Alicisco

ISL vs Dot 1Q

2010-09-20T10:45:00.000-07:00

ISL:
ISL is Cisco Proprietary, not usable in multivendor environments. IT will encapsulate the entire frame and place both header and trailer onto the frame, which will increases the overhead on trunk line. Because ISL does not use the concept of native Vlan (Vlan 1 Default in Cisco switches), every single frame transmitted across the trunk will be encapsulated. ISL adds 26-byte header, which contains Vlan ID and adds 4-byte trailer contains CRC value.
Frames larger then 1518 byte (Max size for Ethernet frame) called GIANTS. ISL encapsulation adds 30 byte to the original frame, which makes them too large for the switch to handle.

Dot 1Q:

Dot 1Q is the IEEE standard suitable for multivendor. Dot1Q does not encapsulate frame, it just adds 4-byte header to the frame and adds nothing to native Vlan frames. Adding only 4-byte to the frame results less overhead then ISL .Maximum frame size of 1522.

Run Linux and Windows simultaneously

2010-05-03T10:22:00.000-07:00

If you are a Windows user and Want to switch or just try Linux. But you don’t want to take a risk of dual boot or you don’t have an extra testing computer.

You can run booth of your Operating systems simultaneously. So you can get use to your new OS while using your current OS (Windows). And that by using your Windows as host and your new OS(Linux) as guest .

Things you need :
1- Desktop or Laptop with at lest 1.8 Ghz processor
2- Extra Monitor (to create dual monitor)
3- 3 GB of Ram at lest.
4- 2GB Flash memory
Software you need:
1- Linux ISO image (Ubuntu, fedora,Opensuse) what every you like.
2- eBooster (converts the Flash memory to Ram) and I don’t care how you get it buy it or ……
3- VirtualBox it is free (www.virtualbox.org) download Windows host version.
4- virtual-box-windows-guest-additions-installer Its also free (http://code.google.com/p/virtual-box-windows-guest-additions-installer/)
steps
1-First you set your dual monitor and to do that just connect your Old monitor to your laptop. If you are using windows 7 Right clickScreen Resolution Detect. Set the Multiple displays to (Extend this displays).
2- Install eBooster and after you finsh connect your flash memory and right click ReadyBooster set the amount of space you want to use (prefer 1024).
3- Install VirtualBox.
4- configure your VirtualBox and create new virtual pc (linux).
5- after you finshed installing your new OS (linux) install the virtual-box-windows-guest-addition inside your virtual pc.
6- now you can run your primary OS in one screen and the virtual OS in other.

Enjoy your both Operating systems

fill free to ask any question about any step you don't understand and I will give a detailed instruction.
or email me ali.2011@live.com

CCNA Certification: Trunking Concepts Part II

2009-12-05T10:03:00.001-08:00

CCNA Certification: Trunking Concepts Part II

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CCNA Certification: VLAN Trunking Protocol (VTP) Part I

2009-12-05T10:02:00.001-08:00

CCNA Certification: VLAN Trunking Protocol (VTP) Part I

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Tour of the Cisco Networkers booth in the World of Solutions Brisbane

2009-10-09T02:50:00.001-07:00

The agenda of the Cisco Networkers event in Brisbane is getting close to one of the most anticipated parts tonight - the customer appreciation event… There’s been a lot of speculation about who the band will be - and we look forward to your guesses on who that. In the meantime, we visited the World of Solutions area today with Andrew Erratt, director of Systems Engineering, Cisco ANZ, to get a view of what attendees can expect to see in terms innovative solutions from Cisco and 40 of its partners.Read More

Cisco Developer Contest – The Winners!

2009-10-09T02:48:00.001-07:00

On October 14th, 2008 we announced the Cisco ‘Think Inside the Box’ Developers contest with an objective to educate our application developer community on the power of the network as a platform for enabling innovation. The response to this contest was phenomenal. With over 900 registrants and 110 qualified teams submitting proposals in Phase-1, to the challenge was to narrow the list down to ten finalists who got a chance to develop applications on the Cisco Integrated Services Router’s Application Extension Platform.Read More

Other CCNA jobs in Conyers, GA | Get CCNA Jobs

2009-09-11T06:44:00.001-07:00

Other CCNA jobs in Conyers, GA | Get CCNA Jobs

VMWorld Starts Today!

