Publications

Cisco CCNA Certification – Cisco VTP VLAN Trunking Protocol

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 Cisco VTP: VLAN Trunking Protocol VLAN Trunking Protocol (VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis.

 

Cisco CCNA Certification – Cisco VTP VLAN Trunking Protocol

By Bob Bello

(VTP) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. Virtual Local AreaNetwork (VLAN) Trunk Protocol (VTP) reduces administration in a switched network. When you configure a new VLAN on one VTP server, the VLAN is distributed through all switches in the domain. This reduces the need to configure the same VLAN everywhere. VTP is a Cisco-proprietary protocol that is available on most of the Cisco Catalyst Family products. VTP ensures that all switches in the VTP domain are aware of all VLANs. There are occasions, however, when VTP can create unnecessary traffic. All unknown unicasts and broadcasts in a VLAN are flooded over the entire VLAN. All switches in the network receive all broadcasts, even in situations where few users are connected in that VLAN. VTP pruning is a feature used to eliminate (or prune) this unnecessary traffic. By default, all Cisco Catalyst switches are configured to be VTP servers. This is suitable for small-scale networks where the size of the VLAN information is small and easily stored in all switches (in NVRAM). In a large network, a judgment call must be made at some point when the NVRAM storage needed is wasted, because it is duplicated on every switch. At this point, the network administrator should choose a few well-equipped switches and keep them as VTP servers. Everything else participating in VTP can be turned into a client. The number of VTP servers should be chosen so as to provide the degree of redundancy desired in the network.

Modes of OperationServer

In VTP server mode, you can create, modify, and delete VLANs and specify other configuration parameters (such as VTP version and VTP pruning) for the entire VTP domain. VTP servers advertise their VLAN configuration to other switches in the same VTP domain and synchronize their VLAN configuration with other switches based on advertisements received over trunk links. VTP server is the default mode.

Transparent

VTP transparent switches do not participate in VTP. A VTP transparent switch does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on received advertisements. However, in VTP version 2, transparent switches do forward VTP advertisements that they receive out their trunk ports.

Client

VTP clients behave the same way as VTP servers, but you cannot create, change, or delete VLANs on a VTP client.

Advertisements Summary Advertisements

When the switch receives a summary advertisement packet, it compares the VTP domainname to its own VTP domain name. If the name is different, the switch simply ignores the packet. If the name is the same, the switch then compares the configuration revision to its own revision. If its own configuration revision is higher or equal, the packet is ignored. If it is lower, an advertisement request is sent.

Subset Advertisements

When you add, delete, or change a VLAN in a switch, the server switch where the changes were made increments the configuration revision and issues a summary advertisement, followed by one or several subset advertisements. A subset advertisement contains a list of VLAN information. If there are several VLANS, more than one subset advertisement may be required in order to advertise them all.

Advertisement Requests

A switch needs a VTP advertisement request in the following situations:

The switch has been reset. The VTP domain name has been changed. The switch has received a VTP summary advertisement with a higher configuration revision than its own. Upon receipt of an advertisement request, a VTP device sends a summary advertisement, followed by one or more subset advertisements.

Configuration To configure an IOS based switch to be a VTP server, issue the following commands: SwitchA# vlan database

SwitchA(vlan)# vtp domain CiscoKits

SwitchA(vlan)# vtp server

SwitchA(vlan)# exit

These commands configure the switch to be a VTP server in the VTP domain CiscoKits. The changes are saved and the revision number is incremented when the exit command is issued. To configure a VTP client, run the following commands:

SwitchB# vlan database

SwitchB(vlan)# vtp domain CiscoKits

SwitchB(vlan)# vtp client

SwitchB(vlan)# exit

To disable VTP, set the vtp mode to transparent as such:

SwitchC# vlan database

SwitchC(vlan)# vtp transparent

SwitchC(vlan)# exit

To monitor the VTP operation and status, use either:

SwitchA# show vtp status

SwitchA# show vtp counters.

