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While I’m always anxious to work with a new NOS such as Microsoft Vista in a lab environment, I’m never one of the first to actually roll a new NOS out into a production network. According to an article in the September 18, 2007 edition of The Wall Street Journal, there are those who are happy to be an early adapter - and Microsoft’s happy to get their feedback!

Robert Guth’s article notes some interesting statistics when it comes to Vista rollouts. Among 565 companies in the United States and Europe surveyed (all companies had at least 1000 employees), 7% are beginning a Vista rollout this year, 25% plan to start a Vista rollout sometime in 2008, but 38% have no plans to move to Vista.

The article mentions that some users may be hesitant to move to Vista because software programs will have to be modified to run on Vista, and that’s certainly true. I do believe that many network admins themselves aren’t convinced that a move from XP to Vista is necessary for their network, thinking that the potential gains aren’t worth the short-term headaches that accompany any NOS upgrade.

Luckily for Microsoft, not everyone feels that way. The article mentions Eric Craig, a managing director for Continental Airlines, and his drive to roll Vista out. They’ve run into some issues with software drivers and some of the usual suspects with an NOS upgrade, but right now they’re moving right along and expect to have about half of their 18,000 PCs upgraded to Vista by early 2008.

Feedback from early Vista adapters like Continental is invaluable to improving Vista, and that feedback is also an important part of Microsoft’s software application certification process. Guth’s article mentions that over 2000 applications have now been Vista-certified, and that’s a large increase over the 250 that were certified at the beginning of 2007.

Microsoft’s got a long way to go with Vista, though, if 38% of companies out there aren’t even thinking of moving to Vista. Several network chiefs interviewed in the article voiced concerns about - you guessed it - having their software programs run smoothly on Vista. With Vista SP 1 on the horizon, though, those concerns may lessen. As an analyst for Forrester Research quoted in the article says of networks upgrading to Vista, “It’s not a matter of if, it’s a matter of when and how”. That sounds like a nice way of saying “You will be assimilated!”

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free Cisco CCNP and Cisco CCNA exam tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages.

You can also visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions!
For a FREE copy of his latest e-books, “How To Pass The CCNA” and “How To Pass The CCNP”, just visit the website! You can also get FREE CCNA and CCNP exam questions every day!

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Computer certifications represent a very effective way to get to know certain technologies and help you advance in your career. The good thing is that certification courses take much less time than complete a university degree and at the end, such computer certifications might even turn out to be more valuable on the job market, because they prove that you posses excellent knowledge in a very strict and well defined field, which could be programming, networking or web design. All these factors make computer certification the perfect option for people who want more education, but don’t want to spend 4 years at a university studying all types of subjects that are not even merely related to what they are planning to work.

Generally, we can say that there are five types of computer certificates and they are: Microsoft; Oracle Database; Cisco Networking; Web Development; PC Service and Support (both hardware and software).

Microsoft is the leader in the world of IT solutions, hence the demand for skilled professionals with a Microsoft certification is quite high, so if you have one, your chances of getting a job like that are extremely good. Because when you are certified, it shows you have went through some of the most demanding and comprehensive training available. The MS certificates are further divided into Microsoft Windows Certified Professional, Microsoft Windows Systems Engineer, Microsoft Windows Networking Professional, Microsoft Windows Professional Engineer.

Especially attractive are the Cisco and Oracle certifications, because the demand for such professionals is extremely high as are the salaries in this sector. Those two companies are as you probably know, the leading providers of database and networking solutions, respectively. The high demand is explained by the Internet boom, which causes networks to expand even further every day, and databases too.

The Web Development types of certifications are intended for people who want to get involved in the production of websites. Those certificates are further divided into - E-Commerce Specialist, Client/Server Web Development, Web Design Specialist.

The PC Service and Support certificates are designed for people who want to learn how to install and set-up computer hardware, Operating Systems and troubleshoot typical problems related with those hardware and software components.