2009-09-11T06:10:00.005-07:00

Today, VMWare kicked off its user conference VMworld in San Francisco, where they expect more than 10,000 customers to attend and learn about the latest virtualization technologies from many different vendors.Read More

Warner Music + Cisco = Next-Generation Online Music Experience

2009-08-15T03:15:00.003-07:00

In a bicoastal media event earlier today, Cisco Chairman and CEO John Chambers, and Edgar Bronfman, Jr., Chairman and CEO of Warner Music Group (WMG),Read more

Change is Challenging - A Perspective on Cisco’s New Management Structure

2009-08-15T03:15:00.001-07:00

You may have seen a recent Wall Street Journal article on Cisco’s new management structure.Read more

Intranets and Extranets

2009-08-15T02:42:00.000-07:00

Intranet and Extranet are the most common terms in business networking.They are not actually descriptions of network type. Instead, they describe methods of accessing a network.
Intranet is a private Transmission Control Protocol/Internet Protocol (TCP/IP). using Intranet in an organization will only allow internal members to access the network. for example setting a web server which host internal information in organization, Which will only allow the employees of the company to access.

Extranet is a access method that allow a connection between Internet and Intranet. For Example the company has a remote users, who wants to access the internal resources of the company, they can access using Extranet, but there should be a authentication process like a user name and password.

Nokia Middle East and Africa - Nokia N97 - Products

2009-07-29T13:12:00.001-07:00

Nokia Middle East and Africa - Nokia N97 - Products

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Packet Tracer 5.2

2009-07-28T12:18:00.000-07:00

Download latest version of Packet Tracer 5.2 Beta

Download here

Session Layer

2009-07-25T03:37:00.000-07:00

Layer 5, session layer, allows two applications on different computers to open, use, and close a connection called a session. (A session is a highly structured dialog between two workstations.) The session layer is responsible for managing this dialog. It performs name-recognition and other functions, such as security, that are needed to allow two applications to communicate over the network.
The session layer synchronizes user tasks by placing checkpoints in the data stream. The checkpoints break the data into smaller groups for error detection. This way, if the network fails, only the data after the last checkpoint has to be retransmitted. This layer also implements dialog control between communicating processes, such as regulating which side transmits, when, and for how long.
What is session layer?

Next Lesson-->

Presentation Layer

2009-07-18T01:38:00.000-07:00

The main functions of Presentation layer are (Data encryption, Compression, and translation services). Presentation layer ensures that data transferred from the Application layer of one system can be read by the Application layer of another one. Some Standards protocols used for tasks like data compression, decompression, encryption, and decryption.

Next lesson--->

Application Layer

2009-07-16T11:32:00.000-07:00

The application layer of the OSI model marks the spot where users actually communicate to the computer. Layers protocols serve as service provider to user application and workstations. Operations, such as electronic mail, file transfer, name servers, and terminal services are provided in this layer.
Some of the layer protocols:
1- TELNET
2- TFTP (Trivial File Transfer Protocol): Simple file transfer services
3- FTP (File Transfer Protocol): For more elaborate file transfer services
4- SMTP (Simple Mail Transfer Protocol): For message transfer services
5- DNS (Domain Name System): For name server operations
6- SNMP (Simple Network Management Protocol): For network management
7- HTTP (Hypertext Transfer Protocol): For transfer of Web traffic

• Function:
– Network virtual terminal (remote login)
– File Transfer, Access, & Management
– Mail Service
– Directory Service (distributed database & access)

Next Lesson>>>

Lesson 1:changing router name

2009-07-13T01:00:00.000-07:00

In this video you can learn how to change the router name from the command line interface of the router follow the steps, to change the router name to any name you want.

2009 Technology of the Year: Networking and Security | Networking - InfoWorld

2009-07-12T13:17:00.001-07:00

2009 Technology of the Year: Networking and Security | Networking - InfoWorld

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Cisco to expand mobile collaboration features | Mobilize - InfoWorld

2009-07-12T13:15:00.001-07:00

Cisco to expand mobile collaboration features | Mobilize - InfoWorld

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Google's next target: Unified communications | Networking - InfoWorld

2009-07-12T13:14:00.001-07:00

Google's next target: Unified communications | Networking - InfoWorld

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Cisco charts new path with Eos media platform | Networking - InfoWorld

2009-07-12T13:13:00.001-07:00

Cisco charts new path with Eos media platform | Networking - InfoWorld

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100 Essential Skills for Geeks