Bob Bello, is the owner of http://www.CiscoKits.com At his site you will find over 200 various articles dedicated to Cisco CCNA and CCNP study help, free CCNA and CCNP study exams, step by step labs along with CCNA and CCNP home lab kits.

Article Source: http://EzineArticles.com/?expert=Bob_Bello
http://EzineArticles.com/?Cisco-CCNA-Certification—Cisco-VTP-VLAN-Trunking-Protocol&id=739778

 

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Cisco Certification – Basics of Cisco Routers

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 This article will help familiarize you with various Cisco routers.  It will describe the various features they support so you can pick the right Cisco router to help you prepare for your Cisco CCNA exam.

Cisco Certification – Basics of Cisco Routers
By Bob Bello

Cisco has a number of different routers, amongst them are the popular 1600 series, 2500 series and 2600 series. The ranges start from the 600 series and go up to the 12000 series (now we are talking about a lot of money). All the above equipment runs special software called the Cisco Internetwork Operating System or IOS. This is the kernel of their routers and most switches. Cisco has created what they call Cisco Fusion, which is supposed to make all these devices run the same operating system.

We are going to begin with the basic components which make up a Cisco router (and switches) and I will be explaining what they are used for, so grab that tea or coffee and let's get going !

The basic components of any Cisco router are

 

  1. Interfaces
  2. The Processor (CPU)
  3. Internetwork Operating System (IOS)
  4. RXBoot Image
  5. RAM
  6. NVRAM
  7. ROM
  8. Flash memory
  9. Configuration Register

 

Now I just hope you haven't looked at the list and thought "Stuff this, it looks hard and complicated" because I assure you, it's less painful than you might think ! In fact, once you read it a couple of times, you will find all of it easy to remember and understand. Interfaces These allow us to use the router ! The interfaces are the various serial ports or ethernet ports which we use to connect the router to our LAN. There are a number of different interfaces but we are going to hit the basic stuff only. Here are some of the names they have given some of the interfaces: E0 (first Ethernet interface), E1 (second Ethernet interface). S0 (first Serial interface), S1 (second Serial interface), BRI 0 (first B channel for Basic ISDN) and BRI 1 (second B channel for Basic ISDN).

You have to connect a digital phone to an ISDN line and since this is an ISDN router, it has this option with the router. I should, however, explain that you don't normally get routers with ISDN S/T and ISDN U interfaces together. Any ISDN line requires a Network Terminator (NT) installed at the customer's premises and you connect your equipment after this terminator. An ISDN S/T interface doesn't have the NT device built in, so you need an NT device in order to use the router. On the other hand, an ISDN U interface has the NT device built in to the router.

Apart from the ISDN interfaces, we also have an Ethernet interface that connects to a device in your LAN, usually a hub or a computer. If connecting to a Hub uplink port, then you set the small switch to "Hub", but if connecting to a PC, you need to set it to "Node". This switch will simply convert the cable from a straight through (hub) to a x- over (Node):

The Config or Console port is a Female DB9 connector which you connect, using a special cable, to your computers serial port and it allows you to directly configure the router.The Processor (CPU) All Cisco routers have a main processor that takes care of the main functions of the router. The CPU generates interrupts (IRQ) in order to communicate with the other electronic components in the router. The routers utilize Motorola RISC processors. Usually the CPU utilisation on a normal router wouldn't exceed 20 %.

The IOS

The IOS is the main operating system on which the router runs. The IOS is loaded upon the router's bootup. It usually is around 2 to 5MB in size, but can be a lot larger depending on the router series. The IOS is currently on version 12, and they periodically releases minor versions every couple of months e.g 12.1 , 12.3 etc. to fix small bugs and also add extra functionality.

The IOS gives the router its various capabilities and can also be updated or downloaded from the router for backup purposes. On the 1600 series and above, you get the IOS on a PCMCIA Flash card. This Flash card then plugs into a slot located at the back of the router and the router loads the IOS "image" (as they call it). Usually this image of the operating system is compressed so the router must decompress the image in its memory in order to use it.

