the major disadvantage of classful addressing is that it does not send subnet information but it will send the complete network address. The router will supply its own subnet mask based on its locally configured subnets. As long as you have the same subnet mask and the network is contiguous, you can use subnets of a classful network address.

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Classless Addressing:Classless addressing system is also known as CIDR(Classless Inter-Domain Routing).Classless addressing is a way to allocate and specify the Internet addresses used in inter-domain routing more flexibly than with the original system of Internet Protocol (IP) address classes.What happened in classful addressing is that if any company needs more than 254 host machines but far fewer than the 65,533 host addresses then the only option for the company is to take the class B address.Now suppose company needs only 1000 IP addresses for its host computers then in this (65533-1000=64533) IP addresses get wasted.For this reason, the Internet was, until the arrival of CIDR, running out of address space much more quickly than necessary. CIDR effectively solved the problem by providing a new and more flexible way to specify network addresses in routers.A CIDR network address looks like this:

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The "" is the network address itself and the "15" says that the first 15 bits are the network part of the address, leaving the last 17 bits for specific host addresses.One more advantage of classless addressing is that classless protocol sends subnet information. This allows you to create discontiguous networks with any given classful network address.

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Sunday, September 28, 2008

Repeater Vs Switch Vs Hub

Hello friends this is my post and i this post i am going to give you a brief description and difference between various networking devices.

As all we know various types of devices like repeaters,hub, routers, switch are used very frequently in the setup of any computer network.Here in this post we see all these devices one by one.

Repeater: A repeater is an electronic device that is used to receive a signal and after receiving, it transmit signal to the higher level so that it can move to long distance without any destruction in its value.In other words we can also say that repeater is a device that is designed to overcome signal attenuation means to recover signal degradation.All repeaters has two ports one for receiving the signal and other for its transmission. Repeaters can be used for carrying electrical signals in the form of copper wire or to carry light in the form of fiber optics.It is a layer 1 device that means Physical layer device.

Hub: In simple words we can say that a hub is a multi port repeater.It means it allows multiple machines to connect to the same network, by broadcasting traffic to all of its ports.The most practical implication of this is that only one device can send data at a time, otherwise a collision occurs. Hubs implement a collision detection multiple access method to detect when two machines attempt to send data at the same time. A hub supports broadcasting of any signal.It is also layer 1 device.

Switch:In general switch is very much different from the repeater and the hub , both of them works on IP address while the switch works on the MAC address. A switch works by keeping track of which MAC addresses are attached to each port. It inspects traffic and only sends it to the port that the destination device is on (based on the destination MAC address). A switch had a finite amount of memory in which it can store MAC addresses, smaller switches such as ones intended for desktop use have less memory then larger ones that may form part of an enterprise networks backbone. When a switches memory becomes full of active MAC addresses it will often revert to functioning like a hub and broadcast traffic to all ports.A switch is a layer 2 device(Data link Layer).

Introducing Blog

Hello friends this is my first blog and in this blog i am going to explore all the important concepts of Computer Networks in which students find themselves in difficulty.Here you will find a complete description of all the topics that will really help you in understanding these concepts.In this blog you will also found some latest hacking technologies in Windows XP,UNIX and Linux that will definitely a fun stuff for you.In addition to this i also give you latest news from the field of technology and also some reviews.