2009-07-10T13:44:00.001-07:00

100 Essential Skills for Geeks

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Boost Your Certification Study Efforts on the Cisco Learning Network

2009-07-09T12:30:00.000-07:00

Where can you find great Cisco certification resources—including fun learning games, exam prep study materials, and access to Cisco-savvy colleagues?
Read more

Final Notice: Retired CCNA Certification Exam Availability Ends July 31, 2009

2009-07-09T12:23:00.000-07:00

The INTRO (640-821), ICND (640-811), and CCNA (640-801) certification exams (all language versions) will no longer be available to Networking Academy students after July 31, 2009. Vouchers for these exams must be used before July 31, 2009 and cannot be exchanged.
For information about accessing these certification exams and exam vouchers, please review the FAQs.

If you have questions after reviewing this information, please contact your local Networking Academy representative for assistance.

ch1:lesson2: Why using OSI model?

2009-07-04T12:30:00.000-07:00

The purpose of OSI model is to allow different vendors' network to interoperate, for example, they enable us to transfer data between UNIX hosts and Windows host.
OSI model is a layered approach of network communication. The processes of affective communication are divided in logical groupings, which call layers. When communication system is designed in this manner, it's known as layered architecture. As we go through these layers you will notes that they are related to each other.

Advantages of OSI model reference model:
1- It provides guidelines that application developers can use to create new applications which can be run over the network.
2- Provides a framework for creating network standards, devices, and internetworking schemes.
3-It prevents changes in one layer from affecting other layers.

OSI has seven layers; these layers are divided into two groups.
1- The top three layers (Application, Presentation, Session), these layers define how the application within the end stations will communicate with each other and users.
2- The bottom four layers define how data is transmitted end to end.

from http://thenewboston.com

In next lesson will talk about each layer in details.

Next lesson

Ch 1:Lesson 1

2009-07-04T04:08:00.000-07:00

In this lesson we will discuses about the use of computer networking and will expelling some basic networks. But to make it easier I will recommend you to start with the network basics topics which will give you some really good idea about network and the devices used in networking….ect.
And if you have gone through them it will be very easy for you to understand these upcoming lessons.
Ok now as you know the simplest network can be created by connecting two computers to each other. As you see in this figure computer (ALI) is connected to computer (TIM) using hub. Hub creates one collision domain and one broadcast domain. Oh God, what is collision domain and broadcast domain?
So when Pc: ALI wants to communicate with Pc: TIM it will simply send a broadcast massage which will send to all nods on the network.
What is nod? Any device connected to the network called nod.
And when the destination computer (TIM) receive the massage, it will say like oh this is my name and by using DNS it will provide the asking computer some information which is important for communication like MAC address and IP address. This information is sent back to the source computer (ALI) so he can send data to Pc: TIM. Ok but how if TIM wants to communicate with ALI?
It has to go through the same process… yes it has to do the same as Pc: ALI did.

Ok as we knew that Hub creates one Collision domain and one Broadcast domain, what about Switch and Router? And what are their advantages over Hub.
Switch creates different Collision domain (each host has its own domain) and one large Broadcast domain. Switch makes the LAN work better, to optimize its performance and provides more bandwidth for the LAN's users. It operates at data link layer (layer 2) of the OSI model. Switch connects two or more network segments.
What is segmenting? Dividing a large LAN network into smaller networks called segment.

Router creates different Broadcast domain and different Collision domain. That is why Routers used to connect two or more LAN networks and also provides connection to the WAN like (Internet). Router some time called layer three Switch, because it operate at Network layer (layer 3) of the OSI model.
Advantages of using routers in networks, they don't forward broadcast messages by default.
As an example:
If PC (A) wants to communicate with PC (B), it will send a broadcast message to Switch 1, which will forward it to all devices connected to directly to it, like PC (B) and the Router. The PC (B) will receive the message and will process it by providing information about it self. But Router will ignore the message and will not forward it to the next network or (to the Switch 2). This is the advantages of breaking the broadcast domain.

The functions of router in a network are:
1-Packet switching
2- Packet filtering
3- Internetwork communication
4- Determining the pest path for data transmitting.

Next lesson(2)

Collision domain

2009-07-04T04:02:00.000-07:00

It is an Ethernet term used to describe a network scenario wherein on particular device sends a packet on a network segment, forcing every other device on that same segment to pay attention to it. At the same time, a different device tries to transmit, leading to a collision, after which both devices must retransmit, one at a time. Not very efficient! This situation is typically found in a hub environment there each host segment connects to a hub that represents only one collision domain and only one broadcast domain. But in switch every port represents its own collision domain.

