Computer Software

Congratulations on your decision to earn your CCNP certification! As a CCIE, I can tell you that Cisco certifications are both financially and personally rewarding.

To earn your CCNP, you first have to earn your CCNA certification. Then you’re faced with a decision – take the three-exam CCNP path, or the four-exam path? They’re both quite demanding, so let’s take a look at each path.

The four-exam CCNP path includes the Building Scalable Cisco Internetworks exam (BSCI), Building Cisco Multilayer Switched Networks exam (BCMSN), Building Cisco Remote Access Networks (BCRAN), and Cisco Internetwork Troubleshooting (CIT) exam.

The three-exam path combines the BSCI and BCMSN exams into a single exam, called the Composite exam.

I’m often asked what order I recommend taking the exams in. After earning your CCNA, I recommend you begin studying for the BSCI exam immediately. You will find the fundamentals you learned in your CCNA studies will help you a great deal with this exam. You’re going to add to your CCNA knowledgebase quite a bit when it comes to OSPF and EIGRP, as well as being introduced to BGP.

I don’t have a preference between the BCMSN and BCRAN exams, but I do recommend you take the CIT exam last. You’ll be using all the skills you learned in the first three exams to pass the CIT. It’s a very demanding exam, and it’s a little hard to troubleshoot technologies that you haven’t learned yet!

The CCNP is both financially and personally fulfilling. Once you complete your CCNA studies, take a little breather and then get started on your CCNP studies. The more you know, the more valuable you are in today’s ever-changing IT job market.

While studying to pass the BSCI exam and preparing to earn your CCNP certification, you’ll quickly notice that while OSPF and ISIS are both link-state protocols, there are a lot of differences between the two. One major difference is the way the two protocols handle hello packets.

Hello packets are imperative to keeping OSPF and ISIS adjacencies alive. Since they are both link-state protocols, neither of them will send updates at any specified time. Hello packets are the only method by which routers running OSPF and ISIS can see that a neighboring router is still available.

OSPF gives us some great options when it comes to keeping routing table size down via the use of stub and total stub areas, but to OSPF, a hello packet is a hello packet. ISIS routers are capable of sending two different types of hellos – Level 1 and Level 2.

ISIS routers are classified as Level 1 (L1), Level 2 (L2), and Level 1-2 (L1-L2). By default, Cisco routers are L1-L2 routers; this means that every ISIS-enabled interface will send out both L1 and L2 hellos.

If one of the interfaces is forming only an L1 or L2 adjacency, there’s no reason to send out hellos for the other adjacency type. For example, if R1 is forming an L1 adjacency with R2 via its ethernet0 interface, there is no reason to allow the router to transmit L2 hellos. To hardcode a router interface to send only L1 or L2 hellos, use the isis circuit-type command.

R1(config)#interface ethernet0

R1(config-if)#isis circuit-type level-1

Note: To configure this interface to send only L2 hellos, the full command is “isis circuit-type level-2-only”, not just “level-2″.

This configuration would prevent L2 hellos from being transmitted out ethernet0. While this does save router resources and prevents unnecessary bandwidth usage, there is also no way an L2 adjacency can be formed – so double-check your network topology before using this command!

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

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

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

To move the cursor through a typed line without erasing characters, you’ve got a couple of options. I personally like to use the left and right arrows, but you can also use CTRL-B to move back and CTRL-F to move forward.

Finally, there’s the combination that Cisco mentions to you when you run ping or traceroute, but they don’t tell you what it is! If you send an extended ping or a traceroute, you could be looking at asterisks for a long time if you don’t know this one. In the following example, a traceroute is obviously failing:

R2#traceroute 10.1.1.1

Type escape sequence to abort.

Tracing the route to 10.1.1.1

1 * * *

2 *

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

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

R2#traceroute 10.1.1.1

Type escape sequence to abort.

Tracing the route to 10.1.1.1

1 * * *

2 * * *

3

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

Does your company need to retain the services of a competent computer consulting firm, but you have no idea how to really evaluate “competence”?

In the first part of this two-part series on Computer Consulting 101 hiring tips, we looked at why small businesses find it so difficult to hire good computer consulting companies, as well as four basic questions that you must be addressed when searching for a new computer consulting vendor.

Now in this second and final installment of this two part series on Computer Consulting 101 hiring tips, we’ll look at how you can evaluate the true, often-confusing expenses of using a computer consulting company, as well as how to more thoroughly review the computer consulting company’s professional credentials and experience.

Reseller, “Pure” Computer Consulting Company, or Hybrid Technology Provider

Does your company resell various technology products, such as hardware and software? Is this a profit center or do you mind if we shop for our products elsewhere? And if we do shop elsewhere, can we still purchase your needs analysis and procurement services?

Are there any other vendors, such as ISPs or telephone companies, that your firm acts as an agent or affiliate for? In other words, do you accept commissions or referral fees for steering business toward certain vendors?

Costs, Hidden Charges, and Billing Procedures

What are your payment terms, rates and hourly billing minimums? What is billable and what is not billable?

Do you charge for your travel time? Telephone support? E-mail/online support? Remote support?

Are there any hourly rate billing premiums for after-hours or emergency service? What constitutes “after hours” or an “emergency”?

Do you offer support contracts? What are the cost and benefits?

Client Reference Accounts, Case Studies, and Testimonials

Can you tell me about one of your more long-term small business client accounts?

Can you tell me about one of your more recently signed-on clients? Can you tell me about a small business client who didn’t work out and why?

Can you provide references?

