New here need help with TCP/IP model troubleshooting

jswerve

Taking Network cabling (CCNA 1 &2) and I'm stuck in molasses here. The assignment is writing a 500 word page on how to use the TCP/IP model to troubleshoot a problem step by step. I was thinking maybe using an office email problem as the issue. I really don't know where to go from here. I have started my paper explaining when TCP/IP model came about, why, and what each of the 4 layers do but I'm stuck on the actual how to use it to troubleshoot problem.

Hoping for some help,
Jesse

Slowhand

You might want to think about what types of devices are in each layer. Like differentiating out if it's a router issue (internet), a switch that's acting up (network interface), or maybe if the issues your hypothetical network is experiencing are related to dropped packets or closed ports (host to host layer) and how that affects open sessions (you guessed it, the application layer). You could also discuss how you work your way through the TCP/IP Application layer, having to delve into the three corresponding OSI layers, and picking out which of those your problem comes from, (like your email client simply going nuts, or if people are having issues accessing an FTP server in the OSI application layer, or maybe there's encryption issues, which would be in the presentation layer, all while still working with the DOD model's application layer.)

You just have to find someplace to start, create or recreate a common networking problem, then break it down. Once you do that, those 500 words should come to you, easy. Heck, if I could fill two paragraphs with just generalized suggestions, you should have no trouble filling a couple of pages with a specific problem and solution(s).

jswerve

Thanks for the reply. Keep in mind I know nothing of this stuff. Im going to school to change careers and I have ZERO networking experience. Im much better at building pc's.

Slowhand

If you don't know anything about TCP/IP and the OSI model, then I'd recommend you start with something a little more basic than CCNA. I would imagine that the Cisco Academy would be teaching about these topics before asking you to write a paper on it, but if they expect you to have prerequisite networking knowledge, I'd say your best bet is to go for the CompTIA Network+ certification first.

EdTheLad

If you get a copy of a CIT book you should be able to complete this no problem,thats a ccnp exam by the way.Its mostly common sense so you should have no problem understanding the recommended troubleshooting steps.There are different approaches,working from the top layer to the bottom,from the bottom to the top and also divide and conquer.
The CIT books are full of pages of drivel explaining these basic concepts so you should have no problem to write 500 words.

jswerve

Slowhand wrote:

If you don't know anything about TCP/IP and the OSI model, then I'd recommend you start with something a little more basic than CCNA. I would imagine that the Cisco Academy would be teaching about these topics before asking you to write a paper on it, but if they expect you to have prerequisite networking knowledge, I'd say your best bet is to go for the CompTIA Network+ certification first.

This is a structered 2 year program from a good college. It's the same stuff they give out every year so I'm not gonna quit and take something new especially since they determined before the program started that all prereqs were satisfied. Thanks for your concern however although it doesn't help much at this point.

jswerve

ed_the_lad wrote:

If you get a copy of a CIT book you should be able to complete this no problem,thats a ccnp exam by the way.Its mostly common sense so you should have no problem understanding the recommended troubleshooting steps.There are different approaches,working from the top layer to the bottom,from the bottom to the top and also divide and conquer.
The CIT books are full of pages of drivel explaining these basic concepts so you should have no problem to write 500 words.

Thanks. Yes common sense I agree to someone with at least some small classroom instruction. Unfortunately for me I'm working full time and raising 3 kids so I have to take all courses online with no classroom. Convenient but I miss the classroom instruction alot.

Kaminsky

Google is a wonderfull thing.. Google-> "Troubleshooting TCP/IP"

http://www.cisco.com/univercd/cc/td/doc/cisintwk/itg_v1/tr1907.htm

Should give you a very good idea of what's expected.

Incidentaly, a good source of information "Straight from the horses mouth" as it were is the Cisco Documentation available herehttp://www.cisco.com/univercd/home/home.htm

Slowhand

It's not really a matter of classroom time, seeing as how most of us here haven't gone to classes to learn this. We all read books, worked our way through projects, and we learned the things we learned, little by little. We can only try to help you, point you in the right direction, but the assignment you're doing requires knowledge of TCP/IP and the OSI model. If they haven't taught you that in the classes you're taking, then you need to go to another source and learn. The Network+, the book recommended by ed_the_lad, and the resources given to you by Kaminsky should be plenty to help you through this assignment. Beyond that, we can't really give you much else, the only thing you can do is learn the material that's required of you.

SV

jswerve,

Might be you could give the example of a user not able to access a website (www.mysite.com) located in the LAN. Lets assume that there are no much security features such as ACLs, etc configured. For example here the website is hosted in a server that has an IP address 192.168.1.2 and the client is supposed to have an IP of 192.168.0.20 (the network is logically divided). Others are able to access the web server properly without any issue.

Here are the steps I could follow:
(a)
Check if all the cables are fixed properly. Check if the system identifies its network card using the command (ipconfig) in the Windows client.
Do a loopback test by using the command “ping localhost”. Check if you get 4 replies. Try this command to clear the ARP cache “netsh interface ip delete arpcache” and check if you could connect to the server now.

(b) Check for the IP address assigned to the system. Check if you can ping other systems in the same segment that have an IP 192.168.0.x. Check if you could ping the gateway. If this does not work we could suspect that the problem might be in the “Internet Layer”

(c) See if you if you can connect to the webserver by using host address. For example “ping www.mysite.com”. If this is giving error could be an issue with UDP protocol or a DNS entry. Try “telnet www.mysite.com 80”. If this works the issue could be with the tcp port used for http in the browser.

(d) If the telnet session using port 80 works, but the browser does not, then we could suspect the issue to be with the browser software. Similarly if http:// 192.168.1.2 works but not www.mysite.com, even then we could suspect the DNS application.

I should definitely tell you that there is no hard and fast rule to troubleshoot a connectivity issue. I myself don’t follow the above-mentioned sequence. However for an assignment purpose, you could use these guidelines. Please do not blindly use this for the assignment, but use it as a guideline.

Paul Boz

The poster above me gave a good explanation of some troubleshooting methods that you could do to solve your connectivity problem, so I thought that I'd offer you some advice instead.

Before you try to tackle this assignment you should have a basic understanding of the terms. I would read up on the DoD, TCP, and OSI models, and understand what the purpose and function of each of them is. Understand what happens at which layer, and what you can do to troubleshoot accordingly. Without understanding the various layered models you really won't have a very strong base for the rest of your studies. The purpose of a hirarchical model like the DoD or OSI layered system is to make questions like this really easy