Free Web Seminars Prepare for Windows 7 at Global Knowledge

2009-07-04T02:19:00.001-07:00

Free Web Seminars Prepare for Windows 7 at Global Knowledge

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Broadcast Domain

2009-07-03T06:12:00.000-07:00

Broadcast domain is a logical part in a computer network. When computers which are connected to the same device like switch they are in a same single broadcast domain, so if one computer wants to communicate with other computer in the same network (LAN), it just broadcast at data link layer, which will sent to all computer on the network, but the only computer whose address matches will receive it.

As an example:
If computer A wants to send a message to computer C, it will just broadcast a message to a logical address like 10.0.0.255, asking for more information about computer C like its IP address and Mac address. But remember that the broadcast message will be sent to all computers on the network like computer B and D. but only C will replay to the message. Ones A got all information about C, it can now send data to computer C.

Cisco Live Blogger Meetup

2009-07-03T05:23:00.001-07:00

Blogger meetups and tweetups are becoming acceptable forums for people with common interests to come together, share ideas and build meaningful relationships Read more

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From CiscoLive! 2009 in San Francisco

2009-07-03T05:22:00.001-07:00

Going into CiscoLive! in San Francisco, we asked our Cisco Twitter-ers (@CiscoSystems, @padmasree to name a few) to gather questions for Cisco Chairman and CEO John Chambers to answer from the show Read more

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Data Security and the Cloud

2009-06-30T12:04:00.001-07:00

Security

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Saudi Telecom Becomes First Cisco WebEx Authorized Partner in Middle East

2009-06-30T11:59:00.000-07:00

Saudi Telecom Becomes First Cisco WebEx Authorized Partner in Middle East

Daily Blogger Techminute -Cisco Live San Francisco - Data Center Networks

2009-06-30T08:18:00.001-07:00

Daily Blogger Techminute -Cisco Live San Francisco - Data Center Networks

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13,000+ to Attend This Week’s Cisco Live Show

2009-06-30T08:13:00.001-07:00

The Platform

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Hosted E-mail's a Hit, But How Far Will Microsoft Go with Cloud? - CIO.com - Business Technology Leadership

2009-06-28T10:13:00.001-07:00

Hosted E-mail's a Hit, But How Far Will Microsoft Go with Cloud? - CIO.com - Business Technology Leadership

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Education and ICT in the Middle East

2009-06-27T17:14:00.001-07:00

Education and ICT in the Middle East

Cisco Live 2009: 20 Years of Networking - The Platform

2009-06-27T17:13:00.001-07:00

Cisco Live 2009: 20 Years of Networking - The Platform

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Coaxial Cable

2009-06-27T14:51:00.000-07:00

Coaxial cable was the most widely used in network cabling. There were a couple of reasons for coaxial cables usage in past: it was relatively inexpensive, and it was light, flexible (thinnet cable) and easy to work with.
In its simplest from, coaxial cable consists of a core of copper wire surrounded by insulation, a braided metal shielding, and an outer cover.

Shielding:
The Term shielding refers to the stranded metal mesh (or other material) that surrounds some types of cabling. Shielding protects transmitted data by absorbing stray electronic signals, called noise, so that they do not get onto the cable and distort the data. Cable that contains one layer of foil insulation and one layer of braided metal shielding is referred to as dual shielded. For environments that are subject to higher interference, quad shielding is available. Quad shielding consists of two layers of foil insulation and two layers of braided metal shielding.

The core of a coaxial cable carries the electronic signals that make up the data. This wire core can be either solid or stranded. If the core is solid it is usually copper.
Surrounding the core is a dielectric insulating layer that separates it from the wire mesh. The braided wire mesh acts as a ground and protects the core from electrical noise and crosstalk (crosstalk is signal overflow from an adjacent wire).

The conducting core and the wire mesh must always be kept separate from each other. If they touch, the cable will experience a short, and noise or stray signals on the mesh will flow onto the copper wire. An electrical short occurs when any two conducting wires or a conducting wire and a ground come into contact with each other. This contact causes a direct flow of current (Data) in an unintended path. In the case of household electrical wiring, a short will cause sparking and the blowing of a fuse or circuit breaker. With electronic devices that use low voltages, the result is not as dramatic and is often undetectable. These low-voltage shots generally cause the failure of device: and the short, in turn, destroys the data.

