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Cisco CCNA Certification Exam: Five Frame Relay Details You Must Know

Thursday, 09 March 2006 Chris Bryant
When you're studying for your CCNA exam on the way to earning this coveted Cisco certification, the details can seem overwhelming! In this article, I'll point out five Frame Relay details that you must keep in mind when you're on your way to the CCNA exam!
 
Inverse ARP starts working as soon as you open the serial interface. This protocol performs dynamic Frame Relay mapping, but you don't have to enable it - it's already enabled as soon as you enter the command "encapsulation frame-relay".

When you're configuring Frame Relay map statements manually, remember that you're mapping the local DLCI to the remote IP address.

When you run "show frame map", the word "dynamic" indicates mappings created by Inverse ARP, and "static" indicates it was manually created.
{mosgoogle}
To spot possible LMI type mismatches, run "show frame lmi". A large number of Status Timeouts indicates that there may be an LMI problem between your router and the frame relay switch.

This last one is for the many of you building CCNA home labs. A frame relay switch is a great addition to your lab! While you're busy putting the configuration together, don't forget the global command "frame-relay switching" - it's this command that allows a Cisco router to act as a frame relay switch!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage ( http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933! For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook and receive a FREE CCNA and CCNP question every day, just visit the website and claim your free copies!
 

Cisco CCNA Certification Exam Tutorial: Prefix Notation

Thursday, 09 March 2006 Chris Bryant
When you're preparing to pass the CCNA exam and earn this coveted Cisco certification, you've got to be totally prepared for the many kinds of binary and subnetting questions Cisco may throw at you. You also have to be familiar with the different manners in which a subnet mask can be expressed, and that's where your knowledge of prefix notation comes in. Prefix notation is an alternate way to express the value of a subnet mask, as opposed to the more familiar dotted decimal format. Not only will you see prefix notation in Cisco documentation, but you'll probably see it on your CCNA exam. Consider the following two values:
 
255.255.255.0

/24

Believe it or not, those two values are exactly the same. The first mask is written out in the more familiar dotted decimal format, and you know by looking at those first three octets that every bit is set to "1", since the maximum value of such an octet is 255.

The second value represents the exact same mask, only this value is expressed in prefix notation. This particular value would be pronounced "slash twenty-four", and the 24 represents the number of consecutive ones that are set in the subnet mask.
{mosgoogle}
Those of us who hate to type numbers are particularly appreciative of this, since it means you'll have to type a lot less numbers to represent a subnet mask. In addition, it's a lot easier to discuss masks in prefix notation than dotted decimal. ("I thought about using a two-fifty-five two-fifty-five two-fifty-five zero mask ,but then decided to use a two-fifty-five two-fifty-five two-fifty-five one-twenty-eight mask...")

Be sure you're comfortable with prefix notation before taking your CCNA exam. As with Cisco documentation, you'll most likely see masks expressed in both dotted decimal and prefix notation, and you've got to be ready to use the both as well!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage ( http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!
For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook and receive a FREE CCNA and CCNP question every day, just visit the website and claim your free copies!
 

Cisco CCNA Exam Tutorial: CCNA Recertification Requirements

Thursday, 09 March 2006 Chris Bryant
Passing the CCNA exam and earning this coveted Cisco certification is an important step in your career, but it's not the end of your responsibilities as a CCNA! When you work with computer networks, you've got to be continually learning and staying up on the latest technologies and changes in the field. Part of this responsibility is keeping your CCNA current by meeting Cisco's recertification requirements.

 
Cisco requires CCNAs to recertify once every three years. While most CCNAs will move on to the CCNP in that time, if you choose not to you must meet certain requirements in order to keep your CCNA valid. Cisco does this to ensure that CCNAs keep their networking knowledge current, which in turn helps the CCNA certification valuable. And that's exactly what you want, since you worked so hard to earn your certification in the first place!

As of March 2006, there are five different options for recertifying as a CCNA. You can take and pass any of the following exams to renew your CCNA - the CCNA exam itself, the ICND exam, any 642 series exam, any Cisco Qualiied Specialist exam (except the Sales Specialist exams - those don't count!), or any CCIE Written Qualification exam.
{mosgoogle}
With all these options, there's an option that's just right for you. Whether you just want to renew your CCNA or pursue a Specialist, CCNP, or CCIE certification, you can easily renew your CCNA along the way. Just don't forget that keeping up with Cisco's latest recertification requirements is your responsibility, and that's easy to do - just visit Cisco's "Learning And Events" section on their website. Cisco will tell you what you need to do to keep your certification, but it's up to you to keep up with certification program changes! Once your certification expires, it's gone, so get in the habit of visiting Cisco's website to make sure you're up to date on important recertification requirements.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage ( http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!

