Network Exam Certification Tutorial The Bus Topology

Writen by Chris Bryant

The Physical layer of the OSI model isn't the most exciting or interesting to work with, but it's the foundation for everything we do in networking. The same goes for the physical side of networking - whether it's cable types, network topologies, or network cards, it's not necessarily the most exciting study you'll ever do, but it is the most important. After all, if a network has physical issues such as a bad Network Interface Card or mismatched cables, there's no way the network can work properly!

My next few Network+ exam tutorials will discuss the different network topology types, and we'll start with a look at the dreaded bus topology. After we define it, I'll tell you why I call it "dreaded".

As you can see, the bus topology is a shared medium in that multiple devices are going to use it to send data. If one host is sending data, none of the other hosts can send data until the sending host is finished. Also, all hosts on the bus will see packets that are destined for one particular host.

A bus segment has to stop somewhere, and the signals transmitted by hosts on this particular bus will be stopped by terminators located at the physical end of the segment.

Now, why did I call this topology "dreaded"? There's more than one reason:

The topology is shared, so only one segment can possibly send data at one time, which is highly inefficient

Bus topologies are not scalable. By "scalable", I mean that we can't add to it in an efficient manner. The more hosts we add to that physical bus, the more hosts we have that have to wait to transmit, the most hosts that have to examine the destination address of packets they won't end up accepting, etc.

Bus topologies are subject to a single point of failure, and we want to avoid that at all costs!

What do I mean by "single point of failure"? If we have nine hosts on a bus, only one can transmit at a time. That's bad enough, but what happens if there's a problem with the physical bus? There's a big problem, because bus topologies are not fault-tolerant.

Then you've got nine workstations that can't send data! The bus segment is a single point of failure - there is no backup way to send data, and an error anywhere on the bus will prevent data transmission by any host. Get used to looking for and preventing single points of failure, because these have to be guarded against in everything from physical network setups to routing protocols, and everything in between!

The only "benefit" to bus topologies is that it uses less cable than the other physical topologies we're going to examine. Cables are pretty cheap, and the drawbacks far outweigh the potential benefits.

I personally recommend you avoid bus topologies in the real world, but you must know all about them to pass the Network+ exam. In my next tutorial, we'll look at star and ring topologies. Until then, keep success as your destination, and keep studying!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate Network+ Study Package, and Ultimate CCNP Study Packages. You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and twice-daily CCNA, Network+, and CCNP certification exam practice questions! Details are on the website. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! And now, you can earn your Network+ certification from The Bryant Advantage!

It Certification

Writen by Moussa Ba

One of the great things about the world of certification is that the possibilities are endless. New certifications are designed with the need of today's fast and growing markets.

There is a finite number of IT certifications that can be obtained in unlimited combinations to give its holders their own unique sets of skills and knowledge in order to compete in the market.

There are two kinds of certification paths: horizontal and vertical. The first path relates more to the IT generalist. Individuals seek a comprehensive understanding of a wide range of technologies; a typical example will be someone who does have interest in Networking+, Security+, A+, and so on. This allows the individual who opts for this certification path to diversify the chances in the job market by not putting all the eggs in the same basket.

Individuals on the horizontal certification path will not stay at a single level of expertise; they will move on to tougher and might continue to cut across different specialties.

IT workers must continually update and acquire new skills to remain employable in the dynamic IT job market. Employers are more demanding and selective in their search for technology workers that are equipped with a broad range of skills. People who want to be in IT need an edge, a means to prove they can do the task assigned. Certifications are a step toward that proof.

Businesses are becoming more willing to pay for technology workers with skills sets that can be used to make the company more competitive and more productive.

Certifications Facilitating Better Careers In The It Industry

Writen by Mark Katz

Many would like to make it to the top in the famed IT world. The top companies around the world are those who have used the internet and other computer related automation to enhance productivity and market competence. There are many fields into which a person can get into when speaking about information technology as a profession. Everyone has some or the other basic knowledge of computers and internet. It is high skills that are in demand in the industry. Many obtain high skills through their college studies. Yet find it inadequate to obtain a well paying job.

Companies on the other hand are churning out newer products daily and a person who has passed out a few years ago may soon feel the irrelevance of their studies. The IT environment has undergone a sea change with the old market leaders no longer in the picture in the following decades. Aspiring IT professionals, IT managers and even experience IT professional all ask the same question; how do we retain our relevance in the present scenario? Major corporations and independent bodies have come up with an answer that is Vendor specific as well as vendor neutral certifications.

The oft assumed fact that certified professionals are better than others is a misnomer as experience in the field teaches more than what a certification can. Yet for all certification hold the sway in the present job market. Popular certifications in networking are MCSA Microsoft certified Systems Administrator, MCSE: Microsoft certifies systems Engineer, CCNA: Cisco Certified Network Associate, CCNE: Cisco certified network Engineer, CCNP: Cisco certified network professional, Network plus from CompTIA, SCNA: sun certified network Administrator, and CCIE: Cisco certified inter network expert. There are many other certification like CNA: Certified Novell Administrator, Linux certifications etc.

The question that would immediately turn up in a persons mind is which certification is better? Assuming the quality of a certification is difficult and its worth can be discerned only in relation to your needs. However Microsoft and Cisco are the most sought after certifications as their hardware and software dominate the industry the world over.

Some important facts for you to pay attention to are

• Certification with out a focus and planned career is useless.

• Certifications can enhance your value in your career.

• Knowledge and experience help you in your work and not the certification.

• Certification is not the only means of the employer to evaluate your performance.

• Certification does not guarantee you a job.

• Certification does not guarantee higher pay.

• Certification will not have nay value if it does not enhance your as well as the organizations productivity.

• Certifications are not necessary for a career. You do not need a network administration certification to become a network administrator.

• Certifications require commitment in addition to money and time.

Before making a decision on certifications here are a few things you need to think about. What is the need of companies that are hiring in and around your area? Are you interested in a certification and are willing to relocate if you do not get jobs in your area? Are you interested in a career as a programmer or in networking? Once you answer these questions you are ready to make your choice or certification and pursue it as your career goal.

http://www.networkingcertifications.com is your guide in a complicated business scenario of certifications. Network Certifications related to Cisco Certification, Microsoft Certification, and Comptia Certificate as well as Computer Security Certification help you make a more informed decision.

How To Become A Cisco Vpn Specialist

Writen by Chris Bryant

There's quite an emphasis on security in today's networks, and that's reflected in Cisco's certification tracks. Cisco offers a CCIE Security track and the Cisco Certified Security Professional (CCSP) intermediate-level certification, but there is no real equivalent to the CCNA on the security side. Instead, Cisco offers several different Security Associate certifications.

The good news is that you've got a lot of security specializations from which to choose; the bad news is that you've got a lot of choices! In choosing a specialization, take some time to choose a certification that will be of practical use to you in your current position or in your "dream job".

One of the more popular Security Associate certifications is the Cisco VPN Specialist certification. This two-exam track consists of a Securing Cisco Network Devices (SND, 642-551) exam and a Cisco Secure Virtual Private Networks (CSVPN, 642-511) exam. To earn the Cisco VPN Specialist exam, you must hold a valid CCNA certification.

What should you expect on these exams? On the SND exam, expect to be grilled on basic security features on both switches and routers, as well as VPN 3000 concentrators, PIXes, and IDS/IPS Sensors. You'll need to be ready to configure and troubleshoot basic AAA configurations, access-lists, syslog, AutoSecure, and much more. You should also be solid with IPSec.

IPSec will also be part of your CSVPN exam. As you'd expect, you'll also be expected to be quite good with the VPN 3000 Concentrator series, including browser configuration, creating users and group, the Windows VPN Software Client, and more.

This is a demanding certification that is an excellent addition to your resume and your skill set. For the latest on this and other Cisco certifications, you should regularly visit the Learning & Events section of Cisco's website. As a Cisco certification candidate, it's your responsibility to stay current of any additions and changes to Cisco's certification paths - and it's good for your career!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNP and CCNA tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Cisco Ccna Exam Tutorial Troubleshooting Directly Connected Serial Interfaces

Writen by Chris Bryant

CCNA exam success depends largely on noticing the details, and this is especially true of configurations involving directly connected serial interfaces. And of course, it's not enough to notice these details - you've got to know what to do about them!

A Cisco router is a DTE by default, but directly connecting two DTEs with a DCE/DTE cable is not enough. In the following example, R1 and R3 are directly connected at their Serial1 interfaces. The line goes up briefly after being opened, but the line protocol goes down after about 30 seconds.