Types of Coaxial Cable

1-Thinnet (thin) cable
2- Thicknet (thick) cable

Thinnet:
Thinnet cable is a flexible coaxial cable about 0.64 centimeters thick. Because this type of coaxial cable is flexible and easy to work with, it can be used in almost any type of network installation. Thinnet cable connected directly to computer's network interface card (NIC)

Thicknet:
Thicknet cable is a relatively rigid coaxial cable about 1.27 centimeters in diameter. Thicknet cable is sometime referred to as Standard Ethernet because it was the first type of cable used with the popular network architecture Ethernet. Thicknet Cable's copper core is thicker than a thinnet cable core.

Cisco use Twitter

2009-06-27T08:09:00.001-07:00

Cisco Partner Shares Twitter Best Practices

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Network Cabling

2009-06-26T09:16:00.000-07:00

Cables acts as a network transmission medium that carries signals between computers. Many cable types are available to meet the varying need and size of networks, form small to large.
Cable types can be confusing. Belden, a leading cable manufacturer, publishes a catalog that list more than 2200 types of cabling. Fortunately, only three major groups of cabling connect the majority of networks:

- Coaxial cable(thinnet and thicknet)
- Twisted-pair (shielded and unshielded) cable
- Fiber-optic cable

Related Articles
Twisted-Pair Cable----- What is Network Cabling?------Network Cables-----Cables and connecters

7 Vendor Tech Certifications End Users Love - Surveys

2009-06-24T06:10:00.001-07:00

7 Vendor Tech Certifications End Users Love - Surveys

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Why Ethernet Wins… - Data Center Networks

2009-06-23T16:28:00.001-07:00

Why Ethernet Wins… - Data Center Networks

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Award Winning Corporate Video - Cisco Interaction Network

2009-06-23T16:02:00.001-07:00

Award Winning Corporate Video - Cisco Interaction Network

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Network Interface Cards

2009-06-23T12:57:00.000-07:00

Image via Wikipedia

Networking hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communaications within the network.

Network Interface Cards:

The network interface card (NIC) provides the physical connection between the computer and the network. Most of the NIC are internal which can be fixed to ISA/ PCI/ PCI Express slots. Some computers, uses external boxes which can be connected to serial port or to a SCSI port. Laptop generally use external LAN adapters connected to the parallel port or network cards that slip into a PCMCIA slot.
Network interface card are one of the major factor in determining the speed and performance of a network.

There are three most common network interface cards; they are Ethernet cards, Local Talk connectors and Token Ring cards. Most popular NIC is Ethernet.

Router

2009-06-23T12:55:00.000-07:00

Routers:

Router translate the information from one network to another, It connect two different network. Router combines LANs and WANs working at different transmission speeds and using different variety of protocols. It reads incoming packet's logical addressing information and determines where to deliver packet, it also determines shortest path to the destination. It operates at Network layer and is a protocol-dependent.
While bridges know the addresses of all computers on each side of the network, routers know the addresses of computers, bridges and other routers on the network.
Routers can even "listen" to the entire network to determine which sections are busiest- they can then redirect data around those sections until they clear up.

Cisco Routers

Switch

2009-06-23T12:53:00.000-07:00

Switches:

Switch subdivides a large network into smaller logical pieces (segments), It can optate at layer 2, 3, or 4 of OSI model. Switch is a Multi-port bridges, most of the switches has internal processor, OS, memory, and several ports. Each port on switch acts like bridge, all the connected devices effectively receive own dedicated channel.

Switch Operating Mode:

Cut- Through Mode:
Switch running in cut-through mode reads frame's header and decides where to forward the data before receiving the entire packet. The biggest advantage is the speed of this mode.

Store and Forward Mode:
Switch running in this mode reads entire data frame into memory and checks for accuracy before transmitting. It transmits data more accurately, slower than cut through mode and can transfer data between segments running different transmission speeds.

Related Articles:
Switch- Definition
What is switch?

Hub

2009-06-23T12:51:00.000-07:00

Hubs:

Hub provides a central location for connecting all the cables from computers in a network. A hub can be Active or Passive

Active Hub: works like a repeater (it amplifies the signal)

Passive Hub: Allows signal to pass from one computer to another computer without any change (No amplification).