The IOS is one of the most critical parts of the router, without it the router is pretty much useless. Just keep in mind that it is not necessary to have a flash card (as described above with the 1600 series router) in order to load the IOS. You can actually configure most routers to load the image off a network tftp server or from another router which might hold multiple IOS images for different routers, in which case it will have a large capacity Flash card to store these images.

The RXBoot Image

The RXBoot image (also known as Bootloader) is nothing more than a "cut-down" version of the IOS located in the router's ROM (Read Only Memory). If you had no Flash card to load the IOS from, you can configure the router to load the RXBoot image, which would give you the ability to perform minor maintenance operations and bring various interfaces up or down.

The RAM

The RAM, or Random Access Memory, is where the router loads the IOS and the configuration file. It works exactly the same way as your computer's memory, where the operating system loads along with all the various programs. The amount of RAM your router needs is subject to the size of the IOS image and configuration file you have. To give you an indication of the amounts of RAM we are talking about, in most cases, smaller routers (up to the 1600 series) are happy with 12 to 16 MB while the bigger routers with larger IOS images would need around 32 to 64 MB of memory. Routing tables are also stored in the system's RAM so if you have large and complex routing tables, you will obviously need more RAM ! When I tried to upgrade the RAM on a 1600 router, I unscrewed the case and opened it and was amazed to find a 72 pin SIMM slot where you needed to attach the extra RAM. For those who don't know what a 72 pin SIMM is, it's basically the type of RAM the older Pentium socket 7 CPUs took, back in '95. This type of memory was replaced by today's standard 168 pin DIMMs or SDRAM.The

NVRAM (Non-Volatile RAM)

The NVRAM is a special memory place where the router holds its configuration. When you configure a router and then save the configuration, it is stored in the NVRAM. This memory is not big at all when compared with the system's RAM. On a 1600 series, it is only 8 KB while on bigger routers, like the 2600 series, it is 32 KB. Normally, when a router starts up, after it loads the IOS image it will look into the NVRAM and load the configuration file in order to configure the router. The NVRAM is not erased when the router is reloaded or even switched off.

ROM (Read Only Memory)

The ROM is used to start and maintain the router. It contains some code, like the Bootstrap and POST, which helps the router do some basic tests and bootup when it's powered on or reloaded. You cannot alter any of the code in this memory as it has been set from the factory and is Read Only.

Flash Memory

The Flash memory is that card I spoke about in the IOS section. All it is, is an EEPROM (Electrical Eraseable Programmable Read Only Memory) card. It fits into a special slot normally located at the back of the router and contains nothing more than the IOS image(s). You can write to it or delete its contents from the router's console. Usually it comes in sizes of 4MB for the smaller routers (1600 series) and goes up from there depending on the router model.

Configuration Register

Keeping things simple, the Configuration Register determines if the router is going to boot the IOS image from its Flash, tftp server or just load the RXBoot image. This register is a 16 Bit register, in other words has 16 zeros or ones. A sample of it in Hex would be the following: 0x2102 and in binary is : 0010 0001 0000 0010.

Bob Bello, is the owner of http://www.CiscoKits.com At his site you will find over 200 various articles dedicated to Cisco CCNA and CCNP study help, free CCNA and CCNP study exams, step by step labs along with CCNA and CCNP home lab kits.

Article Source: http://EzineArticles.com/?expert=Bob_Bello
http://EzineArticles.com/?Cisco-Certification—-Basics-of-Cisco-Routers&id=732737

 

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Linux as an alternative to Windows

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    If you are anything more than a very casual computer user,  you've probably heard someone talking about Linux recently. Perhaps you're wondering exactly what Linux is and what all the fuss is about?  Well, read on and we'll attempt to answer some of the questions you may have and hopefully dispel a few myths and misconceptions along the way.