The best part of it all is that computer certifications can be obtained online. All that is requires is a computer with Internet connection, self-discipline and desire to learn. With an online computer certification, the distance, time and financial constraints are irrelevant.

Steve Gargin owns and operates
http://www.computer-network-certifications.com href="http://www.computer-network-certifications.com" target="_new">Computer
Certifications

IT professionals certified by Microsoft have become hot commodities in the job market. Training is highly necessary to get any of these different types of certifications. MCSE training program is one of those programs that aims at the MCSE certification.

All Microsoft training programs comes under MCP training program. Apart from MCSE training program, the other programs that come under MCP program are MCSD, MCSA, MCDBA, MCT and many more such type of certification training programs.

MCSE training programs are an effort to enhance the understanding of an individual in various Microsoft technologies and thus this ways they really boost the confidence of the candidates. One who gets certified with this course is able to efficiently analyze the business requirements of the information system of an organization and design and implement infrastructure for the same.

MCSE training is available on two windows operating platforms- MCSE 2000 and MCSE 2003. Both require seven exams to be cleared which are based on how to plan, design, implement, manage and troubleshoot these Windows Operating Systems. You can find more information about microsoft certifications at http://www.CertificationsReviews.com

In MCSE 2003 training program, the candidate receives training for six core exams that contains four papers on networking technologies and one paper on client operating system and one on designing concepts. In addition to these core exams, the candidate also has to clear one elective exam which has a number of options for the candidates.

MCSE training is provided to the candidate through various means. One can make use of on line training courses that are easily accessible through the Internet and provide facilities like study materials, practice exams, lab simulators on line at any time or day, for the convenience of the candidates.

Practice exams are actually meant to familiarize the candidate with the actual MCSE exam pattern and environment. Since a candidate has to clear all his exams in one attempt, these practice test exams are of a great help to the candidates.

Classroom style MCSE training courses are just like the usual training courses but they are well equipped with all the facilities that are required by the candidate to fully prepare for the exams.

Then there are boot camps facilities which are basically for those candidate who already holds a MCSE certificate and wants to upgrade their certification in to the latest MCSE certificate.

There is one more option known as MCSE brain dumps that contain questions in the form of a study guide but are not recommended sources of training.

Therefore there are various ways to receive MCSE training. The choice should be made after evaluating the cost of training, convenience and availability of the training program. It is highly recommended to go for these training programs before giving the exams.

Article by Kevin Bing at http://www.certificationsreviews.com For more great free information on everything you should know about microsoft certifications visit => Microsoft Certification Training

How to pass your Information Technology Certification Exam is the question that ALL students who are preparing for their IT certification exam should be asking! With many online sites giving you certification test taking tips and techniques where do you begin with gathering the pertinent information about being prepared for your certification? There are 2 major questions that every prospective student looking for their information technology certification should be inquiring. Certification test taking tips and techniques really come down to the study technique and the appropriate material.

There are many Information Technology Certification practice test questions, free study guides, free online tutoring and practice exam questions that people want such as: Microsoft, Comp TIA, MCDST, MCP, MCSA, MCSE, A+, MCPD, Comp TIA Network, Comp TIA Security, CCNA, CNA, CISA and many others. Knowing the secrets of certification test taking and implementing the most effective technique will give you the edge in passing your certification exam. You can lose your fear of test taking and have the confidence you need when going to your certification exam center.

What is the most effective study technique to use when studying for your information technology certification exam? Many online certification training centers will tell you to relax, use flash cards to prepare, review your material the day before the exam and to think positive about passing. Memorization of all your material is not the most logical choice for exam preparation. If you have a book that is eight hundred pages long and five hundred practice exam questions then you would be foolish to try to memorize all of this material or even part of it. There is another very effective way of retaining the information that you need to pass your information technology certification exam. Simple repetition of the actual exam material will better prepare you for your certification exam.