R3(config-if)#int s1

R3(config-if)#ip address 172.12.13.3 255.255.255.0

R3(config-if)#no shutdown

2d18h: %LINK-3-UPDOWN: Interface Serial1, changed state to up

2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to up

R3(config-if)#

2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to down

The problem is that one of the routers needs to act as the DCE in order for the line protocol to come up and stay up. If this were your CCNA / CCNP home lab, you could just go over and look at the DTE/DCE cable to see which router had the DCE end of the cable attached. In this example, though, we don't have physical access to the routers. How can we tell which router has the DCE end of the cable attached?

R3#show controller serial 1

HD unit 1, idb = 0x1C44E8, driver structure at 0x1CBAC8

buffer size 1524 HD unit 1, V.35 DCE cable

The show controller command gives us this information. (There's a lot more output that this with this command, but it's unimportant for our purposes.) The router with the DCE end of the cable needs to supply a clock rate to the DTE, and we'll do just that with the interface-level clockrate command.

R3#conf t

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

R3(config)#int serial1

R3(config-if)#clockrate 56000

2d18h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to up

In just a few seconds, the line protocol goes up and stays up.

When troubleshooting a connection, always run show interface first. If you see the combination shown below, the connection is physically fine but logically down. That's generally the result of a needed keepalive not being present. With Frame Relay, it's probably an LMI issue, but with directly connected serial interfaces the issue is most likely the DCE end of the connection not supplying clockrate.

R3#show interface serial 1

Serial1 is up, line protocol is down

Troubleshooting is a big part of the job, and it's a big part of the Cisco CCNA and CCNP programs as well. Know your show and debug commands and you're on your way to passing the CCNA!

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

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Get your CCNA study guide with The Bryant Advantage!

Cisco Ccnp Bsci Exam Tutorial Leading Zero Compression

Writen by Chris Bryant

The BSCI exam and CCNP certification requires that you be well versed in the basics of IP Version 6, or IPv6. If you're new to IPv6, you'll quickly learn that it's not exactly just two more octets slapped onto an IPv4 address! IPv6 addresses are quite long, but there are two ways to acceptably shorten IPv6 address expression. To pass the BSCI exam, become a CCNP, and get that all-important understanding of IPv6, you've got to understand these different methods of expressing an IPv6 address. My last IPv6 tutorial discussed zero compression; today we'll take a look at leading zero compression.

Leading zero compression allows us to drop the leading zeroes from every field in the address. Where we could only use zero compression once in an IPv6 address expression, leading zero compression can be used as often as is appropriate. The key with leading zero compression is that there must be at least one number left in each field, even if that remaining number is a zero.

You sometimes see books or websites refer to leading zero compression as "dropping zeroes and replacing them with a colon", but that explanation can be a little confusing, since the blocks are separated with a colon to begin with. You're not really replacing the leading zeroes, you're dropping them.

Let's look at an example of leading zero compression. Taking the address 1234:0000:1234:0000:1234:0000:1234:0123, we have four different fields that have leading zeroes. The address could be written out as it is, or drop the leading zeroes.

Original format: 1234:0000:1234:0000:1234:0000:0123:1234

With leading zero compression: 1234:0:1234:0:1234:0:123:1234

There's no problem with using zero compression and leading zero compression in the same address, as shown here:

Original format: 1111:0000:0000:1234:0011:0022:0033:0044

With zero and leading zero compression: 1111::1234:11:22:33:44

Zero compression uses the double-colon to replace the second and third block of numbers, which were all zeroes; leading zero compression replaced the "00" at the beginning of each of the last four blocks. Just be careful and take your time with both zero compression and leading zero compression and you'll do well on the exam and in the real world. The keys to success here are remembering that you can only use zero compression once in a single address, and that while leading zero compression can be used as often as needed, at least one number must remain in each field, even if that number is a zero.

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

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the BSCI exam with The Bryant Advantage!

Network Certification Exam Tutorial How And When To Use Virtual Lans Vlans

Writen by Chris Bryant

From your Network+ exam studies, you know that switches forward broadcasts, and that sounds great, but that's not always a good thing. A switch can have anywhere from 12 ports to 80 or more, and by default all hosts connected to that switch are going to be in the same broadcast domain. Let's say we have an 80-port switch. If one host connected to that switch sends a broadcast, by default, all of the other 79 hosts are going to receive the broadcast. That will unnecessarily take up our network's available bandwidth.

It gets worse. For some network services and protocols, a broadcast received by a host results in that receiving host transmitting a broadcast of its own. Then when all the hosts receive that broadcast, they all end up transmitting even more broadcasts. Pretty soon, all these broadcasts have snowballed into a broadcast storm, which can take up most of a network's bandwidth and make normal network operations almost impossible.

Most likely, only a few hosts on each switch really need to communicate with each other. Let's take a eight-port switch for example, where three of the hosts are in the Security department, another three in the Accounting department, and the other two in the Publishing department.

If any of these PCs sends a broadcast, every other host attached to that switch is going to receive it, and may well generate a broadcast of its own in response. That's what we want to guard against, and we can do so through the creation of Virtual LANs, or VLANs. Physically, these hosts all reside on the same Local Area Network, but we can configure the switch to place them in different logical (virtual) LANs. When a switch is configured with VLANs, the switch will forward a broadcast only to those hosts in the same VLAN as the host that originated it. By creating three VLANs on this switch, we now have three smaller broadcast domains, which helps to limit the scope of a broadcast.

After placing the Security hosts in their own VLAN, and then doing the same for the Accounting and Publishing hosts, broadcasts are now limited to being forwarded throughout their own VLAN. If a host in the Security department sends a broadcast, only other hosts in that same VLAN will receive it.

Now, here's another one of those good news / bad news scenarios we've discussed. (Better get used to those -- in networking, almost everything we do has a good side and a bad side!)

Good news: Broadcasts will not be forwarded (propagated), between VLANs. A broadcast sent by one host in a VLAN will be forwarded only to other hosts in that same VLAN.

Bad news: No other traffic is going to be able to go from one VLAN to another, either. By default, there will be no inter-VLAN traffic on the switch. For traffic to go between VLANs, a Layer Three device must be involved, and that L3 device will most likely be a router.

Notice I said "most likely".

Most books for exams such as Network+ and CCNA say that a switch is a Layer Two device, and a router is a Layer Three device, and that's it. In today's networking, though, that's not the case, and I don't want you to be confused when you hear the term "layer three switch" in the real world. (Or worse, I don't want you to be confused in a job interview if someone mentions this term.)

There are switches available today that are also capable of routing, and these L3 switches are becoming more and more popular as the price goes down. Having an L3 switch eliminates the need for routers in some small networks, so you need to know about them. For your Network+ and CCNA exams, if the term mentioned is simply "switch", they're talking about a classic "layer 2 switch" that doesn't perform routing.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, Ultimate Network+ Study Package, and Ultimate CCNP Study Packages. You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and twice-daily CCNA, Network+, and CCNP certification exam practice questions! Details are on the website. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! And now, you can earn your Network+ certification from The Bryant Advantage!

Cisco Ccnp Bsci Exam Tutorial Not All Static Routes Are Created Equal

Writen by Chris Bryant

As a CCNP candidate, and in getting ready to pass the BSCI exam, you may be tempted to breeze through your static route studies, or even skip them! That's because static routes are easy enough to configure, and as long as you remember the syntax of the ip route command, you're in good shape.

But there's one vital detail regarding static routes that many exam candidates miss. That's because many CCNA and CCNP books say "the administrative distance of a static route is 1", but that is not quite accurate.

You know from your CCNA studies that the ip route command is used to create a static route, and that you have the option of configuring a local exit interface or a next-hop IP address at the end of the command. However, the administrative distances are not the same. The AD of a static route that uses a local exit interface is zero! (That's because the router considers a static route with a local exit interface to actually be a directly connected network.) The AD of a static route with a next-hop IP address is 1.

Therefore, if the router has the following two ip route statements to consider...

Router(config)#ip route 172.1.1.1 255.255.255.255 fast0

Router(config)#ip route 172.1.1.1 255.255.255.255 210.1.1.1

... the prefix lengths are the same, so the static route using the local exit interface fastethernet0 will be preferred due to its lower AD, and will be installed into the routing table.

Keep the details in mind on the job and in the exam room, and you're on your way to CCNP exam success!

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Cisco Ccnp Certification Bsci Exam Tutorial Route Summarization Basics

Writen by Chris Bryant

As you earn your CCNA and CCNP certification, you're going to have to get comfortable with manually summarizing routes. This isn't just another reason to learn binary math (although it's a good one!), but summarizing routes is a true real-world skill that can help your network operate more efficiently. So the question isn't just how to summarize routes, it's why.