For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook and receive a FREE CCNA and CCNP question every day, just visit the website and claim your free copies!

 

Cisco CCNA / CCNP Home Lab Tutorial: Routing On A Frame Relay Switch

Thursday, 09 March 2006 Chris Bryant
When you're preparing for CCNA and CCNP exam success, the best investment you can make is to put together your own home lab. There is no better way to learn Cisco technologies and prepare for the CCNA, BSCI, BCMSN, CIT, and other exams than by working with the many protocols and services you'll need to master in order to pass the exams.
 
One of the most popular articles I've written over the few years dealt with buying and configuring a Cisco router as a frame relay switch. That article is still available on many websites (including my own), but I want to remind you that just because you configure a router as a frame relay switch, that doesn't mean you can't use it as a home lab router, too!

The global command "frame-relay switching" allows a Cisco router such as a 2520 or 4000 to perform just that, frame relay switching, but this command doesn't disable IP routing. Depending on the router model you use, you will most likely have some extra serial connectors as well as an ethernet port that you can use with your other routers in your home lab.
{mosgoogle}
Let's say you have a 2520 router as your frame relay switch. This switch has four serial ports and an AUI port. You could connect to up to four routers to the 2520's serial ports in order to serve as the frame relay switch for those other routers, and still assign an IP address to the ethernet port and run a routing protocol on the 2520. If you're connecting to less than four other routers as the frame relay switch, you can assign IP addresses to the leftover serial ports as well.

A frame relay switch is a tremendous addition to a CCNA / CCNP home lab, and if you use it as both a frame switch and a router, you get double the bang for your home lab buck!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage ( http://www.thebryantadvantage.com ), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate CCNP Study Packages, and CCNA CBT video training. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!
For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook and receive a FREE CCNA and CCNP question every day, just visit the website and claim your free copies!
 

Cisco CCNA Certification: Five Key Combinations You Should Know

Wednesday, 01 February 2006 Chris Bryant
When you start studying for your CCNA and CCNP exams, many books will present you with a huge list of keystroke shortcuts for use on Cisco routers. While the 640-801, 811, and 821 exams may ask you about one or two of these, you really have to get hands-on experience with these commands to master them. Even better, there are some key combinations that Cisco routers mention, but then don't tell you what they are! Let's take a look at a few of the more helpful key combinations, and conclude with the "secret" way to stop a ping or traceroute.

The up arrow on your keyboard is great for repeating the last command you typed. Let's say you mis-enter an access-list. Instead of typing it from the beginning, just hit your up arrow to repeat it, then fix the problem.

CTRL-A takes the cursor to the beginning of a typed line. If you've written an extended ACL, you know that can be a very long command, and one you probably don't want to retype. If you get a carat indicating there is a problem with the line, use your up arrow to repeat the command. If you see the error is near the beginning, use CTRL-A to move the cursor immediately to the beginning of the line. CTRL-E takes the cursor to the end of a typed line.

To move the cursor through a typed line without erasing characters, you've got a couple of options. I personally like to use the left and right arrows, but you can also use CTRL-B to move back and CTRL-F to move forward.
{mosgoogle}
Finally, there's the combination that Cisco mentions to you when you run ping or traceroute, but they don't tell you what it is! If you send an extended ping or a traceroute, you could be looking at asterisks for a long time if you don't know this one. In the following example, a traceroute is obviously failing:

R2#traceroute 10.1.1.1

Type escape sequence to abort.

Tracing the route to 10.1.1.1

1* * *

2 *

The problem is that you're going to get 30 rows of those asterisks, which is frustrating and time-consuming at the same time. Note the router console message "Type escape sequence to abort". That's helpful - but what is it?

Here it is: Just type CTRL-SHIFT-6 twice, once right after the other. You won't see anything on the router console, but the traceroute will terminate.

R2#traceroute 10.1.1.1

Type escape sequence to abort.

Tracing the route to 10.1.1.1

1* * *

2 * * *

3

R2#
The traceroute was successfully terminated. This combination works for pings as well, both extended and regular. Of all the keystrokes you can learn, this one is the most valuable!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!

For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!

