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Posts Tagged ‘icnd’

One of the first things you do when you start studying for the CCNA exam is memorizing a list of port numbers and the protocols that run on those ports. If you’re an experienced networker, you know most of the protocols that are mentioned – DNS, DHCP, FTP, SMTP, and so on. But there’s one protocol that you might not have experience with, but is actually vital for CCNA exam success and success in working with Cisco routers and switches, and that’s TFTP – Trivial File Transfer Protocol.

TFTP is basically FTP’s non-secure relative. There are no passwords, no authentication scheme, no nothing! As someone once told me, “If I’m transferring my files, there’s nothing ‘trivial’ about it.”

Great. So you’re thinking, “What the heck do we use TFTP for, anyway?”

TFTP is used in the Cisco world to perform IOS upgrades and to save configs to a TFTP Server. Cisco routers can themselves serve as TFTP servers, or you can use a workstation to fill that role.

If you needed to copy an IOS image to a router, for example, you could do so easily by connecting your PC to the router’s console port (via a rollover cable, right?). Your PC would need to run TFTP server software. There are quite a few free TFTP server software programs that work quite well – just enter “free tftp server” into Google or your favorite search engine and you’ll see what I mean.

Using TFTP in this fashion is a great way to have backup copies of IOS images or router configs right on your laptop. And take it from me, when the day comes that you need those backups, you’ll be glad you did!
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When you’re preparing to pass the CCNA exam and earn this coveted Cisco certification, you’ve got to be totally prepared for the many kinds of binary and subnetting questions Cisco may throw at you. You also have to be familiar with the different manners in which a subnet mask can be expressed, as in the following:

255.255.255.0
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In studying for your CCNA exam and preparing to earn this valuable certification, you may be tempted to spend little time studying static routing and head right for the more exciting dynamic routing protocols like RIP, EIGRP, and OSPF. This is an understandable mistake, but still a mistake. Static routing is not complicated, but it’s an important topic on the CCNA exam and a valuable skill for real-world networking.

To create static routes on a Cisco router, you use the ip route command followed by the destination network, network mask, and either the next-hop IP address or the local exit interface. It’s vital to keep that last part in mind – you’re either configuring the IP address of the downstream router, or the interface on the local router that will serve as the exit interface.

Let’s say your local router has a serial0 interface with an IP address of 200.1.1.1/30, and the downstream router that will be the next hop will receive packets on its serial1 interface with an IP address of 200.1.1.2/30. The static route will be for packets destined for the 172.10.1.0 network. Either of the following ip route statements would be correct.

R1(config)#ip route 172.10.1.0 255.255.255.0 200.1.1.2 (next-hop IP address)

OR

R1(config)#ip route 172.10.1.0 255.255.255.0 serial0 ( local exit interface)

You can also write a static route that matches only one destination. This is a host route, and has 255.255.255.255 for a mask. If the above static routes should only be used to send packets to 172.10.1.1., the following commands would do the job.
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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! )
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