When you summarize routes in RIP, IGRP, EIGRP, or OSPF, you're replacing a series of routes with a summary route and mask. With RIP, IGRP, and EIGRP, this actually lessens the size of the routing update packet itself - multiple routes are replaced with the summary route. For instance, the routes 8.0.0.0/8, 9.0.0.0/8, 10.0.0.0/8, and 11.0.0.0/8 can be summarized as 8.0.0.0 252.0.0.0. Only the summary address will be found in the update packet, making it concise yet complete.

Summarizing routes can also make the routing table smaller, yet still allow for complete IP connectivity when done correctly. Using the above example, the four more-specific routes will be replaced by a single summary route. Since the entire routing table is parsed before the routing process is complete, keeping the routing table as small as possible does help speed the routing process as a whole.

To prepare for success on your CCNA and CCNP exam, you've got to know how to summarize routes as well as the specific commands for doing so with OSPF, EIGRP, RIP, and IGRP - but knowing why to summarize routes is just as important as knowing how! Here are some additional tips on route summarization.

With RIP version 2 and EIGRP, manual route summarization is configured on the interface that will be advertising the summary. This is done with the route summarization command "ip summary-address."

RIP version 2 and EIGRP also both perform autosummarization on routes that are advertised across classful network boundaries. This is disabled with the protocol-level command "no auto-summary".

OSPF offers two different route summarization commands. To summarize routes from one OSPF area to another, use the "area range" command; to summarize routes learned via redistribution, use the "summary-address" command on the ASBR.

With proper planning and an understanding of binary math, you'll master route summarization quickly with some practice - and you'll be ready for success on real-world networks as well as the CCNA and CCNP exams!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNP and CCNA tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Cisco Ccna Ccnp Certification Exam Tutorial Configuring Ppp Callback

Writen by Chris Bryant

You may run into situations where a router in a remote location needs to dial in to a central router, but the toll charges are much higher if the remote router makes the call. This scenario is perfect for PPP Callback, where the callback client places a call to a callback server, authentication takes place, and the server then hangs up on the client! This ensures that the client isn't charged for the call. The server then calls the client back.

In the following example, R2 has been configured as the client and R1 is the callback server. Let's look at both configurations and the unique commands PPP Callback requires.

Client:

username R1 password CCIE

interface BRI0

ip address 172.12.12.2 255.255.255.0

encapsulation ppp

dialer map ip 172.12.12.1 name R1 broadcast 5557777

dialer-group 1

isdn switch-type basic-ni

ppp callback request

ppp authentication chap

Most of that configuration will look familiar to you, but the ppp callback request command might not. This command enables the BRI interface to request the callback.

Simple enough, right? The PPP Callback Server config requires more configuration and an additional map-class as well.

Server:

username R2 password CCIE interface BRI0

ip address 172.12.12.1 255.255.255.0

encapsulation ppp

dialer callback-secure

dialer map ip 172.12.12.2 name R2 class CALL_R2_BACK broadcast 5558888

dialer-group 1

isdn switch-type basic-ni

ppp callback accept

ppp authentication chap

map-class dialer CALL_R2_BACK

dialer callback-server username

Examining the PPP Callback Server command from the top down...

dialer callback-secure enables security on the callback. If the remote router cannot be authenticated for callback, the incoming call will be disconnected.

The dialer map statement now calls the class CALL_R2_BACK, shown at the bottom of the config excerpt.

ppp callback accept enables PPP callback on this router.

dialer callback-server username tells the callback server that the device referenced in the dialer map statement is a callback client.

The only way to find out if the config works is to test it, so let's send a ping from R2 to R1 and see if the callback takes place.

R2#ping 172.12.12.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.12.12.1, timeout is 2 seconds:

02:45:42: BR0 DDR: Dialing cause ip (s=172.12.12.2, d=172.12.12.1)

02:45:42: BR0 DDR: Attempting to dial 5557777

02:45:42: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up

02:45:42: BR0:1 DDR: Callback negotiated - Disconnecting now

02:45:42: BR0:1 DDR: disconnecting call

02:45:42: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 5557777 R1

02:45:42: %LINK-3-UPDOWN: Interface BRI0:1, changed state to down

02:45:42: DDR: Callback client for R1 5557777 created

02:45:42: BR0:1 DDR: disconnecting call.....

Success rate is 0 percent (0/5)

R2#

02:45:57: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up

R2#

02:45:57: BR0:1 DDR: Callback received from R1 5557777

02:45:57: DDR: Freeing callback to R1 5557777

02:45:57: BR0:1 DDR: dialer protocol up

02:45:58: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up

The callback was successfully negotiated, and the call then disconnected. R1 then called R2 back, and show dialer on R1 confirms the purpose of the call.

R1#show dialer

BRI0 - dialer type = ISDN

Dial String Successes Failures Last DNIS Last status

5558888 2 4 00:00:20 successful

0 incoming call(s) have been screened.

0 incoming call(s) rejected for callback.

BRI0:1 - dialer type = ISDN

Idle timer (120 secs), Fast idle timer (20 secs)

Wait for carrier (30 secs), Re-enable (15 secs)

Dialer state is data link layer up

Dial reason: Callback return call

Time until disconnect 99 secs

Connected to 5558888 (R2)

Pretty cool! PPP Callback isn't just important for passing your CCNA and CCNP exams – in circumstances such as shown in this example, it can save your organization quite a bit of money!

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Get your CCNA study guide from The Bryant Advantage! And coming in 2007 – Microsoft Vista certification!

Network Certification Exam Tutorial Address Resolution Protocol Arp

Writen by Chris Bryant

When you're studying for the Network+ exam, you've got to master the fundamentals of networking, because the Network+ is a hard exam to pass due to the range of information covered. One such fundamental is the Address Resolution Protocol, commonly referred to as ARP.

ARP operates at the Data Link layer of the OSI model, and its purpose is often overlooked. When Host A wants to send data to Host B, we know Host A must have a destination IP address for Host B (the Network layer address). What we tend to overlook is that Host A must also have a Layer 2 destination address for Host B -- in other words, it's got to have a destination MAC address for Host B. That's where ARP comes in.

Host devices, as well as switches and routers, keep a table that maps IP addresses to MAC addresses. This is an ARP Cache, and in our scenario Host A would first look in its own ARP Cache to see if it has a corresponding MAC address for Host B. If not, Host A will send out an ARP Request. This request is a broadcast, which means that every single device on the network segment will get it. (The broadcast MAC address is ff-ff-ff-ff-ff-ff.)

The ARP Request contains the IP address of the destination host, in this case Host B. The Request is basically saying, "Here's the IP address of the host I need to talk to. Will the device with this IP address send me its MAC address?"

Every host on the segment will receive the Request, but only the device with the IP address contained in the Request will respond to it. In this example, Host B will send a unicast ARP Response to Host A, telling Host A what its MAC address is. Host A now has the IP and MAC address for Host B, and can now send data successfully to Host B.

Since the ARP Request is a broadcast, there is no problem if there is a hub, repeater, or switch physically between Host A and Host B, since those devices forward broadcasts. Routers do NOT forward broadcasts, however, so if there is a router between Host A and Host B, there could be a problem. There is an ARP feature that addresses this problem, though, and we'll talk about that in my next Network+ exam tutorial!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free CCNA and Network+ tutorials, The Ultimate CCNA Study Package, Ultimate Network+ Study Package, and Ultimate CCNP Study Packages. You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and twice-daily CCNA, Network+, and CCNP certification exam practice questions! Details are on the website. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! And now, you can earn your Network+ certification from The Bryant Advantage!

Tips For Taking The Citrix 256 Exam

Writen by John Barrett

If you pass this exam you will become a "Citrix Certified Administrator" for information about citrix certifications go to http://citrix.com/English/SS/education/certifications.asp?ntref=hp_nav_US

The pass mark for this test is 67% I got 79% when I took this exam. To book this exam you will need to register at http://securereg3.prometric.com/Welcome.aspx search the site for a testing centre near you. When you turn up to the exam make sure you have two forms of ID.

I found this exam pretty easy, but that's because I have 6 years experience administering citrix and 1 year with Presentation Server 4.0. I would say that having hands on experience is the best way to prepare for the exam. But you have to be careful as some of the answers are based on "Citrix Best Practices" and not "Real Life Solutions" I believe I got a question of two wrong because of this.

