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What to Know Before Upgrading Your Cisco Router

noreply@blogger.com (Unknown) — Sun, 4 Jan 2009 23:55:00 +0700

What to Know Before Upgrading Your Cisco Router
Expanding the capacity of any high bandwidth network is always an involved process. The actual cost of upgrade hardware and the task of physically installing RAM memory into your Cisco routers' expansion slots is simple enough, but most high-capacity data networks serve production environments which demand fault-tolerance and as near to total uptime as possible. In order to build a network that can be relied upon to guarantee this level of service, network engineers need to plan a long way ahead. In addition to ensuring the servers, workstations, cabling and software can handle increasing loads for years to come, when planning a new segment, a good engineer will consider the possible lifetime cost and load of each and every crucial device on the network. This includes Cisco routers!

As it may be difficult to even temporarily disconnect a mission-critical router to upgrade its memory, one way to "future proof" your network is to upgrade the device at purchase - prior to installation. This may sound expensive, but in any truly high-bandwidth medium, the cost of downtime or loss of connectivity far outweighs the safe option of upgrading your routers memory to the maximum before installing it.

If you do indeed decide to take the path of pre-upgrading a Cisco router for life, you will be choosing to save yourself from ever having to take it out of commission in order to install new Cisco DRAM memory or flash. Though the cost may be significant, not upgrading presents even more significant risks. It's well known that a router is more likely to fail if it is run with insufficient RAM for it to cope with its workload.

This raises the question of Cisco memory will be enough over the lifetime of a given product. Unfortunately, there's no simple answer to this question: How much RAM a Cisco router is going to need changes depending on the enterprise and its scale, what sort of applications your network is (and will be) supporting, and of course, which series router you're using. Cisco makes some forecasts and recommendations available to customers to assist in making this judgment.

Generally, upgrading to the maximum memory your router is capable of supporting takes some of the guesswork out of this equation. The Cisco memory requirements for each are made available in individual the product specifications, and Cisco lists which product lines will be supported at least 18 months in advance. In this way, a diligent network analyst may make fairly accurate predictions of what their individual requirements will be for at least the next couple of years, and likely, much longer.

After checking the installation procedure and maximum upgrade capacity for your particular Cisco router, you have two options, either purchasing the memory directly from Cisco at a considerable markup, or from a memory reseller such as PC Wholesale. Memory resellers offer a tremendous advantage over purchasing directly from Cisco for the budget conscious company – many times their prices can be up to 90% off Cisco’s list price, for the same exact memory!

Upgrading Your Cisco Memory

noreply@blogger.com (Unknown) — Sun, 4 Jan 2009 23:54:00 +0700

Upgrading Your Cisco Memory
Almost all advanced Cisco routers and switches are equipped with the Cisco proprietary operating systems called the IOS (Internetwork Operating System). Cisco PIX firewalls have a special operating system, the PIX Finesse OS.

In some versions of the IOS, there is a MIB (Management Information Base) module integrated into the IOS operating system. The MIB is an operating system component included with all recent IOS distributions that allows network administrators to view and manage device memory over the network. MIB is prerequisite software for other applications that deal with Cisco memory management, reporting data to RME (Resource Manager Essentials) and during installation of other additional software to a given device.

Before discussing the reasons to upgrade your router's memory, the following is description of the different types of memory that used in a Cisco product.

Processor Memory

This memory acts similar to the CPU cache in a computer, controlling all basic computing operations of your switch or router. Regardless of any other memory being used, the processor memory is always the first memory that is accessed and used. All the files needed for booting and essential system files required for functioning for any Cisco device are stored in the processor memory. If you are using a product that has IOS before 11.1, then the total of all types of memory is reported as the processor memory.

Flash Memory Card/Disk or Cisco Memory Card

The flash memory is a special type of programmable memory that is used to store images of the IOS software on it, in addition the flash memory is used to upgrade versions of the router or switch being used. The term 'flashing a product' means upgrading the version of IOS stored on the flash memory card.

Shared Memory/RAM (Random Access Memory)

The reason this is often referred to as the shared memory, is that it is erased every time the router is restarted or when the memory is deliberately cleared. This memory is usually the easiest to upgrade. The RAM stores all data that is temporary in nature, and upgrading the RAM usually helps improve the speed and the computing power of the Cisco product. It is generally cheaper than Flash memory, and manufactured both OEM by Cisco and by third party manufacturers, such as PC Wholesale.

While PIX firewalls and the routers that IOS runs on ultimately have finite processing power, this is often not the bottleneck that first limits their ability to grow. More often, IOS is hampered by having allocated as much (or more) dynamic Random Access Memory (DRAM) than it has available. Older firewalls and routers, which shipped with very small Cisco memory (Flash) cards, the factor limiting the usefulness of the hardware may be the Operating System installed on it.

IOS and PIX OS each have vastly larger memory footprints than they did as recently as a few years ago, and the current versions of these operating systems require more memory than many devices are equipped with. Both the RAM and Flash memory of a Cisco router can be upgraded. Such an upgrade may significantly extend the longevity of a network operating with older equipment. Two of the principal reasons to upgrade your devices memory to increase its speed and to run the most current version of Cisco IOS.

Increasing speed

Just like conventional computers, increasing the memory of a Cisco product increases its speed. If the product is a Cisco router or switch that handles large amounts of data over the network, increasing the RAM of the product can improve both the processing speed and the device's performance.

Upgrading the IOS

For devices with Cisco IOS 11.1 or older the only way to improve its performance is to upgrade the IOS. However, older Cisco hardware is usually not equipped with sufficient flash memory to store a newer version of the IOS. In this case, the only option is to upgrade the flash memory of the Cisco product. All versions of the Cisco IOS after version 11.1, used by most Cisco routers and non-firewall hardware around the world, has functionality to report MIB values over the network via SNMP (Simple Network Management Protocol), allowing network administrators and other authorized device managers to make queries to the database from across the network. Obsolete versions of the IOS, without the MIB module, do not have this functionality and can only report the size of processor memory.

Cisco CCNP Certification FAQ

noreply@blogger.com (Unknown) — Sat, 3 Jan 2009 23:55:00 +0700

Cisco CCNP Certification FAQ
To earn your CCNP, you've got to pass some very rigorous Cisco exams, and you also need to know the rules regarding this important certification. In this article, I'll answer some of the most commonly asked questions regarding the CCNP.

Q: What exams do I need to pass to get my CCNP?

A: You have two options, a three-exam path and a four-exam path. Currently, the four-exam path consists of rigorous exams on advanced routing techniques (BSCI), advanced switching (BCMSN), remote access methods (BCRAN), and advanced troubleshooting techniques (CIT). The three-exam path combines the BCMSN and BSCI exams into a single exam, the Composite exam.

Q: Do I have to take them in any order?

A: No, the order is up to the candidate. Most CCNP candidates take the BSCI exam first and the CIT exam last, but again this is up to the candidate.

Q: What else do I have to do to get the CCNP?

A: You must earn your CCNA before you can be CCNP certified (as well as passing the exams, of course).

Q: Is there a recertification requirement?

A: Cisco CCNP certifications are valid for three years. During that time, you must either pass the Composite exam, the BSCI and BCMSN exams, or pass any CCIE written exam.

Q: What if I don't recertify within the three-year period?

A: You must then meet whatever CCNP requirements there are at that time, from the beginning. It's easier to make sure you recertify!

Becoming CCNP certified is a great boost to your career and your confidence, and as with any Cisco certification, it's up to you to stay current with the CCNA and CCNP requirements. Visit the Career Certification section of Cisco's website regularly to learn about the program's requirements and changes.