    Linux is an operating system much like Windows XP or Vista, Mac OSX, etc. An operating system is basically just a bunch of instructions that manage the software and hardware on your computer. Software refers to all of the applications that you use, such as word processing programs, web browsers, email clients, etc. Hardware is the physical parts of your computer such as the processor, memory, CD drives and the like.

    Why would I want to try Linux? I would have to say that the main reason for using Linux is that it's free. Yes, FREE! Linux is an “open source” operating system. The definition of open source is software that has been developed by a community of folks and provided to the general public, free of cost.  A second reason is that it runs very well on an older computer that may not be capable of running the newest version of Windows. Thirdly, there are literally tens of thousands of open source applications (software) that are available for download. Lastly, there is security.  Linux was developed from the start with security in mind. The Linux operating system is not as susceptible as Windows is to a majority of the threats that are common on the internet today.

    OK, so what's the catch? Well, there is a new user interface to learn. The Linux desktop doesn't “look” like a Windows desktop. Of course, a Vista desktop doesn't look like an XP desktop and a Mac desktop doesn't look like a Windows desktop, so there is a bit of a learning curve going from one operating system to another, regardless of which one you choose.  Linux also has a reputation of being a “techie's” operating system, requiring a bit more knowledge to set up and use than the typical user may possess but this has been largely eliminated as of late. Another issue is that Linux may not work with the latest cutting edge hardware, although as the use of Linux becomes more widespread this is less of a problem that it has been in the past.

    Who is Linux good for? This operating system works very well for those of us that simply need the basics: browsing the web, checking email, writing documents, working with spreadsheets, etc. Linux is a great choice for those Windows 98/2000/XP users whose old computers are running really slow and are considering upgrading but have to buy a new PC just to run Vista. It's also good for those power users that like to dig around and play “under the hood” so to speak. Linux will not work for those users that need to run Windows only software such as QuickBooks, or “gamers” who play games written exclusively for Windows.

    Alright, so you've decided that you want to try Linux, now what? My suggestion is to download a copy from the internet and see how you like it. Linux comes in many varieties called “distributions” (or “distros”). There are several distros that I can recommend for a new user; these are listed at the end of this article. All of these are available in what is referred to as a “live” format, meaning that they can be run from a CD without actually having to install them on the hard drive of your computer. You simply download and burn the CD, put it in your CD player, and reboot your computer. (Keep in mind that they will run a bit slower than they would if they were actually installed). This allows you to get a feel for Linux and how it works, as well as testing whether a particular distribution can detect and correctly configure all of your hardware. If you decide that you like one of these, there is usually an “install to hard drive” option right on the desktop. You can even install Linux in parallel to Windows and choose which operating system to load when your computer boots up!

    What if I have problems, where can I get help? There is a fantastic community of Linux users on the internet that are more than happy to help new users. Google is your friend. Most communities have a local Linux User's Group (LUG) that holds open meetings on a regular basis; new members are always welcome. These LUG's usually have occasional “Install Fests” where you can bring you computer and they will help you install Linux and answer any questions you may have. Check you local computer magazines for information on these type activities and groups.  Again, Google is your friend.

    I hope this article has answered some of your questions about Linux and maybe even made you consider giving it a try. Below is a list of resources you will find helpful if you decide to pursue this further.

Todd Hughes is a Network Security Analyst and long time Linux fan in the Upstate New York area. Send your Questions, comments or feedback to: thughes@fwpm.com.

Copyright  Todd Hughes  2007. Printed by permission.
   

Resources:

Recommended Distributions:

http://www.pclinuxos.com/index.php?option=com_ionfiles&Itemid=28
http://www.xpresslinux.com/download.php
http://www.kubuntu.org/download.php
http://www.knopper.net/knoppix/index-en.html
http://www.mepis.org/mirrors
http://www.mandriva.com/en/download/free

Other Distributions:

http://distrowatch.com/

How to “burn” a disk properly:

-using Windows XP
http://www.petri.co.il/how_to_write_iso_files_to_cd.htm
-using Nero
http://www.wizardskeep.org/mainhall/tutor/neroiso.html

-using Roxio
http://onlinepubs.trb.org/onlinepubs/burning_iso.html

 

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Linux In Easy Steps

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Linux In Easy Steps by Mike McGrath. Published 2006 by Computer Step. Paperback. 240 pages. $9.95.