First thing to do is look at the categories of the exam and what % they have for the overall score. The Citrix Presentation Server 4.0: Administration exam (256) is divided into eleven (11) sections. Each section of the exam is weighted as follows, totalling 100%:

-Applied and Architectural Concepts for Presentation Server 7%

-Installing and Managing Citrix Presentation Server 10%

-Configuring Farm Settings 10%

-Configuring ICA Sessions 7%

-Configuring Policies 10%

-Publishing Applications and Content 8%

-Deploying Applications 8%

-Managing Loads in a Presentation Server Environment 7%

-Configuring Printing 14%

-Enabling Web Access to Published Applications and Content 10%

-Securing Access to Published Applications and Content 9%

The exam will contain 73 questions, Native English speakers will have 90 minutes to complete the exam while non native English speakers will have 120 minutes. I took my time over all the questions and managed to finish with 25 minutes to spare, So don't panic about the time, there is more than enough.

I would recommend starting by going through some test questions, This will give you a feel for the type of questions that you will be asked at the exam. Try out http://www.citrixxperience.com/ they have a free online trial which is pretty good. Stay away from braindumps as a lot of time they are wrong and you are de-valuing everyone else's certification by using them.

Reading the administrators guide is a must, you will learn a lot here. Take special attention to the following sections, Architectural concepts, Farm/ICA settings. I personally think you are better learning the other sections by installing PS4 and having a play around, For example create a few policy's and apply them to users / groups.

There are a lot of questions on printing, Remember the following. A universal print driver is used when clients have lots of different drivers and management of the drivers is not required, for example they are not printing colour or require native drivers. But remember if they do need a certain driver installed on the citrix server, then you will need to configure the citrix policy to "Use universal driver when native driver is unavailable" Basically that is all to it. If you have any questions post them at www.citrixguide.com

Before I took the exam I was lucky enough to go on a training course, If you can afford it do it. It was very useful and I learned a lot about "Citrix best practices" I also told the instructor that I was going to take the citrix cca exam and he was able to give me a lot of very good pointers.

Good luck and let us know how you got on and what you thought of the exam. If you need any more help or have a comment on this document then please let me know at www.citrixguide.com

John Barrett http://www.citrixguide.com

Cisco Ccnp Bsci Certification Introduction To Isis Terminology

Writen by Chris Bryant

When you're studying to pass the BSCI exam and earn your CCNP certification, you're going to be introduced to ISIS. ISIS and OSPF are both link-state protocols, but ISIS works quite differently from OSPF. You must master these details in order to earn your CCNP.

One of the major differences between OSPF and ISIS will be evident to you when you first begin your BSCI exam studies, and that is the terminology. ISIS uses terms that no other protocol you've studied to date uses, and learning these new terms is the first step to BSCI and CCNP exam success.

First off, what does "IS" stand for in "ISIS"? It stands for "Intermediate System", which sounds like a group of routers. As opposed to Autonomous Systems, which are logical groups of routers, an Intermediate System is simply a single router. That's it.

You'll also become familiar with End Systems, referred to in ISIS as an "ES". The End System is simply an end host.

ISIS and OSPF both use the concept of areas, but ISIS takes a different approach to this concept. ISIS routers use three different types of routing levels, according to the area a router has been placed in. Level 2 routers are connected only to the backbone and serve as a transit device between non-backbone areas. Level 1 routers are totally internal to a non-backbone area.

ISIS uses both Level-1 and Level-2 Hellos, meaning that the two types of routers just mentioned cannot form an adjacency. Luckily for us, there is a middle ground, and that is the Level 1-2 router. These routers connect non-backbone areas to backbone areas. L1-L2 routers keep two separate routing tables, one for L1 routing and another for L2 routing. This is the default setting for a Cisco router, and L1-L2 routers can form adjacencies with both L1 and L2 routers.

Part of the challenge of learning ISIS is getting used to the differences between ISIS and OSPF. Keep studying the terminology, master one concept at a time, and soon you'll be a master of ISIS and a CCNP to boot!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNP and CCNA tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Life After Certification What To Do After You Have Passed The Test

Writen by Richard Callaby

Okay you have now passed your certification test, congratulations! Now what? How is this going to actually improve your life, your career? Have you thought about your plans after you have passed the test? For many taking a certification exam is only a stepping stone to true success.

The first thing I would do even before pursuing a certification is to have a plan on how this is actually going to help you in your career. Just because you have passed the test does not mean you are an expert. You must first prove it to the rest of the world. How do you do this?

Sit down at your computer or desk and write out your career goals for the next year, five years, ten years and your entire working career. How does this certification fit into those goals? Can you use it to establish more credibility as an expert?

The first step I would take is to start writing tutorials on the subject matter that you claim to be an expert in. Post these tutorials to your own website, blog or eZine distribution websites. the more you write about a subject the more likely a person is going to consider yourself an expert in the field and the certification just backs that up as well. The more visibility you receive the more likely you are to get clients that are willing to pay for your services.

The second step I would take is not to stop studying! The best thing for you to do is learn as much as possible about your subject matter and to stay on top of it. Each time you learn something new write about it. This not only helps you stay visible but shows that you are up to date with the latest technology. If you are studying for another certification or an upgrade to your existing one learn all you can about the material and then start writing tutorials that teaches others on the same subject. Not only will this help reinforce what you have already learned but it could lead to increased job offers and other opportunities.

The third step would be to visit as many newsgroups as possible to put your knowledge to the test. By helping others this way you reinforce what you have learned and again gain valuable exposure in the field.

Lastly I would find a local user group in your area and start volunteering for it. This will greatly increase the number of contacts you can network with and make your name known in the community. Do not have a user group in your area? See if you can start one and start speaking about your area of expertise to a local crowd. Later I would connect with other regional user groups to see if they are looking for speakers and then start speaking at these user groups. For many the certification test is the place where most people stop in their careers and then complain that this test did not really help them. The test is merely a stepping stone in establishing more credibility. The rest is up to the individual. You reap what you sow. Certification only contains some of the seeds that you need to plant in order to become truly successful.

Richard Callaby is a Independent Computer Consultant, Writer, Author, Speaker and Instructor. More articles from this author can be reached at his blog at http://blog.richard-callaby.net

How To Pass Ccna 6 Steps To Success

Writen by Vanja Buric

CCNA is one of the most respected Associate level Certification in the world today.
Getting a CCNA will definitely help you to get a better job or at least get your foot into Professional Networking Field. When you meet a person that has CCNA degree you will notice that he or she knows something about Networking.
This article will describe and give you some tips on how to achieve CCNA.
I did it so can you, so lets get started.


• 1. Getting ready mentally:
  First thing you need to do is mentally prepare your self. What I mean by that is that you have to seriously think about on why are you getting CCNA and why do you want to be CCNA certified. You have to firmly decide and believe that you will get CCNA within next 3-6 months or so.
  Try to budget your study time well. If you a very social person (like me) you will have to give up some of your social time for the next couple of months.
  Your friends and family will understand. Trust me: it is well worth it. Once you get that cert you can make up for the lost social time.
  
  

• 2. Getting the right study material:
  Second thing you need to do is to get proper study material.
  There is lot of controversy around this and some people go overboard with study guides, books, simulators and such.
  I believe that two Cisco Press books INTR and ICND by Wendell Odom are enough as far as the books go. They are really well written and easy to follow. So sign up at http://www.ciscopress.com and get those two books. Make sure you got the latest version.
  You will also want to get some kind of a simulator that will let you practice commands and that will also build up your confidence.
  You can buy real equipment but that could get expensive. I highly recommend that you become member of Cisco Certification forum.
  Forum is huge and you will get lot of helpful answers, tips and advices pretty quick. (I know I did)
  
  

• 3. Approach and diving deep:
  There are many different approaches to studying from books but I will tell you about mine. This step will take the most of your studying time.
  -Before you even start reading any of the books I suggest learning binary math (really easy) and subnetting so you can do it in your sleep.
  http//www.learntosubnet.com is excellent resource. -read both books casually once from front to cover (make sure you cover introduction and practice questions too). This will give you good overview.
  -Install both CD's that came with books and practices some of the questions. Don't worry if you get lot of them wrong.
  -Now, you will ready both books again but this time you will have to read it to truly understand the concept and how things work. Master one chapter and do questions from just that chapter until you sick of it. Then move to the next chapter.
  -Once you mastered all chapters do lot of questions and labexercises. Those two CD's will give you ability to do that.
  
  

  4. Schedule the test:
  You're not done yet with studying but it is really good to schedule the test after you completed step 3 in this article. Here is why:
  If you schedule the test a month in advance right after you completed step 3, you won't be able to slack and make excuses not to study hard until tests and it is also good to give your self a headline. I have seen people working on their CCNA for 2 years. They master one or two chapters, then they rest for 2 two months and right when they think they are ready for the next chapter, they forget what they have learned in the first chapter.
  