Setting Up As A Cisco Network Engineer

noreply@blogger.com (Unknown) — Fri, 2 Jan 2009 23:56:00 +0700

Setting Up As A Cisco Network Engineer
The individual who works as a Cisco network engineer is one that has some of the most sought after training in the world of Internet technology. Cisco systems are widely used around the globe in the networking of devices and various computer systems. Because of this, individuals who have an inner knowledge of Cisco and can keep the system up and running are greatly in demand.

Though many depend on their computers for a number of daily tasks, few have the skills or knowledge to understand the ins and outs of the systems they use. When that system needs maintenance or repair, most find it is necessary that a professional be used to deal with these issues. This can not only keep a system in tip-top shape but also prevent costly mistakes from being made.

When one decides to become a Cisco network engineer, he or she will find there are a number of certifications and qualifications to achieve. For the most part, individuals will need a strong understanding of the basics. This often consists of an education that combines textbook learning with a hands-on environment.

The curriculum for this type of training teaches an individual how to troubleshoot Cisco Systems from start to finish. Those who pursue this field should have an eye for detail. Learning the various aspects of what can go wrong during such things as installations, upgrades and configurations is what makes the Cisco engineer so important.

Once an individual learns the essential basics, it is then that he or she can move on to other types of certifications. It is not uncommon for some Cisco engineers to carry a number of different certifications under their belt. This not only gives them more career options but also increases their earning potential.

As with all computer-based vocations, Cisco engineers will find they must regularly update their skills. The world of technology simply moves at too fast a pace to assume that this is unnecessary. However, this means a Cisco network engineer can look forward to always being on the cutting edge of technology thanks to their career.

Because it is such a highly popular aspect of Internet technology, finding institutions that offer training is hardly difficult. However, before making a final decision, prospective students should make sure the course is accredited and offers all the necessary skills. Students can expect to invest as little as a year to earn their Cisco Certified Networking Associate, or CCNA.

Once an individual earns their CCNA, he or she can then move on to other certifications if so desired. As some Cisco Systems qualifications only last up to three years, individuals will be required to update their credentials in order to stay certified. While each certification will require a fee to update, the good news is most employers are willing to pick up the tab for their employees.

For those individuals looking to take on this type of training, it is important that the program be fully accredited. This ensures that a certification will be considered legitimate upon completing the required coursework. Without legitimate certification, it will be next to impossible to find employment in this field.

Becoming a Cisco network engineer promises to be one of the most stable IT careers a person can choose. Unlike other vocations that become outmoded with time, the use of computers guarantees there will always be a need for the services of a Cisco engineer. It is also one of the few professions that allow an individual to take their career as far as they see fit.

Cisco Memory Types and Their Function

noreply@blogger.com (Unknown) — Fri, 2 Jan 2009 23:56:00 +0700

Cisco Memory Types and Their Function
Most Cisco networking hardware, with the exception of the Cisco PIX firewall series, ships with the Cisco Inter-network Operating System, or IOS. IOS hardware includes network routers, switches, and other similar devices. The basic design of most of this hardware controls the types of memory a device is equipped with, and what functions the various types of Cisco memory serve. At the hardware level, there are four main types of Cisco memory: DRAM, EPROM, NVRAM, and Cisco Flash Memory.

DRAM, or Dynamic Random Access Memory caters to two main device requirements. The first of these is known as Processor Memory which is reserved for exclusive access by the CPU, which it uses when executing software running on the Cisco IOS platform. Processor Memory also stores crucial data that is used constantly, like the configuration settings in current use, and any routing tables. The second is Shared Memory, also known as I/O Memory, or Cisco Packet Memory. The function of Packet Memory is simple and self-explanatory: Data coming in and being sent out is buffered to the Packet Memory portion of the available DRAM before it is transmitted over the network interface.

EPROM, or Erasable Programmable Read-Only Memory is usually referred to as a BootROM. EPROM is generally programmed at some point during the latter stages of manufacture, and cannot generally be changed by consumers. In Cisco devices, EPROM is generally loaded with two crucial firmware components. The first is a boot loader which takes over should the device fail to find a valid bootable image in Flash Memory, and provides alternate boot options. If even this failsafe should fail, the second firmware application installed on Cisco EPROM is used, the ROM Monitor. ROM Monitor has a user interface and includes options for troubleshooting failures of the ROM chips.

In Cisco devices, NVRAM, or Non-Volatile Random Access Memory, stores important configuration information that is used by IOS during boot and by some programs during startup, which is stored in the Startup Configuration File. NVRAM also allows the functionality provided by the Cisco Software Configuration Register, which allows a device to be booted and selection from multiple Cisco IOS images that may be available in Flash Memory. It is sometimes called Shared Memory.

Cisco Flash Memory is the most diverse of each of these types, and it comes in many forms, however, its primary use is to store a bootable Cisco IOS image from which a device can start. Most devices have onboard Flash memory from which the device boots, however, some equipment - particularly higher-end hardware like Cisco GSR routers - also have the capability to boot from an image stored on a Cisco Flash Memory card, which is removable. Regardless of the memory type, it is important to find a memory reseller who is reliable. Things to look for when choosing a memory reseller are that they have memory for every Cisco device in stock, offer a warranty on the memory, and have technical people with whom you can speak if you have any problems.

Cisco CCNA /CCNP: How And Why To Build An Etherchannel

noreply@blogger.com (Unknown) — Thu, 1 Jan 2009 23:57:00 +0700

Cisco CCNA /CCNP: How And Why To Build An Etherchannel
CCNA and CCNP candidates are well-versed in Spanning-Tree Protocol, and one of the great things about STP is that it works well with little or no additional configuration. There is one situation where STP works against us just a bit while it prevents switching loops, and that is the situation where two switches have multiple physical connections.

You would think that if you have two separate physical connections between two switches, twice as much data could be sent from one switch to the other than if there was only one connection. STP doesn't allow this by default, however in an effort to prevent switching loops from forming, one of the paths will be blocked.

SW1 and SW2 are connected via two separate physical connections, on ports fast0/11 and fast 0/12. As we can see here on SW1, only port 0/11 is actually forwarding traffic. STP has put the other port into blocking mode (BLK).

SW1#show spanning vlan 10

(some output removed for clarity)

Interface Role Sts Cost Prio.Nbr Type

Fa0/11 Root FWD 19 128.11 P2p

Fa0/12 Altn BLK 19 128.12 P2p

While STP is helping us by preventing switching loops, STP is also hurting us by preventing us from using a perfectly valid path between SW1 and SW2. We could literally double the bandwidth available between the two switches if we could use that path that is currently being blocked.

The secret to using the currently blocked path is configuring an Etherchannel. An Etherchannel is simply a logical bundling of 2 - 8 physical connections between two Cisco switches.

Configuring an Etherchannel is actually quite simple. Use the command "channel-group 1 mode on" on every port you want to be placed into the Etherchannel. Of course, this must be done on both switches if you configure an Etherchannel on one switch and don't do so on the correct ports on the other switch, the line protocol will go down and stay there.

The beauty of an Etherchannel is that STP sees the Etherchannel as one connection. If any of the physical connections inside the Etherchannel go down, STP does not see this, and STP will not recalculate. While traffic flow between the two switches will obviously be slowed, the delay in transmission caused by an STP recalculation is avoided. An Etherchannel also allows us to use multiple physical connections at one time.