Having the appropriate material like practice exam questions and study guides will better prepare you for your certification exam then anything else you may obtain. There is much online certification training and the material that they use is extremely important when it comes time to take your exam. There is much IT certification material that will help you understand the operation of a windows operating system but how much of that material will be on the actual exam? In order to pass your information technology certification exam you will want only the material that pertains to the actual exam itself. If you could have the exact IT certification exam right in front of you to study before you took the actual certification exam would you not be better prepared to pass then any other method?

Exam preparation does not have to be difficult. Why spend your money on useless material that is out dated and irrelevant to the actual certification exam. You can learn much from someone who has taken an information technology certification exam and how they prepared using a proven way of success. Their test taking techniques could benefit you more then any study guide. Information technology test taking is unlike other certifications. Certification preparation is really not as difficult as some make it out to be. If you use the most effective study technique and the best test taking tips about studying the exact material on the actual certification exam then you will be able to go to the exam center fully confident about passing. I’m giving you the best knowledge on the subject of Information technology certification test taking tips & techniques.

Bill Naugle has been writing articles, press releases and ebooks to help webmasters achieve success with information technology certification, Internet business and search engine rankings. He has written on many subjects. http://www.billnaugle.com http://www.lulu.com/content/1198023

The Microsoft Certified Professional (MCP) credential (certification) is for professionals who have the skills to successfully implement a Microsoft product or technology as part of a business solution in an organization. Hands-on experience with a product is necessary to effectively achieve certification. There are many Microsoft certifications that one may acquire and many free online training centers that also have pay certification tutoring, free study guides and free practice exam questions to help you pass your IT certification exam.

The Microsoft Certified Professional has many different certifications that represent specialized fields of information technology such as: Microsoft Certified Technology Specialist (MCTS) and Microsoft Certified IT Professional (MCITP) credentials provide IT professionals with a simpler and more targeted structure to display their technical and professional skills. The new Microsoft Certified Technology Specialist (MCTS) credential highlights your skills using a precise Microsoft technology. You can demonstrate your abilities as an IT professional or developer with in-depth knowledge of the Microsoft technology that you use today or are planning to deploy. The Microsoft Certified IT Professional (MCITP) credential lets you highlight your field of expertise. Now you can distinguish yourself as an IT professional with the current skills and proven job-role capabilities to work efficiently with a comprehensive set of Microsoft technologies.

Other Microsoft certifications include: Microsoft Certified Database Administrator
Demonstrate that you have the skills to lead organizations in the successful design, implementation, and administration of Microsoft SQL Server 2000 databases with the following Microsoft Certified Database Administrator (MCDBA) credential. The Microsoft Certified Desktop Support Technician (MCDST) credential proves that you have the skills to support users who run Windows XP. It also proves that you can troubleshoot desktop environments that run on the Windows XP operating system. The pay scale with this position ranges from $35,000 to $55,000 per year. With all of these Microsoft certifications excellent training is obtainable online or classroom. To some degree you will find free Microsoft online certification training along with pay training.

There is also the Microsoft Certified Systems Administrator (MCSA) certification will advance your career by ensuring that you have the skills to successfully manage and troubleshoot system environments that run on the Microsoft Windows operating system. The MCSA: Messaging credential identifies systems administrators who implement, manage, and maintain a messaging infrastructure by using Microsoft Exchange Server. The MCSA: Security credential identifies systems administrators who specialize in managing, maintaining, and implementing security on the Windows operating system and as part of a secure computing environment. Receive the Microsoft Certified Systems Engineer (MCSE) certification and prove your expertise in designing and implementing the infrastructure for business solutions that are based on the Windows 2000 operating system and the Windows Server system. The MCSE: Messaging credential identifies systems engineers who design, plan, implement, manage, and maintain a messaging infrastructure by using Microsoft Exchange Server. The MCSE: Security credential identifies systems engineers who specialize in managing, maintaining, and implementing security on the Windows operating system and as part of a secure computing environment. The pay scale on this job ranges from $50,000 to $80,000 per year.