 

Cisco CCNP / BSCI Certification: The Local Preference BGP Attribute

Friday, 20 January 2006 Chris Bryant

Cisco CCNP / BSCI Certification: The Local Preference BGP Attribute 

When studying for your BSCI exam for the CCNP, you get your first taste of BGP. One of the major differences between BGP and the other protocols you've studied to date is that BGP uses attributes to describe paths, and to influence the selection of one path over the other.

In this free tutorial, we're going to take a look at the Local Preference attribute and compare it to the Cisco-proprietary BGP attribute "weight".

The Local Preference (LOCAL_PREF) attribute is used to influence how traffic will flow from one Autonomous System (AS) to another when multiple paths exist. For example, if AS 100 has two different paths to a destination network in AS 200, the LOCAL_PREF attribute can be used to influence the path selection.

The major difference between the Weight and LOCAL_PREF attributes is that when the LOCAL_PREF attribute is changed, that change is reflected throughout the AS. The new LOCAL_PREF value will be advertised to all other routers in the AS, as compared to the Weight attribute, which is locally significant only. If you change the Weight for a path on one router in an AS, the other routers in the AS will not learn of the change.
{mosgoogle}
A route-map can be used to change a local preference value. For example, if you want to change the local preference value to 200 for the path advertisement 10.2.2.0/24 coming in from neighbor 10.1.1.1, there are three steps involved. First, write an ACL matching the remote network you want to change the local preference for.

R1(config)#access-list 5 permit 10.2.2.0 0.0.0.255

Second, write a route-map setting the local preference to 200. This will double the default value of 100, and the path with the highest local preference will be the preferred path.

R1(config)#route-map PREFER_PATH permit 10

R1(config-route-map)#match ip address 5

R1(config-route-map)#set local-pref 200

Finally, apply the route-map to routes that are being received from 10.1.1.1.

R1(config)#router bgp 100

R1(config-router)#network 10.1.1.1 route-map PREFER_PATH in

R1 will then advertise this new local preference value to all other routers in AS 100 - all of its iBGP neighbors.


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!

For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!

 

Cisco CCNA Certification: How And Why Switches Trunk

Monday, 09 January 2006 Chris Bryant

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!
{mosgoogle}
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!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!

For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!

 

Cisco CCNP Certification: Using The BGP Command ?Update-Source?

Thursday, 15 December 2005 Chris Bryant

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”!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!

For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!
 

Computer Certification: Become A Utility Player

Monday, 28 November 2005 Chris Bryant
In baseball, a "utility player" is one who plays more than one position. These players are usually backups, but they have a job in the major leagues because of their value to the team; since they can play more than one position, they have that much more value to their employer.

Too often in IT, workers become either LAN or WAN engineers, knowing little if anything about the other side. Many LAN administrators I worked with knew little about routing and switching, while many WAN engineers I knew not only didn't know much about the LAN side of their network, but they didn't want to know anything about the servers!

In today's IT world, it's a bad idea to specialize in only one thing and not know how to do anything else. Not only does it limit your future career prospects, but it limits your current prospects as well. Employers don't want to hire someone and have them get up to speed on the job - they want someone who can walk right in and do the job. The more you know, the better your chance of getting a better job - or quickly being able to get another job if you were laid off tomorrow.
{mosgoogle}
A term often heard on Wall Street is "diversification", meaning that investors should not invest heavily or totally in only one stock; if that stock plummets, they're in big trouble. Your career is the most important stock you will ever own, and you're 100% in charge of it. Diversify. If you're working primarily with servers, learn some routing and switching. If you know the routing protocols your company uses on its WAN, learn something about that protocol. (If you don't know the protocol, ask!)

While you’re adding these skills, get certified while you’re at it! Adding a CCNA, MCSE, or other computer certification looks great on your resume while signaling to employers that you’re constantly adding to your skills.

Adding more skills and knowledge to your IT skill set is always a good idea. Don't limit yourself to the technologies you work with every day. Make an investment in yourself and become a well-rounded network engineer. This will help you keep the job you have - and open doors in the future that might otherwise have remained closed.


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!


 For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!

 

Cisco Certification: Recertifying Your CCNA and CCNP

Monday, 28 November 2005 Chris Bryant
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.
{mosgoogle}
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!


Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage (http://www.thebryantadvantage.com), home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. Video courses and training, binary and subnetting help, and corporate training are also available. Pass the CCNA exam and CCNP exam with Chris Bryant, CCIE #12933!
For a copy of his FREE "How To Pass The CCNA" or "How To Pass The CCNP" ebook, just visit the website and claim your free copies!

 
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