Here's how to put these ports into an Etherchannel:

SW1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW1(config)#interface fast 0/11

SW1(config-if)#channel-group 1 mode on

Creating a port-channel interface Port-channel 1

SW1(config-if)#interface fast 0/12

SW1(config-if)#channel-group 1 mode on

SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#channel-group 1 mode on

SW2(config-if)#int fast 0/12

SW2(config-if)#channel-group 1 mode on

The command "show interface trunk" and "show spanning-tree vlan 10" will be used to verify the Etherchannel configuration.

SW2#show interface trunk (some output removed for clarity)

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

SW2#show spanning vlan 10 (some output removed for clarity)

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 12 128.65 P2p

Before configuring the Etherchannel, we saw individual ports here. Now we see "Po1", which stands for the interface "port-channel1". This is the logical interface created when an Etherchannel is built. We are now using both physical paths between the two switches at one time!

That's one major benefit in action let's see another. Ordinarily, if the single open path between two trunking switches goes down, there is a significant delay while another valid path is opened - close to a minute in some situations. We will now shut down port 0/11 on SW2 and see the effect on the etherchannel.

SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#shutdown

3w0d: %LINK-5-CHANGED: Interface FastEthernet0/11, changed state to administratively down

SW2#show spanning vlan 10

VLAN0010

Spanning tree enabled protocol ieee

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 19 128.65 P2p

SW2#show interface trunk

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

The Etherchannel did not go down! STP sees the Etherchannel as a single link therefore, as far as STP is concerned, nothing happened.

Building an Etherchannel and knowing how it can benefit your network is an essential skill for CCNA and CCNP success, and it comes in very handy on the job as well. Make sure you are comfortable with building one before taking Cisco's exams!

Cisco Certification: Recertifying Your CCNA And CCNP

noreply@blogger.com (Unknown) — Thu, 1 Jan 2009 23:57:00 +0700

Cisco Certification: Recertifying Your CCNA And CCNP
Once you get your CCNA and CCNP, you can't just rest on your accomplishment. You've got to continue to study and add to your skill set - and then prove to Cisco you've been doing just that by recertifying.

Recertification sounds like a pain, but it's actually one of the best things to ever happen to computer certification, and it helps your career as well. One trap many LAN and WAN personnel fall into is that they fail to keep up with changes in technology, and if they happen to be laid off or want to change jobs, they're unable to because they didn't keep their skill set up.

Cisco's recertification policies ensure that if you want to keep your CCNA, CCNP, or one of the other valuable Cisco certifications, you've got to take a recertification exam.

As of November 2005, to recertify as a CCNA, you need to pass either the current CCNA exam, ICND exam, or any 642 professional level or Cisco Qualified Specialist exam. (This does not include Sales Specialist exams.) Passing a CCIE written qualification exam also recertifies you as a CCNA. CCNAs are valid for three years.

For the CCNP, you need to pass the 642-891 Composite exam, a CCIE written qualification exam, or BOTH the BSCI and BCMSN exams (642-801 and 642-811, respectively.) CCNP certifications are valid for three years.

As you can see, you've got quite a few options either way. The one classic mistake you must not make is waiting too long to begin preparing for the exams, and give yourself a little leeway just in case you don't recertify the first time around. Once the deadline passes, your certification is gone, and in the case of the CCNP that means taking all the exams again.

As a professional, it's your responsibility to keep up with changes in the Cisco certification world, and this includes changes in the recertification program. Make a point of visiting the "Learning And Events" section of Cisco's website regularly to look for changes in the certification program. And while you're there, you just might see another cert that catches your eye!

Cisco CCNA Certification: How And Why Switches Trunk

noreply@blogger.com (Unknown) — Wed, 31 Dec 2008 00:01:00 +0700

Cisco CCNA Certification: How And Why Switches Trunk
Your CCNA studies are going to include quite a bit of information about switches, and for good reason. if you don't understand basic switching theory, you can't configure and troubleshoot Cisco switches, either on the CCNA exam or in the real world. That goes double for trunking!

Trunking is simply enabling two or more switches to communicate and send frames to each other for transmission to remote hosts. There are two major trunking protocols that we need to know the details of for exam success and real-world success, but before we get to the protocols, let's discuss the cables we need.

Connecting two Cisco switches requires a crossover cable. As you know, there are eight wires inside an ethernet cable. In a crossover cable, four of the cables "cross over" from one pin to another. For many newer Cisco switches, all you need to do to create a trunk is connect the switches with a crossover cable. For instance, 2950 switches dynamically trunk once you connect them with the right cable. If you use the wrong cable, you'll be there a while!

There are two different trunking protocols in use on today's Cisco switches, ISL and IEEE 802.1Q, generally referred to as "dot1q". There are three main differences between the two. First, ISL is a Cisco-proprietary trunking protocol, where dot1q is the industry standard. (Those of you new to Cisco testing should get used to the phrases "Cisco-proprietary" and "industry standard".) If you're working in a multivendor environment, ISL may not be a good choice. And even though ISL is Cisco's own trunking protocol, some Cisco switches run only dot1q.

ISL also encapsulates the entire frame, increasing the network overhead. Dot1q only places a header on the frame, and in some circumstances, doesn't even do that. There is much less overhead with dot1q as compared to ISL. That leads to the third major difference, the way the protocols work with the native vlan.

The native vlan is simply the default vlan that switch ports are placed into if they are not expressly placed into another vlan. On Cisco switches, the native vlan is vlan 1. (This can be changed.) If dot1q is running, frames that are going to be sent across the trunk line don't even have a header placed on them; the remote switch will assume that any frame that has no header is destined for the native vlan.

The problem with ISL is that is doesn't understand what a native vlan is. Every single frame will be encapsulated, regardless of the vlan it's destined for.

Switching theory is a big part of your CCNA studies, and it can seem overwhelming at first. Just break your studies down into smaller, more manageable parts, and soon you'll see the magic letters "CCNA" behind your name!

Cisco CCNA Certification: The (Many) Different Kinds Of Switching

noreply@blogger.com (Unknown) — Wed, 31 Dec 2008 00:01:00 +0700

Cisco CCNA Certification: The (Many) Different Kinds Of Switching
When you're studying for your CCNA exam, whether you're taking the Intro-ICND path or the single-exam path, you're quickly introduced to the fact that switching occurs at Layer 2 of the OSI model. No problem there, but then other terms involving switching are thrown in, and some of them can be more than a little confusing. What is "cell switching"? What is "circuit switching"? Most confusing of all, how can you have "packet switching"? Packets are found at Layer 3, but switching occurs at Layer 2. How can packets be switched?

Relax! As you'll see in this article, the terms aren't that hard to keep straight. Packet switching, for example, describes a protocol that divides a message into packets before they're sent. The packets are then sent individually, and may take different paths to the same destination. Once the packets arrive at the final destination, they are reassembled.

Frame switching follows the same process, but at a different layer of the OSI model. When the protocol runs at Layer 2 rather than Layer 3, the process is referred to as frame switching.

Cell switching also does much the same thing, but as the name implies, the device in use is a cell switch. Cell-switched packets are fixed in length. ATM is a popular cell-switching technology.

The process of circuit switching is just a bit different, in that the process of setting up the circuit itself is part of the process. The channel is set up between two parties, data is transmitted, and the channel is then torn down. The circuit-switching technology most familiar to CCNA candidates is ISDN.

Don't let these terms confuse you. The four different terms are describing much the same process. The main difference is that they are occurring at different levels of the OSI model, and using a different transport method to get the data where it needs to go.