Based on the size of network the hub may be 8 ports, 12 ports and 24 ports.

Hub is a multiple port repeater and it has uplink port (port to connect two hubs together or any other connectivity device). It operates at Physical layer like a repeater.

Related Articles:

Introduction to Hubs
What is hub?
Ethernet hub
What is hub? - a dfintation
The difference between active hub and passive hub.

Bridges

2009-06-23T12:48:00.000-07:00

Connect two network segments of a network analyze the incoming frame (data) and decide where to direct them based on each frames MAC address. Bridges operate in Data Link Layer, it's a protocol independent device, transfer data's more rapidly than traditional hubs, because it builds it own MAC Address table. It can also be programmed to filter out certain types of frames. It can connect different types of cabling or physical topology, but they must be used between the network with same protocol, gives optimum performance by maintaining the traffic with in the network segment.

test

Connectivity hardware

2009-06-23T12:45:00.000-07:00

Repeater:

Repeaters are the simplest type of connectivity devices that regenerate a digital signal. While the signal travels a long distance through cable it losses its strength. Repeater is a device which used to amplify (boost) these signals and rebroadcast. They are used when total length of the network cable exceeds their standard.
Repeater operates in Physical layer of the OSI model. It can't improve or correct bad or erroneous signal. Regenerate signal over entire segment. It suites only the bus topology network.

Other Devices

Hub
Bridges

Switch
Router

Topology

2009-06-23T12:37:00.000-07:00

Topology: More specifically, a network topology refers to the arrangement or physical layout of computers, cables, and other devices on the network. Topology is the standard term which that used by network professionals when they refer to the network's basic design. You will find several other terms that are used to define a network design:
- Physical layout
- Design
- Diagram
- Map

Choosing one topology over another will have an impact on the:
- Type of equipment the network needs.
- Growth of the network
- Capabilities of the equipment.
- Way the network is managed.

Before computers can share resources or perform other communication task they must be connected. However, it is not as simple as just plugging a computer into a cable connecting other computers. Different types of cable combined with different network cards, operating systems, and other components require different types of arrangements (topology).

Network topology takes planning, for example a particular topology can determine not only the type of cable used but also how the cabling runs through floors, ceilings, and walls. Topology also determines how computers communicate on the network. Different topologies require different communication methods, and these methods have a great influence on the network.

Standard Topologies

All network designs stem from four basic topologies:
- Bus
- Star
- Ring
- Mesh

Variatios on The Standard Topologies:
-Star-Bus Topology
-Star-Ring Topology

Mesh Topology

2009-06-23T12:35:00.000-07:00

Mesh topology offers superior redundancy and reliability. In a mesh topology, each computer is connected to every other computer by separate cabling. This configuration provides redundant paths throughout the network so that if one cable fails, another will take over the traffic. While ease of troubleshooting and increased reliability are definite pluses, these networks are expensive to install because the use a lot of cabling. Often, a mesh topology will be used in conjunction with other topologies to form a hybrid topology.

Read more
Mesh topology
Mesh topology
Mesh networking
What is mesh network?

Bus Topology

2009-06-23T04:03:00.000-07:00

In Bus topology network, the computers are connected in a straight line. This is the simplest and most common method of networking computers. It consists of a single cable called a trunk (it also called backbone or segment) that connects all of the computers in the network in a single line.

Communication on the Bus:
Computer on a bus topology network communicate by addressing data to a particular computer and sending out the data on the cable as electronic signals. To understand how computers communicate on a bus, you need to be familiar with three concepts :

- Sending the signal
- Signal bounce
- Terminator

Sending the signal:
Data in the form of an electronic signal is sent to the entire computers on the network. Only the computer whose address matches the address encoded in the original signal accepts the information and all other computers reject the data.

In this topology only one computer can send at a time and because of that, the number of computers attached to the Bus will affect network performance (the more computers there are on the bus network, the more computers will be waiting to put data on the network cable (trunk), consequently the slower the network will be.

The affect on network performance is not related solely to the number on computers.
The following factors in addition to the number of computers will affect the performance:

- Distances between computers on the network
- Types of cable used on the network
- Total number of queued commands waiting to be executed
- Hardware capabilities of computers on the network
- Type of application being run on the network.

Signal Bounce:
The data or the electronic signal is sent to the entire network, it travels form on end of the cable (trunk) to the other. If the signal is allowed to continue uninterrupted, it will keep bouncing back and forth along the cable and prevent other computers from sending signals. Therefore, the signal must be stopped after it has had a chance to reach the proper destination address.