  

  5. Read both books one more time to refresh.
  This is optional, but I highly recommend reading the both books one more time. If you read both books in a three week that will give you one more week before the test to cram which is subject of the next step.
  So by now you should've read both books three times over. I also suggest re-reading questions and answers from both books one more time.
  
  

  6. Cram, Cram and Cram -This is the last part of your study and there is no turning back. Deadline is hanging around your neck like a noose. You should cram Q&A for no more then 10 days before you take the test.
  At this point it is really important that you get fresh and different questions then those included with your CD's. Some people claims that brain dumps or Q&A are bad and evil. I tend to disagree with that. At this point you already firmly grasped the whole CCNA concept and Q&A will only help you. So get some Q&A exam question and cram, cram and cram them for a week.
  Don't use books or CD's anymore. There is no looking back. No worries, material from the books will return to you at the right time.
  -Don't do any studying a night or a day before the test. Go out with your wife or significant other to a dinner and a movie. Relax. It is very important to relax and get a good night sleep since one of those testing boots could really be intimidating. If you did all the steps above and read books with intention to understand the topics and how stuff works (no pun intended), and not just to pass the test you should be more then ready by now.
  
  

  We came to an end of this short tutorial. I hope this article give you at least some ideas on how to approach studying for CCNA.
  If you fail CCNA first time, don't get discouraged. You will have more knowledge and confidence when you attempt it the next time then the person who passed it on the first try. Whatever approach you take I wish you good luck and prosper career.
  
  

Vanja Buric is Network Engineer, and works for Charter Communication Business Engineering Department,
and also owner of the http://www.vanjaburic.com website, where you can get latest networking news, articles,tips, free e-Books, virus alerts and lot more… as well as purchase IT Exam study guides.

How To Pass The Mcse 2003

Writen by Jason Stan

When I started down the certification path towards my MCSE 2003, I really didnt know where to start. Of course, as a helpdesk support person for 2 years I knew that being MCSE 2003 Certified would increase my chances of being promoted to a systems administration job or securing a new, higher paid role with another company.

So I first went to Microsoft's MCSE Certification website to find out which exams I needed to pass. Sure, I wanted to pass these MCSE 2003 exams, but I didnt want to cheat using braindumps which are not only illegal, but I think defeat the whole purpose of being MCSE 2003 Certified in the first place. What I wanted was the pass my MCSE 2003 exams, but actually UNDERSTAND and LEARN the material, so that way, I could hold my head up high, knowing that my skills would match my MCSE 2003 status.

Once I knew which exams I had to pass, I went out and searched the web for more information about each exam. I bought the core set of MCSE 2003 Microsoft Press books from Amazon, but in all honesty, they werent a lot of help. I also bought a few exam preparation software packages, which did help somewhat, but only for last minute revisions...as study and learning material they were grossly ineffective.

It took me a while to find the right information, but finally I came across the CBT Video site, Winstructor.Com. Actually I cant take all of the credit for it, one of our systems administrators recommended them. So I signed up to Winstructor for 12 months and downloaded their MCSE 2003 Training Videos. Now this is what I had been missing.

As far as training goes, I am a convert to CBT, or Computer Based Training. The thing I liked about these videos was that I could watch them over and over until I fully understood what is being taught. During the time that I was watching these videos, I did have a couple of questions relating to different exams. Not only did Winstructor support take the time to answer my questions, which they didnt have to do, but they also gave me the ultimate piece of advice.

"When studying for your MCSE 2003, pick one exam, concentrate on it and forget the others exist. Once you've passed it, only then move onto the next"

Whilst this sounds quite obvious, there I was, wasting my time reviewing subjects that were'nt being tested. Only once it was mentioned to me, did I realize what I was doing and focused on the immediate goal of the exam I was trying to pass.

So if you want to pass your MCSE 2003 like I did, here is what I recommend.

* Visit Microsoft.Com and create a list of the exams that you need to study for and pass.

* Sign up to Winstructor.Com for 12 Months and download their videos.

* Pick 1 exam, only 1, and concentrate on it. Dont be tempted to look at the others.

* When you watch the Winstructor Videos, have 2 computers or a copy of Microsoft Virutal PC handy and Lab out what you're learning. You'll be so surprised at how much more you'll retain and understand about what you're learning.

* If you do fail an exam, get over it, move on. Its not the end of the world. No-one but you will know, so study the areas where you went wrong and you'll be fine the next time around. I found that the areas I did poorly on are now some of my best subjects since I took the time to really learn them and that learning sticks in your memory.

* Enjoy learning and studying for your MCSE 2003. If you dont like learning about IT, then maybe you're in the wrong job.

Best of luck in your exams.

About the Author: Jason Stan regularly reviews Computer Based Training and some of his reviews can be found at http://www.CBTReview.Com. This article may be reproduced as long as all links remain intact.

Comptia Network Certification Exam Tutorial Hot Sites Warm Sites And Disaster Recovery

Writen by Chris Bryant

Part of passing the Network+ exam and being an outstanding network administrator is being prepared for disaster. Sometimes that's a disaster on a relatively small scale, such as a drive failure. If you're running data backups on a regular basis (and you are, aren't you?), you're prepared for that issue.

What is your network's disaster recovery plan from a true disaster, either natural or man-made? What if the entire building your servers are in disappeared tonight? What is your plan if that happens? In today's world, that's not a rhetorical question. Disaster recovery is taken to the next level by preparing a cold site, warm site, or hot site at another physical location.

A hot site is the highest level of disaster preparedness. Hot sites are maintained by commercial companies for their customers, and these sites include everything from the office space itself all the way through telephone and computer equipment. The servers at the hot site will be mirrors of the servers at the primary location. Basically, your staff walks in and gets right to work.

Hot sites are very expensive to maintain. An alternative is a cold site. Cold sites will have the physical devices necessary to get up and running again, but they're not configured or mirrored from the primary site. This is much cheaper than maintaining a hot site, but obviously a lot of work needs to be done before work can continue after a disaster, and this is time many corporations, government offices, and public utility companies cannot spare in such a situation.

There is a middle ground, the appropriately named warm site. Warm sites are going to have all the physical equipment needed along with some of the servers configured and maintained. Disaster recovery using a warm site will still take longer than if a hot site were maintained, but basic communications are back in place much more quickly than if a cold site were used. The "mission critical" servers will be ready to go, but secondary servers will need to be brought up to date through data restores from backups.

You have to know about these sites to pass the CompTIA Network+ certification exam, but the stakes are much higher than that. If you're not the person in charge of network disaster recovery, find out who is and ask if any of these sites are being kept by your company. The better informed you are now, the better you'll be ready to get to work at such a crucial time.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of over 100 free certification exam tutorials, including CCNA and CCNP tutorials. CompTIA Network+, Security+, and A+ certification tutorials are available, also! Visit his blog and sign up for Certification Central, a daily newsletter packed with CCNA, Network+, Security+, A+, and CCNP certification exam practice questions! A free 7-part course, "How To Pass The CCNA", is also available. Coming in 2007 -- Microsoft Vista certification with The Bryant Advantage!

Cisco Ccnp Certification Bcmsn Exam Tutorial The Hsrp Mac Address

Writen by Chris Bryant

To pass the BCMSN exam and earn your CCNP, you've got to know HSRP inside and out! Part of that is knowing how the MAC address of the virtual router is derived, and another part is knowing how to change this address. We'll look at both features in this tutorial.

We've got two routers on a segment running HSRP, so first we need to find out what the MAC address of the HSRP virtual router is. The show command for HSRP is show standby, and it's the first command you should run while configuring and troubleshooting HSRP. Let's run it on both routers and compare results.

R2#show standby

Ethernet0 - Group 5

Local state is Standby, priority 100

Hellotime 3 sec, holdtime 10 sec

Next hello sent in 0.776

Virtual IP address is 172.12.23.10 configured

Active router is 172.12.23.3, priority 100 expires in 9.568

Standby router is local

1 state changes, last state change 00:00:22

R3#show standby

Ethernet0 - Group 5

Local state is Active, priority 100

Hellotime 3 sec, holdtime 10 sec

Next hello sent in 2.592

Virtual IP address is 172.12.23.10 configured

Active router is local

Standby router is 172.12.23.2 expires in 8.020

Virtual mac address is 0000.0c07.ac05

2 state changes, last state change 00:02:08

R3 is in Active state, while R2 is in Standby. The hosts are using the 172.12.123.10 address as their gateway, but R3 is actually handling the workload. R2 will take over if R3 becomes unavailable.