Linux In Easy Steps is an introduction to the world of Linux in simple English and full color illustrations. It covers installation, configuration, file structure, working online, using the shell, networking and working with sound and video in simple language designed for the newbie.

www.ineasysteps.com

www.bn.com  

Upgrading and Repairing Laptops

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Upgrading and Repairing Laptops by Scott Mueller. Published annually by Que Publishing, Inc. Hardcover. Over 800 pages. $49.99.

Scott Mueller, one of the most renowned experts in the industry, covers laptops from A to Z in this comprehensive publication that is used by computer professionals worldwide. He has taught thousands of computer technicians and sold over 2 million copies of his books. Upgrading and Repairing Laptops is the definitive guide that has earned its place on workbenches everywhere.

www.quepublishing.com

www.upgradingandrepairingpcs.com  

Upgrading and Repairing PCs

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Upgrading and Repairing PCs by Scott Mueller. Published annually by Que Publishing, Inc. Hardcover. Over 1500 pages. $59.99.

Scott Mueller, one of the most renowned experts in the industry, covers computers from A to Z in this comprehensive publication that is used by computer professionals worldwide. He has taught thousands of computer technicians and sold over 2 million copies of his books. Upgrading and Repairing PCs is the definitive guide that has earned its place on workbenches everywhere.

www.quepublishing.com

www.upgradingandrepairingpcs.com  

Small Business Kit For Dummies

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Small Business Kit For Dummies by Richard D. Harroch. Published 1998 by IDG Books Worldwide. ISBN: 0764550934 Paperback. 369 pages. $29..99.

Written by an attorney, Small Business Kit For Dummies covers the business and legal aspects of starting and running a small business, from choosing the type of business entity to writing press releases. The book includes a CD with over 250 sample forms, legal agreements and company guidelines.

Direct From Dell

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Direct From Dell. Strategies That Revolutionized an Industry by Michael Dell. Published 1999 by HarperCollins Publishers Inc. SBN: 9780060845728; ISBN10: 0060845724. Paperback Pages: 272 $15.95. Audiobook Abridged 3 Hours read by Michael Dell. $18.00.

Michael Dell, Chairman and CEO, Dell Corporation, tells the story of his rise to success from a freshman college student building computers in his dorm room to a multibillion dollar OEM. He discusses the strategies that made his business successful and outlines his philosophies on how to build a business from the bottom up. A must read for every entrepreneur. 

The E-Myth Revisited

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The E-Myth Revisited: Why Most Small Businesses Don't Work and What to Do About It by Michael E. Gerber. Published 1995 by HarperCollins Publishing. ISBN: 0-88730-728-0 Paperback. 268 pages. $16.00.

Michael E. Gerber reworks the concept of the modern business into a model based on planning and building each small enterprise from the ground up as if it were to become a franchise. The methods are based on principles of clear goals, careful planning and the preparation for future success. Gerber is chairman of The E-Myth Academy with over 15,000 clients. The book has sold over 250,000 copies.

http://www.harpercollins.com  

Start Your Own Computer Business

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Start Your Own Computer Business – The Unimbellished Guide By Morris Rosenthal. Published 2002 by Foner Books. ISBN: 0-9723801-0-8 Paperback. 160 Pages. $14.95.

Morris Rosenthal takes 15 years of experience in the computer business and condenses it into a book that covers it from the business side. This is not a technical how-to manual about how to service computers as a business but a guide on how to run a small business profitably. Rosenthal is also the founder and moderator of the Computer Business support group on Yahoo with more than 3500 members.

 

http://www.fonerbooks.com/compbiz.htm

http://finance.groups.yahoo.com/group/computerbusiness