Free Microsoft certification online training is always limited in the amount of study material that is given. In order for you to be adequately prepared for your certification exam you will need to pay some for complete training so you will be able to pass your information technology certification exam. Many online training centers offer some free Microsoft certification training as a draw to get you to purchase the more in-depth material that will fully prepare you for your final certification exam. You will also need special training in test taking to prepare you to pass your information technology certification exam. All of this information is online ready for you to access. Visit billnaugle.com

Bill Naugle has been writing articles, press releases and ebooks to help Webmasters achieve success with information technology certification, internet business and search engine rankings. He has written on many subjects. He started writing on the internet in 2001. http://www.billnaugle.com http://www.lulu.com/billn

Microsoft has many computer certifications that appeal to a wide range of expert computer repair technicians to operating system geniuses. They also have certifications in administration and engineering. Microsoft Certified Professionals are a standard above in the field of information technology. Microsoft certification is widely accepted and recognized by the service and support industry. Microsoft curriculum has the practical knowledge that only an advanced developed company can provide.

MCDST is one of the most sought after Microsoft certifications on the market today. Microsoft Certified Desktop Support Technician is a title that has much recognition for employers who want a highly qualified technician to work as a help desk specialist and give desktop support by phone and by servicing the individual station. Microsoft Certified Desktop Support Technician (MCDST) on Microsoft Windows XP is a certification that validates the fundamental and higher skills needed to enter the IT industry as a support desk professional.

Because of the recognition that Microsoft Certified Desktop Support Technician (MCDST) receives many online and classroom IT schools are offering some free tutoring. You will find free information technology Microsoft computer training on the web almost as much as you will find pay certification training. There is a long list of online schools that offer free study guides, some free online tutoring and free practice exam questions in order to prepare you for your certification.

MCDST certification demonstrates valuable troubleshooting expertise with the Windows Desktop Operating System to employers and consumers. It provides a structure for learning the skills that support technicians need. As a desktop support technician, you will use excellent customer service skills, educate users, and solve hardware or software operation and application problems on the desktop. You will learn valuable skills and best practices consistent with networking and file sharing to maintaining DHCP communications devices and Domain name system for Internet system to translate names into IP addresses.

Microsoft Certified Desktop Support Technician certification validates the fundamental skills needed to enter the IT industry as a support professional. It communicates the technical skills of the individual to clients and employers and distinguishes career candidates from their peers. MCDST certification enhances job satisfaction through increased technical proficiency as you increase your knowledge and skills. MCDST certification helps advance support technician careers by providing a structured framework for learning skills, and provides a knowledge basis for additional Microsoft certifications, such as the MCSA and the MCSE.

Microsoft Certified Desktop Support Technician Certification Requirements on Microsoft Windows XP are to pass two core exams that provide a valid and dependable measure of technical proficiency. These exams are developed with the input of professionals in the industry and reflect how Microsoft products are used in organizations throughout the world. The two core exams are: Exam 70-271: Supporting Users and Troubleshooting a Microsoft Windows XP Operating System consisting of about 60 questions and Exam 70-272: Supporting Users and Troubleshooting Desktop Applications on a Microsoft Windows XP Operating System consisting of about 50 questions.

A candidate for Microsoft Certified Desktop Support Technician will need training for your Microsoft certification. There is free Microsoft training available online with free Microsoft practice exam questions, free study guides and free MCDST training to make your preparation less complicated. Free will only take you so far, you will need to purchase some Microsoft certification training in order to be fully prepared for your actual exam. Your training is not the objective but receiving your Microsoft certification. Learn how to pass your information technology certification exam. There are good resources accessible all you will need is a little searching. Visit billnaugle.com

Bill Naugle has been writing articles, press releases and ebooks to help Webmasters achieve success with information technology certification, internet business and search engine rankings. He has written on many subjects. He started writing on the internet in 2001. http://www.billnaugle.com http://www.lulu.com/content/1198023

(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.

The Internet has an abundance of online resources of free and pay practice exam questions about information technology computer certification. There are many companies with high visibility websites that offer free practice exam and test questions to show that they are concerned about giving you some certification training. The practice exam questions that are more relevant to the actual certification exam will require a purchase. These websites are hoping that you will like the free practice test questions so you will want to purchase the detail ones that give you an explanation of the answer.