Cisco Ccna Certification Training Tips

noreply@blogger.com (Unknown) — Tue, 30 Dec 2008 00:02:00 +0700

Cisco Ccna Certification Training Tips
Cisco is a famous and large supplier of all types of networking hardware and software including security and router products. The company offers many job opportunities; but to become a member of Cisco, you have to undergo some form of Cisco training. It is only after doing some Cisco training that you will become a Cisco certified Network Associate. With Cisco training, you learn all that is needed about necessary foundation and get a better understanding of IP networking and troubleshooting. And with this Cisco training, you become better prepared to answer the CCNA Routing and Switching Certification, and pass it to get your certificate.

CISCO Training Centers

The first thing you have to do to get Cisco training is to choose the Cisco training center you want to join. Once you have done the required research and chosen the right training center, you will have to first read and accept the terms of the Cisco Career Trainings and Confidentiality Agreement. The reason you have to agree to this agreement is so that Cisco can prevent you from sharing their information with outside sources. And in case you don't agree with the agreement, then your application for Cisco training will not be processed. Once the terms of the agreement are agreed upon, you can start on your Cisco training. Your Cisco training basically consists of teaching you to get a better understanding of the operations and functions of LAN, WAN, VPN, SAN and Cisco IOS fundamentals. In addition to this, there are other topics that are necessary, and will be covered in your Cisco training.

Practice Exams and Prep Centers for CCNA Certification

These topics include the technology and testing for Cisco equipment. There are many practice exams you have to complete after the Cisco training, where these exams are taken like most exams, timed. The best place to visit to learn more about Cisco training is Cisco's website. You will find information here about the CCNA certification training and when exams are scheduled. In addition to this, you find many other types of certificates with descriptions of the certificates and requirements required to get them in this website. There is also a prep center you can join to get the required CCNA certification training with which you will be able to pass the 55-65 question tests. Remember that this is a Cisco system certification; so you have to use your best bet in taking Cisco training courses from them to be successful in getting the certificate.

Becoming a Cisco Certified Network Associate

Once you complete your Cisco training, you are automatically considered to be a Cisco Certified Network Associate where you will be able to configure, install and operate LAN, WAN and dial access services that are used for small networks. In addition to this, Cisco training will make you competent for IP, Serial, IP RIP, Ethernet, Frame Relay, VLAN and Access lists.

So if this is what you intend to make of your career, then you will have to undergo efficient Cisco training to become a Cisco Certified Network Associate where you will be provided with employment wherever you go.

How A Cisco Network Engineer Can Shape The World

noreply@blogger.com (Unknown) — Tue, 30 Dec 2008 00:01:00 +0700

How A Cisco Network Engineer Can Shape The World
When asked what you wanted to be when you grew up, you probably didn’t say a Cisco network engineer. In fact, unless you had a computer geek or an engineer in your family, you probably didn’t say an engineer at all. Kids usually want to be things that they see as glamorous models of people who change their world: firefighters, athletes, and even teachers. But as you grow up and start to learn about the way that the world really works, you realize that these aren’t the only jobs that shape the world. You start to consider work that’s both world-shaping and has duties that actually appeal to you. If you like computers, technology and problem solving, you might consider becoming a Cisco network engineer. And if you do, you might discover that your actions do help to improve the world around you.

The Cisco network engineer resolves computer problems for individuals and businesses that are using Cisco routers. This is a specialized practice but one that is more applicable to the world around you than you might think. Cisco is a brand name, which leads the industry in Internet networking. This means that if you’ve got computers networked together in a business of any size, there’s a good chance that Cisco’s technology is part of the system. If you’re able to troubleshoot and repair any problems that come up in that network, you can provide an important service that can keep that business up-and-running all throughout the year. In a world that relies on regular communication between computers to keep things running smoothly, this service can affect thousands of people at once.

The job of a Cisco network engineer is to know these systems inside and out. The most common thing that you will do if you get this kind of job is troubleshooting and computer repair. By learning the workings of the system, you’ll be able to identify what the problems are as they arise and how to fix them rapidly so that the business can keep its employees productive and its clients happy. But this isn’t all that you’ll do as a Cisco network engineer. You’ll also learn about new technology that is put out by the networking industry so that you can teach people how to incorporate it into their systems. You’ll learn how to install, configure and subnet new Cisco routers and switches. Basically, you’ll get to spend all day playing with computers. That’s a job that more and more kids these days think they might want to have.

So what would you tell a kid who said that they wanted to get this kind of job? In other words, how do you become a Cisco network engineer? Although some people teach themselves this kind of work on their own and others learn on-the-job as they’re moving up in the business world, there’s a much more efficient way to get the skills that you need to get this type of job. You can go to school to get a degree to become a Cisco network engineer. There are degree programs that actually teach you the hands-on specifics of how to work with these types of systems.

With this kind of credibility behind you, you should have no trouble getting the job that you want. It may not be quite what you thought you’d be doing when you were six but when you think about it, it’s probably even cooler! And now that you have a better understanding of the way that the world around you really works, you probably know that these kinds of jobs are the ones that really make a difference to people on a day-to-day basis.

Cisco CCNA / CCNP Certification: Ospf E2 vs. E1 Routes

noreply@blogger.com (Unknown) — Mon, 29 Dec 2008 00:03:00 +0700

Cisco CCNA / CCNP Certification: Ospf E2 vs. E1 Routes
OSPF is a major topic on both the CCNA and CCNP exams, and it's also the topic that requires the most attention to detail. Where dynamic routing protocols such as RIP and IGRP have only one router type, a look at a Cisco routing table shows several different OSPF route types.

R1#show ip route

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

In this tutorial, we'll take a look at the difference between two of these route types, E1 and E2.

Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain. (Static and connected routes can also be redistributed.) When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it's communicating with, that router becomes an Autonomous System Border Router (ASBR).

Let's work with an example where R1 is running both OSPF and RIP. R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP. This means we have to perform route redistribution on the ASBR. The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:

R4#show ip route ospf

O E2 5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

6.0.0.0/32 is subnetted, 1 subnets

O E2 6.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks

O E2 172.12.21.0/30 [110/20] via 172.34.34.3, 00:33:32,
Ethernet0

O E2 7.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

15.0.0.0/24 is subnetted, 1 subnets

O E2 15.1.1.0 [110/20] via 172.34.34.3, 00:33:32, Ethernet0

E2 is the default route type for routes learned via redistribution. The key with E2 routes is that the cost of these routes reflects only the cost of the path from the ASBR to the final destination; the cost of the path from R4 to R1 is not reflected in this cost. (Remember that OSPF's metric for a path is referred to as "cost".)
In this example, we want the cost of the routes to reflect the entire path, not just the path between the ASBR and the destination network. To do so, the routes must be redistributed into OSPF as E1 routes on the ASBR, as shown here.

R1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R1(config)#router ospf 1

R1(config-router)#redistribute rip subnets metric-type 1

Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.

O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0

6.0.0.0/32 is subnetted, 1 subnets

O E1 6.1.1.1 [110/100] via 172.34.34.3, 00:33:21, Ethernet0

172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks

O E1 172.12.21.0/30 [110/94] via 172.34.34.3, 00:33:32, Ethernet0

O E1 7.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0

15.0.0.0/24 is subnetted, 1 subnets

O E1 15.1.1.0 [110/94] via 172.34.34.3, 00:33:32, Ethernet0

Knowing the difference between E1 and E2 routes is vital for CCNP exam success, as well as fully understanding a production router's routing table. Good luck in your studies!