An IP address was statically assigned to the virtual router, but not a MAC address. However, there is a MAC address under the show standby output on R3, the active router. How did the HSRP process arrive at a MAC of 00-00-0c-07-ac-05?

Well, most of the work is already done before the configuration is even begun. The MAC address 00-00-0c-07-ac-xx is reserved for HSRP, and xx is the group number in hexadecimal. That's a good skill to have for the exam, so make sure you're comfortable with hex conversions. The group number is 5, which is expressed as 05 with a two-bit hex character. If the group number had been 17, we'd see 11 at the end of the MAC address - one unit of 16, one unit of 1.

On rare occasions, you may have to change the MAC address assigned to the virtual router. This is done with the standby mac-address command. Just make sure you're not duplicating a MAC address that's already on your network!

R2(config-if)#standby 5 mac-address 0000.1111.2222

1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Active -> Learn

R2#show standby

Ethernet0 - Group 5

Local state is Active, priority 150, may preempt

Hellotime 4 sec, holdtime 12 sec

Next hello sent in 3.476

Virtual IP address is 172.12.23.10 configured

Active router is local

Standby router is 172.12.23.3 expires in 10.204

Virtual mac address is 0000.1111.2222 configured

4 state changes, last state change 00:00:00

1d12h: %STANDBY-6-STATECHANGE: Ethernet0 Group 5 state Listen -> Active

The MAC address will take a few seconds to change, and the HSRP routers will go into Learn state for that time period.

A real-world HSRP troubleshooting note: If you see constant state changes with your HSRP configuration, do what you should always do when troubleshooting - check the physical layer first. Best of luck on your BCMSN exam!

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Get your CCNP study guide with The Bryant Advantage!

Cisco Ccnp Bcsi Exam Tutorial Configuring Eigrp Packet Authentication

Writen by Chris Bryant

Configuring RIPv2 and EIGRP authentication with key chains can be tricky at first, and the syntax isn't exactly easy to remember. But for BSCI and CCNP exam success, we've got to be able to perform this task.

In a previous tutorial, we saw how to configure RIPv2 packet authentication, with both clear-text and MD5 authentication schemes. EIGRP authentication is much the same, and has the text and MD5 authentication options as well. But EIGRP being EIGRP, the command just has to be a little more detailed!

As with RIPv2, the authentication mode must be agreed upon by the EIGRP neighbors. If one router's interface is configured for MD5 authentication and the remote router's interface is configured for text authentication, the adjacency will fail even if the two interfaces in question are configured to use the same password.

We'll now configure link authentication on the adjacency over an Ethernet segment. Below, you'll see how to configure a key chain called EIGRP on both routers, use key number 1, and use the key-string BSCI. Run show key chain on a router to see all key chains.

R2(config)#key chain EIGRP

R2(config-keychain)#key 1

R2(config-keychain-key)#key-string BSCI

R2#show key chain

Key-chain EIGRP:

key 1 -- text "BSCI"

accept lifetime (always valid) - (always valid) [valid now]

send lifetime (always valid) - (always valid) [valid now]

R3(config)#key chain EIGRP

R3(config-keychain)#key 1

R3(config-keychain-key)#key-string BSCI

R3#show key chain

Key-chain EIGRP:

key 1 -- text "BSCI"

accept lifetime (always valid) - (always valid) [valid now]

send lifetime (always valid) - (always valid) [valid now]

The EIGRP command to apply the key chain is a bit of a pain to remember, because the protocol and AS number is identified in the middle of the command, not the beginning. Also note that two commands are needed - one to name the key chain, another to define the authentication mode in use.

R2(config)#interface ethernet0

R2(config-if)#ip authentication key-chain eigrp 100 EIGRP

R2(config-if)#ip authentication mode eigrp 100 md5

5d07h: %DUAL-5-NBRCHANGE: IP-EIGRP 100: Neighbor 172.12.23.3 (Ethernet0) is down: keychain changed

R3(config)#interface ethernet0

R3(config-if)#ip authentication key-chain eigrp 100 EIGRP

R3(config-if)#ip authentication mode eigrp 100 md5

5d07h: %DUAL-5-NBRCHANGE: IP-EIGRP 100: Neighbor 172.12.23.2 (Ethernet0) is up:

As with RIPv2, the existing adjacency was torn down when one side was configured with authentication. If the key chain is correctly defined and applied on both sides, the adjacency will come back up. Always run show ip eigrp neighbor to make sure the adjacency is present. Learn the details of EIGRP key chains by configuring them on your home lab equipment, and you'll be more than ready for BSCI exam success!

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

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Network Certification Exam Tutorial Ethernet Csmacd Explained

Writen by Chris Bryant

When you're studying for the Network+ exam, you've got a lot of new acronyms to learn! One of the basics is CSMA/CD, which stands for Carrier Sense Multiple Access with Collision Detection. That's quite a mouthful, but it's an important term to know for both your exam and real-world success.

On an Ethernet segment, hosts can send data at any time. As you might guess, that's a bit of a problem in itself, because if multiple hosts send data at the same time, a collision will occur and the data will become unusable. That's why CSMA/CD requires a host that wants to send data to listen first. Listen for what? Data being sent by another host. If the host hears data being transmitted, that host will not begin sending data itself. That's the "carrier sense" part of CSMA/CD. If that host hears nothing, the host will begin to transmit.

That's all fine, but what happens if two hosts go through this process at the exact same millisecond, resulting in them sending data onto the segment simultaneously? Their data will collide, and that's where Collision Detection comes in. The collision itself generates "noise", and the hosts that just sent data will realize that their data was involved in that collision. As a result, those hosts will generate a jam signal, which will be heard by all other hosts on the segment. This jam signal tells the other hosts that there has been a collision and that they should not attempt to send data at this time.

That's an effective technique, but the two hosts still have to send their data. What if they send the data at the exact same time again? To avoid that possibility, both hosts that transmitted data will invoke a random timer, and when that timer expires, the hosts will begin the entire CSMA/CD process again - and that process always begins with listening to the segment to see if another host is currently sending data. In this way, the hosts that were involved in the first collision have a very slim chance of being involved in another one right away.

CSMA/CD isn't the only weapon we have to minimize collisions. In the next installment of my exclusive Network+ tutorial series, we'll take a look at how routers, switches, hubs, and repeaters can (or can't!) help us keep collisions to a minimum. Until then, keep studying!

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNA and Network+ tutorials, The Ultimate CCNA Study Package, and Ultimate Network+ Study Packages. You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco and Network+ certification articles, free tutorials, and twice-daily CCNA, CCNP, and Network+ questions! Details are on the website. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Pass your Network+ and A+ Certification exams with The Bryant Advantage!

Taking A Look At Ciscos Certified Voice Professional Certification

Writen by Chris Bryant

I hardly have to tell you how important voice technologies are in today's networks; what we all need to keep in mind to maximize our career potential is how important knowing voice is going to be tomorrow.

We've always got to look forward in IT, both in our work and out studies. Cisco, always the pioneer in technical certifications, now offers a Cisco Certified Voice Professional certification that is gaining a lot of attention from IT professionals looking to add to their skills and their resume.

Cisco's CCVP track is a rigorous five-exam track that requires you to earn your CCNA (Cisco Certified Network Associate) certification before getting started. The five exams cover a myriad of topics - they're not giving this one away! Here are the exam numbers and codes you'll need to know to register for the exams:

642-642 Quality Of Service (QOS)

642-432 Cisco Voice Over IP (CVOICE)

642-425 IP Telephony Troubleshooting (IPTT)

642-444 Cisco IP Telephony (CIPT)

642-452 Cisco Voice Gateways (GWGK)

Many newly-minted CCNAs wonder if they should pursue this or the Security Professional certification immediately after getting their CCNA. I recommend that a new CCNA pursue and achieve the CCNP before going after these more-specialized certifications. While it is not required by Cisco, the routing and switching knowledge your will acquire on your way to the CCNP will be invaluable to your career as well as being helpful with your CCVP pursuits.

Besides, these certifications won't be going anywhere soon. Think of how valuable you will be with a CCNP, CCVP, and CCSP!

To your success,

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNA exam with The Bryant Advantage!

Cisco Ccnp Bcmsn Exam Tutorial Spanning Tree Protocol Stp Timers

Writen by Chris Bryant

In your BCMSN / CCNP exam study, it's easy to overlook some of the details of Spanning Tree Protocol (STP). After all, you learned all of that in your CCNA studies, right? Not necessarily! While some of the BCMSN material will be a review for you, there are some details regarding familiar topics that you need to learn. That includes the timers for STP - Hello Time, MaxAge, and Forward Delay.

