Wednesday, October 21, 2009

Network Crash

In network environment lots of equipments take to make the connectivity between client and servers. Those equipments are transferring data each and every where in side the network. That data is transferring in data packet way.

In a huge network environment there is lots of equipment transferring lots of data packet at once. Some times some data packets are transferring very long distance inside the network and some times lot of data packet traveling inside one cable.

The summery of two paragraphs, the major point is considered about the data packet. We were preparing network Because of transferring data easily between the computers. We must considered about data packets and protect it. If we lost data mean network crash inside the network, in huge network this can be happen,

If we taking this example 1 picture there is a centralize HUB in that network. But the reason is with using HUB we can’t manage a network because it is not providing any traffic management in side the network.

And another point for the cables, if we take coaxial cable for this does this network it is not possible because inside the network environment magnetic affect, long distances can happen if we use coaxial for the ca balling some time data me be lost of that reason.

If the distances is higher we can’t transferring data because if range is high data might be lost by traveling. NIC is another major point is does the network. Because some NIC’s are not speed that mean it is not transferring large capacity of data packet that is a reason for lost the data.

Gigabit Ethernet

Before inception Xerox Corporation in 1970s, Ethernet has been the dominant networking protocol. If we take all protocols Ethernet has, by far, the highest number of installed ports and provides the greatest cost performance relative to token Ring, Fiber Distributed Data Interface (FDDI), and ATM for desktop connectivity. And those Ethernet provide their connectivity from 10 to 100 megabit per second (Mbps).


Gigabits Ethernet build on top of the Ethernet protocol that mean it provide it service speed increases by tenfold over. It is a logical choice for low-cost, high-performance network upgrade, providing unparalleled speed and ease of management. The Gigabit Ethernet provides speed from 1000 megabit per second or 1 gigabit per second (Gaps). This protocol performed high-speed connectivity like lightning; it is gaining more and more presence in the server connectivity market. Network administrators require higher network performance to cope with the increasingly data intensive applications, backup, and software distributions or desktop, educational system. Which is the one success point of the network connection; customers will be able to leverage their existing knowledge base to manage and maintain gigabit networks. In
future it will be more than one gigabit.

Friday, October 16, 2009

windows vista wireless

How to connect a Vista computer to a wireless network using WLAN AutoConfig This document will serve as a guide for Microsoft Vista clients in joining a wireless network using WLAN AutoConfig service.

What is WZC or WLAN AutoConfig?


Wireless Zero Configuration (WZC) or WLAN AutoConfig is a service included with modern versions of Microsoft Windows that dynamically selects a wireless network to connect to base on a user's preferences and various settings. This can be used instead (or in the absence) of a wireless network utility from the manufacturer of a computer's wireless networking device.

To join a wireless network:


1. Open the Start menu and click Control Panel. 2. In the Control Panel Home window, click View network status and tasks.






2.If you are using Classic View, double- click Network and Sharing Center.





3. Click Connect to a network.


4. Select your network from the list and click Connect.


5.If security is enabled on the network, you will be asked to type your network security key or passphrase for your router. After typing security key, click Connect.



6.After typing the correct security key, you should be connected to your router. Click Close.


7.You can select a location profile for your network or skip it by clicking Cancel.



8.You are now ready to connect to the Internet.

Thursday, October 15, 2009

Hybrid topologies


Different topologies may be interconnected to form subnets to a main network. It is possible, for example, to connect a star, a hub and a ring together beneath another star topology network.

Tree


A tree topology is a variation on a star. In this case the central hub might connect to a number of secondary hubs forming a sort of hierarchy of stars. Secondary hubs may be passive or active devices. An active hub acts as a repeater and amplifier for the signals in each direction. This is ideal for networks with remote nodes as link distances can be effectively lengthened without attenuation. A passive hub supplies connections only between the next hub and the nodes below.


Advantages:

  • Secondary hubs increase the number of devices that may be part of the network
  • Hubs can be used to prioritize and isolate traffic on different parts of the network.
  • Other advantages as per star topology

Mesh Topology


A mesh topology is a network topology in which each communicating node is directly connected to all other nodes.
Or
Mesh topology provides each device with a point-to-point connection to every other device in the network. These are most commonly used in WAN's, which connect networks over telecommunication links. Mesh topologies use routers to determine the best path.
Mesh networks provide redundancy, in the event of a link failure; meshed networks enable data to be routed through any other site connected to the network. Because each device has a point-to-point connection to every other device, mesh topologies are the most expensive and difficult to maintain.

Advantages:

  • Dedicated links eliminate congestion due to excessive traffic.
  • Robust as one damaged link will not cripple the network.
  • Point-to-point connections make fault isolation and identification simple.

Disadvantages:
  • High number of connections requires large number of network ports and large amounts of cabling.
  • Wiring bulk may exceed space available.
  • Duplication of hardware becomes expensive

Monday, October 12, 2009

Route

Introduction to Routing

Routing is an extremely important function of IP. It is the process of choosing a path over which to send packets. The device that performs this task is called a router, which forwards packets from one physical network to another. Your knowledge of IP will enable you to see the correlation between IP and routing.
The Internet layer, or OSI/RM network layer (Layer 3), performs the routing function. A packet, or datagram, carries sufficient information for routing from the originating host to the destination host using the IP address. Packets may traverse several networks before reaching their destination host.
Packets are routed transparently, and not necessarily reliably, to the destination host. The term "transparent," when applied to routing, means that after the routing hardware and software are installed, changes are undetectable by users because the routing process is largely automated. The complexity of routing is not visible to the user. The transport or application layer is responsible for reliability, which ensures that the data arrives at the other end.