Passing Cisco’s CCNA And CCNP Exams: Traceroute

noreply@blogger.com (Unknown) — Mon, 29 Dec 2008 00:02:00 +0700

Passing Cisco’s CCNA And CCNP Exams: Traceroute
In preparation for your CCNA and CCNP exam success, you've got to learn to troubleshoot Cisco routers. And while ping is a great basic IP connectivity tool, it doesn't give you all the information you need to diagnose network connectivity issues.

Let's say you have six routers between CityA and CityB. You send a ping from A to B, and get this return:

R1#ping 172.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.1.1.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

The five periods indicate that there is no IP connectivity to CityB. Problem is, that's about all ping tells you. You can have 5 or 50 routers between the two points, so how can you tell which downstream router has the problem?

That's where traceroute comes in. Traceroute sends three datagrams with a Time To Live (TTL) of 1. Those datagrams will timeout once they hit the first router in the path, and that router will respond with an ICMP Time Exceeded message.

In response, the sending router sends three more datagrams, but these have a TTL of 2. This means that the next router in line will send back ICMP Time Exceeded messages. This process continues until the final destination (CItyB) is reached the output of the command shows us the path the data took:

Router1#traceroute 271.1.1.1

Type escape sequence to abort.

Tracing the route to 271.1.1.1

1 20.1.1.1 4 msec 4 msec 4 msec

2 30.1.1.1 20 msec 16 msec 16 msec

3 271.1.1.1 16 msec * 16 msec

How does this help troubleshoot a problem? Let's say that the second router in this path, 30.1.1.1, doesn't know how to get to 271.1.1.1. The output would look like this:

Router1#traceroute 271.1.1.1

Type escape sequence to abort.

Tracing the route to 271.1.1.1

1 20.1.1.1 4 msec 4 msec 4 msec

2 30.1.1.1 20 msec 16 msec 16 msec

3 * * *

This indicates that the router at 30.1.1.1 doesn't know how to get to the final destination. Now you have a better idea of which router has an issue!

Now here's the bad part: you're going to get 30 lines of three asterisks, and until you abort this traceroute, you're going to just watch those asterisks go across the screen. There's an abort sequence that the router mentions in the first line of the console output, but the router doesn't tell you what it is! So I will - this top-secret sequence is TWICE, one right after the other.

That keystroke takes a little getting used to, but a CCNA or CCNP can do it! Add this command to your Cisco skill set, and it will serve you well both on the CCNA and CCNP exams and your real-world networks. And you'll impress your friends by knowing how to stop a traceroute!

Cisco CCNP Certification: The BGP Weight Attribute

noreply@blogger.com (Unknown) — Sun, 28 Dec 2008 00:04:00 +0700

Cisco CCNP Certification: The BGP Weight Attribute
When you're studying for the CCNP certification, especially the BSCI exam, you must gain a solid understanding of BGP. BGP isn't just one of the biggest topics on the BSCI exam, it's one of the largest. BGP has a great many details that must be mastered for BSCI success, and those of you with one eye on the CCIE must learn the fundamentals of BGP now in order to build on those fundamentals at a later time.

Path attributes are a unique feature of BGP. With interior gateway protocols such as OSPF and EIGRP, administrative distance is used as a tiebreaker when two routes to the same destination had different next-hop IP addresses but the same prefix length. BGP uses path attributes to make this choice.

The first attribute considered by BGP is weight. Weight is a Cisco-proprietary BGP attribute, so if you're working in a multivendor environment you should work with another attribute to influence path selection.

The weight attribute is significant only to the router on which it is changed. If you set a higher weight for a particular route in order to give it preference (a higher weight is preferred over a lower one), that weight is not advertised to other routers.

BGP uses categories such as "transitive", "non-transitive", "mandatory", and "optional" to classify attributes. Since weight is a locally significant Cisco-proprietary attribute, it does not all into any of these categories.

The weight can be changed on a single route via a route-map, or it can be set for a different weight for all routes received from a given neighbor. To change the weight for all incoming routes, use the "weight" option with the neighbor command after forming the BGP peer relationships.

R2(config)#router bgp 100

R2(config-router)#neighbor 100.1.1.1 remote-as 10

R2(config-router)#neighbor 100.1.1.1 weight 200

Learning all of the BGP attributes, as well as when to use them, can seem an overwhelming task when you first start studying for your BSCI and CCNP exams. Break this task down into small parts, learn one attribute at a time, and soon you'll have the BGP attributes mastered.

Cisco CCNA Certification: Broadcasts, Unicasts, And Multicasts

noreply@blogger.com (Unknown) — Sun, 28 Dec 2008 00:03:00 +0700

Cisco CCNA Certification: Broadcasts, Unicasts, And Multicasts
When you begin your CCNA studies, you get hit with a lot of different networking terms right away that you might not be familiar with. What makes it a little more confusing is that a lot of these terms sound a lot alike. Here, we're going to discuss the differences between broadcasts, multicasts, and unicasts at both the Data Link (Layer 2) and Network (Layer 3) layers of the OSI model.

A broadcast is simply a unit of information that every other device on the segment will receive. A broadcast is indicated by having every bit of the address set to its highest possible value. Since a hexadecimal bit's highest value is "f", a hexadecimal broadcast is ff-ff-ff-ff-ff-ff (or FF-FF-FF-FF-FF-FF, as the upper case does not affect hex value). The CCNA exam will demand you be very familiar with hex conversions, so if you're not comfortable with these conversions, get comfortable with them before taking the exam!

At layer 3, a broadcast is indicated by setting every bit in the 32-bit binary string to "1", making the dotted decimal value 255.255.255.255. Every host on a segment will receive such a broadcast. (Keep in mind that switches will forward a broadcast, but routers do not.) In contrast to a broadcast, a unicast is a packet or frame with only one destination.

There is a middle ground between broadcasts and unicasts, and that is a multicast. Where a broadcast will be received by all, and a unicast is received by only one host, a multicast will be received by multiple hosts, all belonging to a "multicast group". As you climb the Cisco certification pyramid, you'll be introduced to creating multicast groups and controlling multicast traffic, but for your CCNA studies you need only keep certain multicast groups in mind.

Class D addresses are reserved for multicasting this range is 224.0.0.0 - 239.255.255.255. The addresses 224.0.0.0 - 224.255.255.255 are reserved for use by network protocols on a local network segment, and like broadcasts, routers will not forward these multicast packets. (Packets with these addresses are sent with a Time To Live of 1.)

As a CCNA candidate, you should know that OSPF routers use the address 224.0.0.5 to send hellos, EIGRP routers use 224.0.0.10 to send updates, and RIP version 2 uses 224.0.0.9 to send routing updates. RIP version 1 and IGRP both broadcast their updates.

Multicasting gets a bit more complicated as you go from your CCNA to the CCNP and CCIE, but by simply understanding what multicasting is, you go a long way toward securing the CCNA

Cisco Certification: The "Secret" Key To Getting Your CCNA And CCNP

noreply@blogger.com (Unknown) — Sat, 27 Dec 2008 00:04:00 +0700

Cisco Certification: The "Secret" Key To Getting Your CCNA And CCNP
Whether you're working on your CCNA or CCNP, Cisco certification exams are the most demanding computer certification exams in the IT field. Cisco exams are not a test of memorization, they're a test of your analytical skills. You'll need to look at configurations and console output and analyze them to identify problems and answer detailed questions. To pass these demanding exams, you've got to truly understand how Cisco routers and switches operate - and the key to doing so is right in front of you.

The debug command.

Of course, there is no single "debug" command. Using IOS Help, you can quickly see that there are hundreds of these debugs, and I want to mention immediately that you should never practice these commands on a production router. This is one major reason you need to get some hands-on experience with Cisco products in a home lab or rack rental. No software program or "simulator" is going to give you the debug practice you need.

