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How do you troubleshoot your OSI model?

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Just curious what the masses do in general for troubleshooting?

Do you troubleshoot downward, starting with the application or start at transport working your way up?

For me, it depends on the customer and if the trouble is reported from an admin rep or tech rep, so the trouble description is wildly ambiguous.

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Clarifications

In reply to How do you troubleshoot your OSI model?

Clarifications

santeewelding is the

In reply to How do you troubleshoot your OSI model?

expert in this area, I’d suggest you ask him.

Oh.

In reply to santeewelding is the

Oh. Oh. Oh.

Oh.

Oh, my.

Someone ring him for an answer, please. My desire to see this is overwhelming.

Like the man said

In reply to Oh.

Wildly ambiguous.

Oh?

In reply to Like the man said

I must confess I’m somehow disappointed with that answer, though it is a good one.

Yours

In reply to Oh?

Came closest to addressing me directly. Being that it was you, and being that animadversion was my other purpose, I constructed the answer as such.

‘Twas fine.

In reply to Yours

And I have no right to expect a reply with any particular entertainment value, but to take such as it comes. Strangely, it did seem to me that that you did eschew animadversion, so my grokbox may just be misaligned.

Truthfully, I did not expect to see a reply at all, so you did surprise me a bit simply by making an appearance in this thread. Nice to see you again. 😉

Spectral

In reply to ‘Twas fine.

Were you able to track my clicks, you would see I am here ghost-like, without necessarily commenting, in near every Question, no matter how arcane — in fact, the more arcane the better. Goes for trifling, too.

OSI, however, is neither arcane nor trifling to me. I took coursework and testing on the layers at Phoenix University. I know its importance enough to follow here.

It’s what drew me to the original post, before the remark by what’s-his-face, who does appear to track my clicks.

I hope [b]paradimes[/b] is able to get answers to his question. Unlike my cursory study, you (all) both know and do troubleshoot on the basis of “up” and/or “down”. I am interested in precisely how.

Depends on the problem

In reply to How do you troubleshoot your OSI model?

A user can’t print to a networked printer, if the NIC shows activity, then you can set aside both the Physical layer (layer 1) and Data Link layer (layer 2) and go straight to the Network layer (layer 3). If the user’s computer has a proper IP address, then Layer 3 is done and you can move on up to check other layers to solve the problem.
Remember:
Programmers Dare Not Throw Salty Pretzels Away 😉

Yes it does

In reply to Depends on the problem

When it isn’t clear what layer the problem is at (from the symptoms) I try to start in the middle and go up or down as the initial check indicates. Using the example of the networked printer problem in a remote building, I start off knowing that the building is probably on-line because failure of a bridgehead switch generates audible alarms from our network monitoring software.

Our network printers have static addresses and I can pull up a spreadsheet with all the IP Addresses tied to building and room number. If I enter the IP address in my browser and get a web admin screen showing printer condition/status that confirms all the lower levels are good and I may see that the printer is out of paper or has low toner. If I don’t see any obvious problems, I’ll check the print server queues with a Remote Desktop connection to see if more than one queue is having problems. That might call for restarting Print Services to see if that clears a bigger problem than reported, or maybe indicates that a hung print job needs to be restarted or deleted on the one queue.

If I can’t get there with the web browser, it is a lower level problem that I’d tackle by trying a ping from the command prompt. If I can ping, I’d try to telnet to the IP address of the NIC to see if it is operating.

If I don’t get a good ping, I’d (no groans, now) walk over to the Apple Admin workstation and use Apple Remote Desktop to get a list of all the active IP addresses on the appropriate VLAN and check to see which printers are on (from our designated printer range). If the IP isn’t active, I’ll probably have to walk over to see if the printer is turned off, the local circuit breaker has tripped, the data cable is unplugged, or try to print a configuration page to see if the NIC has lost its IP address.

The Layer 0 problems require a bit more work, like the call from a secretary that her computer wasn’t booting up. When she was asked for the State Tag number (our asset accounting tag) of the system she said that she couldn’t find it because the room lights were off. The electrical service panel for about a quarter of the building had its main breaker trip, but her problem was that the computer wouldn’t boot.

John

In reply to Yes it does

Perfect degree of droll.

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