What are the advantages of purchasing computer certification practice test questions over the free practice exam questions that are available? Free practice exam questions can be helpful for those want to save on your expenses. Free practice exam questions are usually the basics of information technology. The real in-depth material of computer technology will have to be purchased. The best practice exam questions usually come at a moderate price.

Where does a student who is preparing for an IT certification exam find practice exam questions that are similar or practically identical to the real certification exam? Can there possibly be a place for a person to find practice test question on computer certification that would be just like the ones on the actual exam? What would you look for in finding the best and most applicable practice exam questions about the actual certification exam? I would look for a place that had up to date practice exam question. Microsoft and others are constantly changing the test questions on the certification exam. All software companies have updates to there system, so the test questions should change also.

A student who had practice exam questions pertaining to the field of technology that they were studying that were almost identical to the original certification exam, wouldn’t they be better prepared for the final certification exam? Knowing what is on the final certification exam can build your confidence and ability to pass it. I would say that there are very few places where you could find practice exam questions that would be the same as the actual certification exam and have the price be reasonable.

Is it possible to find a Website or book that tells you how to pass your information technology certification exam? Who would have information on the best practice exam questions that would be closest to the actual certification exam? Knowing what a certification test looks like and how to prepare for it would be very beneficial. Practice exam questions can tell you what material you should be studying for the final certification exam. No one can memorize all of the material related to a field of IT certification. Practice exam questions are very important to use in preparing for your certification exam.

Getting some advice from someone who has gone through the whole experience of receiving his or her information technology certification would greatly help. Someone who has not only a success story to tell you about when passing a certification exam but also can tell of a failure in order for you to better learn from their mistake. They probably could tell you where you could get the best computer training and find the best practice exam questions that would be the closest to the actual certification exam at a good price.

Does anybody really know how to use practice exam questions to prepare for a computer certification exam? How do you study practice questions for an IT certification exam? Most practice exam questions purchased will be 300 or more and there are only about 60 questions on the actual certification exam. Is it possible to memorize all 300 questions to be completely prepared to take your certification exam? Some certification practice questions come in a package of about 700 questions and only 100 actual questions on the exam. Do you really need to memorize the practice test questions or is there another way? I bet someone on the Internet has the information that you are looking for.

Bill Naugle has been writing articles, press releases and ebooks to help Webmasters achieve success in with information technology certification and search engine rankings. He has written on many subjects. He started writing on the internet in 2001. http://www.billnaugle.com http://www.lulu.com/content/1208271

If you have been searching for MCSE certification exams then you probably have noticed that there are so many to choose from. So how on earth do you know which one’s are going to be the best. Getting the proper training for your MCSE certification exam is the key to passing the exam with flying colors.

There are many online MCSE certification training classes that you can join and this is great if you have limited amount of time due to your current working situation. It’s self paced so you have to be sure that you are conditioned enough to study the right amount of time in order to gain the necessary knowledge that you will need in order to pass the MCSE certification exams.

I suggest that if you have the time that you should take the classes at one of the local schools in your area. Classroom training is the best way to learn all of the information. I understand that this may not always be an option, but if you can find a way to make it work then you should. A teacher will be there to help you in area’s that you need help with. There is a lot of information that you are going to need to know and it’s not always so easy to remember or understand.

After you have completed your MCSE training you will be ready to take your MCSE certification exams. These exams will be announced directly through Microsoft, but you can also find out about them in other ways as well. Such as through your training course, and Microsoft website.

Once you have passed your MCSE certification exam you will have your certificate and you that is your proof that you have the knowledge to do the job of a MCSE. You should be proud of yourself, and now you will have many other opportunities available to you. There are plenty of other things that you can do to increase your income such as taking another course to get certified in many other IT careers. The IT profession is ever changing and there is always new things coming out and there is always going to be many different opportunities within this field and by understanding this and progressing even further by advancing your career you will be offering yourself more pay and much more stability in your life.