Now, why am I so insistent that you use debugs? Because that's how you actually see what's going on. It's not enough to type a frame relay LMI command, you have to be able to see the LMIs being exchanged with "debug frame lmi". You don't want to just type a few network numbers in after enabling RIP, you want to see the routes being advertised along with their metrics with "debug ip rip". The list goes on and on.

By using debugs as part of your CCNA and CCNP studies, you're going beyond just memorizing commands and thinking you understand everything that's happening when you enter a command or two. You move to a higher level of understanding how routers, switches, and protocols work -- and that is the true goal of earning your CCNA and CCNP.

Cisco CCNA Certification: Defining Broadcast Domains

noreply@blogger.com (Unknown) — Fri, 26 Dec 2008 00:05:00 +0700

Cisco CCNA Certification: Defining Broadcast Domains
When you're studying to pass the CCNA exam and earn your certification, you're introduced to a great many terms that are either totally new to you or seem familiar, but you're not quite sure what they are. The term "broadcast domain" falls into the latter category for many CCNA candidates.

A broadcast domain is simply the group of end hosts that will receive a broadcast sent out by a given host. For example, if there are ten host devices connected to a switch and one of them sends a broadcast, the other nine devices will receive the broadcast. All of those devices are in the same broadcast domain.

Of course, we probably don't want every device in a network receiving every single broadcast sent out by any other device in the network! This is why we need to know what devices can create multiple, smaller broadcast domains. Doing so allows us to limit the broadcasts traveling around our network - and you might be surprised how much traffic on some networks consists of unnecessary broadcasts.

Using the OSI model, we find devices such as hubs and repeaters at Layer One. This is the Physical layer, and devices at this layer have no effect on broadcast domains.

At Layer Two, we've got switches and bridges. By default, a switch has no effect on broadcast domains; CCNA candidates know that a switch will forward a broadcast out every single port on that switch except the one upon which it was received. However, Cisco switches allow the creation of Virtual Local Area Networks, or VLANs, that are logical segments of the network. A broadcast sent by one host in a VLAN will not be forwarded out every other port on the switch. That broadcast will be forwarded only out ports that are members of the same VLAN as the host device that sent it.

The good news is that broadcast traffic will not be forwarded between VLANs. The bad news is that no inter-VLAN traffic at all is allowed by default! You may actually want this in some cases, but generally you're going to want inter-VLAN traffic. This requires the use of a router or other Layer 3 device such as a Layer 3 Switch. (Layer 3 Switches are becoming more popular every day. Basically, it's a switch that can also run routing protocols. These switches are not tested on the CCNA exam.)

That router we just talked about also defines broadcast domains. Routers do not forward broadcasts, so broadcast domains are defined by routers with no additional configuration.

Knowing how broadcasts travel across your network, and how they can be controlled, is an important part of being a CCNA and of being a superior network administrator. Best of luck to you in both of these pursuits!

Cisco CCNA Certification Tutorial: Segmenting Your Network

noreply@blogger.com (Unknown) — Thu, 25 Dec 2008 00:06:00 +0700

Cisco CCNA Certification Tutorial: Segmenting Your Network
When you're getting started on your CCNA studies on your way to earning this certification, you're swamped with network device types that you're familiar with, but not quite sure how to use. Let's look at these networking devices and their main purposes.

Hubs and repeaters operate at Layer One of the OSI model, and they have one main purpose - regenerating the electrical signal that Layer One technologies carry. This regeneration helps to avoid attenuation, the gradual weakening of a signal. Much like a radio signal, the electric signals that travel at Layer One gradually weaken as they travel across the wire. Hubs and repeaters both generate a "clean" copy of the signal.

While hubs and repeaters can be helpful, they do nothing as far as network segmentation is concerned. The first such device we encounter as we move up the OSI model is the switch. Operating at Layer 2, a switch creates multiple collision domains by default each switch port is considered its own little collision domain. If 12 PCs are connected to a Cisco switch, you have 12 separate collision domains.

Switches can be used to segment the network into smaller broadcast domains, but this is not a default behavior. Virtual LAN (VLAN) configuration segments the network into smaller broadcast domains, since a broadcast sent by a host in one VLAN is heard only by other devices in the same VLAN.

Routers operate at Layer 3 of the OSI model and segment a network into multiple broadcast domains by default. Routers do not forward broadcasts as switches do, making the router the only device of the four we've discussed today that create multiple broadcast domains by default.

Knowing what each of these devices can and cannot do is essential to passing the CCNA and becoming a great network administrator. Good luck to you in both of these goals!

Cisco CCNA Exam Tutorial: Route Summarization

noreply@blogger.com (Unknown) — Wed, 24 Dec 2008 00:06:00 +0700

Cisco CCNA Exam Tutorial: Route Summarization
Preparing to pass the CCNA exam and earn this important Cisco certification? Route summarization is just one of the many skills you'll have to master in order to earn your CCNA. Whether it's RIP version 2, OSPF, or EIGRP, the CCNA exam will demand that you can flawlessly configure route summarization.

Route summarization isn't just important for the CCNA exam. It's a valuable skill to have in the real world as well. Correctly summarizing routes can lead to smaller routing tables that are still able to route packets accurately - what I like to call "concise and complete" routing tables.

The first skill you've got to have in order to work with route summarization is binary math; more specifically, you must be able to take multiple routes and come up with both a summary route and mask to advertise to downstream routers. Given the networks 100.16.0.0 /16, 100.17.0.0 /16, 100.18.0.0 /16, and 100.19.0.0 /16, could you quickly come up with both the summary address and mask? All you need to do is break the four network numbers down into binary strings. We know the last two octets will all convert to the binary string 00000000, so in this article we'll only illustrate how to convert the first and second octet from decimal to binary.

100 16 = 01100100 00010000

100 17 = 01100100 00010001

100 18 = 01100100 00010010

100 19 = 01100100 00010011

To come up with the summary route, just work from left to right and draw a line where the four networks no longer have a bit in common. For these four networks, that point comes between the 14th and 15th bits. This leaves us with this string: 01100100 000100xx. All you need to do is convert that string back to decimal, which gives us 100 for the first octet and 16 for the second. (The two x values are bits on the right side of the line, which aren't used in calculating the summary route.) Since we know that zero is the value for the last two octets, the resulting summary network number is 100.16.0.0.

But we're not done! We now have to come up with the summary mask to advertise along with the summary route. To arrive at the summary route, write out a mask in binary with a "1" for every bit to the left of the line we drew previously, and a "0" for every bit to the right. That gives us the following string:

11111111 11111100 00000000 00000000

Converting that to dotted decimal, we arrive at the summary mask 255.252.0.0. The correct summary network and mask to advertise are 100.16.0.0 252.0.0.0.

For the CCNA exam, emphasis is put on knowing how to advertise these summary routes in RIPv2 and EIGRP. For both of these protocols, route summarization happens at the interface level - it's not configured under the protocol. On the interface that should advertise the summary route, use the command "ip summary-address". Here are examples of how the above summary route would be configured on ethernet0 in both RIPv2 and EIGRP.

R1(config-if)#ip summary-address rip 100.16.0.0 255.252.0.0

R1(config-if)#ip summary-address eigrp 100 100.16.0.0 255.252.0.0

The main difference between the two is that the EIGRP command must specify the AS number - that's what the "100" is in the middle of the EIGRP command. Since RIPv2 does not use AS numbers, there's no additional value needed in the configuration.