You may remember these timers from your CCNA studies as well, and you should also remember that these timers should not be changed lightly. What you might not have known is that if you decide to change any and all of these timers, that change must be configured on the root bridge! The root bridge will inform the nonroot switches of the change via BPDUs.

Hello Time is the interval between BPDUs, two seconds by default.

Forward Delay is the length of both the listening and learning STP stages, with a default value of 15 seconds.

Maximum Age, referred to by the switch as MaxAge, is the amount of time a switch will retain a BPDU's contents before discarding it. The default is 20 seconds.

The value of these timers can be changed with the spanning-tree vlan command shown below. Verify the changes with the show spanning-tree command.

SW1(config)#spanning-tree vlan 1 ?

forward-time Set the forward delay for the spanning tree

hello-time Set the hello interval for the spanning tree

max-age Set the max age interval for the spanning tree

priority Set the bridge priority for the spanning tree

root Configure switch as root

SW1(config)#spanning-tree vlan 1 hello-time 5

SW1(config)#spanning-tree vlan 1 max-age 30

SW1(config)#spanning-tree vlan 1 forward-time 20

SW1(config)#^Z

SW1#show spanning-tree vlan 1

VLAN0001

Spanning tree enabled protocol ieee

Root ID Priority 32769

Address 000f.90e1.c240

This bridge is the root

Hello Time 5 sec Max Age 30 sec Forward Delay 20 sec

Bridge ID Priority 32769 (priority 32768 sys-id-ext 1)

Address 000f.90e1.c240

Hello Time 5 sec Max Age 30 sec Forward Delay 20 sec

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Fa0/11 Desg FWD 19 128.11 P2p

Fa0/12 Desg FWD 19 128.12 P2p

Again, you should always take great care in changing these timers. Those defaults are set for a reason - helping to prevent switching loops!

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!

Cisco Ccna Certification Exam Tutorial The Ospf Rid

Writen by Chris Bryant

OSPF is a major topic on your CCNA exam, as well it should be. OSPF is a widely-used WAN protocol, and you need to learn the fundamentals before moving on to more complicated configurations. One such detail is the OSPF Router ID, or RID.

The RID is the dotted decimal value by which other OSPF routers will identify a given OSPF router. There are some interesting defaults for this value, and a command you should know to hardcode the RID. You had also better know what has to happen for this command to take effect, so let's take a more detailed look at the OSPF RID.

In this example, R1 has an adjacency with R2 and R3 over the 172.12.123.0/24 frame network. R1 is the hub, with R2 and R3 as the spokes. No other interfaces are OSPF-enabled on any of the routers. Running show ip ospf neighbor on R1, we see some unusual values under "Neighbor ID", which is another name for the OSPF RID.

R1#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

3.3.3.3 0 FULL/DROTHER 00:01:57 172.12.123.3 Serial0

2.2.2.2 0 FULL/DROTHER 00:01:57 172.12.123.2 Serial0

Notice the Neighbor ID of each remote address is the loopback address. How can that be if they're not OSPF-enabled?

When determining the Router ID (RID) of an OSPF-enabled router, OSPF will always use the numerically highest IP address on the router's loopback interfaces, regardless of whether that loopback is OSPF-enabled.

What if there is no loopback? OSPF will then use the numerically highest IP address of the physical interfaces, regardless of whether that interface is OSPF-enabled.

BOTTOM LINE: An interface does not have to be running OSPF to have its IP address used as the OSPF RID.

The OSPF RID can be changed, but it requires a restart or to reinitialize the OSPF routing process. Use the router-id command to change the default RID of each router as shown, and clear the OSPF process to do so.

R1#conf t

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

R1(config)#router ospf 1

R1(config-router)#router-id 11.11.11.11

Reload or use "clear ip ospf process" command, for this to take effect

R1#clear ip ospf process

Reset ALL OSPF processes? [no]: yes

1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 3.3.3.3 on Serial0 from 2WAY to DOWN, Neighbor Down: Interface down or detached

1d05h: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on Serial0 from 2WAY to DOWN, Neighbor Down: Interface down or detached

After entering the router-id command, the router console informed you that you have to reload the router or reset the OSPF processes for this to take effect. You enter the clear ip ospf process command to do this. Notice that when you're asked if you really want to do this, the prompt is "no"? That's because all the OSPF adjacencies on this router will be lost and will have to begin the process again. That's OK on a practice rack, not good in a production network. Don't use that one at work.

The OSPF RID is not a complicated concept, but the fact that an interface doesn't have to be OSPF-enabled in order to have its IP address act as the RID takes some getting used to. And remember - when the router or switch asks you a question and the prompted answer is "no", take one step back and make sure you really want to do what you're about to do!

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Get your CCNA study guide from The Bryant Advantage!

Cisco Certification The Joy Of Hex

Writen by Chris Bryant

Cisco certification candidates, particularly CCNA candidates, must master binary math. This includes basic conversions, such as binary-to-decimal and decimal-to-binary, as well as more advanced scenarios involving subnetting and VLSM.

There's another conversion that might rear its ugly head on your Cisco exam, though, and that involves hexadecimal numbering.

Newcomers to hexadecimal numbering are often confused as to how a letter of the alphabet can possibly represent a number. Worse, they may be intimidated – after all, there must be some incredibly complicated formula involved with representing the decimal 11 with the letter "b", right?

Wrong.

The numbering system we use every day, decimal, concerns itself with units of ten. Although we rarely stop to think of it this way, if you read a decimal number from right to left, the number indicates how many units of one, ten, and one hundred we have. That is, the number "15" is five units of one and one unit of ten. The number "289" is nine units of one, eight units of ten, and two units of one hundred. Simple enough!

Hex numbers are read much the same way, except the units here are units of 16. The number "15" in hex is read as having five units of one and one unit of sixteen. The number "289" in hex is nine units of one, eight units of sixteen, and two units of 256 (16 x 16).

Since hex uses units of sixteen, how can we possibly represent a value of 10, 11, 12, 13, 14, or 15? We do so with letters. The decimal "10" is represented in hex with the letter "a"; the decimal 11 with "b"; the decimal "12" with "c", "13" with "d", "14" with "e", and finally, "15" with "f". (CCNA candidates will remember that a MAC address of "ffff.ffff.ffff" is a Layer 2 broadcast.)

Practice Your Conversions For Exam Success

Now that you know where the letters fall into place in the hexadecimal numbering world, you'll have little trouble converting hex to decimal and decimal to hex – if you practice.

How would you convert the decimal 27 to hex? You can see that there is one unit of 16 in this decimal; that leaves 11 units of one. This is represented in hex with "1b" – one unit of sixteen, 11 units of one.

Converting the decimal 322 to hex is no problem. There is one unit of 256; that leaves 66. There are four units of 16 in 66; that leaves 2, or two units of one. The hex equivalent of the decimal 322 is the hex figure 142 – one unit of 256, four units of 32, and 2 units of 2.

Hex-to-decimal conversions are even simpler. Given the hex number 144, what is the decimal equivalent? We have one unit of 256, four units of 16, and four units of 4. This gives us the decimal figure 324.

What about the hex figure c2? We now know that the letter "c" represents the decimal number "12". This means we have 12 units of 16, and two units of 2. This gives us the decimal figure 194.

Tips For Exam Day

Practice your binary and hexadecimal conversions over and over again before you take your CCNA exams. Binary math questions come in many different forms; make sure you have practiced all of them before exam day. The number one reason CCNA candidates fail their exam is that they're not prepared for the different types of binary math questions they're going to be asked, and that they aren't ready for hexadecimal questions at all.

You don't have time to learn how to do in on exam day. You've got to be ready before you go into the exam room, and the only way to be ready is a lot of practice.

Finally, make sure you read the question carefully. You've got hex, decimal, and binary numbers to concern yourself with on your CCNA exams. Make sure you give Cisco the answer in the format they're looking for.

Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of free CCNA and CCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNA exam with The Bryant Advantage!

The Secret To Passing The Microsoft Office Specialist Exam

Writen by Chris Le Roy

If you are trying to get ahead in you career today, you will know that the computer skills you have under your belt are what will make the difference between you moving up the ladder or down. When it comes to trying to prove your computer competency in using office applications there is no other certification path that stands out like the Microsoft Office Specialist program. With over 3 million exams now undertaken and well over 2 million Microsoft Office Specialist Certificates issued, this certification has become the one to get to prove your skills in using Microsoft Office.

One thing I have found though is that many people fail these exams first time around and there really is no reason for it. The way the Microsoft Office Specialist exam works is that you will be taken into a room and sat at a computer. On this computer you will be asked by the computer to carry out a series of tasks. Each set of tasks is designed to represent tasks you would be expected to do on a day-to-day basis.