P Abbey owns and operates http://www.mscertificatetips.com/mcsecertificationexams.html MCSE Certification Exams

The standard model for networking protocols and distributed applications is the International Standard Organization’s Open System Interconnect (ISO/OSI) model. It defines seven network layers.

Short for Open System Interconnection, an ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.

At one time, most vendors agreed to support OSI in one form or another, but OSI was too loosely defined and proprietary standards were too entrenched. Except for the OSI-compliant X.400 and X.500 e-mail and directory standards, which are widely used, what was once thought to become the universal communications standard now serves as the teaching model for all other protocols.

Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.

Layer 1 - Physical

Physical layer defines the cable or physical medium itself, e.g., thinnet, thicknet, unshielded twisted pairs (UTP). All media are functionally equivalent. The main difference is in convenience and cost of installation and maintenance. Converters from one media to another operate at this level.

Layer 2 - Data

LinkData Link layer defines the format of data on the network. A network data frame, aka packet, includes checksum, source and destination address, and data. The largest packet that can be sent through a data link layer defines the Maximum Transmission Unit (MTU). The data link layer handles the physical and logical connections to the packet’s destination, using a network interface. A host connected to an Ethernet would have an Ethernet interface to handle connections to the outside world, and a loopback interface to send packets to itself.

Ethernet addresses a host using a unique, 48-bit address called its Ethernet address or Media Access Control (MAC) address. MAC addresses are usually represented as six colon-separated pairs of hex digits, e.g., 8:0:20:11:ac:85. This number is unique and is associated with a particular Ethernet device. Hosts with multiple network interfaces should use the same MAC address on each. The data link layer’s protocolspecific header specifies the MAC address of the packet’s source and destination. When a packet is sent to all hosts (broadcast), a special MAC address (ff:ff:ff:ff:ff:ff) is used.

Layer 3 - Network

NFS uses Internetwork Protocol (IP) as its network layer interface. IP is responsible for routing, directing datagrams from one network to another. The network layer may have to break large datagrams, larger than MTU, into smaller packets and host receiving the packet will have to reassemble the fragmented datagram. The Internetwork Protocol identifies each host with a 32-bit IP address. IP addresses are written as four dot-separated decimal numbers between 0 and 255, e.g., 129.79.16.40. The leading 1-3 bytes of the IP identify the network and the remaining bytes identifies the host on that network. The network portion of the IP is assigned by InterNIC Registration Services, under the contract to the National Science Foundation, and the host portion of the IP is assigned by the local network administrators. For large sites, the first two bytes represents the network portion of the IP, and the third and fourth bytes identify the subnet and host respectively.

Even though IP packets are addressed using IP addresses, hardware addresses must be used to actually transport data from one host to another. The Address Resolution Protocol (ARP) is used to map the IP address to it hardware address.

Layer 4 - Transport

Transport layer subdivides user-buffer into network-buffer sized datagrams and enforces desired transmission control. Two transport protocols, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP), sits at the transport layer. Reliability and speed are the primary difference between these two protocols. TCP establishes connections between two hosts on the network through ’sockets’ which are determined by the IP address and port number. TCP keeps track of the packet delivery order and the packets that must be resent. Maintaining this information for each connection makes TCP a stateful protocol. UDP on the other hand provides a low overhead transmission service, but with less error checking. NFS is built on top of UDP because of its speed and statelessness. Statelessness simplifies the crash recovery.

Layer 5 - Session

The session protocol defines the format of the data sent over the connections. The NFS uses the Remote Procedure Call (RPC) for its session protocol. RPC may be built on either TCP or UDP. Login sessions uses TCP whereas NFS and broadcast use UDP.

Layer 6 - Presentation

External Data Representation (XDR) sits at the presentation level. It converts local representation of data to its canonical form and vice versa. The canonical uses a standard byte ordering and structure packing convention, independent of the host.

Layer 7 - Application

Provides network services to the end-users. Mail, ftp, telnet, DNS, NIS, NFS are examples of network applications.

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.