For OSPF, the commands differ. If you're configuring inter-area route summarization, use the "area range" command; if you are summarizing routes that are being redistributed into OSPF, use the summary-address command under the OSPF routing process on the ASBR. Neither of these are interface-level commands.

I speak from experience when I tell you that practice makes perfect on the CCNA exam, especially with binary and summarization questions. The great thing about these questions is that there are no grey areas with these questions - you either know how to do it or you don't. And with practice and an eye for detail, you can master these skills, pass the exam, and become a CCNA. Here's to your success!

Cisco/Microsoft Computer Certification: Be Ready For Your Opportunity

noreply@blogger.com (Unknown) — Tue, 23 Dec 2008 00:07:00 +0700

Cisco/Microsoft Computer Certification: Be Ready For Your Opportunity
I was reading The Big Moo: Stop Trying To Be Perfect and Start Being Remarkable this morning, and I’d recommend a copy of this to anyone who wants to improve their career and their future. And that’s all of us, right?

There was one particular line that really stood out to me: Betting on change is always the safest bet available. That describes life perfectly, but it also describes a career in Information Technology perfectly as well. There is no field in the world that has the constant and never-ending changes that IT does. And every single one of us can look at this as a massive opportunity for personal and professional growth.

Is that how you’re looking at it? I remember when I passed my first certification exam, the Novell CAN, back in 1997. Man, I thought I knew it all then! But I quickly learned that you’ve got to keep learning in IT. I also learned that if you’re willing to put in the work and make the sacrifices, there’s no other field with the limitless potential for growth and excellence.

Like everyone else, my career has had its ups and downs, but I always kept learning and growing. Today, I’ve got my dream job, working with students and customers just like you – to help you create your own future.

The next 18 months are filled with endless possibilities, particularly with the rapid growth of VoIP and Microsoft Vista on the horizon. There will be those who rationalize their inertia, saying “I’ll never have to support those, so I don’t need to learn them."

There will also be those who see VoIP and Vista as enormous opportunities to learn and advance in their careers and their lives. These people will get started today, learning the fundamentals of Cisco and advancing their networking knowledge in order to be ready for opportunities as they come along.

You can’t start studying and learning when the opportunity arrives – you’ve got to be ready when opportunity knocks. If you’ve been putting off studying for a Cisco or other computer certification – and I know the summer is a really good time for putting off studying – get back on track today.

Because you never know what opportunities are going to come along – but you do know that when they do, you’ve got to be ready to take advantage. After all, opportunity really does knock only once!

Cisco CCNA Exam Tutorial: Loopback Interfaces

noreply@blogger.com (Unknown) — Tue, 23 Dec 2008 00:06:00 +0700

Cisco CCNA Exam Tutorial: Loopback Interfaces
As a CCNA candidate, you most likely have some background in PC hardware and workstation support. If so, you're already familiar with loopback interfaces, particularly 127.0.0.1, the loopback address assigned to a PC.

When you're learning all about the different physical interfaces for your CCNA exam - serial, ethernet, and BRI, among others - there's one logical interface you need to know about, and that is - you guessed it! - the loopback interface.

What isn't as immediately apparent is why we use loopback interfaces on routers and switches to begin with. Many of the Cisco router features that can use loopbacks are intermediate and advanced features that you'll learn about in your CCNP and CCIE studies, but these features all come back to one basic concept: If the loopback interface on a router is down, that means the router is unavailable as a whole.

In contrast, a physical interface being down does not mean the router itself is out of commission. A router's ethernet port can go down, but the other physical interfaces on that router are still operational. Since a loopback interface is logical, there's nothing physical that can go wrong with it.

As I mentioned, you'll learn different Cisco router and switch features that utilize loopback interfaces as you climb the Cisco certification ladder. There's one misconception about Cisco loopback interfaces that you want to get clear on now, though. You’re probably familiar with loopback interfaces on a PC, and may even know that the address range 127.0.0.0 is reserved for loopback addressing.

Note that this reserved address range does not apply to loopbacks on Cisco devices, however. If you attempt to assign an address from this range to a Cisco loopback interface, you get this result:

R1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R1(config)#interface loopback0

R1(config-if)#ip address 127.0.0.2 255.255.255.0

Not a valid host address - 127.0.0.2

R1(config-if)#ip address 127.1.1.1 255.255.255.0

Not a valid host address - 127.1.1.1

The range 127.0.0.0 is reserved for host loopbacks (such as PCs), not routers or switches. The most commonly used address from this range is 127.0.0.1 – if you can’t ping that on a workstation, that means you can’t ping yourself, which means there’s a problem with the TCP/IP install itself.

Keep these details in mind on the exam and in the workplace, and you’re on your way to CCNA exam success!

Cisco Business VoIP – an Answer to Unified Communication

noreply@blogger.com (Unknown) — Mon, 22 Dec 2008 00:08:00 +0700

Cisco Business VoIP – an Answer to Unified Communication
The advent of technology never stops. There is this never-ending quest for perfection and change. Every sector is constantly changing due to the advances in the technology so that it offers something new to the general public and will keep abreast of the developing times and people. Like any other industry, the advent of technology has changed the way film-making and video gaming has evolved.

Lot of changes has happened over a period of time in the way films are made. With the modern methods employed by film makers of current times, movies of today have evolved in a way to generate more viewing pleasure to the public. Lots of options like science fiction, fantasy and animation are now available thanks to technology. The same goes to the gaming industry. In the beginning, we had only the 2D graphics and the boring audio of gaming consoles like Magnavox and Atari while we are now seeing seventh generation gaming consoles like the Xbox 360 and PlayStation 3 that are really captured the world by storm.

Technology has altered the outlook of People

As with any other sector, communication has also developed with the changing face of technology. Earlier means of communication was restricted to using Morse code and telegraph. Now, we have evolved means of communication that has served in bringing people all over the world together and has really made the Earth a smaller place.

The initiation of the world of communication began with the telephone. This mode of communication allowed people to talk to other people anywhere in the world in real time and were charged for the call on a minute basis or a flat rate of the entire call based on the mode followed by the service provider. Then came the mobile phones which further revolutionized the communication sector by allowing people to talk to one another even while on the move and even when the person was in any isolated part of the world provided that the service provider had network coverage in that area. So, technology has really made communication an easy and convenient resource for one and all.

The growth in communication sector has not been restricted to these devices. The beginning of the 21st century saw the entry of another powerful communication tool that has not only improved communication means it has also reduced costs to the consumer. This tool is the Voice over Internet Protocol or VoIP. This new tool has become quite popular in the short while that it has existed and is still growing.

VoIP is a very efficient tool in providing for better communication. It differs from the conventional telephone in that it does not rely on cables nor does it use signal towers like the mobile phone. VoIP uses the internet to allow person to handle calls. So, VoIP as the name suggests sends voice through the Internet or an Internet Protocol (IP) based network.

The popularity of VoIP boomed suddenly and is still growing because of the low cost rates it offers in terms of the setup and the regular bills every month. The basic requirement is only one VoIP infrastructure that can be further modified if more lines are needed later. The operational costs of VoIP are around 22% lesser than what is required by circuit switched networks. For this reason, the setup costs and the bills incurred by a consumer monthly is much cheaper while using VoIP in comparison to a conventional telephone.

These qualities have pressurized many telecommunication majors to move over to the VoIP system. One such organization is Cisco that offers VoIP systems to businesses to help them incorporate a common platform for their communication needs and their business processes and also to ascertain the safety of data which is sent across through this system.