Routing can be summarized as:

  • The process that determines the path that packets will travel across networks.
  • One of the most important IP functions.
Routing can be divided into two general classifications: direct and indirect.

Bluetooth

Named after a tenth-century Danish king, Bluetooth is a specification for a small form-factor, low-cost radio solution providing links between mobile computers, mobile phones and other portable handheld devices, and connectivity to the internet which it is hoped will revolutionise mobile computing and communications by providing freedom from wired connections. The initiative is backed by leaders in the telecommunications, computing, and network industries - including 3Com, Ericsson, IBM, Intel, Lucent, Motorola, Nokia and Toshiba - and more than 1300 adopter companies. Microsoft's decision to join the group driving the standard at the end of 1999 significantly increased hopes that one of the problems that had afflicted Bluetooth hitherto - namely that the standard had yet to extend beyond hardware compatibility to encompass the software that runs across it - would not be allowed to undermine the standard to the extent that it had its forerunner, infrared.

Bluetooth's chief advantage over infrared is that Bluetooth does not require line of sight. Its backers hope the component costs will be so low that it will ultimately replace infrared. Others believe that, although there are clear areas of overlap, IrDA and Bluetooth are complementary with either being the most appropriate for certain applications and intended usage models.

Bluetooth operates in the unlicensed Industrial Scientific and Medical (ISM) 2.4GHz band, ranging from 2.4 to 2.4835 GHz in the US, Japan and Europe. Parts of this band are also available in France and Spain. By using the 2.4 GHz band, Bluetooth Wireless Technology promises to be a universal wireless solution. Essentially, it is the same kind of microwave radio technology that has given us wireless door chimes and automatic garage door openers. It draws heavily on existing wireless LAN technology since it is based around the IEEE's 802.11 - the existing standard for wireless Ethernet. The main differences are that in order to consume less power, Bluetooth is initially restricted to an operating distance of just 10 metres and a speed of approximately 1 Mbit/s.

Saturday, October 10, 2009

Network Topology

The term network topology is, refers to the way a network is laid out, either physically or logically. The topology of a network is the geometric representation of the relationship between the links and linking devices (called nodes). There are five basic topologies possible: Combining these topologies, a more complex hybrid network topology can be created.


The topology of a particular network can be chosen depending upon the relative status of each device in the network. A peer-to-peer relationship, where each node has equal importance and make equal use of each link lends itself to a ring, mesh or bus topology. Where there is a 'master-slave' or primary-secondary relationship between one device and the rest then the star, tree or bus topologies best fit.

Wednesday, October 7, 2009

Protect Network

The threat of email viruses & Trojans

The widespread use of email has provided hackers and crackers with an easy way to distribute harmful content to the internal network. Hackers can easily circumvent the protection offered by a firewall by tunneling through the email protocol, since it does not analyze email content.

CNN reported says that the MyDoom virus cost companies about US$250 million in lost productivity and tech support expenses, while NetworkWorld (September 2003) cited studies that placed the cost of fighting Blaster, SoBig.F, Wechia and other email viruses at US$3.5 billion for US companies alone.

Furthermore, email is also used to install Trojans, targeted specifically at your organization to obtain confidential information or gain control of your servers. Described as "instructive viruses" or "spy viruses" by computer security experts, these can be potent tools in industrial espionage. A case in point is the email attack on Microsoft's network in October 2000, which a Microsoft Corp. spokesman described as "an act of industrial espionage pure and simple". According to reports, Microsoft's network was hacked by means of a backdoor Trojan virus maliciously emailed to a network user.

Saturday, October 3, 2009

Tag

Assignment Lanka Tag Cloud
Computer Networks The History of Local Area Networks, LAN, The Topologies of a Networks, LANs describe different types of transmission Medias, Local Area Networks Access Methods, Carrier Sense Multiple Access with Collision Detect, Development of LAN Technologies. LAN -Token Ring, LAN Ethernet Digital, LAN - Ethernet Sun microsystems, LAN - Ethernet Mixed Environment, LAN - Token Ring was introduced by IBM LAN - IBM implementation of Token Ring, Token Ring Novell, LAN Token Ring - in a mixed environment, LAN - Fiber Distributed Data Interface, LAN - ATM, LAN Components, LAN Switching Methods, Virtual Local Area Network, Port based VLAN, Mac based VLAN, Protocol based VLAN, User Base VLAN, PC networks Components, PC networks Shared resources, PC Network operating systems, PC networks Novell Netware, PC networks Windows NT, PC networks IBM LAN Server Computer Programming Languages HTML Language, The Generations of Programming Languages, Different types of High Level Languages, Different types of High Level Languages Disadvantages
Computer Networks - IBM LAN Server, Windows NT Networks, Novell Netware, Network operating systems, Networks Shared, Networks Components, User Base, Protocol based, Mac based, Port based, VLAN, LAN Switching, LAN Components, ATM, Fiber Data, Token Ring, Token Ring Novell, IBM implementation, Ethernet, Sun microsystems, Ethernet Digital, Token passing, LAN Technologies, CSMA/CD, Access Methods, Transmission, Networks, The History of Local Area Networks, LAN