Terminator:
To stop the signal from bouncing, a component called a terminator is placed at each end of the cable to absorb free signals. Absorbing the signal clears the cable so that other computers can send data. If any computer which was connected to the network, have been removed than open cable end must plugged into terminator to prevent signal bounce.

Extending Bus topology:
The bus topology can be extended by using one of the following methods:
- Component called (barrel connector) which connect two pieces of cable together to make a longer piece of cable.
- A device called (repeater) which is better than (barrel connector), because it boosts the signal before it send the signal on its way.

Read more
Bus Network
Bus topology
What is bus network?

Ring Topology

2009-06-23T03:59:00.000-07:00

The ring topology connects computers on a single circle of cable. Unlike the bus topology, there are no terminated ends. The signals travel around the loop in direction and pass through each computer, which can act as a repeater to boost the signal and send it to the next computer. In this topology the failure of one computer can have impact on the entire network.

More Articles
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Ring Topology
What is ring network?
What is token-ring network?

Star Topology

2009-06-23T03:56:00.000-07:00

In star topology, Number of computers are connected through different cables to the centralized component called Hub.
Signals are transmitted from the sending computer through the hub to all computers on the network. This topology originated in the early days of computing when computers were connected to a centralized mainframe computer.

The advantage on star topology that it provides centralized resources and management. However, because each computer is connected to a central point, this topology requires a great deal of cable in a large network installation.

More Articles
Star network
What is star network?
Star Topology
Topology

Star Ring Topology

2009-06-23T03:54:00.000-07:00

The star ring appears similar to the star bus. Both the star ring and the star bus are centered in a hub that contains the actual ring or bus. Figure shows a star-ring network.

Topologies

Star-Bus Topology (Extended Star)

2009-06-23T03:51:00.000-07:00

The star bus topology is a combination of the bus and star topologies. In a star-bus, several star topology networks are linked together with linear bus trunks.
If one computer goes down, it will not affect the rest of the network. The other computers can continue to communicate. If a hub goes down, all computes on that hub are unable to communicate. It a hub is linked to other hub, those connections will be broken as well.

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What are star and extended star?

Why use a Computer Networking?

2009-06-22T15:54:00.000-07:00

With the availability of today's powerful computers, you maight ask why networks are needed. from the earliest networks to today's high-powered personal computers, the answer has remaind the same :( To increase efficiency and reduce cost).Computer networks achives these primary goals:
- Sharing information (like me and you)
- Sharing hardware and software (like in companies the staff shares the same printer)
- Centralizing administration and support (like connecting client computers to the server).

2009-06-10T09:16:00.000-07:00

Cisco History

In the early 1980s, Len Bosack and Sandy Lerner, a married couple who worked as computer operations staff at Stanford University, were having trouble getting their individual systems to communicate. So in their living room they created a gateway server that made it easier for their disparate computers in two different departments to communicate using the IP protocol. In 1984, they founded cisco Systems with a small commercial gateway server product that changed networking forever. In 1992, the company name was changed to Cisco Systems, Inc. The first product the company marketed was called the Advanced Gateway Server (AGS). Then came the Mid-Range Gateway Server (MGS), the Compact Gateway Server (CGS),the Integrated Gateway Server (IGS), and the AGS+. Cisco calls these “the old alphabet soup products.” In 1993, Cisco came out with the amazing 4000 router and then created the even more amazing 7000, 2000, and 3000 series routers. These are still around. Cisco has since become an unrivaled worldwide leader in networking for the Internet. Its networking solutions can easily connect users who work from diverse devices on disparate networks. Cisco products make it simple for people to access and transfer information without regard to differences in time, place, or platform. In the big picture, Cisco provides end-to-end networking solutions that customers can use to build an efficient, unified information infrastructure of their own or to connect to someone else’s. This is an important piece in the Internet/networking–industry puzzle because a common architecture that delivers consistent network services to all users is now a functional imperative. Because Cisco Systems offers such a broad range of networking and Internet services and capabilities, users who need to regularly access their local network or the Internet can do so unhindered, making Cisco’s wares indispensable. Cisco answers this need with a wide range of hardware products that form information networks using the Cisco Internetwork Operating System (IOS) software. This software provides
network services, paving the way for networked technical support and professional services to maintain and optimize all network operations.