The initial VoIP system provided by Cisco known as Cisco Unified Communication has become a popular communication tool not only for voice but also to send data. It provides a wonderful blend of networking safety and open application programming interface to create a proficient channel for all business communication and has made network management much easier and reduced the operational costs to the organizations.

Cisco now plans to provide a VoIP system meant to serve the needs of every common man. With this new step, they will be entering a realm of providing cost effective and a great communication tool to the entire world.

CISCO Certification: An Introduction To Multilayer Switching And SVIs

noreply@blogger.com (Unknown) — Mon, 22 Dec 2008 00:07:00 +0700

CISCO Certification: An Introduction To Multilayer Switching And SVIs
Sure, you have to know all about SVIs and multilayer switching to earn your CCNP, but you also need to know about them because they’re so commonplace in today’s networks!

Why? We can use an SVI to allow inter-VLAN communication on a multilayer switch, eliminating the need for a separate router to get involved.

In this example, we have Host_1 in VLAN 11 and Host_3 in VLAN 33. Before we begin configuring, we'll send pings between the two hosts. (We’ll use Cisco routers for the hosts in this lab, which is why the ping output may look familiar!)

HOST_1#ping 30.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds:.....

Success rate is 0 percent (0/5)

HOST_3#ping 20.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds:

.....

Success rate is 0 percent (0/5)

As we expect, there’s no IP connectivity between the hosts. Assuming the appropriate switch ports are already placed in VLAN 11 and VLAN 33, we’ll now create two switched virtual interfaces on this multilayer switch. One will represent VLAN 33, and the other will represent VLAN 11.

SW1(config)#int vlan11

01:30:04: %LINK-3-UPDOWN: Interface Vlan11, changed state to up

01:30:05: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan11, changed state to up

SW1(config-if)#ip address 20.1.1.11 255.255.255.0

SW1(config-if)#int vlan33

01:30:11: %LINK-3-UPDOWN: Interface Vlan33, changed state to up

01:30:12: %LINEPROTO-5-UPDOWN: Line protocol on Interface Vlan33, changed state to up

SW1(config-if)#ip address 30.1.1.11 255.255.255.0

At this point, we’ve still got a problem when we look at the routing table.

SW1# show ip route

Default gateway is not set

Host Gateway Last Use Total Uses Interface

ICMP redirect cache is empty

The problem is that we don’t have a routing table, because IP routing is off by default on a multilayer switch. Let’s turn IP routing on and then check the routing table.

SW1(config)#ip routing

SW1(config)#^Z

SW1#show ip route

Gateway of last resort is not set

20.0.0.0/24 is subnetted, 1 subnets

C 20.1.1.0 is directly connected, Vlan11

30.0.0.0/24 is subnetted, 1 subnets

C 30.1.1.0 is directly connected, Vlan33

Now we’re in good shape! The hosts need to have their default gateway set to the appropriate SVI IP address; here, Host_1 should have its gateway set to 20.1.1.11, and Host_3 to 30.1.1.11. After doing so, inter-VLAN communication is now in place, as shown by the ping output below.

HOST_1#ping 30.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 30.1.1.1, timeout is 2 seconds: !!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

HOST_3#ping 20.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds: !!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms

In a future Cisco certification tutorial, we’ll take a look at configuring a multilayer switch port as a routed port, and assign an IP address to that port. See you then!

Cisco CCNP Certification: Using The BGP Command “Update-Source”

noreply@blogger.com (Unknown) — Sun, 21 Dec 2008 00:09:00 +0700

Cisco CCNP Certification: Using The BGP Command “Update-Source”
When you start preparing for your CCNP exam, particularly the BSCI exam, you're introduced to Border Gateway Protocol (BGP) configurations. BGP is unlike any protocol you learned during your CCNA studies, and even the similarities are a little bit different!

BGP forms neighbor relationships, much like EIGRP and OSPF do. The interesting thing with BGP is that potential neighbors, or "peers", do not need to be directly connected and can use their loopback interfaces to form the peer relationships.

It may well be to your advantage to use loopbacks to form peer relationships rather than the actual interface facing the potential neighbor. This can be done because BGP uses static neighbor statements rather than any kind of dynamic neighbor discovery process.

Consider a router that has two paths to a BGP speaker. The interfaces are numbered like this:

Router1: Serial0, 172.1.1.1 /24, Serial2, 179.1.1.1 /24, loopback0, 1.1.1.1 /32.

Router2: Serial0, 172.1.1.2/24, Serial2 179.1.1.2/24, loopback0, 2.2.2.2 /32.

We could configure Router1 like this:

router bgp 200

neighbor 172.1.1.2 remote-as 200

In this case, BGP would automatically use 172.1.1.1 as the source for the TCP connection that has to be set up with the neighbor before updates can be exchanged; this address is known as the best local address. However, if the remote peer's serial0 interface is shut down or goes down for another reason, the peer relationship would be lost even though Router2 is still available.

Instead of using one of the physical interfaces, we can use the loopbacks on each router to establish the TCP-based peer connection. The configurations would look like this:

Router1:

router bgp 200

neighbor 2.2.2.2 remote-as 200

neighbor 2.2.2.2 update-source loopback0

Router2:

router bgp 200

neighbor 1.1.1.1 remote-as 200

neighbor 1.1.1.1 update-source loopback0

In this case, losing one of the physical connections does not necessarily mean the BGP peering is lost; as long as the routers have a valid path to each other's loopback addresses, the BGP peer relationship will stay in place. And better yet, we avoid the dreaded “single point of failure”!

Cisco CCNA/CCNP Home Lab: Why You Need An ISDN Simulator

noreply@blogger.com (Unknown) — Sun, 21 Dec 2008 00:08:00 +0700

Cisco CCNA/CCNP Home Lab: Why You Need An ISDN Simulator
ISDN is a vital topic for today's CCNA and CCNP candidates, especially for the ICND and Intro exams - you've got to know ISDN inside and out to pass those exams. Naturally you want to include it in your home lab. What many candidates don't realize is that you can't connect two Cisco routers directly via their Basic Rate Interface (BRI) interfaces you've got to have another device between them called an ISDN simulator.

An ISDN simulator is not one of those software programs pretending to be routers ("router simulators") this is a piece of hardware that acts as the telephone company in your home lab. Older simulators come with preprogrammed phone numbers and SPIDs, where newer ones let you program the phone numbers you want to use. Either way, an ISDN simulator is great for your CCNA/CCNP home lab, because you can practice dial scenarios that actually work. And you get to troubleshoot the ones that don't, which is also important to learn!)

You don't need any special cables or connectors you just connect both of your routers' BRI interfaces to the ISDN simulator with a straight-through cable and you're ready to go.

In years past, this was a major problem for 640-801, 811, and 821 studies, because the simulators used to be so expensive. New ones can still be pricey ($600 and up), but with the sudden influx of used ISDN simulators on ebay and Cisco resellers, you can get a used one that will do the job for you.

Why are there suddenly so many ISDN simulators on the market? Cisco recently removed ISDN from the CCIE R&S exam, so a lot of CCIE rack resellers as well as private individuals are selling their simulators. There's never been a better time to add ISDN to your home lab. If taken care of (kept out of extreme heat), they can last for quite a few years. The one I purchased for my IE home lab is still working well.

If you choose to purchase a new simulator, you can run a Google search to find vendors. I've made two purchases from www.vconsole.com over the last few years and both of those simulators have worked beautifully.

As I said earlier, there's never been a better time to add ISDN to your home lab. Don't just settle for trying to memorize theory - get your hands on the real deal, practice and fix your configurations, and you'll be amazed at what you learn and how well you do on your CCNA and CCNP exams!