Research/Developments and Keeping Skills Sharp

How do you keep up with new tech developments?

What do you bill clients for and what do you absorb internally? Are there any gray areas?

Training Approach and Knowledge Transfer

How do you feel about handholding and in-depth training with users?

What kind of user and technical training can you provide?

Will you train our internal computer administrator to become more self-sufficient, even if it takes away from your “job security” and opportunities to bill more hours?

The Bottom Line

Don’t fall into the ultra-common trap of hiring an independent computer consultant or computer consulting firm that isn’t a good fit for your business. Use these Computer Consulting 101 hiring and screening questions as the basis for making a more informed hiring decision for your computer consulting vendor. And if you have any doubts, don’t be afraid to seek out a second opinion with another computer consulting company.

Copyright MMI-MMVI, Computer Consulting 101. All Worldwide Rights Reserved. {Attention Publishers: Live hyperlink in author resource box required for copyright compliance}

BGP is one of the most complex topics you’ll study when pursuing your CCNP, if not the most complex. I know from personal experience that when I was earning my CCNP, BGP is the topic that gave me the most trouble at first. One thing I keep reminding today’s CCNP candidates about, though, is that no Cisco technology is impossible to understand if you just break it down and understand the basics before you start trying to understand the more complex configurations.

BGP attributes are one such topic. You’ve got well-known mandatory, well-known discretionary, transitive, and non-transitive. Then you’ve got each individual BGP attribute to remember, and the order in which BGP considers attributes, and what attributes even are… and a lot more! As with any other Cisco topic, we have to walk before we can run. Let’s take a look at what attributes are and what they do in BGP.

BGP attributes are much like what metrics are to OSPF, RIP, IGRP, and EIGRP. You won’t see them listed in a routing table, but attributes are what BGP considers when choosing the best path to a destination when multiple valid (loop-free) paths exist.

When BGP has to decide between such paths, there is an order in which BGP considers the path attributes. For success on the CCNP exams, you need to know this order. BGP looks at path attributes in this order:

Highest weight (Cisco-proprietary BGP value)

Highest local preference (LOCAL_PREF)

Prefer locally originated route.

Shortest AS_PATH is preferred.

Choose route with lowest origin code. Internal paths are preferred over external paths, and external paths are preferred over paths with an origin of “incomplete”.
Lowest multi-exit discriminator (MED)

External BGP routes preferred over Internal BGP routes.

If no external route, select path with lowest IGP cost to the next-hop router for iBGP.

Choose most recent route.

Choose lowest BGP RID (Router ID).

If you don’t know what these values are, or how they’re configured, don’t panic! The next several parts of this BGP tutorial will explain it all. So spend some time studying this order, and in part II of this free BGP tutorial, we’ll look at each of these values in detail. Keep studying!

When you start preparing for your CCNP exam, particularly the BSCI exam, you’re introduced to Border Gateway Protocol (BGP) configurations. BGP is unlike any protocol you learned during your CCNA studies, and even the similarities are a little bit different!

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

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

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

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

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

We could configure Router1 like this:

router bgp 200

neighbor 172.1.1.2 remote-as 200

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

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

Router1:

router bgp 200

neighbor 2.2.2.2 remote-as 200

neighbor 2.2.2.2 update-source loopback0

Router2:

router bgp 200

neighbor 1.1.1.1 remote-as 200

neighbor 1.1.1.1 update-source loopback0

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

OSPF is a major topic on both the CCNA and CCNP exams, and it’s also the topic that requires the most attention to detail. Where dynamic routing protocols such as RIP and IGRP have only one router type, a look at a Cisco routing table shows several different OSPF route types.
R1#show ip route
Codes: C – connected, S – static, I – IGRP, R – RIP, M – mobile, B – BGP
D – EIGRP, EX – EIGRP external, O – OSPF, IA – OSPF inter area
N1 – OSPF NSSA external type 1, N2 – OSPF NSSA external type 2
E1 – OSPF external type 1, E2 – OSPF external type 2, E – EGP
In this tutorial, we’ll take a look at the difference between two of these route types, E1 and E2.
Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain. (Static and connected routes can also be redistributed.) When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it’s communicating with, that router becomes an Autonomous System Border Router (ASBR).
Let’s work with an example where R1 is running both OSPF and RIP. R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP. This means we have to perform route redistribution on the ASBR. The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:
R4#show ip route ospf

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

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

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

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

15.0.0.0/24 is subnetted, 1 subnets

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

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

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

R1(config)#router ospf 1

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

Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.
O E1 5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0

6.0.0.0/32 is subnetted, 1 subnets

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

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

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

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

15.0.0.0/24 is subnetted, 1 subnets

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

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

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

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

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

SW1#show spanning vlan 10

(some output removed for clarity)

Interface Role Sts Cost Prio.Nbr Type

Fa0/11 Root FWD 19 128.11 P2p

Fa0/12 Altn BLK 19 128.12 P2p

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

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

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

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

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

SW1#conf t

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

SW1(config)#interface fast 0/11

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

Creating a port-channel interface Port-channel 1

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

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

SW2#conf t

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

SW2(config)#int fast 0/11

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

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

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

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

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

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

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

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 12 128.65 P2p

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

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

SW2#conf t

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

SW2(config)#int fast 0/11

SW2(config-if)#shutdown

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

SW2#show spanning vlan 10

VLAN0010

Spanning tree enabled protocol ieee

Interface Role Sts Cost Prio.Nbr Type

Po1 Desg FWD 19 128.65 P2p

SW2#show interface trunk

Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1

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

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

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

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

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

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

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

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

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