These exams really are a good representation of what people would be expected to do on a day-to-day basis. I should say I am a little bias since I am a Microsoft Office Specialist Master Instructor and my company is a Microsoft Office Specialist Authorised Testing Centre but having trained about 4,000 to 5,000 students through my training centre in Townsville, Australia the certification exams really do represent the skills you would be expected to perform in your workplace.

There are in fact seven exams in the Microsoft Office Specialist Program and they are the Microsoft Word Core and Expert Exams, Microsoft Excel Core and Expert Exams, Microsoft Outlook Core Exam, Microsoft PowerPoint Core Exam and the Microsoft Access Core Exam. If you were a Secretary or Personal Assistant, I would expect at a minimum you would have passed the Microsoft Word Core Exam and the Microsoft Excel Core Exam. If you hold the position of a salesman, I would expect you to have the same certifications as the Personal Assistant or secretary plus the Microsoft PowerPoint Core certification and maybe the Microsoft Excel Expert Certification and Microsoft Access Core Certification.

Ok, so how do we prepare for these exams.

First of all, you need to choose how you want to study for these exams. In terms of passing these exams it doesn't matter whether you want to do a course at a training centre, buy a self paced training program or doing the training on the Internet. Use the form of training that you feel most comfortable with. Me personally, I prefer to use self-paced training where as many of my students prefer classroom based training. Each training method has its own advantages and disadvantages. One thing to note, if you are going to go to a training centre, make sure at the very least they are a Microsoft Office Specialist Testing Centre and that they will give you a training manual and exercise disk to take home with you to keep. If the training centre doesn't give you a manual then don't waste your time with the course even if they might be the cheapest. In computer training, cheapest definitely does not mean the best.

Step 1. Once you have done the course or studied the Self-Paced material make sure you redo all the material within 7-days!

One mistake many people make, is thinking that they can do a two-day computer training course then walk away as an expect. If that's what you think, than it is totally fanciful. Computer Training is like a sport, if you want to be a professional then you must train as a professional. The first step you need to do in any training regime is to go back through all the material you did in the computer training course in the first 7 days after you the finish of the course.

Studies have shown over the years, that each 7 days you don't review your material, you will loose 50% of the material. Each week you don't review the material you loose another 50% which means in 6 weeks or so, you will remember nothing from your course. All in all you may as well, not have done the course in the first place.

Step 2. Write a brief statement in your own words, the key terms used during your course.

The next thing you must DO! Is to write a brief statement in your own words about all the key terms you learnt during the course or in your self-paced material. One of the challenges you will have in the exam is deciphering what they are asking you to do. Sometimes, I have found the language is very difficult to understand because it is written in American English (no offence intended to my American colleagues). In one of my Microsoft Outlook Core Exams, I was certain I was going to fail the exam. The only reason I passed was by identifying the key terms in the text that related to the application and by knowing those I worked out in each question what exactly they were asking me to do.

Step 3. Practice, Practice, Practice – Get lots of Practice Exercises

The next thing you must do is to get as much practice as possible. Most training schools will have structured their material so that at the end of each topic you will have some questions to answer and also some sort of homework exercise to do that will put all the tasks together into one exercise. The key here is to practice as much as possible. Check out the internet for places where you can get lots of practical exercises or make up some of your own.

Step 4 – Do a Pre-Assessment Exam to see if you are ready.

One thing I have learnt from doing these professional exams is that they are absolutely nothing like the exams you would have undertaken at school, college or at University. My recommendation that I would make to anyone sitting computer certification exams is to purchase a pre-assessment exam for the exam you want to take. What the pre-assessment exams do is to test your skills prior to sitting the real exams. Most of the pre-assessment exams I have seen are pretty good and pretty close to the real exams. I personally recommend either the pre-assessment exams from Certiport, Transcender or Self-Test Software.

When you do the pre-assessment exam, you should score 80% or above on the first go. If you don't, do not do what I have seen many people do, and that is to just keep doing the exam till you get all the questions right. What will happen if you do this is you will build up a memory of the questions and you end up knowing the requirements of the question without truly being able to interpret what the question is asking you to do.

Once you have done the exam once; DO NOT under any circumstances re-do that exam for 7 days. This will help stop the memory build up, of the questions.

What you MUST do once you have completed the pre-assessment exam and got a result is to look at the results of the test and find out which questions you got wrong and go back and study those areas more thoroughly. Then, after you have reviewed the material and waited 7 days, then try the pre-assessment test again.

You should in the second attempt score 90% or better. If you do achieve this then you are ready to sit the real exam. If you don't, then you need to follow the same process again for the next 7-days.

After the third time using the same Pre-Assessment exam, I recommend people try a different pre-assessment exam before being 100% sure they will pass the exam. The more you use the same exam, the bigger risk you face in retaining that memory of questions.

Most pre-assessment exams usually come with 2 or 3 different exams to try. If after three attempts of each pre-assessment exam and you still find that you can't pass at 80% or better, I would strongly recommend finding a mentor and also checking to make sure the training material you have purchased is covering the required material.

Step 5 – Pass the Microsoft Office Specialist Certification Exam!

Obviously once you have done this much training and practice and you have passed your pre-assessment exams you are now ready to sit the real exam. One thing to remember, Microsoft Office Specialist Exams are commercial exams and because of this, if you fail the exam, you have to pay to resit the exam. The cost to resit these exams can vary from as low as $80 US to $135 US, in many cases the prices are set by the Microsoft Office Specialist Testing Centre.

The good news is that if you have followed the steps I have outlined, I will be very surprised if you didn't pass on your first attempt.

Step 6 – You Are Finally A Microsoft Office Specialist

The Author Chris Le Roy is a Microsoft Office Specialist Master Instructor and trains over 2000 students per year to become Microsoft Office Specialists. His company One-on-One Personal Computer Training has a range of training kits to help you prepare for the Microsoft Office Specialist Certification Exam. Chris also has a range of pre-assessment exams available for sale as well at his website at http://www.1-on-1.biz

Cisco Ccnp Bcmsn Exam Tutorial Multicasting And Reserved Addresses

Writen by Chris Bryant

Ever since you picked up your first CCNA book, you've heard about multicasting, gotten a fair idea of what it is, and you've memorized a couple of reserved multicasting addresses. Now as you prepare to pass the BCMSN exam and become a CCNP, you've got to take that knowledge to the next level and gain a true understanding of multicasting. Those of you with an eye on the CCIE will truly have to become multicasting experts!

Having said that, we're going to briefly review the basics of multicasting first, and then future tutorials will look at the different ways in which multicasting can be configured on Cisco routers and switches.

What Is Multicasting?

A unicast is data that is sent from one host to another, while a broadcast is data sent from a host that is destined for "all" host addresses. By "all", we can mean all hosts on a subnet, or truly all hosts on a network.

There's a quite a bit of a middle ground there! A multicast is that middle ground, as a multicast is data that is sent to a logical group of hosts, called a multicast group. Hosts that are not part of the multicast group will not receive the data.

Some other basic multicasting facts:

There's no limit on how many multicast groups a single host can belong to.

The sender is usually unaware of what host devices belong to the multicast group.

Multicast traffic is unidirectional. If the members of the multicast group need to respond, that reply will generally be a unicast.

The range of IP addresses reserved for multicasting is the Class D range, 224.0.0.0 - 239.255.255.255.

That range contains a couple of other reserved address ranges.

224.0.0.0 - 224.0.0.255 is reserved for network protocols only on a local network segment. Packets in this range will not be forwarded by routers, so these packets cannot leave the segment.

Just as Class A, Class B, and Class C networks have private address ranges, so does Class D. The Class D private address range is 239.0.0.0 - 239.255.255.255. Like the other private ranges, these addresses can't be routed, so they can be reused from one network to another.

The remaining addresses fall between 224.0.1.0 and 238.255.255.255. That's the "normal" range of multicast addresses. These addresses can be routed, so they must be unique and should not be duplicated from one network to the next.

In my next BCMSN / CCNP multicasting tutorial, we'll take a look at the different ways in which Cisco routers and switches interact to forward multicast traffic.

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

You can also join his RSS feed and visit his blog, which is updated several times daily with new Cisco certification articles, free tutorials, and daily CCNA / CCNP exam questions! Details are on the website.

For a FREE copy of his latest e-books, "How To Pass The CCNA" and "How To Pass The CCNP", just visit the website! You can also get FREE CCNA and CCNP exam questions every day! Pass the CCNP exam with The Bryant Advantage!